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BMW 330i 325i E46 Using Fuel Trims To Diagnose Engine Problems P0171 P0174

827 ratings | 51451 views
This video explores vacuum leaks and fuel system delivery problems in depth by using an OBD2 scanner to look at fuel trims and determine what kind of problem an engine has.
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Text Comments (288)
Steven Schwarz (13 hours ago)
I'm wondering if you may be able to point me in the right direction. I'm getting a lean code (bank 1 only) and a insufficient flow on secondary air pump on an 02 e46. I have checked trims, all are less than 5% (-2 on long term and 4 to 6 on short term). Smoke test revealed nothing. Is there another possible cause? Air pump works, relay works, I replaced the vacuum lines to the air pump valve on manifold, tested the switch at the intake, replaced fuel pressure vacuum line and filter, replaced MAF. new upper and lower intake Oh and also replaced fuel pump which is running 40+ PSI. Thanks in advance for your reply. Love your videos as well, they have helped me eliminate all but these two pesky codes.
Ignacio Romero (13 days ago)
VALUABLE info here. Thanks!!!
javr604 (28 days ago)
Hi please help with p1092
Ash H (1 month ago)
Juan Carlos Bermudez (1 month ago)
I need help, I have a BMW 325xi 2003, I have a code P0303, I change spark plugs, coil and injectors but it still has the same code, I appreciate any information that you can help me
Keith Wolford (1 month ago)
Can’t figure out why STFT is almost 30% on bank 1 under acceleration only. Any ideas?
iGMAS (1 month ago)
Hope you will see this. I had fuel trim on bank2 of my m73 up to 20%, did your tests and found out its a vacuum leak(I sort can hear it). But I fixed the fuel trim issue when I removed the Air Injection valve it went to almost perfect 0%. Why is the air injection valve causing a fuel trim of 20%?
waleed Al-shareef (1 month ago)
Hi , i have 330 ci and i have positive 10 percent on idle and it will decrease to 0 only once i hit the accelerator or if i let the car idling for long time , no vacuum leak spotted an as i test the vacuum system and no codes , what it could be the issue ??
12:20 do you put the fuse back in or start it up without again
dak don (2 months ago)
Ive got on my diagnostic saying Fuel trim limit bank1 Fuel trim limit bank 2 What would that mean?
dak don (1 month ago)
@Sam arnold yea 100% but its just that the car would be laggy
Sam arnold (1 month ago)
@dak don that sucks. Is it safe to drive until pay day (friday) you think?
dak don (1 month ago)
@Sam arnold second time fuel pump And 3 time the sensor...
Sam arnold (1 month ago)
@dak don ouch
dak don (1 month ago)
@Sam arnold i found out the problem Fuel pump and camshaft sensor
brian fleming (3 months ago)
You make great videos, which I really appreciate, but please, air does not burn. The oxygen is required to support combustion, it is the fuel that burns.
Terry Buxton (3 months ago)
Hey great video's, I've been chasing high LTFT for a while. I"ve replaced pre-cat O2 sensors, CCV system, fuel pump, fuel filter, both intake boots, IAC boot, rebuilt the DISA valve, replaced the Brake master cylinder vacuum hose, the tee that connects to the boot, checked all vacuum lines. I've cleaned the MAF sensor. The STFT will hanging around 0, but the LTFT still reads around 11. I finally replaced the MAF sensor and It corrected the problem. After about a 30 min drive , STFT was reading around 2 and long LTFT fell to 0. My car is an 06 325ci vert with 112k miles. So it seems that the old MAF was not correctly reading the amount of air entering the engine, so it looked like a vacuum leak / lean condition but in accuality it was a faulty MAF sensor not measuring the correct amount of air entering the engine. I guess the most puzzling thing was the car ran and idled good and smooth.
X X (3 months ago)
My bank 2 trim idles at -8% and goes lower on acceleration. Im throwing the exact same code..please help...4.4liter 750li 2011..car runs great, really would like to properly diagnose this rather than throwing parts at it
Uyen Ngo (4 months ago)
Hi Jason, Thank you for informative video. I watched both of yours, and try to trouble shoot my P0174 code, which recently pop up (don't have P0171) Engine idles and car driven normal on both city and highway P0174 came back after reset, while driving but not after engine starts , not at traffic light. Here some additional info... -New Valve cover gasket (less than 3K) -New fuel pump (less than 15k) -New DISA (less than 18K) -New fuel regulator (less than 50K) -New CCV valve (less than 50K) -MAF is original, cleaned few times I will your technique to determine to see it is a Vacuum leak or lack of fuel? Again, thank for video. Please let me know your thoughts
if it's just 174 and not 171 it could be o2 sensor. check o2 sensor voltages to see if that's the problem
Jorge Avila (5 months ago)
You solved the problem í have a bmw325i 2003 with the same problem fuel trim bank 1 and 2 that must change?
John's Crazy adventures (5 months ago)
I have a 2006 bmw 330i just changed both mass air valves and sensor and my car still runs rich till it dies but will start right up but smells like it’s running rich
Tony Huggins (5 months ago)
i have a 2003 x5 what is the color code for 02 sensors that determines rear or front
roy jennison (6 months ago)
what about blocked fuel filter
Max Smith (6 months ago)
hi , i am a bit late 4 years but this is the best tutorial on fuel trims.
