Running weak?

Tiny
PONTIACPEOPLEPERSON
  • MEMBER
  • 1995 PONTIAC GRAND PRIX
  • 3.1L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 95,000 MILES
I have the car listed above SE model. It seems to be running weak, barely gets to 3,000 RPMs when flooring it. It still gets up to speed just I feel like with a V6 I should be thrown back in my seat, lol.

Any ideas? Brought it to the shop for a "tune up" and they cleaned the fuel system and installed TR55IX and 4641 tune up parts.

Seems to run a little better after that but still not enough power. It doesn't stall or anything. Has a little jerk in the idle maybe but very slight. Starts up fine and no check engine lights on.

Would love any ideas or suggestions.

Thanks!
Monday, January 18th, 2021 AT 2:51 PM

7 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Has anyone checked for a plugged catalytic converter? A potential clue is the sound at the tail pipe will be a steady hiss instead of the normal pulsing sound. Your mechanic should have a back-pressure gauge to test for this. It involves drilling a small hole in the exhaust pipe ahead of the converter, then you stick the gauge's probe in there to measure pressure while the engine is running.
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Monday, January 18th, 2021 AT 4:14 PM
Tiny
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  • 5 POSTS
Thank you! I'm not sure but I will look into it. Is this something I should get checked out immediately or am I good to drive it around for now?
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Monday, January 18th, 2021 AT 4:42 PM
Tiny
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  • MEMBER
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I can't hear any hissing, just "glug glug glug etc."
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Monday, January 18th, 2021 AT 5:07 PM
Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
A plugged converter can lead to engine overheating. Another way to check for it is to unscrew the oxygen sensor. Leave it connected to reduce the chance of setting a diagnostic fault code. Also don't unplug it while the ignition switch is in the "run" position. Setting a fault code while working on the system can confuse mechanics in the near future when there's codes set that aren't really indicating a defect or problem.

You might also look at these articles:

https://www.2carpros.com/articles/engine-has-low-power-output

https://www.2carpros.com/articles/symptoms-of-low-engine-power

Low power can also be caused by a timing chain that has jumped one tooth. This starts to be a good suspect at the mileage you listed.

Whether it's okay to drive it depends on what is wrong and if it will get worse. Take a look at this article too:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms
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Monday, January 18th, 2021 AT 5:44 PM
Tiny
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  • MEMBER
  • 5 POSTS
So I figured it out. My floor mat was stuck up under the gas pedal : |

Much anticlimax.

Thank you anyways.
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Wednesday, January 20th, 2021 AT 7:33 PM
Tiny
PONTIACPEOPLEPERSON
  • MEMBER
  • 5 POSTS
Oh, one other thing. The mechanic said I could get some kind of aftermarket sensor to help the car MVAP or MAP or I can't even remember. Any ideas what he was talking about?
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Wednesday, January 20th, 2021 AT 7:34 PM
Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Not sure what he's referring to.

Happy to hear you solved the problem. That would take a while to figure out when you can't see it. Please come back to see us with your next problem.
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Wednesday, January 20th, 2021 AT 9:08 PM

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