2000 granx prix gt going through mafs?

[dcobra22322]

Hi guys,

I have a 2000 grand prix gt non sc with arount 190k miles on it and to this point its been a grear car. The last 3 months it has broke down 3 times each time throwing a code for the maf sensor.

The first time i replaced the maf sensor and all was well and it made it 2 months with no problems and the car responed as it always has with plenty of power. Then one day while driving out of the driveway it the eng rpms started fluctuating up and down randomly from idle to 3k and finally it cut off and would not start again. Yet again my scanning tool showed a maf sensor code and when i looked at the actual reading on the maf sensor it was zero while trying to strt the car.

So i get yet another maf sensor. 2 days later my wife says it has died on her again and I go out to her hook up my scanner. The car would start and stay running but for a short amount of time only if you feathered the gas. I checked the maf sensor data and it was reading 40 or so at idle which i know to be way high as normally at idle its around 6. So i replaced it yet again and car has ran fine for the last 2 weeks.

Last night the wife made it 5miles from the house and she said it just started losign power and got sluggish and while turnign around to come home it cut off. luckily it started again and ran poorly on the way home with less than adequate power. I went and started this morning and all seemed fine. The maf readings were normal the IAC TPS and all read normal through 3k rpm.

The codes I pulled were

P0171
P0420
P0128

Im out of work due to major back surgury and cant afford a costly visit to the dealership and i normallly do all my repair work myself but this one is puzzling me.

[Couch]

the first 2 codes are related to catalyst performance (o2 sensor or clogged cat)

2nd and 3rd codes can also be related to the coolant temperature sensor.

i would try crawling under your car and seeing i there is any discoloration on the exhaust near the cat as well if the connector to the oxygen sensor is still connected.

while your under there bang the cat a few times with a hammer it could be clogged up.

if that doesn't help i would try replacing the coolant temperature sensor. it's inexpensive and not too hard to change. i've added a picture below to show you where it's located.

i would try these steps. clear the codes. and see if any come back.

[dcobra22322]

Thanks for the great reply and I will change that temp sensor out since that is easy. Thanks for the pic as well it was helpful.

As for the O2 stuff i kinda figured one of them is bad because a few years ago we had a fuel pump start giving low pressure and with it runnign lean the cat clogged up i guess due to heat? Any how the Cat is no longer anythign but a strait tube as i cut it out punched out the honeycomb and rewelded it back in.