Ok folks, Gotta big issue and I want to know if anyone out there has had the same one and may be able to shed some light. Ive got a pretty stout LT1 in my '94 Trans Am. I have only put about 5k miles on it since the rebuild about two years ago. The car has recently began acting up almost as if it has a spark issue yet the plugs,wires,Opti, ICM, Ignition Coil, and MAP have all been replaced. The TPS is newer and has been set to .67. The issue is when I accelerate the car surges and shudders but does not backfire, it really only does this under heavy loads such as quick acceleration or climbing a hill. At first I thought it was a fuel delivery issue until I pulled the plug to the MAF and the car went into limp mode and seemed to run a bit better than with the MAF connected. Ive dumped a whole lot of money into this thing and just want it to run..................any ideas would be great.

 

Could be a cat cloggin up on you. Does it still have the issues when you're running it in speed density? Also, how're the O2s?

 

Maybe I missed it, but is it throwing any codes?

 

Not throwing any codes. Still acting about the same in speed density mode and there's no cat. So I'm kind of lost as to what issue I'm looking at...

 

Try running it with the O2s unplugged. Even in speed density mode, the computer relies on input from them to adjust the a/f mixture.

Also, check your fpr. On the right side of the intake, There's a vacuum hose that goes to the regulator at the back of the engine. Pull the line off the manifold and if any fuel comes out or it smells like gas, there's your problem.

 

Unplugging the MAF puts the car into SD mode which is not limp mode. Most people do away with the MAF and tune for SD.

 

dirty MAF????? clogged injectors? maybe a dying fuel pump????

If it's none of those either clean the O2 sensors or replace them outright..... could be feeding bad data to the PCM causing it to go lean or rich.... if it's bucking but not backfiring sounds like a lean condition...

 

That sounds like a fuel issue to me. Do you have a fuel pressure guage inside? If not, you can just get the test guage, attach it to the schrader valve in the fuel rail and just temporarily tape the guage to the outside of the windshield for testing while driving.

You said unplugging the MAF only made it run "a bit" better, right? I recently had one of my MAF wires break but the car didn't act like you are describing. It would want to die at idle and slow speed. Unplugging the MAF made it run fine.