Question about Pontiac Grand Prix

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Only runs full throttle

Start the car and its full throttle. ive changed the tps and other sensors.. sprayed the motor for vac leak. nothing.. now im stuck and dont know where to go from here.. the car just wants to max out and run as fast as it will go.

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Disconnect the MAF sensor and see if it changes rpm's. Pull off the big boot at the intake. Is the throttle valve wide open? If it is, the throttle body assembly needs cleaning-maybe it is stuck?
Have you scanned for trouble codes?

Posted on Jul 23, 2013

Testimonial: "the codes it threw were tps and 2 evac codes. im pretty sure its not stuck. "


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Posted on Jan 02, 2017

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SOURCE: buick lesabre nightmare

Need to get a scan tool and look at the data stream while it is running for alot more info.Also any trouble codes.Sounds like initially,the engine isn't getting any fuel.I would have a pressure gauge connected to the fuel rail on the engine,so i could monitor the fuel pressure while all this is going on.Items to look at on the data stream would be timing,what timing is the PCM commanding for the engine.Also,have you checked for continuos power feed to the coils during this no start condition,and fire at the plugs while cranking.You could possibly still have spark,but maybe it is extremely weak?I have seen bad ignition switches cause weird problems before too.Many things power up through the ignition switch,just a thought.Have also seen bad PCM's cause strange problems..38 volts is a little on the low side for GM.Usually see those at,at least .50 and up,and rise steadily while pressing the throttle,up to just under 5.0 volts.Potentiometer with 5 volt supply.Vacuum leak can be checked with engine running at a steady idle speed,spray brake cleaner all around the intake manifold and listen for engine speed change.

Posted on Jul 31, 2008

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SOURCE: buick lesabre no start

Hi you have replaced allmost everything ,(try fuel pump relay)

Posted on Aug 18, 2008

  • 2 Answers

SOURCE: my corolla 2000 1.8 dont respond well when i push the accelerator

its a dirty injector

Posted on Apr 15, 2009

  • 74 Answers

SOURCE: full throttle all the time

We actually have a TSB for the drive by wire systems that calls for both a TPS sensor/actuator replacement but it's required that you also do a PCM reflash at the same time. If you put in the new updated part without doing your reflash then you've found your problem.

Take it to the dealer and get the reflash done.

Posted on Nov 23, 2009

  • 4669 Answers

SOURCE: 84 Fiero. trouble starting and runs rough and the surges/stalls

It sounds like a fuel pump. Check the fuel pressure. What size engine?

Posted on Aug 01, 2010

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