[bimmertt]

I just replaced my injectors and my car is still misfiring on several cylinders during cold starts. Once the rpms settle down, the engine is nice and smooth. I tried resetting adaptations hoping that would resolve it, but the rough idle is still happening specifically during cold starts. Ignition coils and spark plugs were replaced ~100 miles before injectors were replaced. Any ideas?

[rjahl]

Originally Posted by bimmertt

I just replaced my injectors and my car is still misfiring on several cylinders during cold starts. Once the rpms settle down, the engine is nice and smooth. I tried resetting adaptations hoping that would resolve it, but the rough idle is still happening specifically during cold starts. Ignition coils and spark plugs were replaced ~100 miles before injectors were replaced. Any ideas?

Did you code the injectors properly?

[bimmertt]

Yes, injectors were coded with protool. It does look like the last value for several of the injectors changed after coding, but apparently that's normal behavior.

[feuer]

Originally Posted by bimmertt

Yes, injectors were coded with protool. It does look like the last value for several of the injectors changed after coding, but apparently that's normal behavior.

Did you perform synchronization per cylinder? Reset Lamba too? This might not be an injector issue at all. Not sure why you replaced them.

[_N54]

Originally Posted by feuer

Did you perform synchronization per cylinder? Reset Lamba too? This might not be an injector issue at all. Not sure why you replaced them.

Is that procedure part of protool? I replaced my injectors with index 12 and I have small misfires on a cold start and once the cold start rpm settles down it's smooth. I thought it might of been from running full E85.

[BSM n54iS]

Bosch plugs or gapped NGK's?

[bimmertt]

Originally Posted by feuer

Did you perform synchronization per cylinder? Reset Lamba too? This might not be an injector issue at all. Not sure why you replaced them.

Several injectors were leaking which is why I replaced them with index 12s. Not sure what you mean by synchronizing each cylinder. I just tried resetting lambda using MHD and still experienced the same stumbling on cold start.

[bimmertt]

Originally Posted by BdSM n54iS

Bosch plugs or gapped NGK's?

NGKs gapped to .020

[BSM n54iS]

Originally Posted by bimmertt

NGKs gapped to .020

How cold is the weather for you? Stock turbos? I'm gapped to .022 on stock turbos and cold start disabled, still have had a stumble last 2/4 cold starts from plugs. I am most likely switching to stock plugs for colder weather soon while still on stock turbos

[bimmertt]

Originally Posted by BdSM n54iS

How cold is the weather for you? Stock turbos? I'm gapped to .022 on stock turbos and cold start disabled, still have had a stumble last 2/4 cold starts from plugs. I am most likely switching to stock plugs for colder weather soon while still on stock turbos

Hm that's a good point. It's 32 degrees right now and yes I'm on stock turbos. I just enabled the cold start noise reduction in MHD and most of the stumbling is now gone since it drops right to the idle rpm upon startup. Will try another cold start tomorrow morning to confirm, but I think that might be the fix!

[feuer]

Originally Posted by _N54

Is that procedure part of protool? I replaced my injectors with index 12 and I have small misfires on a cold start and once the cold start rpm settles down it's smooth. I thought it might of been from running full E85.

I don’t know if is part form protocol but after replacing many injectors have had issues when misfire continues at idle and high revs under boost unless the synchronization per cylinder is performed. I think it has to to do with long term trims. There is a good article, European I think, because is on n53. Try to find it. I do it in Inpa.

[_N54]

Originally Posted by feuer

I don't know if is part form protocol but after replacing many injectors have had issues when misfire continues at idle and high revs under boost unless the synchronization per cylinder is performed. I think it has to to do with long term trims. There is a good article, European I think, because is on n53. Try to find it. I do it in Inpa.

This is good information. Would the ISTA software be able to do it?

[feuer]

Originally Posted by _N54

This is good information. Would the ISTA software be able to do it?

I wound not know. I have only used inpa for this.

[Soden82]

Sounds to me like a small vacuum leak or even boost leak. When your car is in open loop on start up, the car is using DME values to target fuel trims until it goes into closed loop and uses the o2 values. If there is unmetered air getting in then it can cause this stumble.

[_N54]

Originally Posted by Soden82

Sounds to me like a small vacuum leak or even boost leak. When your car is in open loop on start up, the car is using DME values to target fuel trims until it goes into closed loop and uses the o2 values. If there is unmetered air getting in then it can cause this stumble.

Would a bad valve cover cause this issue? I know my valve cover has a small leak and it's the original with 100k miles. I have a brand new oem going in this weekend.

[Soden82]

Originally Posted by _N54

Would a bad valve cover cause this issue? I know my valve cover has a small leak and it's the original with 100k miles. I have a brand new oem going in this weekend.

Yes 100%. That was the cause of my cold start stumble.

[_N54]

Originally Posted by Soden82

Yes 100%. That was the cause of my cold start stumble.

Well hopefully the new one over the weekend resolves my cold start issue

[Tyc0]

My fix was MHD cold start reduction. I now almost never have any stumbles upon cold starts.

[_N54]

Originally Posted by Soden82

Yes 100%. That was the cause of my cold start stumble.

I replaced my entire valve cover today with a new OEM. The car did not misfire on the first cold start so well find out tomorrow if its really fixed. Its actually driving a lot better now I'm pretty sure the internals were plugged or something was going on. The other thing I noticed was a small amount of smoke coming out the VTT oil filler breather cap I'm running with the engine hot even with it removed just wasn't sure if its condensation or if its normal to have a little bit of smoke coming out. Checking the VTT oil filter cap for the 2nd time, the smoke appears to have disappeared after doing another quick run and a couple of WOT pulls.

[Slade_]

This is interesting.. I have index 12s on my car that were swapped over from the previous motor. I was under the impression that they may be leaking and causing stumbles on cold start. Upon checking for codes on MHD today I was warmly greeted by a 2C9D code. I’m certain my primary o2 sensor is toast.

Going to replace that, change VC gasket, coils, and try the MHD cold start option mentioned here before buying new outrageously priced injectors.

[iqraceworks]

Originally Posted by bimmertt

Yes, injectors were coded with protool. It does look like the last value for several of the injectors changed after coding, but apparently that's normal behavior.

What do you mean that some of the values changed after coding.....like they changed from the new values you entered in for the injectors, or they changed from the values you entered in.

The numbers on the injectors is what need to show on ProTool when you look at injector calibration numbers. If those numbers don't match what's printed on the injectors, something went wrong....code them in again.

[Soden82]

Originally Posted by iqraceworks

What do you mean that some of the values changed after coding.....like they changed from the new values you entered in for the injectors, or they changed from the values you entered in.

The numbers on the injectors is what need to show on ProTool when you look at injector calibration numbers. If those numbers don't match what's printed on the injectors, something went wrong....code them in again.

I think he means that you initially code them and input the numbers for each injector, and then when the car is first started the values change slightly.