Recently purchased a 1985 Camaro 2.8L TBI. Car was parked for a couple of months as it started to sputter and backfire thru TBI. Idle seems to smooth out at higher RPMs. Drove it home without too much problem. Haven't dug too deeply into the car yet, but I recently discovered that when idling for a few minutes and with the car backfiring at times thu the TBI, the cat converter was glowing red hot.

Could this be cause of backfiring (clogged) or effect of backfiring

Thanks.

gene

 

If the manifolds or cat is glowing red then yeah its clogged.

 

That is NOT the cause you are looking for. First off, are you talking about a FI motor or a carb'd motor. F-Bodies never had a 2.8L TBI engine installed, only the S10/S15's did.

The glowing cat is from excess fuel going down into the cat, which is at about 600*F, and burning, setting fire to the substrate, and eventually melting/clogging the cat. VERY BAD PROBLEM.

If you are popping and firing out the intake you either have a valvetrain problem or an ignition problem. As long as no one messed with the car before you got it, like did a timing chain or something, then immediatly had the problem start, then I would look at the upper part of the valvetrain. Most Likely lookin' at a burnt intake valve or a broken intake spring. For some reason, fire is getting into the intake section.

The red-hot cat is not your cause, but an effect of something else going wrong, but if left untouched, will become a seperate problem all by itself.

 

Thanks for the info. And I stand corrected as it is MP FI, not TBI.

G

 

did the v6's have mpfi in 85?

 

yep, the 85 had the mpfi. It was the same year that nice little tpi setup also came out for them bigger engines. Lucky year. Check out the tech data section -> very useful for these sort of questions

 

TPS Throttle Positioning sensor is my guess.

 

Do a compression check on all the cylinders. That will tell you if you have a burnt valve or broken spring, at least it should. The key is to have about the same compression in all the cylinders.

Then check timing. Is your spark bright white, check/change plugs.

 

Cat is probably now shot although not the original problem especially if OEM.