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Misfiring question

Posted: Fri May 23, 2014 12:23 pm
by 25centguy
My car has been having a rough idle on cold starts. When I start it the idle is at 1200 rpm and then its like the engine is misfiring because I can feel it shake and then the idle goes up to 1500rpm slowly idles down and then when it gets warm has a nice idle at around 750rpm. Someone said he was having the same problem and when putting back the stock ecu everything was ok. Any ideas?

Re: Misfiring question

Posted: Sun May 25, 2014 5:00 pm
by hackish
Can you post a list of mods? In general I don't normally change the fuel or timing settings for the idle portion of the map.

-Michael

Re: Misfiring question

Posted: Tue May 27, 2014 11:49 am
by 25centguy
List of mods: not much

AEM CAI
Full exhaust with OBX header
RRM UDP

Re: Misfiring question

Posted: Tue May 27, 2014 10:46 pm
by hackish
Should be no real effect there. It is possible that your MAF or primary O2 sensor is starting to die. After a flash is done it's normal to have a little bit of rough idling while the ECU re-learns the idle throttle positions.

-Michael

Re: Misfiring question

Posted: Thu Jul 03, 2014 9:07 am
by darewood
Exactly what Michael said, but the idle goes up also because of the operating temperature so low. If you have the editor and the tune you can see at what temperature corresponds to what rpm the car will idle at. Once the car is warm it will go to the standard 750 I think it is. I have mine set at 1,000 just because I have a stiffer motor mount haha, so I don't really remember what stock idle sits at.