Engine Surges

My sister has a 1992 Crown Vic. It surges whenever it idles. Sometimes it stalls at stop signs. She just had the spark plugs changed, and it still going on. Whats up?

check your fuel filter if it needs changed change it but it might be the fuel injectors too so have it checked out

My neighbor has a 94 Crown Vic. that had a surging problem at idle while in gear. I could hear a hissing sound that sounded like it was coming from the idle air control motor. If I sprayed carb. cleaner around the idle control motor it would rev up. I finally found a large hole in the rubber hose that runs on the back of the intake manifold. The hose runs just under the grey fuel line that connects one injector rail to the other. Once this was repaired the the engine ran 100% better. I hope this helps.

My neighbor has a 94 Crown Vic. that had a surging problem at idle while in gear. I could hear a hissing sound that sounded like it was coming from the idle air control motor. If I sprayed carb. cleaner around the idle control motor it would rev up. I finally found a large hole in the rubber hose that runs on the back of the intake manifold. The hose runs just under the grey fuel line that connects one injector rail to the other. Once this was repaired the the engine ran 100% better. I hope this helps.
Replace the idle air control vlv, attached with two screws on the throtle vlv box. Guarenteed George

The Idle Air Control (IAC) valve is causing your concern. It is located at the rear of the engine, on the LH side of the maniflod, and it is accesable from the top. About $60 at the stealership.

I have the same problem. I just replaced the idle air control valve, and it didn't fix the problem. The hose going into the air control valve intake was cracked also. I repaired it by attaching a hose to the end and connecting the hose to the air control intake. I'm 99% positive there the seal is good and there is no leak on the line, but I'm still having the same problem. I can hear a hiss that sounds like it's coming straight from in the air manifold on the top of the engine, but I trace the lines and I can't find any vacuum leaks. any suggestions?

There is a plastic vacuum tee at the passenger side rear of the engine, it can break and cause a vacuum leak. That *usually* does not cause surging, but it could.

thank you, I will have a look at it tonight or tomorrow and let you know the result.

had the same thing on a '93 p71, it was that T on top the intake, the back cracked, i took some silicone sealent let it sit over night now its good as new, i need to replace it though the silicne gets ya by for awhile.