02 Grand Prix SE 3.1

cool02grandprix · 03-07-2007, 07:48 AM

Hey there everyone.....This is my first post....

My problem is my 02 grand prix se 3.1 liter, my car starts perfect, idles perfect, just when I give it gas, it bogs down very bad, it will not rev above like 2000 rpm. I hear a lot of air , its just louder than normal. I inspected for leaking vacum lines, none. I pulled off upper intake, just to look, found a leaking injector, So I replaced all injector o-rings, upper intake gaskets and throttle body gasket, plugs and wires.. Put all back together, still same problem, I rented a code scanner from Auto zone, No codes in computer at all.

Help I need my car back.....Please...

cool02grandprix · 03-07-2007, 07:55 AM

By the way, the car has 114,000 miles on it......

GPFred · 03-07-2007, 09:04 AM

Have your catalytic convertor checked. Even though you are not getting a code set, it could be going bad. Did this just start occurring recently?

cool02grandprix · 03-07-2007, 09:16 AM

Yes, it did, I have had the car for 1 year now, never had any problems, good gas mileage and eveything you would wish forin a car

All the sudden on Saturday morning, I drove it in the morning and it was fine, drove it again that after noon and BAM, it was bad.

Thanks for the reply

GaryFenza · 03-07-2007, 09:31 AM

your car might not be getting enough air/fuel. Hows your airfilter and fuel filter???

cool02grandprix · 03-07-2007, 09:43 AM

changed fuel filter a few months ago, have a k & N air filter, I keep clean. But even with the air filter box opened up it still does the same thing.

What I don't understand is it starts perfect and idles fine around 700 rpm

I can give a little gas, up to about 1500 rpm and its fine, as I go higher is starts to bogg down and surge

Brian

cool02grandprix · 03-07-2007, 10:04 AM

Ok New Update....

I just let the car idle for around 30 minutes,

checked the codes again with a scanner and got

P0300 Random/Multiple Cylinder Misfifes Detected

I cleared the code and did the above again and same code.

I did change the Plugs and Wires on Saturday when all this happened. Still same problem. So that should rule out Plugs and Wires.

But remember it idles smooth and starts fine, first turn of the key,,eveytime

tblake · 03-07-2007, 10:36 AM

check for an exhaust restriction.

cool02grandprix · 03-07-2007, 10:54 AM

Went out and check the exhaust, I have plenty of exhaust......Exhaust does not smell, which I have smelled on cars with bad cat conv.

Thanks

Brian

indyram · 03-07-2007, 05:56 PM

Not likely the problem, but check to make sure all the plug wires are seated correctly and on the correct cylinder.

cool02grandprix · 03-07-2007, 09:50 PM

All plug wires are on correctly and seated.............

Thanks

Brian

corning_d3 · 03-07-2007, 10:56 PM

Quote:

Originally Posted by cool02grandprix

All plug wires are on correctly and seated.............

Thanks

Brian

Then pulling the plugs and checking them out would be a good idea.

cool02grandprix · 03-08-2007, 06:14 AM

Brand new plug and wires.......

the car starts fine, everytime, smooth idle, but will not rev above 2000 rpm without bogging down

Brian

corning_d3 · 03-08-2007, 06:44 AM

Y said you hear air. Think you might have an intake tube loose or torn? Did you have to remove the intake when you did the plugs? I doubt it but you never know..

BNaylor · 03-08-2007, 09:19 AM

Based on these symptoms you can run two simple tests.

#1 - Fuel pressure check at the rear fuel injector rail to make sure it is in specs an not a fuel feed problem. At least rule it out.

#2 - With an automotive vauum gauge (0-30 in hg) connected at the uppper intake manifold check engine vacuum. If the exhaust is restricted or CAT convertor clogged due to a defective end cone you will see the results. Baseline vacuum check is at idle to verify vacuum is good and then rpms are increased to 2000-3000 rpms. The gauge will fluctuate and then settle out. If vacuum is good settle down to a range of 15-22 in hg. With a clogged CAT or restricted exhaust the vacuum will decrease below specs and drop off towards zero.

Several models of GM "W" body cars ('01-'02) had defective CATs from the factory causing the symptoms seen and P0300 random/multiple misfires. GM extended the warranty to 10 years or 120K miles, whichever comes first. So do not wait too long with your mileage. We had a few SE 3100 owners that had bad CATs and GM decided to test and replace it free of charge or waived at least 50% of the cost. I would not rule out the CAT convertor.

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