My 1999 grand prix gtp hesitates on acceleration when boost guage kicks in i replaced plugs and plug wires and the mass air flow sensor also cleaned the throttle body out its throwing multiple misfire

Asked by Nov 06, 2014 at 07:33 PM about the 1999 Pontiac Grand Prix 4 Dr GTP Supercharged Sedan

Question type: Maintenance & Repair

my 1999 Pontiac grand prix gtp is running poorly when boost kicks in...it throws multiple misfire codes and nothing else..i replaced the plugs and wires with iridium plugs and mid grade wires also replaced the air filter and mass air flow sensor as well as the air filter what could be the issue....the car idles somewhat normal after it warms up but runs rough when first started in the morning...could it be a cat...or a bad plug or what could cause this issue...as long as I don't push the car it does fine but under high load it boggs down and acts like it misses

4 Answers

60

Almost seems like a vacuum leak, low fuel pressure, or your intake hose not seated properly into the super charger.

60

My fault, typing before I think, intake hose onto the throttle body.

60

It is a 3800 engine ?

3,705

Yes Steve, they are all 3.8s. I did have to have the blower to intake gasket changed on one of my supercharged 3.8s years ago. I can't remember what the symptoms were but if Steve is on the right track with vacuum/air pressure issues that might be another place to look.

1 out of 1 people think this is helpful.

Your Answer

Add photo

Related Questions

  • Hesitation when accelerating 5 answers

    I have 01 Pontiac Grand Prix, the last couple weeks it's been hesitating when accelerating. Spark plugs and wires just replaced, new fuel filter replaced and injectors cleaned too. I took it in tod...

    2001 Pontiac Grand Prix

    -

    Maintenance & Repair

  • It won't boost properly. The Guage only goes half way up and feels weak and almost like hesitates 1 answer

    Hi , I have a 1999 Grand Prix gtp that seems to not be boosting correctly .... Why? I changed the plugs the wires put a new catalytic converter on it . It feels like a misfire kind of but then it f...

    1999 Pontiac Grand Prix 4 Dr GTP Supercharged Sedan

    -

    Maintenance & Repair

  • Tps sensor and mass air flow senspr low voltage. Help gurus. 3 answers

    So I did a cat delete replaced all spark plugs and wires now have a tps sensor low voltage and mass air flow sensor low voltage and random multiple misfires. Could it be something simple or am I ...

    2002 Pontiac Grand Prix SE

    -

    Maintenance & Repair

  • gtp hesitates 3 answers

    i was driving my gtp and got on the throttle about 3/4 while it was boosting it felt like something gave out... now when i drive normal with light throttle its fine but when i try press it so the car ...

    2000 Pontiac Grand Prix GTP Coupe

    -

    Maintenance & Repair

  • Misfire after i changed spark plugs, checked all my coils, and cleaned throttle body? 1 answer

    I put brand new spark plugs and checked all my coils. I also had my throttle body cleaned and still yet it is misfiring. Could it be the mass air flow sensor or an o2 sensor?

    2004 Chevrolet Colorado 4 Dr Z85 Extended Cab SB

    -

    Maintenance & Repair

Grand Prix

Looking for a Used Grand Prix in your area?

CarGurus has 3,715 nationwide Grand Prix listings starting at $1,100.

ZIP:

Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Js08016
Reputation 3,980
#2 Tom Demyan
Tom Demyan
Reputation 2,660
#3 munron
munron
Reputation 2,070
View All

Related Models For Sale

Used Chevrolet Impala
793 Great Deals out of 34,384 listings starting at $799
Used Pontiac Bonneville
5 Great Deals out of 655 listings starting at $1,599
Used Chevrolet Monte Carlo
15 Great Deals out of 1,662 listings starting at $2,000
Used Pontiac Grand Am
1,649 listings starting at $1,995
Used Chevrolet Malibu
1,006 Great Deals out of 85,672 listings starting at $1,995
Used Ford Mustang
362 Great Deals out of 44,486 listings starting at $1,000
Used Chevrolet Camaro
282 Great Deals out of 38,299 listings starting at $1,250
Used Honda Accord
811 Great Deals out of 81,613 listings starting at $899
Used Nissan Maxima
347 Great Deals out of 25,223 listings starting at $1,400
Used Jeep Grand Cherokee
845 Great Deals out of 68,679 listings starting at $864

Used Cars For Sale

2008 Pontiac Grand Prix For Sale
13 Great Deals out of 462 listings starting at $1,200
2007 Pontiac Grand Prix For Sale
5 Great Deals out of 542 listings starting at $3,250
2006 Pontiac Grand Prix For Sale
8 Great Deals out of 605 listings starting at $1,999
2005 Pontiac Grand Prix For Sale
451 listings starting at $5,900