[FatFingers15]

Hi all

Sorry didnt log in for a few days so i didnt know there were replies.

Anyway a quick update, the misfiring is now only on cyl 6 and 7. I changed those 2 coils and car seem to work fine for a but heavy misfiring returned shortly after. Now its to the point where by the car will just start in limp mode and misfires. Clearing the codes didnt help.

I bit the bullet and changed all 8 coils, oem was not available anywhere so had to get the originals. BUT, the misfires did not cease. 6 and 7 was still misfiring and the diagnostic showed the entire bank 2 was faulty, figures were way off. A deeper scan showed that 6 and 7 had a "short circuit to positive" message. Mechanic suspected that the dme is fried.

Originally Posted by nycplumber

I would check for vacuum leaks. I would also run multimeter under hood to see how many volts you're pulling when car is on/off. When these batteries hit 12v they start to cause issues.

Thanks, battery was checked just today and is working fine. Will the vacuum leak cause that "whoop" sound?

Originally Posted by amrazM

Usually a icv does produce these codes, generally a single ramp factor not ok still yields a working icv but there is still a problem with your icv. you sure it was replaced with a new part?

Thanks, but thats the thing, the owner said he had changed them, whether or not it was used or even changed is not verifiable but no reason to doubt at this point as the fault was no longer present. The ramp factor is back to normal now. So hopefully its not the issue.

Originally Posted by Redd

You probably have two separate issues. The DSC, DBC, FTM errors should be wheel speed sensor. Common fault, change all 4.

Now on to the engine. 8 cylinder misfires usually point to an intake issue, usually an air leak somewhere. I would remove all components and do smoke test to check for air leaks. This includes all the connectors that go into the chargepipe and plenum. Pay particular attention to the intake air temp sensor hole at the plenum. There should be 4 small locating tabs just inside the hole. Improper/forced removal of IAT sensor could damage these 4 small tabs and air can leak in under vacuum. The rpm range where your problem occurs - between 2-3k rpm, part/low throttle - is also the range where high intake vacuum occurs. I personally experienced this. Took me weeks of troubleshooting before I found the culprit.

Prolonged misfiring can damage the O2 sensors (again from personal experience). So once u find the root cause, symptoms may persist slightly even without errors due to damaged O2s. Be prepared to change those out too.

Good luck! I hope these tips help in some way cos air leaks are a bitch to diagnose.

Thanks, thats a very specific area, i can imagine the headache u went through. What u said makes sense, i'd probably do the same. Yeah im standing by for the o2 sensors just in case. Just hope i find the root cause soon enough.

Currently the dsc faults didnt return, so i hope it was sort of collateral damage from the misfiring. If it comes back on, i'd probably change those for peace of mind and also to rule out those parts.