intermittent random misfires
06-02-2018, 01:14 PM
#41
New Member
Thread Starter
Join Date: 10-06-2017
Location: Toledo, OH
Posts: 15
Final Resolution. Random Misfires.
Purchased HPTuners so that I could do a scan log of this SS and to make sure that it contained a "stock" tune in the PCM.
Verified that it was indeed a "stock" calibration GM file in the PCM.
Did several Logs of the vehicle. Found that no misfires would show unless the vehicle was running at a steady approx. 70 mph.
Intermittently, about 10 minutes apart, all misfire counters would max out and set a pending cel. What was interesting is the Log showed no other change in the recording other than the misfires (RPM, Power, O2 sensor) all remained steady.
Concluded that these were indeed "phantom" misfires. Decided to replace the PCM with a new unit loaded with the GM stock calibration.
Problem solved. Car has run great with no misfires in over 6 weeks.
Purchased HPTuners so that I could do a scan log of this SS and to make sure that it contained a "stock" tune in the PCM.
Verified that it was indeed a "stock" calibration GM file in the PCM.
Did several Logs of the vehicle. Found that no misfires would show unless the vehicle was running at a steady approx. 70 mph.
Intermittently, about 10 minutes apart, all misfire counters would max out and set a pending cel. What was interesting is the Log showed no other change in the recording other than the misfires (RPM, Power, O2 sensor) all remained steady.
Concluded that these were indeed "phantom" misfires. Decided to replace the PCM with a new unit loaded with the GM stock calibration.
Problem solved. Car has run great with no misfires in over 6 weeks.
Thread
Thread Starter
Forum
Replies
Last Post
silver2LT
Problems/Service/Repairs
28
06-09-2013 11:51 AM
