I've done alot of work on my Bird and am very close to rolling it out, but I've still got 1 nagging performance problem I can't figure out.

Here is what's been done:
- Cyl Heads overhauled
- Ported TPI Air Intake Plenum
- New O2 sensor
- Removed Smog Pump, plugged outlet on stock exhaust manifold

What I know is right:
- Valve lash set right
- Plugs firing in right order
- Fuel flow not a problem

What is wrong:
- When I hit the gas the engine stumbles as if choking on the air.
- When I pull throttle open, I can hear a major suck of air before the stumble, then it runs fine. (i.e. jerky from a dead stop)

Possible problems (???):
- Could the IAC or TPS be shot?
- Would a vacuum leak or inadequate seal on the Plenum/runners cause this behavior?
- I plugged the smog outlet on standard exhaust manifold, does this have to breathe?

Car specs: 1990 Formula 305 tpi, F engine

Other thoughts?

Thanks, Lance

 

Ok, the silence is deafening. I gave up too and took it to the professionals. Guess what, nothing related to what I've done (yeah, I guess I'm still competent to work on my own car) but it turns out to be the Fuel pump is shot. Only pumping 22 psi instead of 40-47.

I'm outa here.

Lance

 

Wow. You're lucky it was running at all. the specification at idle is 37 PSIG ±3 PSIG, so below 34 is the ragged edge. At 22 you were maybe just dribbling gas out of the injectors. You might want to change oil in case you have raw fuel contamination from gas that didn't vaporize in the normal spray "cone" that the injectors are supposed to produce.

I hope they also changed the fuel filter to keep your new pump happy for a long time. If not, you probably should add that to your "to do" list.