Sputter/backfire and sulfur foul smell on heavy acceleration


Asked by Oct 05, 2015 at 08:17 PM about the 2000 Pontiac Grand Prix GTP Coupe

Question type: Maintenance & Repair

Changed iac,maf,tps,fuel pressure
regulator,fuel pump, air filter, fuel filter,
csps, egr, oil change, exhaust
work(mufflers) and ignition module. Got the
car to stop stalling on start and runs great
besides odd idle and foul smell on heavy
acceleration. Only things I haven't changed
are plugs wires, coil packs and injectors. I
cant find an evap leak but line from gas cap
to fuel tank are rusty.

5 Answers


Also have codes p0102, 0440, 0306

1 of 1 people found this helpful.

Sounds like catalytic converter is getting bad.


P0102 is Mass Airflow Sensor circuit, low input. Possible bad connection or bad sensor. P0440 is an EVAP system leak. The system is leaking vacuum. Gas cap is #1 cause for this trouble code. P0306 is misfire on cylinder #6. Do you have an aftermarket air filter, such as a K&N, which requires oil? If so, get rid of it! The oil contaminates the Mass Airflow Sensor. The sulfur odor is most likely the catalytic converter overheating due to the misfiring on cylinder #6. HTH. -Jim

Best Answer Mark helpful

I do have an aftermarket air intake came with the car when I bought it 2 years ago have never oiled it just changed the cone filter on it about a year ago when I did the first maf sensor. I have gone through 2 maf sensors in the last year the second one about a month ago when I changed the iac , tps, and crank sensor. Also cleaned the throttle body while I was at it but didnt check any of the connections so ill take a tomorrow and get a new gas cap. As far as vacuum leaks I haven't been able to find one under the hood any of the times ive checked but im going to put a stock air filter on it and ill get back with the results. Thanks for the answers guy much appreciated!

1 of 1 people found this helpful.

Ok, sounds good. You're welcome. Glad to help. Thank you for the best answer click. -Jim

Your Answer

Grand Prix

Looking for a Used Grand Prix in your area?

CarGurus has 1,896 nationwide Grand Prix listings starting at $3,000.


Pontiac Grand Prix Experts

  • #1
  • #2
    Tom Demyan
  • #3
View All

Related Models For Sale

Used Chevrolet Impala
370 Great Deals out of 27,543 listings starting at $1,499
Used Pontiac Bonneville
342 listings starting at $2,000
Used Chevrolet Monte Carlo
953 listings starting at $3,786
Used Chevrolet Malibu
635 Great Deals out of 48,775 listings starting at $1,500
Used Pontiac Grand Am
756 listings
Used Ford Mustang
294 Great Deals out of 38,678 listings starting at $1,995
Used Chevrolet Camaro
257 Great Deals out of 30,437 listings starting at $4,200
Used Nissan Maxima
223 Great Deals out of 18,273 listings starting at $1,500
Used Pontiac Firebird
5 Great Deals out of 656 listings starting at $4,999
Used Honda Accord
565 Great Deals out of 92,859 listings starting at $1,495

Used Cars For Sale

2008 Pontiac Grand Prix For Sale
285 listings starting at $3,995
2007 Pontiac Grand Prix For Sale
270 listings starting at $3,800
2006 Pontiac Grand Prix For Sale
331 listings starting at $3,900
2005 Pontiac Grand Prix For Sale
256 listings starting at $3,000

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.