flashing check engine light
Thread Starter
Cruising
Joined: Aug 2021
Posts: 13
Likes: 0
flashing check engine light
figure ill post here. I was having the dreaded 8l90 transmission issues so I took the car to a performance shop. we did a Tim king stage two 8l90, circle d torque converter, long tubes, BTR stage two cam, dod delete, ported intake and throttle body. car runs great shifts absolutely amazing now but we are having an issue when the car sits and idles it gets a flashing check engine light once you start driving it the light turns off. it is not throwing a code for it and the tuner is still looking into the issue some more. he has done a lot of the c7s and has never had the issue before. we have done a new set of plugs and wires already but I figured I would post up and see if anyone else has had this issue and got it sorted out. thanks for any info.
Melting Slicks
Joined: Oct 2010
Posts: 3,030
Likes: 794
From: Tollesboro Kentucky
Had the same issue with my C6.Would do it at each startup and sometimes when idling for a few minutes.My issue was with the misfire count.Tuner said it was due to the cam.After adjusting it the issue went away and has never happened again.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,628
Likes: 4,074
From: Cape Coral, Florida
figure ill post here. I was having the dreaded 8l90 transmission issues so I took the car to a performance shop. we did a Tim king stage two 8l90, circle d torque converter, long tubes, BTR stage two cam, dod delete, ported intake and throttle body. car runs great shifts absolutely amazing now but we are having an issue when the car sits and idles it gets a flashing check engine light once you start driving it the light turns off. it is not throwing a code for it and the tuner is still looking into the issue some more. he has done a lot of the c7s and has never had the issue before. we have done a new set of plugs and wires already but I figured I would post up and see if anyone else has had this issue and got it sorted out. thanks for any info.
If you have just a flashing MIL with NO misfires felt you should do a crankshaft variation relearn with the engine work that was performed…you will need a bi directional scan tool for this procedure
Safety Car
Joined: Nov 2011
Posts: 3,715
Likes: 343
From: Norman OK
A flashing check engine light is for a Random Misfire detected. It can trip a P0300 code. If the misfire gets bad enough or if the ECM can narrow the misfire down to a offending cylinder it will set a code for the cylinder (P0301 for cylinder 1, P0302 for cylinder 2 and so on). If the car has been started and only let run for a minute and then turned off it can cold foul the plugs, if that is the case you can do 2 things. You can start it and drive easy for a long drive and get the plugs warmed up, then once up to temp get on the car hard and get the cylinder temps up and see if it will clear the plugs up.
Otherwise the other option is to change the plugs out and try and keep the short starts to a minimum.
Otherwise the other option is to change the plugs out and try and keep the short starts to a minimum.
Thread Starter
Cruising
Joined: Aug 2021
Posts: 13
Likes: 0
not sure how there is not a code being generated. probably since it only happens when it is idling stationary. once you start moving and get a little ways down the road it clears up and the light goes away. plugs have been changed, injectors are new and coils are new. the tuner is going to dive into it some more. he has done a bunch of C7s and never ran into this issue.
