02 Grand Prix SE 3.1

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

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. :banghead:

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

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

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?

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

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

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

:banghead: :banghead: :banghead: :banghead: :banghead: :banghead:

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

:screwy: :screwy:

check for an exhaust restriction.

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
:banghead: :banghead:

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

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

Thanks

Brian:banghead: :banghead:

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

Thanks

Brian:banghead: :banghead:

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

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

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


Brian

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..

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.

Ok I will try that,,,,,,What should the fuel pressure be at the rail./.

Brian

Ok I will try that,,,,,,What should the fuel pressure be at the rail./.

Brian

Fuel pressure will vary depending on the year of your Grand Prix and engine size. For GPs with the SII 3800 VIN "K" and "1" the target is 48-55 psi at fuel pump prime (ignition to on). Then you will have different readings at idle because vacuum is connected at the fuel pressure regulator (FPR). So you will remove the vaccum line at the FPR and reconnect and then review a total of three readings. Further, this will test the fuel pressure regulator located at the front fuel injector rail (driver's side) in addition to the fuel pump pressure.

The fuel pressure on GM cars with the 3100/3400 60 degree VIN "J" and "E" engine is most likely going to be higher than above. Also, it is a good idea to have a new fuel filter if it has not recently been replaced.

Here is an Actron fuel pressure tester connected to a 3400 VIN "E" and the reading at idle is well over 55 psi.

http://i5.photobucket.com/albums/y186/lizzywiz/alerofp.jpg

I had this exact same problem on my 2000 GP before and the dealer thought it was the cat converter, which was still under GM's 8 yr/80,000 mile warranty on exhaust. So they replaced it, after 3 days of agonizing wait due to them ordering the wrong cat:screwy: , and I drove it home. And they forgot to put the donut back on...I sounded like a diesel going down the road!

However, I still had the problem. I had also changed the plugs and wires recently. Same code too, come to find out I had 2 bad coils, generating no spark to the cylinders, thus multiple misfires! Replaced them and away I went.

Hope this helps!

Ok here I go


I went and got a vacuum tester

results
----at idle I had about 14-15 in hg.

----reved to 2000 to 3000 rpm vacuum decreased to 10-13 in hg..

and once idled back to normal around 15 in hg.

and one more thing, with the car starting so good and idling almost perfect, is there any chance of a bad coil pack....the post above this one had the same problem and his was 2 bad coil packs.....

also bricker82 a question for you, How was your start up and idle?


Thanks

Brian

It was a normal startup and idle after the cat was replaced. Just the same thing when I accelerated, bogged down with minor shaking!

Just to be sure what brand spark plugs and ignition wires did you install?

BTW - The vacuum reading at 2000 rpms is abnormal but it is hard to say whether the coils are having the effect on your low engine vacuum problem.

You can check coil primary and secondary resistance with a DMM or use coil tester.

I ran this test at 1500 and 2000 rpms respectively so you can run a comparison. Engine vacuum held steady at least 18 in hg and stayed in the green area at both rpm ranges. Your reading is way too low. See below. Idle was 16 in hg.

http://i5.photobucket.com/albums/y186/lizzywiz/test_01.jpg

ok I went and got a vacuum tester like you have.....

at idle I get 13-14 in hg
rev to 2000 to 3000 and it drops to basically to about 0 (zero) and then at idle back to 13-14 in hg

ok I went and got a vacuum tester like you have.....

at idle I get 13-14 in hg
rev to 2000 to 3000 and it drops to basically to about 0 (zero) and then at idle back to 13-14 in hg

Basically we can only give you advice. The decision on what corrective action to take is yours. Based on what I see on the results you have exhaust restriction. Your vacuum readings are definitely abnormal.

Once you have ruled out misfire cause by ignition or a fuel related problem I would seriously consider getting the CAT convertor tested and replaced.

Just an update on my Grand Prix


Ok I removed my cat, and replaced it.

The engine runs awesome now,,,Has more power now than when I bought the car.

I rechecked my vacuum and it is perfect at idle and 2-3k rev..

My car also runs cooler now, I was having overheating problems before

I just want to say thank you to all the people who helped with the advice, I would have been lost without your help...

I ended up just spending $300 for a new cat and 2 new O2 sensors and put it on myself....

Thanks again......:grinyes:

Bnaylor is right! I thank him for this post. I have been searching for this same problem on my car.

I saw this post. I checked the vacuum on the engine. It went low as soon as I would touch the gas pedal. I drilled a hole in the exhast pipe on the inlet side of the cat converter and used my bore-scope to look at the converter. It was plugged. Replaced converter and it runs great.

I also know that this is an old post, but if anyone reads this in the future, please know that even though there appears to be good exhaust flow, you still may have a very dirty catalytic converter.

I also had a difference in temperature from the gauge on the dash, to the scanner temp. The scanner would read 186 and the gauge on the dash would go over 210. I figured out what was causing this. It was that the gauge sensor is located in the end of the cylinder head and the computer sensor is located in the block. The heads were getting hot due to the restricted exhaust.