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Idle feels like slight misfire but no CEL
Posted: Tue Mar 22, 2016 5:14 pm
by saintjah
- serial number of your K-Pro4
- 4.2.3.0
- ECU part number 37820 PRB A05
- KManager version 4.2.3
- Modifications: Comptech supercharger, ID1000 injectors, CT exhaust, Flexfuel,
- Science of Speed 2009
- a specific description of the problem:
Car seems to have a slight cough or choke at idle, intermittent. Almost seems like a misfire but there are no CELs present and the car runs fine other than that. The Kpro4 is also tuned on E85 and the problem at idle does not exist when ethanol content is over 70% idle is perfect. Seems to only do this on octane.
Re: Idle feels like slight misfire but no CEL
Posted: Tue Mar 22, 2016 5:19 pm
by saintjah
2003 Honda S2000
Re: Idle feels like slight misfire but no CEL
Posted: Wed Mar 23, 2016 10:59 am
by Spunkster
You have not included a datalog showing the issue.
Re: Idle feels like slight misfire but no CEL
Posted: Tue Apr 26, 2016 8:49 pm
by saintjah
it gets perfect if I fatten it up to 12.5/1 but isnt that too rich? The data logs dont show any abnormalities and the slight idle misfire doesnt throw any cel.
Re: Idle feels like slight misfire but no CEL
Posted: Mon May 02, 2016 8:10 pm
by saintjah
heres a data log
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 11:43 am
by Spunkster
Have you tried changing the AF ratio at idle when this happens to see if that makes it go away either making it richer or leaner?
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 11:58 am
by saintjah
Around 12.5 it will smooth out, is that not too rich for idle?
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 12:43 pm
by Spunkster
IS this when it is both hot and cold?
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 1:16 pm
by saintjah
Only when warm, once it gets up to temp 180f~ is when it starts.
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 1:16 pm
by saintjah
Im pretty sure it is not the ECU, I have just recently purchased a NEW Kpro4 from a licensed vendor and it does the exact same thing.
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 1:39 pm
by Spunkster
Have you tried replacing your spark plugs?
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 1:49 pm
by saintjah
Yes, they are new. I also have an AEM infinity and it idles perfectly on it. Coils, plugs etc.. all new
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 2:06 pm
by Spunkster
Then it sounds like it may just be a tuning issue if it only does it when hot, and another system works ok as well. Have you discussed the issue with your tuner?
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 2:13 pm
by saintjah
He took the same route and said to check the ECU. New has to be fine.
Is 12.5/1 at idle too much? If I set it to that it is fine and no misfires
Re: Idle feels like slight misfire but no CEL
Posted: Tue May 03, 2016 2:16 pm
by Hondata
The KPro is not the ECU. It still could be the ECU.
I'd lower the overrun cutoff pressures and try changing the idle ignition parameters, but the main thing that stands out is that the injector dead times are very low. ID1000s should be around 1.2 ms at 14V.
The other issue common with idle mixture is any very slight exhaust leak will give the o2 sensor a false reading.