PontiacBonnevilleClub.com

Vehicle: 2002 Grand Prix GT
Mileage: 234,000

I need help diagnosing a loss of power issue that just started occurring 3 days ago. It is very intermittent, the car starts up, idles, drives fine when the engine is cold. After it warms up it will run normally, no issues to be found. However, every once in a while it will start to hesitate and lose power, the tach bounces between 0 and 2000 rpms and it gets to the point where it wants to die. Most of the time it will catch itself and run fine again, other times it will just die altogether. It will do this in park or in drive, idle or at cruising rpm. The Check Engine or Service Engine Soon light does NOT come on when it acts up.

I have checked and cleaned the MAF sensor. I've slowly moved the throttle up and down and cannot detect any dead spot with the TPS.

The only engine parts replaced on the vehicle ihave been the alternator, water pump, idler pulley, Coolant Temp Sensor and Coolant Temp Sensor Pig Tail

I hooked up my scanner and no current or stored codes appear.

Do any of you 3800 gurus out there know where I should look next?

It sounds like a bad maf to me, but It could be coil/ICM related. You might want to see if you can get a known good maf to swap in and see if it improves.

x2 does sound like the MAF even if you cleaned it.

Also might want to check out the oxygen sensor on the rear manifold. If it is running fine when cold, those 2 things work together when warmed up.

That's what I was afraid of that it might be the MAF sensor. Unfortunately I do not have any extra known "good" MAF sensors lying around since I've never had to replace one up until now.
My wife said that it didn't matter if the car cold or warmed up, it would sporadically hesitate and catch itself again. Last night it acted up the worst and actually died on her. She got it started again but then it would want to cut out at higher rpms as she was trying to get it home.

The Delco O2 sensor is about 2 years old.

Cat.

I'm thinking the cat as well, does it seem to be getting worse since it started acting up? This sounds alot like the symptoms my Alero started with. Plugs, wires, coils are also something you will want to check I think.

I ended up taking it to a GM garage to have it looked at. Within about 20 minutes after dropping it off they pin pointed the problem. A cracked MAF sensor. Apparently when the mechanic wiggled the sensor the car would die. He showed me a different way of checking too. He lightly tapped the top cover of the MAF sensor while the car was idling, every time he tapped the cover the car would stall and recover. So I have a new sensor on order, it should be here by tomorrow. Hopefully it doesn't get damaged in transit.

How much did GM want for the sensor? Haro's not that far from you, could maybe meet you in Sauk Centre...

00Beast wrote:How much did GM want for the sensor? Haro's not that far from you, could maybe meet you in Sauk Centre...

GM wanted $250 for the sensor and $150 for installation (1.5 hours @ $100/ hr).
I ordered one online this morning prior taking it in just to have one on hand. Final cost: $124 for the sensor (online) and $111 for the diagnostic test (dealership).

Holy sh*t! That's a lot! Andrew would have been way cheaper. Is that for a GM one or aftermarket? Always avoid a dealer if possible, yea they know what they're talking about but it comes at a hefty price.

I bought a new AC Delco one online at half the price the dealer wanted. Yeah, i usually avoid dealer garages as much as possible but they were the only one that could squeeze me in today to have it tested.

Had the same thing go wrong on my Regal this week - intermittently stumbling all over the place at partial warm-up, sometimes dying too. I paid $92 via O-Reilly's for one.

How could they possibly justify 1.5 hours to install a maf? It takes like 15 minutes tops

It only takes 15 if you include running to town to the hardware store to buy the right bit! Jesus. What dealer is this?

It takes an hour just to figure out why your torx bit isn't working on the bolt because you need a security torx...

Clearly that's all that I can think of?

Unless that's an across the board time for a MAF whether it's in the intake ducting or not lol

Installed the new sensor tonight. So far everything is running normally *knock on wood*.
On a side note, I've noticed that the vapor canister purge valve was making a really loud clicking noise, is this normal?

Yes, that is the solenoid. Normal operation.