Justin Hazlett (7 months ago)
gi2668 (8 months ago)
good job man . thanks for explaining all that stuff to me.just got 330 ci and everything needs to be changed .
oke139 (8 months ago)
Hello, So what are your thoughts on aging sensors? I have a kind of interesting problem but a little theory first(skip to last paragraph if you have no time). With M52 they used Titania sensors that lasted a long time but looking at my M54 voltages i'm reading zirc values (up to 0.9 V etc), so sensors are probably more prone to aging problems. Anyway according to my logic a vacuum leak would cause high trim because of the higher amount of unmetered air resulting in a lower amount of fuel being injected according to fuel maps and because lambda sensor catches the excess air due to lower amount of fuel injected, it will add more fuel and thats why we see higher numbes on fuel trim, same thing with dirty MAF (lower air). My E60 M54 has a little rich idle i think, because although i can not smell rich exhaust, during colder periods it has a little too much condensation at idle coming from the exhaust. I presume my cats work fine and thats why i cant smell rich exhaust and they transform the unburnt fuel into H2O. It's not just the normal higher condensation that occurs during winter etc of that i am sure, because it still happens after longer drives and is always there, even when all the other cars around do not produce "condensation vapors". My fuel trims are fine and i have no codes, lambda voltages are fluctuating like their supposed to, so i'm thinking the ageing oxygen sensors are the culprit since the effects would not even be registered by fuel trims and the sensors are "bad" due to voltage not reaching that high anymore?
oke139 (8 months ago)
All the other problems that would cause rich mixture would probably be picked up by oxygen senors and in turn by fuel trims i would guess.
pablo vazquez (9 months ago)
Are you looking at "post" or "pre" catalyst live data?
Mike (3 months ago)
Pre. Post cat sensors are just for emission light.
Zeus Agtarap (9 months ago)
Hi your content has been amazing! So I used the fuel trim to help identify my p0174 p0171 codes but after fixing the vacuum leaks I continue to have the codes. Now that all the vacuum leaks are fixed I notice the fuel trim goes 27.3% at idle and holding at 2500rpm it drops to zero then within 5-10 seconds climbs back to 27.3% on the STFT. Here's a list of the work done. Cleaned the MAF, changed the intake boots, all the vacuum lines, intake manifold gasket, new spark plugs, ccv replacement, icv grommet, throttle body grommet, new fuel filter and fuel pump was replaced last year. I appreciate any help thanks!
Vic Orlando (10 months ago)
Damn that was bad ass!!!
Skorpe (11 months ago)
could you be soh nice to give me link to that diagnostic tool !?
Matteo Moretti (11 months ago)
Forgive me for my bad english. I have a problem similar to the one in the video. My short fuel trims are about 25% at idle. I've checked for vacuum leaks with a smoke machine but I've found nothing. The MIL light is on with P0150, P0170, P0173, P1250 and P1520. I've bought the car 2 months ago and since then I don't know where to look. The O2 sensors are ok (checked voltage), i have changed the oil and fuel filter 4 days ago but nothing changed. The MAF is working properly (I've also cleaned it but no luck). The fuel trims when I start the car are about at 3%, then slowly go up at ~25%. When accelerating they drop at 11% but they won't go down over that. I don't know what to do 😪 Thank you for any response
Abdulla Jaafari (1 year ago)
Hey man, that's such an informative video and a great way for diagnosing the fuel trim bank 1/2 issue .. I'm facing the exact thing and I'm going to try this method to figure out the issue. My E46 330Ci is a japanese import and almost no OBD tool is working with it, I just purchased a BMW Scanner and hopefully receiving it soon .. Can I do the tests using the BMW scanner and its software?
Arturo Olvera (1 year ago)
What’s the scanner program that you are using
Would a maf sensor problem cause multiplicative adaptions of 12% but nothing on additive adaptations? CA & CB Fuel trim bank 1&2 control limit but no P0171 code?
imobilaizeris com (1 year ago)
What can cause long term both banks about 15% Short term is about 0% boath banks
David Elsberry (1 year ago)
This has saved me countless hours. Thank you.
Joe Hinkle (1 year ago)
hello Jason recently replaced ccv all vaccuum hoses on my 04 330ci rebuilt disa with g.a.s. kit. the service engine soon light is still on disconnected batt still is on do i need to erase the codes in order to reset the light. codes show bank1 bank2 lean also shows replace pvc valve which i have already done.your videos and your help is greatly appreciated.
Chuck Workman (1 year ago)
Have a ? I own a 2004 z4 2.5 I changed the ccv I disconnected the battery before I started and color coded the plugs so I wouldn't mix them up even tho they will only fit the right one but after I hooked the battery back up after completing the job and now it will crank but won't start any idea
Jeremy Westwood (1 year ago)
Hi jayson sorry if im asking too much im just confused and need your expertise. What would be the normal range of 02 sensor volt at idle and with 2500-3000 rpm? I want to rule out via volt reading if my o2 sensor is the culprit? Also the normal range g/s of the MAF sensor. At idle and 2500-3000rpm?thank you very much.
Jeremy Westwood (1 year ago)
Hi does + - 5 is normal at idle? Thank you.
Jeremy Westwood (1 year ago)
In addtion to my question...my car is running fine but i noticed when starting the car i didnt hear a priming sound in my fuel pump do you think not hearing a fuel pump priming would indicate thats its going to fail soon? right now it takes me 3 cranks to start the car at cold start after it dies at 1st to 2nd crank battery sign on dash board pops up.i consider changing the battery but no priming sound bothers me.
Jeremy Westwood (1 year ago)
50sKid Hi jayson, pls correct me if im wrong, do you think tracing vacuum leak via fuel trim must be done at idle? When im at 2500 to 3000 at the road my STFT kicks to 17% that because engine needs fuel to run right thats why fuel demand goes up when driving on the road.my LTFT both bank 1 and 2 is pin to 11.7 which i know its always adding 11.7% to maintain the ratio. (Could i reset this LTFT?) or incase if i fix the leak would this 11.7% on my LTFT will go normal. Sorry if im wrong i guess its always adding 11.7% fuel to maintain the ratio?
50sKid (1 year ago)
yeah that's ok
armando R (1 year ago)
What should be the maf gms at idle
Cherrymae Bautista (1 year ago)
Hi im having this on my e46. Idle: STFT1 = 8.6 STFT2= 0.0 MAF = 0.565 2500 -3000 rpm STFT1 = 3.1 - 4.7 STFT2 = -0.8, 0.0, -2.3 MAF = 1.870 I think its a vacuum leak...going for a vape test I just want to rule out if MAF is failing /failed? Thank you.
Jerry Rievel (1 year ago)
This video just may be what I needed. I've been looking for solutions and this may be the ticket to fixing my car! Kudos to you.
