[Pladi]

My car misfires only on cold starts for about a a few seconds to a minute. Only throws misfire codes. For all cylinders and random misfire.

What did not fix the issue:

New injectors, spark plugs, coils and adaptation resets as well as valvetronic start up procedure for limit learning.

What i noticed recently from MHD logging during a cold start. See the link:

If O2 Pre cat is selected as well as AFR and RPM. Also STFT. We can see that for a split second the O2 goes to 0v. That i am assuming is not normal because i dont see that value on any of my other logs. Sometimes the car will cold start normal with no misfires. The issue is very intermittent.

Should i replace O2 pre cat ?


https://datazap.me/u/pladi/log-15149....46&tmax=64.76

[prime300]

Mine did the same thing, 2 days ago my car stalled twice in my driveway when i started to heat up (-25Celcius) and also sometime when im driving it does have hesitation, but never gave me a code

[Pladi]

Mine never throws a CEL code but there are always shadow codes.

If you want to know more about how ur car is doing invest in MHD logging at least. You can see in more detail if its a fuel issue or timing or spark.

But i noticed that these engine dont quite like the cold. very finiky.

[OneMoreAlex]

Do you have cold start delete on MHD enabled? I was getting the same issue, resetting adaptations worked occasionally but wasn't a proper fix since it always came back. Finally I disabled it and it's been good since.

[Pladi]

Originally Posted by OneMoreAlex

Do you have cold start delete on MHD enabled? I was getting the same issue, resetting adaptations worked occasionally but wasn't a proper fix since it always came back. Finally I disabled it and it's been good since.

So you mean you disabled the stock cold start high RPM ?

You are using the MHD option ?

But there is a reason cars have that high RPM. To warm up quicker. The car should not stumble have bad idle at any temperature. Wondering what is the cause for this.. seems like a pretty common occurrence. I am noticing that during this stage the computer is not adding any short term fuel trims. As soon as the computer starts to add trims the idle becomes better. Not sure if this is some loop back problem with the o2 sensors ..

[proj335i]

cold start option seems to be working properly in summer time. Once it gets close to freezing point, idle is rough for the first two minutes, you cannot drive it if you are MT. It stalls immediately no matter how throttle you give when you work the clutch.

Disabled it like every one who faces a real winter season. Drives perfectly ever since.

[Pladi]

Originally Posted by proj335i

cold start option seems to be working properly in summer time. Once it gets close to freezing point, idle is rough for the first two minutes, you cannot drive it if you are MT. It stalls immediately no matter how throttle you give when you work the clutch.

Disabled it like every one who faces a real winter season. Drives perfectly ever since.

Thank you sir but there is some confusion. I never had that option enabled. My issues seem to have disappeared after a battery change. I know its sounds weird. My battery was original cranking fine but could have been a bad cell or not enough amps available.. not sure either way i have fixed this issue with a new battery somehow.

[proj335i]

faultive battery seems to cause a lot of weird problem on our cars... good thing it has resolved your issue!

[Pladi]

Originally Posted by proj335i

faultive battery seems to cause a lot of weird problem on our cars... good thing it has resolved your issue!

Yes very true. I learned alot about E90s from this experience to be honest.