randome cylinder misfire code only on the highway
06-01-2011, 10:54 AM
#1
randome cylinder misfire code only on the highway Hey all, I just got my pcm back from frost which is tuned for my ls6 swap with the bolt ons in sig. First off let me say he did a great job tuning the car and has done a lot to help me work these little bugs out so I am in no way bashing him just trying to get some ideas on what could be causing my issue. Around town the car drives great but for some reason it will not go into lockup except maybe every once in a blue moon. Also the instant I get on the hwy and start cruising say around 65mph my ses starts flashing for a misfire code. If i stab the throttle and let it downshift and pass someone it will go away until I start cruising at a constant speed. Around town I can cruise at 50mph no problems whatsoever its only on the hwy, after I get off the exit ramp the light doesnt come back on again until next time. Any ideas on what could be going on could a sensor or electrical problem be causing the issue?
06-05-2011, 01:49 PM
#5
yup i also found out it was rpm dependent meaning if i was around 1800 rpm in the city (3rd gear) it would also do it. I borrowed hp tuners from a friend and saw that cylinders 1,3,5,6 were all showing 20-30 misfires at idle. I performed a case relearn for the pcm to re-sync with the crank sensor since it was a new motor and the misfire count immediately dropped to maybe 1-2 per cylinder since then I haven't had an issue.