Frank Penzo (1 year ago)
what version of the scanmaster are you running or it doesnt matter
Cloud Man (1 year ago)
Thanks for a real good tutorial on fuel trim
Robert Demirovic (1 year ago)
Hello can some one help me i have this code P0170 fuel trim bank 1 My engine goes uneven and turns off when it's in a minute and can not run it at all because it loses all the Power i changed air flow meter but is stil The same i have dont change fuelfilter and power train regulator and I dont know If I have some where vacuum leaks so on the last i scaned it on garage with data tool scanner and I get catalytic fault code Could it be wrong that it goes uneven i Will be very grateful for respond back Thanks
Alexan Gulbudaghyan (1 year ago)
Hey @50sKid thanks for detailed instructions, can fuel pressure regulator also cause missfiring codes with p0174 and p0171? I have p0174 p0171 p0305 and random missfires code
Robert Demirovic (1 year ago)
50sKid Hello can some one help me i have this code P0170 fuel trim bank 1 My engine goes uneven and turns off when it's in a minute and can not run it at all because it loses all the Power i changed air flow meter but is stil The same i have dont change fuelfilter and power train regulator on the last i scaned it on garage with data tool scanner and I get catalytic fault code Could it be wrong that it goes uneven i Will be very grateful for respond back Thanks
50sKid (1 year ago)
+Alexan Gulbudaghyan if it was sap you would also have sap codes. You have a vacuum leak somewhere. Watch my common vacuum leaks video
Alexan Gulbudaghyan (1 year ago)
50sKid thanks for reply, i noticed that the first code that is thrown is p0174 and only after driving a while i get p0171, does it have to do something with SAP or it will be triggered only on cold starts?
50sKid (1 year ago)
I doubt it. You would have to have a severely restricted fuel filter which usually doesn't happen. P0171 and P0174 are almost always caused by vacuum leaks.
danytrabolsy (1 year ago)
@50sKid, i have a problem with my 2002 330ci, sometimes i have lean codes thrown at bank 1 and 2 other times MAF code. at cold start the car hesitates and sometimes stalls but very responsive and alot of power, once it reaches operating temperature no more stalling but most of the time it has no power like accelerating in 4th gear and other times it jumps and awakens then back to no power, above 4000 rpm the car runs fine. reading the fuel trims, at idle everything is close to 0 (fluctuates between -2 and 2) but once i put a little acceleration the trims are flying (up to 18 to 22% inpa lambdaintegrator bank 1 & 2) the things i've done : replaced O2 sensors (maintenance) replaced fuel filter and fuel pump replaced CCV, oil filter housing gasket, valve cover gasket checked the fuel pressure both at idle and throttle it's stable at 3.2/3.3 bar any ideas where i should be looking next ? i eliminated the vacuum leak since at idle the trims are normal could it be the MAF ? cleaned it (with no change), if the MAF is dead would the fuel trims be normal at idle? thanks.
danytrabolsy (1 year ago)
Thanks for your answer, i'm back with more data. the gauge i'm using is not very good, i ordered it on the net and it's like a tire gauge so i ordered another one waiting for it. in the mean while i got a new MAF VDO and tested it but changed nothing so i returned it back. and i got my self an OBII scanner and here are the results after resetting the fuel trims : at idle the short term fuel trims are - 4 to -5 at 3000 rpm the sft are at 19/21 then at 4000rpm i got 10/9, all in closed loop. the catalyst, secondary air system, oxygen sensor, and oxygen sensor heater status says : not complete. i measured the sensor 2 short fuel trims (post cata.) and they both had 99.2% not sure if that means anything, also measured the voltage that drops when accelerating. i'm waiting for the new fuel pressure gauge to get an accurate result, but i think i eliminated the MAF, but i don't know where to go from there.
50sKid (1 year ago)
Your fuel pressure actually sounds low. It should be 3.5 bar/50psi. What brand gauge did you use for that test? Anyway, if the MAF was dead your car would either not run or the computer would recognize that and substitute a value for the MAF reading and that value would most likely be higher than normal and you'd see that reflected in the fuel trims. But your MAF could be out of calibration and causing the problem. Anyway, the most important thing I want to explain is to not use INPA fuel trims to diagnose things. The INPA "trims" are not the same thing as the OBD2 short and long term fuel trims. They mean different things and they can't be used to diagnose problems the way I explain in this video. You need to get an OBD2 code reader that supports live data and you need to look at short and long term fuel trims on banks 1 and 2. Now, once you do that and IF you still have the same behavior (normal at idle, higher at speed), the possible causes for the problem you are describing are: bad O2 sensors, insufficient fuel delivery, or bad MAF. So first confirm that your fuel pressure really is low, and especially confirm that it doesn't drop lower at speed, and if not, replace the MAF with an OEM Siemens one.
blackpassenger (1 year ago)
domo arigatou gozaimashita, sensei. so a positive fuel trim will cause increased fuel consumption with no other effect on performance? i think it could be a vacuum leak, been hearing some hissing near my intake conduit.
50sKid (1 year ago)
Daniel Segledi (1 year ago)
Hey kid, love all your vids...have def used more than one for some DIY. I have a p0174 lean code on 2003 330i. My STFT on both banks are ar 6/7% and mt LTFT are at 11.7% at time of code. I was at 73mph when the code was thrown. I feel a slight hesitation at around this speed. I've had the car checked for vacumn leaks and have replaced the usual suspects. Just replaced the fuel filter. This car hasn't had the fuel pump changed or MAF as far as the records show. Any help is appreciated...ty
Salvaytion (1 year ago)
What if only one bank’s LTFT (bank 2) is 8-10%? What would be the causes of that? Bank 1 is perfect.
Norman Silva (1 year ago)
I’m sure you heard this before but THANK MAN!!! If your ever out east come to the Hamptons We’ll smoke a bowl!!!!
Tim Davis (1 year ago)
This was the easiest video I’ve watched explaining the way most modern fuel injected computer based cars run. I am so grateful that you are so willing to share your knowledge! This will help me on much more than my e46, I can use this knowledge troubleshooting my other vehicles as well.
