Help with a false misfire code
07-12-2011, 07:55 PM
#1
Help with a false misfire code Hi guys I've got an 02 camaro with an ls6 crate motor swap in it with the stock stalled a4 behind it and originally when I swapped the motor in I was getting some misfire codes at hwy cruising speed (over 1500 rpm). I did a case relearn and it all seemed to go away, the motor never actually felt like it had a misfire during any of this but according to the misfire counters I was getting 20-30 misfires on 4 cylinders.
Fast forward one month later to today and I am getting the same blinking ses light on the hwy but it now comes on at 2500 I dont normally spin the motor this high so I dont know if it was there before. I could also make the ses blink if I stayed at 2500 rpm in park. When I got home from work today I plugged in the vcm scanner and watched the LTFT's and misfire counts. However this time the ses light would not blink and the misfire counters on all cylinders were at 0 with the exception of 7 and 8 which had 1 or 2 misfire counts. The ltft's were also either slightly in the negative or at 0 on bank 1. While the car was "misfiring" today though I did get a chance to plug in my handheld scanner and once again my ltft's were slightly negative or 0 and the rpms while cruising on the hwy were at 2490 rpm +/- 10rpm so I wouldnt call that a misfire either.
Can someone point me in the right direction. Does the misfire sound false, and is there some other way I can check it before I deem it is false and alter the misfire tables?
Thanks Dan
Fast forward one month later to today and I am getting the same blinking ses light on the hwy but it now comes on at 2500 I dont normally spin the motor this high so I dont know if it was there before. I could also make the ses blink if I stayed at 2500 rpm in park. When I got home from work today I plugged in the vcm scanner and watched the LTFT's and misfire counts. However this time the ses light would not blink and the misfire counters on all cylinders were at 0 with the exception of 7 and 8 which had 1 or 2 misfire counts. The ltft's were also either slightly in the negative or at 0 on bank 1. While the car was "misfiring" today though I did get a chance to plug in my handheld scanner and once again my ltft's were slightly negative or 0 and the rpms while cruising on the hwy were at 2490 rpm +/- 10rpm so I wouldnt call that a misfire either.
Can someone point me in the right direction. Does the misfire sound false, and is there some other way I can check it before I deem it is false and alter the misfire tables?
Thanks Dan
07-13-2011, 08:47 AM
#2
hey guys i managed to get a log file this morning where the car was recording misfires at around 3k at rpm ranges below it the misfires were either significantly less or non existant. After I logged it I did another case learn because after I did the first one a month ago I didnt let the car sit for 15 secs so maybe something got messed up with the learn. anyway after I did this I could not get the car to replicate the misfires atatched here is the hpl file where the car had no recorded misfires and the excel file where the car was recording 195 total misfires at 2700 rpm, once again the motor ran fine the whole time . Sorry about the excel file for some reason I messed up saving and now I cannot convert it back to an hpl file. Please look and tell me what you think I dont mind adjusting the misfire tables or deleting the code because I am mechanically inclined enough to detect a real misfire I just want to make sure none of the parameters are out of whack and do indicate a misfire. Please Help.
EDIT: for some reason my excel file wont load up here however it is on the hptuners site heres the link. thanks again http://www.hptuners.com/forum/showthread.php?t=35163
Dan
EDIT: for some reason my excel file wont load up here however it is on the hptuners site heres the link. thanks again http://www.hptuners.com/forum/showthread.php?t=35163
Dan
