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Engine has no power

M

Midgethockey

New member
Its a 99 Pontiac Grand prix GTP supercharged. It changed all of a sudden with the load noise and then barely made it home.

It started about 4 weeks ago. Engine light came on telling me cylinger 1 misfire after a hard weekend of driving. As long as I didn't stomp on it you wouldn't know there was a problem. When you went to pass, car would not accelerate. I changed the spark plugs, wires, air/fuel filter and light went out but power was the same. Going home one day I stomped on it and then there was a loud growl and then the car would only go 30 miles an hour. Once you RPM's reach 3500, the car just dies. There was a grinding noise from the supercharger so I changed the supercharger with a rebuilt and still the same. Changed camshaft sensor,crankshaft sensor, and mass air flow sensor and nothing has changed.
I have disconnected O2 sensors and it does not make a difference. I have scanned it many times and it usually just comes up as mis fires. It seems to idle fine but as soon as you rev it up over 3000 it begins to die and the back on the motor smokes.

Please help
Thanks
 
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Well, whats the make, model and year; and is there anything else on the car turning on or acting weird? I need to know as descriptive as possible, exactly what the car is doing and if possible the history if anything significant happened to it in its lifetime. Thanks
 
did you hook it up to a computer? ignition module? engine rough at idle? supercharger still making grinding noise?

I think local AAP has computers they can lend you.
 
I have disconnected O2 sensors and it does not make a difference. I have scanned it many times and it usually just comes up as mis fires. It seems to idle fine but as soon as you rev it up over 3000 it begins to die and the back on the motor smokes.
Thanks
 


Please hook the O2 back up. That will make diagnosis harder. All the misfires point to an engine issue. Check the oil level and look at the oil for any silver streaks etc.
 


Do you still have a catalyic converter? Sounds like a clogged cat to me. Have someone revv the car while you hold your hand in front of the muffler. If you barely get any gases or its really cool then your cat is bad. If you had a timing chain jump a tooth then it would run like **** all the time. Just think about the smoke at the back of the engine. Sounds like congestion because even with 5 cylinders you should be able to rev it over 3 grand.
 
Does your TCS light come on? I had the same symptoms like no power after 3500rpm and such, and after repairing the shorted TCS wire, my GP worked like a charm.
 
load noise or loud noise? Where any of the plugs bent when you pulled them out? It if changed all of a sudden with a load noise your piston could be screwed on the cylinder that is misfiring.
 


Thanks to everyone's input, my car is still not running. I am going to disconnect the converter and go from there to start. If no success, I am going to start on the timing chain . Does anyone know of a good web site for directions how to change a timing chain on a 99 grand prix?
Thanks Again
 
Loss of power under load sounds like it could be failing coil pack(s) to me. As for grinding noise, did you check the pulleys? Could be worn bearings.

I just had a couple pulleys replaced recently and at least one was making a mild grinding noise. It wasn't too noticeable except when I lifted the hood, but I suspect it would have gotten much worse, had I not had them replaced.
 
Sounds similar to what happened to my bro-in-laws Monte Carlo a week ago. It ended up being the cat. The dealership replaced it for free since he was under 80k miles.
 
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