UTUBED (1 year ago)
Thank you so much ⭐⭐⭐⭐⭐
jamminjj19 (1 year ago)
Thanks Dude for keeping it real! Good info and very knowledgeable! Sounds like you have years of experience. BMW trained?
50sKid (1 year ago)
self taught!
PeteAU9 (1 year ago)
My scantool & app is showing banks 1,2,3,4. Should I be ignoring 3 and 4 on an M54 engine? Banks 1 and 2 show good numbers (3%) while banks 3 and 4 show high (8-14%). Can anyone confirm banks 3 and 4 are bogus data?
50sKid (1 year ago)
Yeah there is no bank 3 & 4, not sure what that is--maybe the scantool is reading some data pids wrong
Elvin Novruzov (1 year ago)
man, you bring so much happiness to the life of e46 owners
Raul Reyes (1 year ago)
Very good job, 5 stars
Gibran Carrillo (1 year ago)
Very good video
mindurbusiness (1 year ago)
your very talented not only with motor mechanics but you explain things very clearly and easily. you have been a huge help, thank you very much sir.
I Got A Bimmer! (1 year ago)
50skid hey man I finally got ahold of a scanner and my stft bank 1&2 are both -28.1, long terms Both 0. Does that sound lean or rich? I have a little video with the scan tool hooked up and I still have it available if I need it. I'm not really sure what to look at or look for. Check the video out when u have a minute (8mins). And don't be shy to hit that subscribe button lol
50sKid (1 year ago)
Negative fuel trims are rich
Jose Bracero (1 year ago)
Excellent job, thanks
Andy williams (1 year ago)
Hi. I have a bmw X5 with M54. Brand new motor but it runs rough when cold and fuel trims are 25+ on both banks. I have checked the fuel pressure and it is at 50 steady. I am working on building a smoke machine but everything is new. I replaced the pcv system tried 2 different IDC's and Disa valves. New MAF that is platinum based not the cheap version. I know i have a bad O2 on B2S2 it stays around .400MV B1S1 is about .05 MV B1S2 is about .05 and B2S2 is .10MV . The system does tell me B2S2 is out of range. I guess my question is, can the one O2 sensor throw the STFT's off by that far? Thanks I used your videos to help me build the motor.
Tam Hamill (1 year ago)
Andy williams Did you get this problem fixed bud
Andy williams (1 year ago)
Thanks. I ordered all 4 new so i know they are all good. If i unplug the MAF it will let it idle ok but the bank 2 STFT is still high from the bad O2. The odd thing I am seeing now is that if I plug the MAF back in (old or new) then all 4 O2,s go nuts and do not show properly. With it unplugged the front bank O2's are acting normal. Would the B2S2 being bad make the MAF mess with all of them? I guess I will find out when I install the new O2's.
50sKid (1 year ago)
Yeah if your precat O2s are not oscillating between 0.1 and 0.9 something is wrong. Replace them.
Andy williams (1 year ago)
Oh and the fuel trims do not go down when I bring up the RPM,s to 2500.
Glen Stevens (1 year ago)
Really good video and explanation of the process and diagnostics.
bimmer325cic lee (1 year ago)
Hi Thanks for informative info. I just became one of your subscribers. I am wondering why you decided to perform this diagnostic procedure. Did u have any sysmtoms or any un- usual things happened. Or poor milage? The reason I am asking is this. I just got e46 with 70k mile( All my cars I've owned is compact cars so I don't have no idea about fuel consumption of this 325ci ) and notice milage is not great in the city compared to my Jetta and Civic. My e46 has no check engine light and recently replaced both air filters. How to verify milage. And how to increase milage if result is poor. Sorry for long story. thanks
bimmer325cic lee (1 year ago)
50sKid thanks for kind explanation. I know it was fuel and regulator filter in your case. I already saw your video. Actually I watched most of your videos. I was just wondering if you had any problem before performing fuel trim procedure..And I found obd scanner tool you mentioned. But where can I buy a software. I tried e Bay and Amazon. and no luck. thanks
50sKid (1 year ago)
I think the cause of the problems in this video was a clogged fuel filter. What kind of mileage are you getting? You'll know if your mileage is normal if you look at fuel trims and they are roughly about plus or minus 5%
Brandon Douglass (1 year ago)
Good video, do you know what it means if my STFT is fluctuating from +25 all the way to -25 at a steady, constant rate, I can feel the car running poorly when it gets to the extremes of the spectrum
Brandon Douglass (1 year ago)
Thanks for the reply, if you or anyone else reading this has this problem it's because you can't read your own handwriting.where you labeled the sensors and you plugged the two (upstream in my case) o2 sensors in the opposite ports, so any thing the car does to try and correct the mixture it gets the opposite result, hence the scrolling through the Spectrum of the fuel trim. I was getting codes for being too lean and too rich at the same time.
50sKid (1 year ago)
You likely have a bad O2 sensor. Use a scan tool with live data to confirm that your pre-cat O2 sensors (sensor #1 on banks 1 & 2) are working correctly, cycling from 0.1 volts to 0.9 volts. You can also unplug them and use a mutlimeter to check the black and white wires. You'll see the same voltage as you would inside the scan tool. They may be getting stuck rich (0.9v) and stuck lean (0.1v).
vaah (1 year ago)
Positive fuel trim means bad fuel consumption, right? Right now my car doesn't throw fault code, but my fuel consumption is very bad, usually at 5.5km/l or 13mpg. This is with city driving only and i drive mildly. Also when i opened the oil cap, i out my hand over it and i didn't feel reasonable suction from it. I only have pa soft scanner, not sure if i can check fuel trim with it.
