99 Grand Prix dies randomly

big bearz fan · #1 06-06-2007, 08:15 PM

My daughter has a 99 GP GT 3800 with 112,000 on it. Lately it has been dieing on her at randon times. No codes. The crankshaft sensor was replaced about 35,000 miles ago. it has a new fuel pump and filter. Could the crank sensor be bad again? What about the fuel pressure regulator?

Tonyr · #2 06-06-2007, 08:28 PM

Check the O2 sensor. Had an older Grand Prix that would die driving down the road. Put it in park and restarted it right back up again. It would die every once in a while. I changed plugs, wires, and fuel filter before finally someone figuring out that it was the oxygen sensor.

big bearz fan · #3 06-06-2007, 08:54 PM

Wouldn't an O2 throw a code?

richtazz · #4 06-07-2007, 05:54 AM

Welcome to AF big bearz fan.

Does the car die only when you slow to a stop, when the car is cold, warmed up, totally randomly, etc.... A little more specific info would help a ton here.

big bearz fan · #5 06-07-2007, 11:37 AM

It is totally at random. I has started and died 1st thing in the morning, after driving an hour. It died twice while I was monitoring the fuel pressure, and both time were when I turned my back or walked away for a minute. It started right back up. The fuel pressure is about 42-44psi while running. 2 days ago it died right after she started it and it would fire back up. Took off a plug wire to check for spark, it fired up.

BNaylor · #6 06-07-2007, 02:51 PM

It would help to post what your fuel pressure is at fuel pump prime (ignition to on only) and while engine is running at idle with the vacuum line disconnected at the fuel pressure regulator. By comparing readings you can determine whether the fuel pressure regulator is the cause or if it really is a fuel supply problem.

When the engine stalls what does the tachometer do and do you get any ABS or TRAC OFF lights? Also, to rule it out disconnect the MAF sensor and see how driveability is.

eippermx · #7 06-08-2007, 12:08 PM

Quote:

Originally Posted by big bearz fan

It is totally at random. I has started and died 1st thing in the morning, after driving an hour. It died twice while I was monitoring the fuel pressure, and both time were when I turned my back or walked away for a minute. It started right back up. The fuel pressure is about 42-44psi while running. 2 days ago it died right after she started it and it would fire back up. Took off a plug wire to check for spark, it fired up.

I'm having a deja vou (hope I spelled that rite) moment after reading this thread.

big bearz fan · #8 06-19-2007, 08:32 PM

Well the problem didn't go away. I changed the fuel pressure regulator back on the 8th of June and it has ran fine until tonight, 6/19. She said the "Trac Light" did come on right when it died, but she didn't look at the tach. What does everyone think? Another Crank Sensor?

eippermx · #9 06-19-2007, 08:58 PM

Well I just went through troubleshooting this type of symptom with my '99. (Thanks again Rich, GTPDad, forum)

Try these two easy things.

1. Disconnect the MAF sensor located on top the throttle body. Drive the car and see if you can duplicate the problem. It seemed to me that my car ran better with the MAF disconnected.

2. If it still dies, re-connect the MAF and disconnect the MAP sensor located on the top/front of the engine near the coils.

My car it turns out had a bad MAF sensor that was causing it to die suddenly and of course was throwing no codes.

BTW, don't discount that crankshaft position sensor. Especially if it wasn't replaced with a GM/OEM unit. You might want to consider it as a possibility for your GP's sudden death syndrome if it was an aftermarket part.

Also have you check the grounds at the battery? At the block?

BNaylor · #10 06-19-2007, 09:07 PM

Quote:

Originally Posted by big bearz fan

She said the "Trac Light" did come on right when it died, but she didn't look at the tach. What does everyone think? Another Crank Sensor?

Based on the symptoms (trac off light) after stall it sounds like a classic crank position sensor problem. Not uncommon to have one go bad again especially with the warmer weather. Sometimes hard to tell watching the tach but a second or two before the stall the tach reading will dip or be erratic.

big bearz fan · #11 06-19-2007, 09:10 PM

I never considered the ground at the block. The CPS was replaced with a NAPA not a GM. I will try the MAF & MAP tomorrow. I is really impossible to duplicate what it is doing, because there is no pattern. Hell I thought I had it fixed after the fuel pressure regulator, like I said it was fine for almost 2 weeks that is close to 1000 miles of driving. Oh well the hunt continues. Thanks for the pointers I will see what I find

eippermx · #12 06-19-2007, 09:42 PM

Your symptoms are EXACTLY what I ran into that were caused by the MAF sensor.

Check out this thread:
http://www.automotiveforums.com/vbul...d.php?t=712348

masseyj · #13 07-05-2007, 09:19 PM

where is the crankshaft sensor located on the 2000 grand prix gtp

masseyj · #14 07-05-2007, 09:21 PM

every so often my rpm needle will go down to 0 and stay there and my engine light comes on and stays on for a few days, does anybody know what the problem could be

BNaylor · #15 07-05-2007, 10:01 PM

Quote:

Originally Posted by masseyj

where is the crankshaft sensor located on the 2000 grand prix gtp

The crank position sensor is located behind the crankshaft harmonic balancer. See link below located at our Tips & Maintenance forum which has a tech procedure for replacement.

http://www.automotiveforums.com/vbul...d.php?t=652664

If the SES/CEL light is on best thing to do is get it scanned with an odb-ii scan tool.

And welcome to AF.

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