the check engine flashes then goes off at idle. i just got my car back for a full 403ci ls2 build and now problems are happening first it said i had a vaccum leak so i messed with all the catch can hoses, and tightened the map sensor since it was really loose and i could move it and twisted the vacuum cap on the back of the fast 102 manifold to make sure it was still there. and the codes went away. now today the car started with this engine flashing but then went away when i started driving it? Is this a tuning issue? That check engine light flashing also happened on the first start after a few minutes on the first startup. all my plug & wires look good and i dont see any loose connections on the coils or injectors wires any suggestions? How bad is engine missfire? can it ever be fully tuned out of fully built 403ci ls2. does my compression of 11.1 have anything to do with it since i rasied it? I am all new to this fully built motor stuff. i never really had any problems at all when i did heads cam and bolt ons. I did add ud pulley,ewp, bigger cam 234,242 608 612 112 lsa. does that have anything to do with it?

 

Engine misfire with a flashing CEL is bad. Get that thing back to your tuner and have them fix the issue.

Elmer

 

Just a question about the flashing check engine light from elmer. This actually happened before when the car was just heads and cam but it only happened like 2 or 3 times in 2 year period but it never threw a code. form what i remember it only happened on the startup and it just flashed for like 5 seconds and went away and i never saw it again for another year or so?? the light flashing did not happen at all for the first 4 days after the tuning so why would it now start after the my tuner tuned it? I would ask my tuner but he is out of AZ for another week!

 

A flashing CEL that doesn't throw a code is unreal. The flashing CEL indicates a misfire and that can be very bad. I would not drive my car with a flashing CEL for a P0133. I would have it flat bedded to my tuner.

Elmer