Annihilate

iTrader: (1)

Hey guys, I've been chasing down a weird misfire and low blms for a while now.

I've eliminated many things however it still hasn't been 100% fixed.

Here is a quick list of what I've done so far:

Ignition
Cap, rotor, coil, module, plugs, wires. Only thing I haven't done is change the distributor. I plan on taking off the cap again this weekend to take a closer look and perhaps just replace it to eliminate any potential issues.

Fuel
Next I've done fuel injectors TWICE, I've tried the Bosch 3s and then this past summer I've installed the Delphi replacement. Much quieter and a definite improvement.
Replaced fuel pump, sending unit, and filter.

Vacuum
No detectable vacuum leaks, holding a good psi.
all rubber hoses have been replaced, visible hard hose is still solid.

General Tuneup
I've adjusted timing and iac many times, however my most recent iac reset yielded a more desirable performance I am going to go over my timing once more to see if I can detect any difference.

I've also just replaced the o2 sensor.

Question/Theory

I've recently discovered a concept that the AIR diverter check valve can potentially break and cause backflow into the manifolds causing a lean condition? Excuse me if im a bit off.

My blm holds around 113-117 at idle with int around a steady 128 I've also got that slight misfire/afterfire

Id like to eliminate the diverter valve as an issue and briefly read about being able to tube the diverter so everything flows to the cat.

Would anyone be able to break this down for me real quick? Not really interested in removing the whole AIR system right now, just trying to get my car to run as smooth as possible with its stock setup.

One more factor to note, I am running a stock ANYX tune as I've deleted my cold injector. I know this is for a trans am, however the one for my car (APYS?) Didn't seem to run as smooth.

ALSO how hot is too hot for the ECM?

Any ideas or help would be wonderful.
Thanks!

88 Iroc 305TPI 5 speed.

tom3

Might first check or replace the check valves in the AIR pipes. Two in the main lines and one more for the line down to the middle of the cat. converter. Mine were blowing wide open and I was fighting a poor idle for a long time. Replaced those checks and it idles really nice. Not an expensive part if you look around some.

tom3

I later did away with the stock AIR pump and the whole diverter setup, went with an electric pump that runs on cold startup and hardly ever after that. Kind of an involved deal though with that.