drjimmy

I just had a 94 camaro engine rebuilt. The car starts fine but will not rev past 1000rpm with my foot to the floor or part throttle. I dropped my y-pipe to test for plugged cat - didnt help. I plugged all my vacum lines - didnt help.
Computer is not sending any codes. Data from scanner appears to be inline but I am not an expert. Anybody have a clue? Could a bad coil do this?

Slowmaro95Z28

Is it holding steady at 1000 or is it breaking up really bad like it has a miss?

drjimmy

It actually holds at 1000rpm. Sounds like it is bogging like it cant get enough air. No restrictions in the intake. Took the air box right off.

Slowmaro95Z28

If the motor was just rebuilt check every connection. Make sure no sensors are left unplugged and take it from there.

C5042081

iTrader: (5)

sounds stupid but did the throttle cable break, check if its connected to the TB also look to see if the Tb is opening

Slowmaro95Z28

That's also a good idea. Try revving the motor by hand from under the hood.

drjimmy

The throttle cable is fine. I have reved it from under the hood. Throttle position sensor also indicates 100% when stepping on the gas. An unplugged sensor should give a code. Really strange bug.

dhdenney

iTrader: (53)

Like it shows 100% all the time? Or when it's actually WOT? Shows 0% when closed and everything in between?

drjimmy

Yes, shows 100% at WOT and 0% when closed.

transam5.7lt1

iTrader: (18)

Low fuel pressure? It will not throw a code for a low fuel pressure condition. Check your fuel pressure regulator, if the diaphram inside the regulator is broken, fuel pressure goes back to fuel tank via the return line, if thats the case, not enough fuel pressure is build in the injectors, showing a similar condition as you mentioned.

drjimmy

Fuel pressure is 40psi at idle and 45psi under load.
Replaced ignition coil - didnt help.

transam5.7lt1

iTrader: (18)

Even at that fuel pressure, if you have a bad fuel pressure regulator, not enough fuel pressure will build in the injectors.

drjimmy

Not really. The fuel pressure is measured at the fuel rail which is at the same pressure as each injector. The regulator bleeds off pressure to the return line. If the regulator was defective, you would see little pressure on the rail.

drjimmy

Pulled the valve covers off and reset the valve lash. Still no good. Running out of ideas.

mattdb2377

Try checking something as simple as the plugs (gap, boots, etc) My car wouldnt rev past 1k with 3 plug wires disconnected and fuel cut off to another 2 (animal ate a bunch of wires!!!) Maybe the guy who rebuilt it gapped them wrong or messed up the firing order. Throwin out an idea for ya.

Scrapin'4.8

iTrader: (3)

maybe cam was installed 180 out???

dhdenney

iTrader: (53)

Would it even run with cam 180 out? I don't think it would run.

ThoR294

iTrader: (6)

pressure doesn't mean much, you gotta have a flow tester as well to test the flow of the fuel.

Whats the MAF reading and your MAP/BARO readings also when you revv

drjimmy

Baro is 29"hg when reving and idle
Maf is 12 at idle and 18 when reving
iac counts is 160 at idle.
Knock retard is 0 deg at idle
spark advance is 15 deg at idle
rpm is 450 and req rpm is 800.

drjimmy

How can I test the injector circuit to see if they are actually opening. The injectors themselves were tested prior to installation.