I have a 89 Firebird with a 357 Tpi with a mild cam, low temp stat, adjustable fuel presure regulator, and ecm chip. The car seem to fall on it's face about 3000 rpms. The exhaust smell like it's running rich and when you get into the throttle for a moment there is a dark poof of smoke out the pipes. I've replaced the injectors already when I rebuilt the motor. I have the fuel pressure set on the stock setting and the timing a 6 degress. The store I got the cam from said to run at 12 degress but the motor chatter and mid to high rpm so I put it back to stock. Any idea would be great! I'm at a loss Thanks

 

There are so many different things it could be that it'll be tough to diagnose over the internet.

How long has it been acting this way? How are your spark plugs and wires? Are they all connected and in the right order?
How about your injectors? Measure each one and verify the resistance is 14-16 ohms. Any less than 12 ohms and its probably bad. You could also have a bad injector wire.

 

Other than their may be a problem, dont expect the motor to 'wake up' above 3000rpm when everything is said and done.

A stock TPI setup tends to fall on its face pretty fast, if you havent done so, i would be looking into getting some better flowing base/runners/plenum or at least optimizing what you have!

I assume you have already checked for any codes?

Like kevin said, double check the injectors. Though they are new, you would definately not be the first person to have a brand new part be DOA!



Is the car a little hard to start? I might even go as far as checking to see how fast the fuel pressure drops after the pump is off. You might have a leaky injector.

 

There is no code. I relieve that tpi is not going to wake up above 3000 rpm but the car ran a 16 sec on the quarter mile late week. My stock RS is only .2 of a sec slower with a 5.0. Injector check out today