Posted by: swamper8
rev limiter - 03/28/07 02:22 PM
1999 Grand Prix 3.8L Non-supercharged
While in park, is it normal for the engine to hit the rev limiter at 4000-4500RPM? Thanks
If I remember right, that sounds like the Crank Position Sensor (CPS). That particular sensor should be bolted into the front (pulley side) of the engine. The others should be able to steer you in the right direction. Welcome to the boards.
Posted by: swamper8
Re: rev limiter - 03/28/07 03:03 PM
Thanks, I've placed a few posts here trying to track down the problem with my intermittent stalling and missing during hard acceleration. One thing I wanted to add was that while under hard acceleration the car will rev all the way to the red line. It's only when it's in park does it max out at around 4000RPM. I thought that might be some type of safety feature Pontiac programmed into the PCM.
THe car misses occasionally during hard acceleration, usually in the 3000-4000RPM range. My next step is to put a scope on some of the sensors while driving and monitoring the signal(s) to see if any drop out during the hesitation. I think I will start with the crankshaft position sensor!
Posted by: RooK
Re: rev limiter - 03/28/07 03:22 PM
It's a GM safety feature. It cuts fuel to prevent high revs in park.
Perfectly normal. You don't wan't to rev a motor very high with out a load on it. The PCM prevents you from reaching damaging rpms. Put it out on the road and your shift point should be about 5800 rpm.
Posted by: ordonez1307
Re: rev limiter - 03/28/07 11:56 PM
thats normal. you dont want to rev that high in park
ARe you sure the car is "missing" at about 40 mph? If you are at WOT and have a stock PCM, there is some lag when shifting out of 1st and into 2nd.
Buying an aftermarket PCM will eliminate this lag and make the shift smoother and more natural feeling.
But if it's not happening at 40 mph at WOT, I'm sorry, I'm not much help.
Originally posted by lonezergling:
[b]ARe you sure the car is "missing" at about 40 mph? If you are at WOT and have a stock PCM, there is some lag when shifting out of 1st and into 2nd.
Buying an aftermarket PCM will eliminate this lag and make the shift smoother and more natural feeling.
But if it's not happening at 40 mph at WOT, I'm sorry, I'm not much help. [/b]
He is in Park and reving to 4k
Posted by: swamper8
Re: rev limiter - 03/29/07 08:53 PM
Well it certainly feels like a miss, not just shift lag. I believe I have hit upon the answer though. I unplugged the MAF sensor on the car. after 20 minutes the SES light came on but wouldn't you know the hesitation has disappeared for 2 days now. tomorrow i'm going to clear the code and plug the MAF back in and see if the problem returns. This problem threw me for a while because no DTC was being set. But based on the fact that it took 20 minutes just to throw the SES light when the sensor was unplugged, I now understand why no MAF sensor code was being tripped when the sensor was intermittently cutting out.
If it's misfiring the SES light will flash while the miss is occurring.
Posted by: JPGTP
Re: rev limiter - 03/30/07 06:26 PM
That's normal for it to do that at 4k rpms. I had the damnest time trying to explain it to my race buddy. It's a safety feature unlike fords...