50sKid (1 year ago)
The data that you will read from the pa soft and inpa cables is BMW's "additive" and "multiplicative" fuel adaptation values which are different from obd2 fuel trim percentages. Not helpful
vaah (1 year ago)
50sKid ah alright.. i thought there should be suction because when i compared it to my honda or my wife's nissan there is quite strong suction from the engine oil hole. I do have the exact obd adapter you mention the first time in this video, my is bluetooth version and it once worked but no longer, i don't know why. I was never able to read freeze frame using obd fusion android app. I also have 2 others, tahg won't work at all with this bmw but the other one works with my honda and the other last one never worked with my cars. I have cable that should work with inpa/ediabas, but have never got around to install it till now. Does it have live fuel trim data? Thank you for the video, i watch most of your e46 repair videos, they are very helpful. :):)
50sKid (1 year ago)
Yes positive trim = bad fuel consumption. You're not supposed to feel suction on a stock system. No you can't check it with pa soft you need an OBD2 scan tool. Search my channel for my review on the foxwell one. Cheapest one I have found that can read live data.
Kyle Montanaro (2 years ago)
Hello mate, brilliant videos, thanks for all the explanations and example. I've got a 2001, 316Ti (the liftback ones) with the N42 engine (I know, 1.8l, small, blah blah...) and I've been using these bluetooth OBD2 reader and the Torque app on my phone, which has already helped me out a few times. Recently after every (relatively) cold start, the acceleration of the car suffers a lot and it makes a muffled noise as if it's overfuelling or chocked. This continues throughout the warmup and usually doesn't go away on its own until i turn off the engine and switch it back on, at which point it works as if nothing happened. After seeing this video, I've configured the app to read short and long term fuel trims on all sensors and what I've noticed is that after a cold start, the short term fuel trim goes crazy and fluctuates from around +8 to -8 all the time even once the engine warmed up, but after shutting it down and restarting it, it all smooths out nicely. Any idea of what might be going on please?
madison prettyman (2 years ago)
you are the man
Mac Jr (2 years ago)
fuel trim was positive then went to 3000 rpm went to zero then negative. would that be a faulty maf sensor. changed boots, changed throttle gasket, disa gasket, valve cover gasket, sprayed around the engine with carb cleaner no rpm change
Mac Jr (2 years ago)
50sKid MAF fluctuates between 0.01 to 0.07 lb/s = 4.5 to 31.5 g/s at 2400 rpms
Mac Jr (2 years ago)
50sKid at a stop light reading 27.3 short term on bank 1 and 2 long term of -6.3 after driving for a while long goes back to 0 when at a light with short of 27.3
Mac Jr (2 years ago)
50sKid I'll be looking at some live stats today
Mac Jr (2 years ago)
50sKid I would also like to add that the CEL went off but came back on later. my MAF is aftermarket. I'm also getting an oil leak. last time I got it checked at the shop they said it was oil pan gasket which is what I really don't want to deal with until I get this lean situation fixed.
50sKid (2 years ago)
That is a vacuum leak.
Salvatore Barrile (2 years ago)
what software are u using? my1999 523i smells alot of fuel from engine bay and exhaust,spark plugs are ash black but dry ,can it be a faulty regulator and running rich? thanks
Salvatore Barrile (2 years ago)
is there a way to test those items? what software are you using on the video thanks
50sKid (2 years ago)
Or bad O2 sensor(s)
50sKid (2 years ago)
certainly sounds like it's running rich. More likely from a leaking fuel injector or a bad MAF
Norman Silva (2 years ago)
Wats up Mr 50 You said to watch out for cheap mass air flows on eBay. Can you tell me why? They go from 20 dollars to 300.
Norman Silva (2 years ago)
Yo 50's dude!!! Any chance you might have a link to that software you used? I tried looking it up and got all confused.
50sKid (2 years ago)
They don't work. Instead of using a more expensive platinum wire they use a cheap resistor.
Ray Solis (2 years ago)
Great video 50's kid the computer software you are using did you purchase it from eBay or ? I know you mentioned the cable was eBay but wanted to make sure the scan master elm softwares was eBay also thanks in advance Ray
50sKid (2 years ago)
Check google for where to buy scanmaster elm
Traqn Savov (2 years ago)
number 5: co2 sensor dozent work correctly
Gabriel Lee (2 years ago)
Hey how r u? Can you check my car's fuel trim video? Thank you
Michael M (2 years ago)
You my friend are a genius! Just bought the obd and software für my M54B30. Thanks a lot! By the way... Many ELM 327 china chips are Bad copys and the software can have a virus. Be ware
roosterkitten (2 years ago)
Hey 50's kid. Love your vids! Im really hoping you can help me out here. I have a 2000 328ci with 328k km on it (im not kidding:) canadian car. I am due for emissions inspection but im throwing a couple codes - 1423 and 1421 secondary air systems bank 1 and bank 2 respectively. I borrowed an obd2 scanner from a friend and it wont show real time data of the fuel trims but it does provide a "freeze frame data" of the values (i suspect from the time it registered the codes). Checked and erased the codes twice and basically im getting negative fuel trims (-5% to -3%). I have cleaned the MAF about a month ago. Not sure if it has ever been replaced or if its working well or not (same for the fuel regulator). I did replace a couple of rubber boots due to being cracked. Idle is rough when engine is cold, rpm dances between 500-1300. On deceleration it dips real low when its out of gear, like it wants to stall. Thats all the info i can give you, hope you see this and i will really appreciate if you can give me any pointers of what to look at. Thanks mate! Keep up the good work. Your youtube channel is much better than any tv car repair show i've ever seen. Cheers
50sKid (2 years ago)
The vacuum hose going to the secondary air valve could be broken at either end (check for breaks). The valve could be stuck closed and not opening when vacuum is applied (remove it and test it with a vacuum pump). The secondary air passages could also be clogged inside the head (remove the valve and the precat o2 sensors & blow compressed air through the valve opening--see if you hear the air inside the o2 sensor holes).
roosterkitten (2 years ago)
Forgot to mention: the secondary air pump does work. Also i read on bimmerforum someone successfully got rid of the codes by pouring seafoam into the hose that exits the secondary pump in order to clean the carbon build up on the valve passages or something like that. Several people claim this procedure has help them. It did not help me :(
Manuel Rodriguez (2 years ago)
This helped so much but now my codes switched. I was running rich and then I switched the fuel pump and fuel pressure regulator and now I'm running lean. E46 m3
Sam V (2 years ago)
thanks again for this great video and a very well explainable finally someone that knows exactly how to explain fuel trims and diagnosing it. I have a problem with my BMW X5 3.0si 52 engine. can a vacuum leak cause misfires I did a diagnostic analyze data and it shows that my short-term fuel trims are 29.9 on both Bank 1 and bank 2 but I am also having misfires can this cause it and also the error leak is coming from the variable motor gasket should I replace the whole entire valve cover
Sam V (2 years ago)
50sKid thanks I appreciate I did a smoke test there was so much smoke coming from the variable actuator gasket if it correctly. and now apparently there's a whistling sound coming from the ccv valve I'm not sure but I guess I have to replace the whole entire valve cover thank you 50 skid appreciate what you do will get back to you on that
50sKid (2 years ago)
Yes a vacuum leak can cause a lean condition and misfires, which is what you have based on the fuel trims you reported. Find and fix all leaks.
