The idle sounds fine but when the car warms up it won't rev past 3000 rpm before it bogs down to almost shutting down. I let it cool and restarted it and it seemed to rev better but still had the problem. I replaced the opti twice, so I really don't think its that. Also put new plugs and wires. Does anyone know whats causing this?

 

sounds like the cat has seen it's last day, when you rev all that extra flow cause s to much back pressure and kills the motor. cut a hole in front of the cat and the car will drive just fine.

 

sorry forgot.. its a 94z28 6spd, pretty much stock so far. I wish I could figure out a way to diagnose the problem, Ive scanned it and everything, no codes came up..pple on here have mentioned, egr, fuel pump, coil. But why wouldn't any codes come up on the scanner? Judging by the symptoms ive described above has anyone had this same problem and knows what it is?

 

Yea my brother had the same problem with his car and it was the cat an easy to tell is when it warms up does the exhaust get quiter or did on my brothers(slp loudmouth).
IT would not rev above 3grand and also it did not have any power at all.


But you can un bolt the y pipe and crank it up and see if that is your problem.
if so you can either gut the cat or you can get a high flow cat put on.

 

here's the thing..when its cool it seems to rev up like normal, but when it gets hot it bogs when I rev to about 3000 rpm, it also overheats..

 

Replace the cat.

 

Its unanimous...THE CAT HAS TO GO!!!.. thanks alot..I'll update you all on how it runs after I replace it..

 

Just pull the y- pipe and then crank the car up and see if it is the cat first
and if it is then(this is only for off road vehicles)disclimer but get a pry bar and stick it in the cat and get a bfh and beat all the honey comb material out and they you go no more cat.

BTW what year is your car and were do you live?
becasue if you have to get emmisoins test then you are going to have to replace it with a high flow or a regualar cat to be able to pass emmisions.

 

I'm in Cali, its so strict here with emissions and all.. ill probably put a new stock cat on just so I can pass. If I didn't have to get it smogged id gut the cat and run it. I really hope its just the cat because I have no idea of what else it could be since no codes show up on the scanner..