Misfire Under Cold Starts?

06_civic_si_gi · Post by **06_civic_si_gi** » Wed Mar 23, 2011 5:20 pm

im not sure what is causing this but here is alil background on it. i drive a 06 supercharged si.

if i cold start my car is weather of -10 to 10 degrees outside the car usually gets a error code sayin its misfiring. also now that it warmer out ive been noticing it again but its only if i let the car set lets say more than 24hrs. its weird becuz when it does the misfire code its a different cylinder each time but usually its either 4th or 3rd cylinder. so that takes the idea of having a coil pack issue. but as soon as the car gets to normal op temp u can hear the difference as the misfiring goes away and starts to work normal again

ive also replaced plugs (ngk 8s), fuel injectors, 02 sensor
ive also messed around with cranking trim n it doesnt seem to fix anything

so if anyone has any comments or suggestion that would be great its kinda annoyin letting the car warm all the way up if its misfiring just so i can drive 10mins later

Anyone else have this issue? hondata have you ever came across this issue?

i will include a datalog also

Post by **Hondata** » Wed Mar 23, 2011 6:26 pm

It is because the car is running at 18:1 AFR. Can you post your calibration?

06_civic_si_gi · Post by **06_civic_si_gi** » Wed Mar 23, 2011 7:14 pm

when the car starts and runs normal i never see those readings its only when it has a rough cold start and when it misfires that when it usually hangs around the 18+ a/f ratio area...

i cant remember wut datalog that was from, the one i included was the one i was thinking

but it happens with any map i have under the conditions i posted earlier
setting for long periods of time or if its extremely cold out

Post by **Hondata** » Thu Mar 24, 2011 10:36 am

Can you post your calibration?

06_civic_si_gi · Post by **06_civic_si_gi** » Thu Mar 24, 2011 12:38 pm

this was the calibration i was using at the time

Post by **Hondata** » Thu Mar 24, 2011 4:39 pm

Thanks. I've got the order wrong - the misfire code is causing the ECU to run in open loop, not the other way around.

So:
1. Fix the U0122 error. If you have an 06 Si then you need to disable VSA.
2. Find out why the ECU is running 15% lean during a cold start. Start by changing the 'Water temperature fuel compensation low table' and seeing if the short term fuel trim is less after a cold start.