Bobby O'Hearn (2 years ago)
What program are you using to get this data?
50sKid (2 years ago)
Erkan U. (2 years ago)
hi Jason I have just recorded my fuel trim readings but they are kinda weird they move too much up and down even during idle position and both bank moves up and down independently I didn't know what that means here is the video link that I recorded thank you https://youtu.be/8LzM2_WXuU8
50sKid (2 years ago)
What is on the other end of that hose? Where it does it go to?
Erkan U. (2 years ago)
50sKid thank you Jason one last question I have removed the whole intake manifold and put everything back with new ccv valve and hoses but one thing I had problem to figure out .there little tiny hose in back of the manifold next to two plugged wholes that hoses was totally broken and didn't see anything that can be connected to it on yours it's connected to a solenoid mine is e83 and I didn't find any online diagram showing that either .so I just connected that the little end on the oil separator do you think I have left the other end of that hose leaking somewhere I couldn't figure ? thank you
50sKid (2 years ago)
You have a vacuum leak.
austin mays (2 years ago)
So once the vacuum leaks have been remedied, do long term fuel trims automatically adjust? Or will the MAF unplug trick reset? I'm getting 0171,0174 lean and 1190 1192 fuel trim codes. Have recently cleaned maf, replaced ccv, o rings on dipstick and disa, new fuel filter w regulator and replaced vac lines for fuel deliver and secondary air pump and replaced the brake boost suction jet pump that leads behind the throttle body. Just curious if the long term fuel trims are triggering my CEL until they're able to come back down (currently @ 11.7; STFT range from -5 to +5)
austin mays (2 years ago)
+Joe Orlando when I replaced the MAF, the short term fuel trims immediately adjusted to the correct air to fuel ratio by going -25% which eventually brought the long term trims back down to about 4-5% instead of 11.7%. It had been running lean for a long time and the MAF was just sluggish, not completely dead. My lean codes (0171 and 174) were gone once I replaced the MAF AND the DISA valve o-ring. Every once in a while I still get p1192 and p1193 and everything i can find about this suggests an ECM reflash/software update from dealer. If you've replaced all the vac lines behind the intake manifold, checked the suction jet pump from the brake booster to under the manifold and checked the DISA VALVE and replaced o-ring, then I think replacing the MAF is a good next move.
Joe Orlando (2 years ago)
I have a 2001 330Ci with 175k miles, original MAF sensor. I get P0171 and P0174 lean codes off and on, and it seems to only trigger the service engine soon light when I drive on the highway for a period of time. I don't get the light when I'm only driving around town. Did you have similar issues? And what do you mean that the fuel trims are now -25 when you changed the MAF sensor?
austin mays (2 years ago)
doubt it. Your content is solid. Vid and sound quality is top notch. Out performing your peers from a consistency perspective but more importantly from a step by step DIY perspective, which is why most of us are here. You keep the regular DIY'er in mind. I hate watching a 5 minute vid of some guy saying "oh here's some things you gotta watch out for...." like, no shit I've gotta watch out for that, but I didn't, so now what do I do?? lol Your branding is even spot on, I can find your vids first among the others. When you do branch off I'll still have this catalogue to refer to.... so don't remove these!!! :-) Good luck in the future, hopefully it's encouraging to you knowing you're providing really valuable content to your followers!
50sKid (2 years ago)
Yeah that has always been a problem in my mind--I've got a very specific audience because I mostly work on the E46, so I'll probably take a little hit when I start working in vids on other cars again, but that will happen eventually.
austin mays (2 years ago)
+50skid Put the new MAF in today ... problem solved. Fuel trims now -25 and bringing LT back down. You're obviously an extremely skilled diagnostician and I can't thank you enough for the vids! These are basically digital and "digestible" chiltons manuals. Are you planning on doing other cars after this and having a catalogue of automotive content??
Brian Jenkins (2 years ago)
@50skid I have a p0150 on my 1998 740il. The car feels like it's misfiring but the coils and plugs are new and good. I looked at the fuel trim and when it shakes the fuel trim drops. But when it rises it's fine but it rises above 20. Is this because the precat o2 sensor is bad on bank 2? The bank 1 sensor and fuel trim look fine; they go up and down constantly staying within +/- 10.
Brian Jenkins (2 years ago)
I went with universal 4 wire NGK/NTK o2 sensors from eBay. They were $30 shipped for both work better than the bosch ones on my E38. No more shake or CEL.
Jose martinez (2 years ago)
50sKid. great video ! and very clear . 👍 i have a question. and i just want to clarify so does fuel trim banks staying at 0 a good thing ? because you mentioned anything above 10% is adding too much fuel and anything (-) is removing from too much fuel right ?
Brian Jenkins (2 years ago)
Ok thanks sir
50sKid (2 years ago)
Ok sorry I didn't look up that P0150 code the first time I responded to you (sometimes I have a lot of msgs to go through). P0150 is O2 Sensor Circuit Malfunction Bank 2 Sensor 1, which does point to either a bad O2 sensor OR a problem with the wiring. Check the wiring integrity on that sensor before you replace it (meaning check for continuity between the white and black wires in the harness). The other 2 codes are idle control codes which could be caused by the bad O2 sensor--so start with that.
