[Guapped]

I have a 07 335i and I have a subtle misfire only at idle when my car is warm, it starts with no issues ever, and never misfires on cold starts. I only notice it after I drive a bit and stop at a light. No codes are thrown and I installed new plugs and coils 2k miles ago and it did not change anything. I have been looking on forums for awhile now trying to figure this out but now I have the money for a single turbo and would like to take care of this before I go to a single. Any suggestions appreciated I have a old log I will attach as well, I am now stage 2+ fbo.

[Milan]

Usually these cars start to misfire when something is about to die. I would guess your o2 or injectors are on their way out.

For now check to make sure you have no vacuum leaks. You do a walnut blast ever?

[Guapped]

Originally Posted by Milan

Usually these cars start to misfire when something is about to die. I would guess your o2 or injectors are on their way out.

For now check to make sure you have no vacuum leaks. You do a walnut blast ever?

I kind of don’t think it’s injectors due to symptoms of injectors typically are more then what I have issues with, it’s never been walnut blasted but I ordered a walnut blasting kit from fcp Euro hoping it fixes it and if not just good maintence, idk if It has ever been done I bought the car 6k miles ago and it’s at 88k now. I haven’t really thought about O2 sensors much, I’ll look into it and see what tests or if logs can maybe give me some suggestion there going bad. Thank you for the suggestions!

[N54_ABQ]

Do a compression test. If one or more cylinders are low do a leak-down test. 170-180 is preferable. 140-150 can be considered low, but if all cylinders are the same there's no great cause for concern.

Do this especially if you're planning on single turbo. No sense in throwing more boost at a sick motor.

[Guapped]

Originally Posted by N54_ABQ

Do a compression test. If one or more cylinders are low do a leak-down test. 170-180 is preferable. 140-150 can be considered low, but if all cylinders are the same there's no great cause for concern.

Do this especially if you're planning on single turbo. No sense in throwing more boost at a sick motor.

I will look into this, thank you.

[Milan]

Originally Posted by Guapped

I kind of don’t think it’s injectors due to symptoms of injectors typically are more then what I have issues with, it’s never been walnut blasted but I ordered a walnut blasting kit from fcp Euro hoping it fixes it and if not just good maintence, idk if It has ever been done I bought the car 6k miles ago and it’s at 88k now. I haven’t really thought about O2 sensors much, I’ll look into it and see what tests or if logs can maybe give me some suggestion there going bad. Thank you for the suggestions!

If it’s only when your car is warm I would bet it’s o2. Can you log them and see if they are switching normally or if one is lagging?

[Guapped]

Originally Posted by Milan

If it’s only when your car is warm I would bet it’s o2. Can you log them and see if they are switching normally or if one is lagging?

I can take new logs in a few hours, what should I be looking for in the logs, I have probably 5 old logs on my laptop I can look at for now.

[Guapped]

Originally Posted by Guapped

I can take new logs in a few hours, what should I be looking for in the logs, I have probably 5 old logs on my laptop I can look at for now.

I looked at old logs and afr`s seem pretty good from what I can tell. I will do some more logs tonight and see what I can find.