2002 Pontiac Grand Am Very week and drinking gas.

Tiny
PAULTL80
  • MEMBER
  • 2002 PONTIAC GRAND AM
Engine Performance problem
2002 Pontiac Grand Am 4 cyl Two Wheel Drive Manual 70k miles

This all started a few months ago, with it running like my tail pipe was clogged.

Very slow, revving up to 3 or 4 RPM while driving, unable to get above 45, drinking gas, and running VERY rough. Idling very low. It normally idles just under 1RPM when warm. It now idles just under 1/2RPM.

Looked under the car and saw the front and back of the CAT was glowing red. My father had a spare CAT, from a V6 Oldsmobile Silhouette Minivan. I had a local muffler shop install that. (Note: I am aware that this is an over sized CAT for this car, it was free.)

Still running the same way, but a bit better. Had the code read. It showed a multiple miss fire code.

Pulled off the "coil pack" off the top of the engine and test fired the spark pluggs(after buying new plugs). Only the 2nd and 3rd was sparking.

Purchased a new coil pack, same thing.
Purchased a new control module(the thing that screwed into the coil pack), all plugs sparking, pute everything back together and Problem SOVLED!

For a few weeks.

Started running the same way agian with the Check Engine light on agian. Took it up to the local auto shop. The code read "Catalyst System Efficiency Below Threshold". P0420 OBD-II Trouble Code.

Cleared the code, the car started and drove home like it was brand new. For about a week.

Same code agian. Replaced the O2 Sensor after the CAT, cleared the code, drover perfect for about 2 months.

Drove to work on 8/12 Tuesday, ran just fine but a bit sluggish. Went to lunch and the car was running back the SAME EXACT way agian.

Reset the codes, but this time it didn't fix anything, the code showed up agian within one minute and was running the same way.

Now it's in the back yard while I drive another car to work this week.

I read somewhere that I can try cleaning the Mass air flow sensor, unplug the battery for 10+ mins, and that may reset everything. (Sound's a bit too easy.)

Any ideas?
Does this car have an O2 Sensor before the CAT?
MAS Sensor issue?
Do you
have the same problem?
Yes
No
Friday, August 15th, 2008 AT 11:05 AM

4 Replies

Tiny
MERLIN2021
  • EXPERT
So you are getting a P0420? Replace the converter with the one for your car, an old cat from a different car will fix nothing. Especially for an efficiency code. Go to Chevy and see if your car has a flash update for the PCM, some models did for this problem.
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Friday, August 15th, 2008 AT 12:59 PM
Tiny
PAULTL80
  • MEMBER
Sorry, that was a typo. The CAT was new and unused.
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Friday, August 15th, 2008 AT 1:33 PM
Tiny
MERLIN2021
  • EXPERT
But not for your car? For a larger engine? Still check on the reflash with chevy, have your VIN ready!
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Friday, August 15th, 2008 AT 2:29 PM
Tiny
HMANMGT
  • MEMBER
I was told that there is a sensor in your wheel bearing that if your wheel bearing is bad ocationally you might hit a bump which sends a faulty signal to your brain box that causes it to fire wrong and blow the ignition control module I checked to air in my tires and as long as I keep them aired up all the way this does not happen when it gets cold out and the air in the tires goes low it will trip it every time the wheel bearings are $119.99 at autozone that is why I have not replaced them but I have found that they do unplug right behind the rotors so try that it has worked for me. You will probally need to get a new ignition control module first because your old one is blown again sorry for the bad news hope it works for you also I know it sounds crazy but the 2.2 L has had this problem for years from what I have been told it is a peace of junk
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Tuesday, October 21st, 2008 AT 1:21 PM

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