Brian Jenkins (2 years ago)
Thanks, I'll see if it goes down when I raise the rpm to 3000. If not could it just be the sensor? Yesterday I had pending p0150 p1509 & p1550, still could be vacuum leak?
Ted Schoenling (2 years ago)
First, Love the videos, thanks! I've watched most of them even though I don't have most of the issues you are having, it is good to know these things and you cover them well. So I'm going nuts here. My fuel trims are 20+ when in Open Loop, with a misfire on various cylinders. Once the ECU transitions to closed loop (warmed up) the misfire goes away and idle smooths out (not perfect, but pretty darn close). Fuel trims drop to around 6. I have pending lean codes as well as misfires (random) on 5 of 6 pots. When RPM rises fuel trim approaches zero regardless of Open or Closed loop. So I'm sure I have a vacuum leak, but why would things get better when the car warms up? I've replaced the DISA O-Ring, secondary air pump hose, upper intake hose (lower is on the way) and checked other issues. I don't suspect CCV but that my be wishful thinking (no smoke, no excessive oil consumption, vacuum on oil fill cap not excessive. arrggghhh
Ted Schoenling (2 years ago)
Oh, and thanks for responding, really awesome!
Ted Schoenling (2 years ago)
Yeah I ordered a catch can, I'm going to cut the CCV, the fittings still work, and since that pipe is cracked at the fitting to the CCV, I'll just cut it and be done with it. I did, however, try a different can from what you got, hopefully it won't have the oil smell, and if so, I don't drive all that much so it won't bother me too much (I hope)
50sKid (2 years ago)
It's not the oil filter housing.
Ted Schoenling (2 years ago)
I just looked closely at the line between the valve cover and the CCV, the connection to the CCV has oil all over it. I'm trying to decide if it is from the CCV or from the aforementioned oil filter housing gasket leak. After I do the lower boot, I'll wait and see if the issue resolves. If not, I'll do the CCV.. not a job I want to do myself this time.
Ted Schoenling (2 years ago)
I'll do that when I get the new one.. the (not so nice) guy who put this boot on put the clamp on so that it is facing down and away, I'm afraid I'll have to rip it apart to get it off. I did get the car up in the air, the 0-ring on the dipstick may be suspect, but I do have vacuum at the top of the dipstick so I'm not sure about that. I also have an oil leak at the oil pump filter gasket, which was a known issue, but it is starting to make a mess... that will be the next job.
Jerome Griebelaar (2 years ago)
Great video!
oespo oespo19 (2 years ago)
Dude awesome videos!
David Donoghue (2 years ago)
thanks for a great video. very informative i was able to figure out what this issue was with my bmw 330i. I replaced the reg/filter and that solved the codes.
carlos verduzco (2 years ago)
Thank you for the great videos! I went to Harbor Freight and got the same gauge that you did. My pressure was barely above 10 with just the pump activated. 47-49 with the car running. I changed the fuel filter/pressure regulator combo unit, and pressure is still reading 10-12. Do you suppose I have a bad pump...?
carlos verduzco (2 years ago)
50sKid, since you asked: I am having cold start issues such as shaking until the secondary air pump shuts off, and rich smelling exhaust. checked injectors and changed all six due to one leaking. I also have medium vacuum at the oil fill cap. when removed, the idle gets rough. today, I disconnected the CCV hose leading to the Vanos, plugged it with my thumb and felt suction there too. once thumb is removed, I could hear oil gurgling. in addition to low mpg's, and oil/mayo under the filler cap, the spark plugs have oil on the threads, disa is oily as well.
50sKid (2 years ago)
Well that doesn't make sense then, but if it's 49 while running it sounds like you're fine. So what problem are you having?
carlos verduzco (2 years ago)
50sKid , I just replaced it last weekend...
50sKid (2 years ago)
I would say your fuel filter is probably severely clogged.
carlos verduzco (2 years ago)
50sKid , it starts at 20psi and slowly settles at around 10- 12
Gabriel Ševeček (2 years ago)
Great videos man! Do you know if ScanMaster-ELM ELM327 OBD 2 Software works with 20pin round connector via cable reduction to obd2?
Gabriel Ševeček (2 years ago)
50sKid thanks
50sKid (2 years ago)
It should but if you put the cap on the 20 pin round connector then you should be able to connect your obd2 reader to the regular obd2 port inside the car.
Carlos A (2 years ago)
I'm having the p0171 code Bank 1 running lean on a 2005 330i I've taken it to the mechanic because it had p0171 and p0174 and they were able to get rid of p0174 but the p0171 code keeps coming back could it be the fuel regulator? Because they've connected a smoke machine to the car twice and haven't been able to find any more vacuum leaks from when they found the first two and got rid of the p0174
Carlos A (2 years ago)
50sKid hey so I've replaced both fuel pump and pressure regulator and the CCV but the same freaking codes keep coming back I've also cleaned the MAF and the ICV What do I do?!!!! These codes are fringe me crazy
Carlos A (2 years ago)
Gavin Baumanis I cleared them
Gavin Baumanis (2 years ago)
did you clear the code, before rescanning? Or are you just getting the old code over and over?
Carlos A (2 years ago)
50sKid right now I'm thinking it's a duel delivery problem because we've connected a smoke machine to try and find any vacuum leaks and we've found 2 but those are fixed and the code is still appearing
50sKid (2 years ago)
Yes a positive fuel trim means lean condition, but what type of lean condition is it? Is it a vacuum leak or is it a fuel delivery problem?
bfngl17 (2 years ago)
Great tutorial, thank you. :-)
Italo Orellana (2 years ago)
Hi +50sKid does it make sense to say that when the Fuel Trims are Higher to that 5% the car is less MPG efficient?
50sKid (2 years ago)
Yes, when fuel trim is higher than 0%, fuel efficiency goes down proportionally.
Froilan (2 years ago)
this is awesome! I've been chasing fuel trim problems on my e46 for over a year now. Thanks!
Froilan (2 years ago)
I still have to check the values. I've done a smoke test, found some leaks and repaired them, yet the codes still come back for both O2 banks. I use a peake tool and E3, E4 keeps coming back. I'll come back and update you. Thanks.
