THAT SERVICE ENGINE SOON LIGHT COOMS ON AFTER ABOUT 30 MILES OF HIGHWAY DRIVING. I CHECK MY ENGINE ANDTHERE IS NO VISABLE PROBLEM. WHEN THE LIGHT COMES ON IF I TURN THE ENGINE OFF THE LIGHT GOES OFF AND DOES NOT COME BACK. THE CAR IS NOT OVERHEATING. ANY IDEAS?

 

either your gas cap isnt screwed in tight enough. u need tail lamp oil a muffler bearing or

ok ok...sorry......sounds like an emission problem to me...

 

Read the error code stored in the ECM & it will point you in the direction of the fault. Click on the "FAQ" link on the main page & scroll down to "Miscellaneous". It describes how to short the upper right two pins together to read out ECM error codes.

Tim

 

Just takin a stab at it, but my guess is you have an EGR problem my friend.

 

by the way, third gen cars have no clue when their gas caps are on or not!! It is not OBD II. Pull the code, doesn't sound like a big deal

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1991 Firebird
350 L98 (was a 305 TBI)
T-5 transmission
Edelbrock TES and cat back
Accel manifold
NOS
subframes
jegster torque arm
MSD Digital 6
AFPR
Lakewood lcas
hurst linelock
SLP cam
relocated battery
cold air
Hypertech chip
centerforce clutch
poly bushings and mounts
etc..

14.1 @ 99mph with just headers and catback

with NOS and other mods???? twelves??

 

i had the same problem...and my code read that the exhaust was running to lean/rich....once i fixed the exhaust leaks everyhtign ran fine

 

When I had that problem I had to replace the EGR valve.