Question about 2003 Pontiac Grand Prix

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My tach floats while under load 2003 grand prix what would cause this?

While driving down the fwy at constant speed or under acceleration load, the tach will drop out to about 2000 then float back up to 3000 rpm. this happens without shifting into overdrive. what could the possible problems be?

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  • 61 Answers

Sounds like a tcc issue in the transmission. some times it can be fixed with an ecm flash. often it is a bad tcc solenoid inside the trans. valve body.

Posted on May 08, 2014


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Posted on Jan 02, 2017

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SOURCE: My grand prix, shifting problem.

sounds like you need to check your throtle position sensor first. that will cause this can go to autozone they cancheck it with a scanner. hope this helps you out . Phil

Posted on Jan 17, 2009

  • 15 Answers

SOURCE: 2000 Grand Prix does not shift into overdrive.

Could be a solenoid, there are solenoids accessible thru the bottom pan that control shifting functions. Do you have a check engine light on? If so An OBD2 scanner can tell you what code was set.

Posted on Mar 12, 2009

  • 61 Answers

SOURCE: 2000 grand prix w/auto transmission wont shift into overdrive

some of the trannys has straps in them that sometimes needs to be tightened and that could be the cause of it

Posted on Mar 24, 2009

  • 158 Answers

SOURCE: 2001 Pontiac Grand Prix Gt not shifting into OD

this trans is the 4T65E. It needs a 4th clutch hub. The splines strip off around 120k or more because they weren't hardened from the factory. The new ones have the hardened splines. The trans needs to come out and be partially torn down. I've fixed alot of these. Change the EPC solenoid while you are there. They wear and hang up causing intermittent harsh shifts

You can drive them forever without changing the hub but you'll never have 4th gear

Posted on Apr 02, 2009

  • 12 Answers

SOURCE: Hesitation and slight rpm drop at idle and while driving.

it is possible there is a soft vacuum line. try looking behind the maf sensor [attached to the air filter box] on the right side near the plenom next to a blue connector. it's a small piece of hose that is looped from one vacuum circuit to another. I have found them to get very soft and **** air.

Posted on May 19, 2009

Testimonial: "The problem seems to be less consistent now. Guessing maybe there is still a vacuum leak somewhere else. Thanks for the tip :)"

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I have a 00 pontiac grand prix gt and I dont know why my car hesitates when I am accelerating. Also I can feel and hear my engine bogging down like it wants to shut off esp when I am stopped or driving...

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In my 2005 grand prix in the front end when i accelerate there is a clicking noise when i first accelerate. Any ideas of what could be causeing this?

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Sep 09, 2010 | 2005 Pontiac Grand Prix

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signal for a moment

Jan 19, 2010 | 1998 Pontiac Grand Prix

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Trac on/off switch

This switch is for your traction control system. The system is there so that your tires do not spin under acceleration. It is supposed to help maintain better control of the car on slippery road conditions. For the average driver it is best to leave the system on.

Oct 23, 2009 | 2003 Pontiac Grand Prix

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I have a 98 grand prix 3.8L and sometimes it's hard to start. then sometimes going down the road the tach goes to zero and the speedometer starts swinging while the car is trying to stall.

If the vehicle cranks normally when not starting check the tach see if it is reading any engine speed. Sounds like the crank sensor is going bad very common fault on the 3800 series 1 & 2 engines. You must remove the harmonic balancer to replace the sensor.

Apr 09, 2009 | 1998 Pontiac Grand Prix

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Engine misfires under load when warmed up. Replaced all six injectors and problem persists. Tach and speedometer both go gonzo when accelerating/rounding curves. Lowell, MN

check the mass air flow sensor, does it idle back and forth between 500-1000 rpms? if yes mass air flow sensor is the problem.

Apr 07, 2009 | 2002 Pontiac Grand Prix

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