I picked up a '94 Firebird 3.4L auto (140k miles) for a really good deal - seller reported that it had a blown head gasket. I pulled the heads & had them machined. I reinstalled them, with new head gaskets, and all new manifold gaskets, new plugs/wires, O2 sensors, & fuel filter.

I can start the engine, but it won't idle. It'll only run at 2 - 3k RPM. No codes. Is it possible that the injectors are shot (I sprayed them out with spray cleaner while I had them out), or is it more likely fuel pressure?

I hate to start chasing rabbits, if it's a simple problem. Any thoughts?

 

Update:
I checked the fuel pressure, and it's solid 40psi, so that's not the problem. However, after hooking up the fuel pressure gauge, and starting the car, it started OK, and idles, although it's still a rough idle. Revving it to about 2000RPM it runs better. Could be just sitting overnight? The way it's running, if it had a carburetor, I would adjust the idle mixture.

I need to check coils packs. I checked the resistance, per the manual, and they read OK, but I suppose it could be a coil. Or maybe the idle air control? Or is it likely injector issues?

 

You can see if you have a leaky injector by popping up the rail and putting the key in the on position, don't start it though. Then observe to see if any of the injectors are spitting out gas.

 

My 3.4L idled really high too, It was the coolant sensor ... It thought the car was runnin REALLY hot even though I just turned it on...So I replaced that...and The idle was still high (1500RPMs) so I checked out the injectors and they were all junked up...cleaned that and the car was fine!

 

OK, I verified that the coils are firing OK, but it still feels like a fuel and/or vacuum problem. I can't find anyone around this area to service injectors. I did spray them with cleaner while they were out - maybe that wasn't a good idea? I will check the injectors for leakage, as 2000GTP suggested, but that won't indicate clogged (?) I'm about to the point of installing a new set of injectors. but I don't want to get into the routine, and expense, of swapping parts unless I can verify that's the problem.

 

Correct, it wont indicate if they are clogged, but it will indicate if they are leaking fuel, which can lead to a rough idle.

 

Thanks for the suggestion, 2000GTP. I checked the injectors, and no fuel leakage. They still could be fouled. I replaced the IAC, and the cam position sensor, but that didn't help. I also tested the MAP, and temporarily blocked the EGR (at the tube inlet to the intake manifold), and so far all that appears to be OK.

Anybody got any other ideas?

 

I had the same issue ! Unplug the maf sensor and see if the idle drops. If it makes the idle a lot better then change the mass air flow. keep us posted

 

check for vacum leaks and also that all the sensors are plugged in

 

pull iac sensor and tps sensor both are on top of the throttle body if either of them fix your idle issue then you know.

 

Have you done a fuel pressure test on it to confirm good pressure at the rail? Also, have you inspected the fuel pressure regulator for any signs of fuel leakage?

 

ah i know what your problem probably is i bet your injectors arnet seated properly. take a little carb cleaner and spray it around each injector once it starts to ideal nice thats the injector thats not seated properly