50sKid (2 years ago)
What do your numbers look like?
Kendrick Cheng (2 years ago)
@50sKid hey mate, been trying to figure something out - I currently have both my long term ratios at ~-5%/-6%. This was after I reset adaptations on my car (325i), as my long term ratios were at -8/-8. After I reset the adaptations, I monitored the short terms for a while, and the cold starts were obviously quite negative, as our cars I believe like to run a bit rich on cold. As the car warmed up though, the short term fuel trims for the most part stayed between -5% and +3%. The car has most things already replaced (necessary repairs as they were failing etc), including: CCV, VCG, DISA Valve rebuilt, VANOS seals, Fuel Pressure Regulator, OFHG, OPG, intake boots, and the F-Connector's lower hose rubber sheath has also been replaced. The fuel pump has not been replaced. Any ideas?
Kendrick Cheng (2 years ago)
The latter. Just seeing the numbers and not being happy. Probably just going to leave it since it doesn't seem to actually be causing any issues.
50sKid (2 years ago)
Are you noticing any problems associated with this or are you just seeing these numbers and not happy?
Martin Dvorský (2 years ago)
wow, I've never seen better explanation of fuel trims than yours, big thanks!
Eddie Diaz (2 years ago)
hey 50s Kid... i bought the elm 327 and using the short term fuel trim gauge.. with live data.. and im getting a range of -1.8 to 5.5 %.. some times it will go up 7%.. pretty normal as per ur info in this video.. but as im at a stop light..it idels normal.. but the guage will spike to -100.8... just for a sec.. i dont feel the diff. in the car but it does it quite offten in the guage.. is this normal?
billy mitchell (2 years ago)
great vid again trying to learn about E46 fuel trim ..never had this when I was working on cars back in the 70's I have torque pro app on the car DVD and there are a few questions I hope that you can help me with these figures I have LTFT1 =11.7% LTFT2=11.7% STFT1= -0.8% STFT2= +8% O2 1x1 .06v O2 1x2 .07v @-2.3v stft O2 2x1 .04v O2 2x2 .04v most of these figures fluctuate but LTFT stays the same I am concerned with economy being 9.4km/lt to city 6.5km/lt now my DISA I think is not working because after I removed it and checked out the unit I sprayed WDF to check diaphragm which started working and would hold flap .. when I refitted unit there was a vacuum noise from DISA at idle ...unplug connector to DISA and noise stopped indicating diaphragm has a leak cause flap returned to center ... funny thing is the motor idles perfectly and car has heaps of go but!!! have ordered a DISA complete kit from Russia so have you any thoughts on these figures I am going to get that program Scanmaster because of how you described how it worked and is easy to load to pc am a bit concerned on fuel economy
billy mitchell (2 years ago)
code P1250 fuel regulator ..checked this out and there is no vacuum from this hose so maybe this is the problem ...have had a problem with starting if the car was left for an hour I found it would not start unless turned key on and off and then on ...then it would start so am thinking that vacuum hose is broken under manifold ...your thoughts on this but I know the DISA has to be faulty because won't hold vacuum
billy mitchell (2 years ago)
checked out the vacuum hose to dipstick and looks brand new, no oil but after un-connecting and re-connecting MAF now fault codes have come up P0170/P0172 and have now p1250 codes
billy mitchell (2 years ago)
can I get to this without pulling all the manifold off
billy mitchell (2 years ago)
no but will have a look when car cools....would have been better off eliminating all this plumbing and fit a catch bottle back to manifold ..just a thought ..never had a car with so much plastic on the motor
50sKid (2 years ago)
Yeah you have a vacuum leak for sure. Did you check the lower CCV to oil dipstick hose?
Vincent Steenmeijer (2 years ago)
Love the internet. Thanks for sharing and explaining so well. I'm gonna have a look at my fuel trim.
Terrence G (2 years ago)
Could you do a video on how to set up the hardware and software. How much should i pay for the Program? What features should I look for when purchasing the ELM adapter? Thanks!
KingRichard (2 years ago)
Couldn't you damage your catalytic converter by causing the engine to misfire? Just wondering if that was a potentially risky demonstration at the end there when you intentionally caused the vacuum leak.
50sKid (2 years ago)
Thanks for the question! I understand why it may have seemed that way, but it was actually ok because the engine computer is able to compensate for a lean or rich condition up to a point. That is exactly what fuel trim is. It's the engine compensating by adding or removing a percentage of fuel to keep things in balance. It can usually go about 25% on the short trim and 25% on the long term, so about 50% in total. Once those values are maxed out, THEN you have a true lean/rich condition that is causing damage.
toto dona (3 years ago)
Hi, great bravo from France ! You speak very clearly and your are very good at explaining stuff, your video have helped me a lot with my E46. Keep up the good work!
50sKid (3 years ago)
SMVK (3 years ago)
Great video, very instructive but your engine still sound funny at 14:16 some kind of ticking and wobbling, maybe a pulley is bad ...
Edmond Hung (3 years ago)
Hi, I am using your technique to find out what happen on my 325ci(M54B25 engine). Can you help me with analyze the data? Here is my situation, after I reset the adoption value, I got average 16.266/16.185 Lambda 1&2 integrator when idle at ~850rpm. When I push it to ~3000rpm, I got 19.396/21.561 BUT when I let to throttle go, it immediate jump to 0(almost). It clime slowly up to 16~19 after the rev. become stable. I don't know what should I look for, vacuum or fuel. One more thing, I tried to remove the oil cap when the engine running idle, it have little suction, not to much, the cap have to be take away with the force like open a fridge door. Is that normal or I got vacuum leak from there? PS. MAF cleaned
The Owl Guy (3 years ago)
My fuel trims were erratic with the scan tool. I had no vacuum leaks. I had 0171/0174 codes.  I replaced both upstream O2 sensors and it is now completely stable. Bosch O2 sensors only have a 100,000 mile life span I found out.
50sKid (3 years ago)
+Robert Tison Both oxygen sensors died at the same time? Statistically, I think you just won the lottery, lol.

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