Help if you can????

[J.S.]

I have a 92 Grand Prix with a 3.1 motor. I just finished replacing all the gaskets and am now trying to get the kinks out of the motor. It starts and runs well. But if I give it a hard rev it will die. My guess is that its a plugs and wires problem or maybe even the coil pack, For some reason it looks like a common problem. also I here an airy sound coming from the intake manifold which might have something to do with it. Basically when I smash on the accelerator the motor makes a sound like the exhaust overloads. Any help is appreciated.

[richtazz]

If you're revving it hard in neutral/park, the rev limiter kicks in at about 4k, so that may be normal. Why would you not change the plugs and wires while you had it torn down? They're so much easier to reach. The "airy" sopund you describe sounds like a vacuum leak. Check for any vacuum lines you may have forgot to re-connect.

[J.S.]

Coulnd't get back to the computer till today; but to update everyone. I installed some new plugs yesterday. There was no change but I am able to explain the problem a little better. Once the car is started it idles at about 2 on the rpm gauge. This is higher than it idled before the gasket installation and we think it's due to a bad idle sensor or egr vavle. That is our main problem. We are trying to find a way to idle it down. Secondly when I start it and gradually press the accelerator to the floor it revs fine, but if I smash down as if I'm trying to spin the tires the engine stalls out. To be more clear, when I smash the eccelerator the motor missis and make sthe sound I would compare to a trans downshiftin and then dies. So like a reverse vacumm type stall.

[richtazz]

The high idle still points to a vacuum leak. It's possible you forgot to hook a vacuum hose back up, or you cracked one of the hard plastic lines. If it didn't idle high before, I doubt it's an IAC or EGR issue.

On the 92 Vin-T, there is a vacuum block, with 3 lines by the throttle body. One goes to the MAP sensor and FPR, one goes to the transmission vacuum modulator, and the 3rd goes to the HVAC system via a vacuum storage "ball" located at/near the firewall. Check to see if your heater controls switch from floor to vent to defrost (they are controlled by vacuum).

Also, that engine uses a metal valley pan intake gasket. Did you install it dry, or did you spray it with spray tack as you're supposed to? If you didn't coat it with spray tack, you have a manifold vacuum leak.

[J.S.]

Gotcha..but what about the engine dieing when I smash the accelerator. Is that also caused by a vaccuum? Or does the motor need to build pressure before it's smashed on again. Thanks though

[J.S.]

I just got through applying the gasket tack to the plenum and hooking evrything back and wanted to let everyone know what happened. Basically it is doing the same thing. The airy noise has quieted but the motr still is dieing when I smash the accelerator and the idle is still high as it was. I checked the plastic lines and found no leaks...oh I forgot the hvac panel trick so maybe it is still crack. Tommorrow I will do the panel test and see what that does. My only problem now is the high idling and the motor shutting off when I smash the gas.

[tblake]

Tazz said that the valley gasket needs to be sprayed with tack. Did you spray the upper intake plenum gaskets or the lower intake gaskets?

Could also buy yourself a can of carb spray and with the motor idling, start spraying anywhere you might suspect a vacuum leak and listen for an increase in rpms. Spray around the upper intake gasket, lower intake gasket, vacuum lines and fittings and fuel injecter o-rings.

[J.S.]

I sprayed the plenum, both sides and the intake surfaces and thread bolts. I will try the carb spray idea. Any more suggestions?

[J.S.]

To update everyone I found a egr and throttle body leak using some carb spray. I replaced both egr gaskets and the throttle body gaskets and took the car for a drive. The idle got a little better as I drove but I couldn't give the accelerator any gas without the engine dieing. I stopped at a couple buddies shops and they all said it was a vacumm leak. One said that it may even be the fuel pump that is making the motor shut down when accelerated. I haven't been able to locate this leak at all. Maybe I need to take the intake up and spray the entire line. If anyone can cancel out this being a fuel problem let me know.

[richtazz]

check the vacuum line at the FPR (fuel pressure regulator) for raw fuel. If it is present, the FPR diaphram is leaking and could be causing both your funky idle and bad WOT performance.

[J.S.]

Canb you tell me where on the motor to look for the regulator and diapragm. thanks for the idea too.