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No engine power above 2-3K?

S

scottm

New member
Hi all, I have seen similar issues reported by others but the resolutions seem to vary so if anyone can point me in the right direction I would appreciate it.
My daughter complained that her 2001 grand prix was driving "funny". When I finally got to drive it myself it seemed to be starving under a load. If going up a hill it would shift down but not be able to turn more than 2500 rpm or so even stepping the pedal down all the way. Engine seems to rev fine in park. Problem only happens under load. She had the SES light on. She didn't know how long it had been on. There were several codes regarding the EGR and maybe one other. Since she didn't know how long the light had been on I cleared them and drove the car to see what would come back in. The only code that reappeared was P1404. I replaced the fuel filter. Had access to a cheap used but known good fuel pump so I replaced that also. No difference. I removed the EGR. It didn't look too bad but I went ahead and cleaned it up, made sure the pintle moved easily, reinstalled it with a new gasket and did the "reset the sensor position" procedure mentioned in other posts. The SES hasn't reappeared but the engine power problem remains. After reinstalling the EGR it seemed as though the power had improved slightly but still not normal. I do have access to an autotap and a laptop so I can monitor sensors while operating but I don't really know what conditions to look for. Any ideas?
Thx
Scott
 


Check for misfires, bad cat is a very real possibility with an 01 L36, and it will cause misfires, mine were mostly on cylinder 1, but happening on others as well.
 
OK, I was differentiating between the SES light on the dash as opposed to the actual associated code that has to be scanned. I understand you can't have one without the other. The question remains though, wouldn't cylinder misfires cause a "SES misfire code" to be posted?
 


It's possible it won't.

Check your coil packs. I had one go out and it felt like the car was just shuddering anywhere above 2000 rpm's. IT was the coil pack. No SES. Also check your sparkplugs and make sure they are not cracked. Just go over everything.
 
Thanks for all suggestions. I will pull the plugs and possibly replace the wires but it doesn't "feel" like it's missing any on any cylinders. It just won't "go". Is there any good method of testing coil packs without spending $50 per pack to find out? Thx again.
 
I test the coil packs by removing the boots on the packs VERY VERY SLOWLY, you should hear the spark, DO NOT TAKE THEM OFF, BECAUSE YOU WILL GET SHOCKED. When you do this make sure the boots can still arch, but again do it slowly, because getting shocked sucks pretty bad and will make you jump.

As to the EGR, I know the other engines (3100) have an issue with the EGR passage needing to be cleaned out, I don't know if the same problem exist on the 3800
 
Well, replaced the plugs and wires, no difference. (What a pain, old wires were practically welded on to the plugs.) Also completely blocked the EGR holes as a test to verify it wasn't a stuck open issue. No difference.
Strange thing is it only happens when accelerating after 2500 or so. Parked I can rev it over 3000 and no issues. If it was a bad coil pack wouldn't it be missing regardless of the engine load?
I drove it for a while with the pedal all the way down at 2500 or so and it finally threw a P0300 code. (multiple/random misfire).
If it is the cat is there a way to verify that with the OBD monitor? O2 sensor readings?
Thx
 


Thanks. I had seen that same cat service issue on another thread so I went ahead and took it to the dealer. It was already scheduled for a factory recall repair. Unfortunately the car is at 140k so it's technically excluded. However if they come back and say the cat is bad I will try and get them to go halfway on the replacement. If I can't I'll take it somewhere else rather than pay dealer prices. Thanks again.
 
Thanks to all suggestions. Dealer indicated that it was indeed the cat. Unfortunately I am over the 120k limit for a GM paid replacement so I'll have to bite the bullet...
 
Well, since you're going to replace it... Why don't you buy a 2.5" Catted downpipe from one of the vendors? You'll end up spending as much or more if you let the dealer sell/install a new one.
 
I just changed out my cat and bought it at autozone with the downpipe for $200, you can just get the cat itself for about 80, just need someone to weild it on for you. As to changing the cat yourself, it you get the direct fit bolt on, its pretty easy, just make sure you have wd40.
 


^^ Was that a stock DP? What a waste of money. Should have gotten a larger catted downpipe for the same price, if not cheaper, especially since you had to have it welded in...ZZP's are direct bolt-ins.
 
DanGTP said:
Well, since you're going to replace it... Why don't you buy a 2.5" Catted downpipe from one of the vendors? You'll end up spending as much or more if you let the dealer sell/install a new one.
Click to expand...

I'm certainly not having the dealer do it. I just had it in to get a recall done. They wanted $640. I laughed. I'm having a local muffler place replace it for $225. It's my daughter's car, has no tuning done to it. I'm just trying to get her back on the road. Thanks for the suggestion though. If it was mine I would probably do the 2.5.
 
Glad you got it fixed. I bought my 01 GT for a steal because he thought the trans was bad when it was really a bad cat. GM did mine though...112k.
 
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