I have a 1999 Grand Prix GT that stalls out in park when it heats up and won't start back up until it cools off why?

Asked by Mar 04, 2012 at 02:17 PM about the 1999 Pontiac Grand Prix 4 Dr GT Sedan

Question type: Maintenance & Repair

my car starts up fine and idles good. When it starts to warm up it stalls out and won't start back up. If i
let it cool down it fires back up and the cycle repeats it self.

10 Answers

35

There has to be a sensor on the engine that tells the computer your car is running hot and it's cutting it off to protect the engine. Find and replace that sensor, and you'll be ome free.

1 of 1 people found this helpful.
595

It is more then likely your ignition control module or your ECM getting to hot. there is no real good way to check this other then swapping it out with a known working ICM or ECM an other possibility is your fuel pump getting over heated. check your fuel pressure when your car stalls to see if you still have fuel pressure that is with-in spec.

There are a few possibilities i know of, that can show similar symptoms. A plugged exhaust will allow the idle until the engine can no longer force the exhaust out, could be a kink in the pipe, mud in the tail pipe, or last resort plugged catalytic converter. (sometimes the plugged converter can glow red if you get it hot enough accompanied by odd burning smell.) As pbjunkie mentioned it could be electronic but i think it could also be the crank sensor or ignition module, both of which will quit after they heat up, if they are bad. A bad Idle Air Control motor will not automatically adjust itself as demand requires, as well a plugged port in the throttle body may show similar symtoms. Hope this helps. Lastly did you check to ee if engine light was on, if so do have a fault code?

2 of 2 people found this helpful.
65

I agree to the prevous post... see about engine light, then if not it's probably mechical.

595

I know that with the ECM or ICM( Ignition Control Module ) there May not be any kind of trouble codes.... I have worked on many Buick and pontiac cars with the 3800 that had a bad ICM and there were no Trouble codes. Do a process of elimination and start with the cheap stuff Electronics get very expensive.

2 of 2 people found this helpful.
35

i had a older bonneville that did the same thing it was the crank sensor but my engine light was on

400

2000 Grand Prix GT 3.8 non-supercharged engine was randomly stalling when at operating temperature, at any speed, at any rpm, or idling. Ran well when it ran, but RPMs would randomly drop to zero and the engine would stall. Worsening occaisional no-start condition with no spark. All power in the vehicle remained on. Sometimes would start right back up and other times would not start for 3-30 mins. No check engine light and so no codes to pull. No traction light issues which sometimes occur when the crankshaft position sensor is failing. I didn't want to change the crankshaft position sensor because, quite frankly, it sucks. Changed the ignition control module. No change. Changed plugs and wires with no change. Finally decided to change the CPS. After much research and finding conflicting information I compiled a procedure with just the truthful parts I found and it worked beautifully and the car runs perfectly now. The CPS on these cars fail. If you have decided to change yours out it is a $35 part and is DIY with the proper information, which follows, some ingenuity, and some mechanical apptitude: Jack and secure car. Remove passenger side tire and the plastic wheel well. The clips will probably break, so buy new ones at a hardware store later. Number and remove spark plug wires from the ignition control module so the car won't start. Remove the center bolt (15/16th inch head) from the harmonic balancer. Easiest way to do this without a doubt is to postion a flat wrench on the bolt, rest the boxed end of the wrench on the car frame in front of the harmonic balancer, and tap the starter. Remember to disable the car from starting. Bolt will break loose. To pull off the harmonic balancer use a standard harmonic balancer puller, but you will need special grade 8 bolts and washers. 1/4-28 bolts, 3" long, one inch of thread is o.k. Place a short 3/8" extension in the crank bolt hole to protect the threads. Carefully, by hand, thread the specialty bolts through the puller and into the 3 holes on the balancer that seemingly have no threads. The threads are farther in and not visible. Make sure the bolts are straight, and inserted to an even depth into the harmonic balancer. Use washers or the bolt heads will gouge and pull through the puller. I turned my specialty bolts 15 quarter turns into the harmonic balancer. Turn the puller's main bolt that it is pushing on the 3/8"extension you placed in the crank bolt's hole. Balancer came right out/off. Remove crankshaft position sensor shield. Mine was plastic. Spread the teeth that connect the shield to its bolts with a small standard screwdriver and pull/pry just a bit. No reason to remove the shield from the bolt farthest towards the rear of the car. You'll be using thread glue on the main bolt when you put in in so you can use some of that on the shield where it connects if you mess up the plastic teeth on the shield a bit. Remove the old sensor's two bolts, and save the part to torture in fire later. Bolt in new sensor, replace shield. Line up the harmonic balancer with its cotter key deal and start pulling the balancer back on with a torque wrench. To keep the engine from turning open the smalll access hole to the flywheel on the bottom of the car (two bolts). Place vicegrips on the flywheel or wedge something in the teeth. Tighten your glued main bolt to 112 lbs plus 76 degrees. You now have a car you can count on and need not worry about it dying while driving down the road. I love mine now. Just wish someone would have made these all inclusive and accurate directions for me.

11 of 11 people found this helpful.

after reading this, i am 99.9% sure this is my problem! Same exact car, same symptoms, etc. I copied and pasted the above instructions into a quick e-mail message and printed it for myself to follow this weekend. thank you, sylvester2000, for such detailed instructions.

Is there a way of bypassing crankshaft sensor?

10

No. It's a hall-effect sensor that tells the ECU and ICM what speed the engine is turning at to calculate spark advance and air/fuel requirements.

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