Pontiac Grand Prix Forums : Grandprix
 

Grand Prix Forums is the premier Pontiac Forum on the internet. Registered Users do not see the above ads. Please Register - It's Free!

Pontiac Grand Prix Forum - Welcome Register today! Contact us!

Results 1 to 12 of 12
  1. #1
    SE Level Member
    Join Date
    Oct 2017
    Location
    CO
    Posts
    8
    Chats
    0

    Default Sputtering 2005 Pontiac Grand Prix

    Check engine light is on, and has been for months, because of the EVAP system. Codes it is currently throwing are P0300 and P0446.. I'm at my wits end with this car! 205,000 miles on it. It's been sputtering for a few months now. We just put on a brand new cat, at it is gorgeous! We replaced all of the spark plugs and wires and the vapor canister vent solenoid valve. This morning, it started on the 6th try, thankfully. It was super cold, but I have never had it take so long to start. When it sputters, it will do it between 1500 RMP and 3000 RMP. It doesn't sputter all the time. I went a week without it doing anything and now it's doing it all over again. Yesterday as I was leaving work, it didn't sputter at all! I'm pretty sure I also have a fuel leak, as I am going through gas like crazy lately, but I want to get the sputtering under control first. When it does sputter, the check engine light flashes and it seems like it has a hard time revving up, but once it stops sputtering the check engine light just stays solid. Any ideas? I don't want to just keep throwing parts at it as it will start becoming even more expensive!

  2. #2
    SE Level Member
    Join Date
    Sep 2017
    Location
    Arizona
    Posts
    15
    Chats
    4

    Default Re: Sputtering 2005 Pontiac Grand Prix

    that's kinda the same problem I'm having I also have a 2005 gtp mine is throwing p0300 and p0306 ive changed the plug plug wires checked the injectors swaped coils to see if misfire chaged with it did not going to do a compression test hopefully today I think maybe lim gasket but idk let me know what u find out hope fully we can solve r problem together

  3. #3
    SE Level Member
    Join Date
    Oct 2017
    Location
    CO
    Posts
    8
    Chats
    0

    Default Re: Sputtering 2005 Pontiac Grand Prix

    I really hope so too! I need to keep this car running for as long as possible. We were thinking the fuel pump, but we are trying to avoid dropping the tank, so we are looking at other things.

  4. #4
    SE Level Member
    Join Date
    Sep 2017
    Location
    Arizona
    Posts
    15
    Chats
    4

    Default Re: Sputtering 2005 Pontiac Grand Prix

    yea I would like to avoid that to but I defently feel like it has something to do with fuel or spark

  5. #5
    SE Level Member
    Join Date
    Oct 2017
    Location
    CO
    Posts
    8
    Chats
    0

    Default Re: Sputtering 2005 Pontiac Grand Prix

    That's what we are thinking too. But the fuel pressure is okay, but it's on the low side so we're not too sure.

  6. #6
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
    Join Date
    Sep 2009
    Location
    Rogers, MN
    Posts
    20,608
    Chats
    80891

    Default Re: Sputtering 2005 Pontiac Grand Prix

    Figure out exactly what cylinders are misfiring, then diag from there.

    Could be bad wires or a cracked spark plug even a bad coil or ignition control module.

    I'd stop driving it before you destroy the brand new cat you just bought, the unburnt fuel being dumped into the exhaust will super heat the cat converter and melt it down internally if you aren't careful.

    SMGPFC Member #1

  7. #7
    SE Level Member
    Join Date
    Oct 2017
    Location
    CO
    Posts
    8
    Chats
    0

    Default Re: Sputtering 2005 Pontiac Grand Prix

    We have tested all of the cylinders and they are fine. We just changed the spark plugs and wires a few weeks ago. We have checked coils and the ignition control module and all is fine.

  8. #8
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
    Join Date
    Sep 2009
    Location
    Rogers, MN
    Posts
    20,608
    Chats
    80891

    Default Re: Sputtering 2005 Pontiac Grand Prix

    Just because you replaced parts does not mean they are good. New parts can be bad or maybe they weren't AC delco plugs or not iridiums or not gapped right or the plug is indeed cracked if you haven't inspected them again.

    ICM can test good but still be faulty, it's best to swap ICM's with a known running car to rule that kind of stuff out. Though that is not always an option for some.

    P0300 means misfire and the flashing SES light means the same thing with possible cat converter damage, doesn't hurt to go over everything again. Then log the vehicle with a live data scanner to pinpoint exactly what cylinders are misfiring in real time.

    SMGPFC Member #1

  9. #9
    SE Level Member
    Join Date
    Oct 2017
    Location
    CO
    Posts
    8
    Chats
    0

    Default Re: Sputtering 2005 Pontiac Grand Prix

    I'll pull the plugs out tonight and look at them again. I would love to down my car and properly take care on the CAT and not damage it, but it is my only form of transportation to and from work.. What kind of live data scanner would you recommend?

    I just checked the codes again, I currently have 5. P0300, P0449 (three times), P0304. I just checked the codes last night and it was just for the EVAP, but of course now it is showing cylinder 4 is misfiring.
    Last edited by jesspontiac; 1 Week Ago at 03:40 PM.

  10. #10
    SE Level Member GrandPrixGT1's Avatar
    Join Date
    Jan 2017
    Location
    Mount Airy, MD
    Posts
    63
    Chats
    127

    Default Re: Sputtering 2005 Pontiac Grand Prix

    Can you confirm the fuel leak? I wonder if at those RPMs you putting just enough load on the fuel system that due to a leak (would have to be pretty extensive) that the car isn't getting enough fuel. I use an Aeroforce Scan Gauge but just a basic OBD2 scan tool with live scanning will do. I an Autel 519 and works great when I rarely need it. Ive used it more to help friends out then myself luckily.

  11. #11
    SE Level Member
    Join Date
    Oct 2017
    Location
    CO
    Posts
    8
    Chats
    0

    Default Re: Sputtering 2005 Pontiac Grand Prix

    We have almost fully confirmed the fuel leak. We can obviously smell it and see how much I'm going through and how on the low end the fuel pressure is. We're still working on that one.

    I did check the spark plugs and wires last night, all is fine.

    My car did absolutely fine this morning. Started right up and didn't sputter the whole way to work. I'm so confused with this car!

  12. #12
    SE Level Member
    Join Date
    Sep 2017
    Location
    Arizona
    Posts
    15
    Chats
    4

    Default Re: Sputtering 2005 Pontiac Grand Prix

    Quote Originally Posted by GrandPrixGT1 View Post
    Can you confirm the fuel leak? I wonder if at those RPMs you putting just enough load on the fuel system that due to a leak (would have to be pretty extensive) that the car isn't getting enough fuel. I use an Aeroforce Scan Gauge but just a basic OBD2 scan tool with live scanning will do. I an Autel 519 and works great when I rarely need it. Ive used it more to help friends out then myself luckily.
    What whould u look at on the areoforce to know if im getting enough fuel


    Sent from my LGMS550 using Tapatalk

Similar Threads

  1. 2005 pontiac grand prix 3.8L V6
    By BarginBin Deals in forum Bargain Bin
    Replies: 0
    Last Post: 04-26-2015, 03:00 AM
  2. Pontiac grand prix 2005
    By babyboomer in forum Introductions/Noob Questions
    Replies: 20
    Last Post: 01-05-2015, 11:37 AM
  3. Replies: 0
    Last Post: 11-28-2014, 03:20 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •