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Flashing check engine light with no noticable misfires?
08 SS/TC 76k miles. I hadn't driven it for about two weeks, due to winter weather. The other day I was cruising on the interstate at a steady 80-85mph when my check engine light started flashing. Absolutely no noticable difference in how the engine was running and no loss of power. I Checked the code and it was misfires on all cylinders. My plugs are probably 10k miles old andI made sure they were gapped properly. I do an intake cleaning once a year. Could it be a bad knock sensor? I cleared the code and it hasn't come back yet.
Edit: sorry I forgot. It has a catless downpipe, CAI, muffler delete, zzp intercooler and upper and lower charge piping, zzp bigger radiator, and has a trifecta custom tune. The tune was off when this happened.
Last edited by tamadrummer; 01-17-2017 at 04:55 PM.
Sorry, I forgot. It has a catless downpipe, CAI, muffler delete, zzp intercooler and upper and lower charge piping, zzp bigger radiator, and has a trifecta custom tune. The tune was off when this happened
I have a supercharged l61 Cobalt and I had this exact same thing happen to me today. Only time it has ever happened and it was repeatable every time I went WOT. I could not feel the car stumble at all, AFR was normal and holding steady. I wouldn't have even known it happened if I hadn't noticed the light flashing.
So right now it is parked and waiting on new spark plugs but I am concerned because I have never seen anything like this. Car idled fine and cruised fine. During a WOT pull if anything maybe feels like power is down a little bit with the flashing CEL.
Did some pulls on the way to work today and it seemed healthy. It seems to be higher load pulls that do it. In the higher load pull I again got the misfire flashing light and maybe could feel a loss of power. Not like a jolt or anything just less get up than usual. I have a freeze frame from when I threw the code if there is any telling information in there.
New spark plugs are going in today and I have a spare ICM to swap out as well. I would think I could rule out mechanical because it isn't a specific RPM and really only seems load dependent, otherwise it runs like normal. It seems fueling is normal as the AFR is right were it usually is. I even have my tune with lower ignition timing flashed.
So I went to Mode $06 screen on my OBDII scanner and it looks like the misfires are coming from cylinder 1. Cylinder 1 is the one closest to the timing chain correct? I swapped the spark plug between Cylinder 1 and Cylinder2 and it didn't affect this count. I also swapped out the whole ignition bar assembly with another unit and it didn't change anything either. Unfortunately this leaves me with fuel and compression. I don't think my year old injector is having problems so as my luck would have it it appears something is proper fubared. I have compression and leak down kits so I suppose those are the next thing to check. I just figured if it was compression loss it would also not want to fire right while idling or cruising as the problem area is only WOT. I can even do non full throttle pulls and it seems to run fine with minimal misfire counts. Power feels good and healthy. Fuel pump and filter are around 5 months old.
This is why everyone says to sell your base model and just get an SS lol.
Below is a video I took on the way to work hoping to capture the misfire flashing CEL event. But of course because I had the camera on it wouldn't do it. I decided to upload the video anyway so you could see how it is running. When I had the misfire light before I never felt anything. I wonder what the hell is going on.
01-17-2017, 02:28 PM
