Thread: 02 GT hesitation/chugging

I've lurked here for a long time and have found a ton of useful info, so I thank you guys for that.

Here's my issue. About 3 or 4 days ago, my 02 GT (about 143k miles) started having problems accelerating. At first it seemed to only be in second gear from about 2500-3000 rpm. The car would seem like it was sputtering or hesitating and having difficulty getting going. During this time you could also hear something going on and off (whirring) in the times when the car was chugging down. In other words, when the issue arises, you'll hear normal engine noise and then a strange noise, then normal engine, then noise, etc...

Also, the shift points seemed to be higher and I was lacking power across the entire range (not a lot but enough to be noticeable.)

This happens mostly when the vehicle is under load; going uphill or accelerating heavily. I unhooked the battery, let it sit, and hooked it back up. That seems to have worsened the problem.

It doesn't trip any codes, but my TCS and ABS light have been on for awhile.

Is there any directions you can point me in that can remedy the situation? I'm unsure if it's engine, tranny, torque converter, catalytic converter, egr, other electronics, etc... Help me please!

Come on, someone has to have a tip. I picked up plugs and wires and plan on throwing those in tonight. I'll update and give any information if it presents itself.

Usually when you have a misfire it will throw a CEL, but new plugs/wires can't hurt. Clean the MAF.

Check for vacuum leaks. Spray carb cleaner around the UIM and all vac. lines while its running and see if the tone of the motor changes.

Have you changed the fuel filter ever? Could be starving for gas under a load. If then engine is sensing anything wrong it may be pulling timing to prevent KR (spark knock), hence the strange drivability.

And if all else fails, it could be a clogged cat. Do the normal maint. items first before jumping to the cat. If all else checks out then we can go down that road.

The cause of the TCS/ABS light is a wheel speed sensor in one (or more) of your hub assemblies. You can have it scanned for free at Vatozone or the like and see what the code is.

So new plugs and wires didn't solve the problem. Would a clogged cat or clogged fuel filter still allow the car to rev freely across the entire rpm range while sitting in park? I've taken videos of the tachometer when the car is doing this, I just have to take a look at them and see if you can hear the noise the car is making while revving. After that I'll post them and hopefully that will help narrow things down.

Thanks guys.

You never mentioned a "noise". Post up the vid and see what we can do.

YouTube - ‪02 grand prix sluggish acceleration‬‏

It doesn't happen on the first acceleration run, probably because I didn't have space to get up to a speed where it would act up. The second one you should be able to hear it clearly. You might have to turn up your speakers a bit though.

I'm going to pull the mass air flow sensor tonight and try to drive it and see how it acts, then clean the thing while I'm at it.

I pulled the MAF sensor connection and drove it. It didn't do the chugging noise or movements but it also didn't seem like it was upshifting until I let off the gas and reapplied. I've got to head to the store to pick up a screwdriver to take the screws out and I'll clean the MAF afterward.

I cleaned the sensor and put it back in and the problem returned. From what I read, this means its the MAF right? I'm going to call Morad tomorrow morning and see if they have one handy and, if not, head over to the local parts store and grab one.

Please do let me know if I've got it wrong though. I'd hate to buy an MAF and not it be the remedy to what ails me.

It does seem to point to the MAF. The lack of upshifting is probably the result of the car running from the stock tables in the ECU since you had the MAF disconnected. Maybe Bill can verify this. I've never tried driving my car w/ the MAF disconnected to tell you for sure.

Hopefully you can get a good used one because a new one is going to be upwards of $150.

I called Morad and managed to get a mass airflow sensor (used stock unit) for 78 bucks shipped. Should be here by Saturday, Monday at the latest. I'm crossing my fingers this fixes my problem and I'll report back if there are any other problems or if it doesn't work.

Well, I put in the MAF and got nothing. Same problems as before. Still not allowing the car to get over 3k rpm before bogging down.

So i managed to get the front O2 sensor out and went for a drive. The idle was a little weird and it actually stalled out in the parking lot when I returned from my short trip, but no more chugging or weird shifting. Is a new catalytic converter my remedy?

Can't delete the cat, unfortunately. I live in Colorado and our emissions are no joke. Sniff and all.

Originally Posted by SeanGTP

Oh bummer. I was going to say gutted, but you said sniff.
Maybe it's time to move? :P

Nowhere I'd rather live that Colorado mate.

I ordered a Bosal catalytic converter earlier today. After looking around and hearing issues with Magnaflow/ZZP cats throwing codes or not passing emissions because of the high flow, I went with what seemed to be relatively stock from my research. 175 bucks shipped. We will see what happens when I get it and attempt to put it on.

Finally got the cat on. My car's undercarriage was rusted as a mofo but I managed to cut off the old bolts and get the new one on. Had to get a new rear o2 sensor too.

Success! The car stopped acting up and runs like a champ now. More power, better mileage. It was a beast to get into the garage (which was my friend's 20 miles away) but everything seems lovely now.

Thanks to everyone who helped. I hope this thread can assist someone in the future when they run into this problem.