Hessitation really bad!

About a day or 2 ago my car (2001 Grand Prix SE 3.1 V6) started hessitating really bad and the SES light was showing for a day then went off. I am looking everywhere for a possible solution. One guy told me that it could possibly something called a " Throttle Positioning Sensor". I don't know what it is, I just want it to go away. Looking for all possible solutions besides getting rid of the car. Thanks.

Welcome to AF.

It would help to list your engine size. The TPS is located on the right hand side of the throttle body. Based on accelerator position it sends a feedback voltage to the powertrain control module (PCM) to let it know where the throttle position is. It can be checked with a multimeter if no DTC codes or SES light are showing.

I edited my first post with requested info.

Also, how many miles? When was the last basic tune up performed. Spark plugs, wires or fuel filter? Has been fuel pressure been checked? Has the SES light returned?

IF you have an Auto-Zone/Advance in your area, tell them the CEL came on then went off. They should be able to pull the code(s), even though the light isn't currently on. Get the code(s) and post them here.

Autozone policies vary nationwide so assuming AZ will scan without a SES light is a misconception. All 17 AZs in my area will not scan unless the SES/CEL MIL light is on. Big sign on the storefront too now. Plus you cannot depend on old stored history codes if any. High probability there are none anyways.

OK, when I hooked up the odb-II i got no codes no nothing. I'm going to have the tune-up done today though. When I try to accelerate to quik, the gears don't shift from 1-2 and 2-3 unless I let off the gas a little. Could this be a possible missfire problem? Oh yeah, the SES light still has a mind of its own.

I figured the AZ trip, since it would be free, was at least a worth a shot. Most AZ's around here will scan it if you tell them the light came on and went off. If it's been a while since a tune up has been done, I'd start there. If it's been recently tuned up, since it's a 2001 model, it's possible you have a bad catalytic converter. Without any codes stored, it's just a guess, but a high probability one.

Okay, today i had the tune up done and the mechanic noticed the problem before I could even tell him anything. But anyways he mentioned something about cylinder 6 misfiring or something like that. So am I looking at a pretty costly repair?

What was replaced as part of the tune up? What brand spark plugs and wires? Another common problem on the 3100 engine is the fuel injectors causing misfire. If you are sure the wire and plug on cylinder #6 is good then thats a possibility. Costs will vary if replacing fuel injectors because the upper intake manifold must be removed. You may just need a professional fuel injector cleaning service.

The ignition control module (ICM) and/or coil packs is another possibility. Also, you may want to get the CAT convertor tested since a clogged or defective CAT with a broken end cone can cause a misfire condition. Normally misfires cause the CAT to go bad but GM did deliver defective CATs with certain 2001 - 2002 "W" body cars such as the Grand Prix. Mainly applicable to the 3800 and 3400 engines but the 3100 may qualify.

Hey, you guys are really good! I was given the bad news today that its the Catalytic Converter. Now, should I get a direct fit or universal fit converter and would someone happen to know the price ranges on such a repair? Once again thanks for your knowledge and advice.

What is yor current mileage? The GM basic CAT warranty is 8 years/80kmiles. The warranty extension if applicable is to 10 years/120K miles. Check with Pontiac Customer Service first to see if you qualify or a local GM dealer. All they need is the VIN number. If out of warranty aftermarket CATs like Magnaflow (hi-flow) work fine. Around $55 on EBay with shipping. Installation around $50 - $100. Or you can spend more and get a direct fit or GM CAT. Good luck.

Would a universal fit magnaflow work fine?

can you put a 92 pontiac trans am motor 5.7 and trans in a 83 pontiac gran prix. jaykaro