negative fuel trims + cold start misfire

[besembo]

hi guys
so i got my next headache - 320 automatic 2.2 2002 (steering is moved to the left, originally it was rhd) 112 k kilometers on clock, full sport package
this one had negative long term fuel trims -11 % when i was buying it i already knew
drove for about 3 months and its time to fix problems.
1) maf is not oem but it has standard reading on idle 2.6-2.7 in ,,p'' and 2.8-2.9 in ,,d''
2) also yasterday i tested my 0-100 time with elm 327 and got 11.5 seconds, it was raining a little and not the best launch but still slow
3) today i don't work, got in my car and started, wanted to find something strange. connected elm327 and felt that cold start misfire again, tested for errors and got 1 and 5 cylinder misfire as bonus
4) i also did not make s smoke test (but i could), just pulled out disa and big hose after maf sensor as i already knew disa gasket should be replaced and big hose would be teared - i was right.
5) previous owner told me he replaced spark plugs and 2 of them were black - that was the only thing he did, not to consider angle eyes - so i knew i had to deal with negative fuel trims.
6) check engine does not lit coz those misfire codes are yallow they go away after engine is warmed i guess

any ideas guys ?

[whiskychaser]

-11% means the system thinks the mixture is too rich and is trying to lean it out. Odd you only have two black plugs. Leaking injectors?

[MIKYZZ4]

Smoke Test intake.

[RobertDenali]

^ Agreed

[whiskychaser]

If the misfire is always on cylinders 1 and 5, maybe try swapping the coils to different cylinders and check if the fault follows? That is a lot easier than moving the injectors. If the misfires were really that bad, you would get misfire with fuel shut off to the affected cylinders.

To get a level playing field, you do need to ensure you have no vacuum leaks as mentioned above. But unless your ELM is reading upside down, the trims are going to go even further into the negative when you have corrected that problem. At that point, the ECU may well throw the towel in and put the SES light on

[RobertDenali]

ok guys i made a smoke test. and found a huge vacuum leak close to disa valve
i don't know who did this but in the name of whole bmw society - f...k your hands idiot !

Lol!!! You made me laugh with your reply

You will need a new DISA valve. They are over $300 US. You might be interested in look at G.A.S. DISA valves. They are original however built with a metal pin.

[RobertDenali]

Excellent! Next step is to get a genuine or OEM MAF from bosch or siemens. I forget who makes these for bmw or go to a junk yard.

[RobertDenali]

There are a lot of variables involved in that number. So your MAF is good?

[RobertDenali]

Again there are too many variables. For example barometric pressure, outside temperature, height above sea level etc.

I baselined my car when working in the summer fall winter and spring. This only gave me numbers for where I live.

[RobertDenali]

Your fuel trims shouldn’t be negative.

Here are two discussions on negative fuel trims.

https://e46fanatics.com/forum/showth...topics/1220970

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https://m.youtube.com/watch?v=jqef_Xpz7Og

[RobertDenali]

Lol indeed. So I did ask you if your MAF is good. Maybe i should have been descriptive on the meaning of “good”

If it is not the true OEM or genuine then it is no good or if it is no longer functioning correctly.

[RobertDenali]

Did you clear adaptations?

[RobertDenali]

There are various ways snd software to use. The software I use is on the expensive side so I would research this a bit to find a solution that works for you. Your car has been learning incorrectly so if you fixed all the issues it might take time to to re-adjust or if you clear adaptations then it is instant plus learning new.

Is your car auto or manual trans?

[MIKYZZ4]

https://www.bimmerforums.com/forum/s...1#post30020821

[MIKYZZ4]

The scan tools available are listed above ^

[RobertDenali]

Whatever you end up choosing don’t reset your auto trans adaptations if your vehicle is an automatic trans.

[RobertDenali]

https://m.autoserviceprofessional.co...t-work-for-you

[besembo]

Problem solved. Pm me if you want to know more.

[besembo]

wow I forgot this thread even existed. Done so many things , now fuel trims go where I want them to go
Cold start problem is still there even after engine rebuild and doing things some can not even imagine.
When system is good it can happen so even after 6 maf replacement you won't catch a good one.

[harrier]

I have never heard of a bad new MAF unless it was aftermarket. Which brand did you buy

[besembo]

I have never heard of a bad new MAF unless it was aftermarket. Which brand did you buy

tried 6 or 7...

[MIKYZZ4]

When it comes to BMW electrical/electronic parts, it's critical that you install only OE or OEM BMW replacement parts.
It might not save you money, but it will save you time and headaches. Hint: (Siemens/VDO)

[harrier]

Was any one of them a VDO/Siemens?
Did you replace O2 sensors (Bosch)?