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2002 GTP problem

I have a 2002 GTP that cuts in and out at about 122 mph. I am at a loss as to what is causing it. For mods, I have a cold air induction, Autolite 104 spark plugs, DHP Ver 1 PCM, and a 3.4 pulley. For exhaust, I have a Catco high flow cat convertor, u-bend and resonator were replaced with straight pipe, along with 2 Flowmaster 40 series mufflers. The only pipe that is 2 1/2 is the U-bend/resonator replacement. The rest of it is stock piping. It starts cutting out at around 123. Before I installed the pulley, it would cut out at 123 then stopped after installing the plugs, but wouldn't hit any higher speeds. Once in a while I would be able to hit 129. After installing the pulley, it is cutting out at 123 again and will not go any higher. I do have an enhanced Autotap if it will help any. If I am correct, wouldn't I have a SES light if I had a true knock retard? I'm at a loss on this one. Thanks

Reply to
Nascar24Rulz
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Do you think the problem is really speed related or is it rpm related?

Reply to
« Paul »

Could be a speed/rpm limiter? I have a '96 grand am that cuts out at

104mph. Did it once and scared the crap out of the wife who wanted to know exactly what I thought I was doing at that speed.... :)
Reply to
Alex Devlin

Hey Johnnie Lightning,

What highway are you on? I'd like to avoid it if possible.

How often and how many continuos miles do we crusie above 122 mph?

========= Harryface =========

1991 Pontiac Bonneville LE 3800 V6 ( C ), Black/Slate Grey _~_~_~297,525 miles_~_~_

~_~_~_~_U.S.A._~_~_~_~_~_

~~~The Former Fleet ~~~

89 Cavalier Z 24 convertible 78 Holiday 88 coupe 68 LeSabre convertible 73 Impala sedan
Reply to
Harry Face

Alex, the reprogrammed pcm has the speed limiter removed

Reply to
Nascar24Rulz

All GM cars since 1993 have a computer program limiting the speed to the speed rating of the tires that the car was assembled with.

This was a particular issue with Firebirds and Camaros with the V8 engine. Two versions were made. One with the Z rated tires which would limit the speed to 149. The other was assembled with S rated tires with a speed limit of approx. 112.

Check the speed rating of the original tires and find a web site that gives you the speed rating of the tires Bob K

Reply to
Robert Klauka

That's ok, this car shouldn't be visiting those speeds anyway. :)

Reply to
Alex Devlin

Why do you want to go that fast? Man, I've had my 2000 GP up to 100 once for about a second on a long stretch of straight highway and that was scary enough.

Reply to
tony kujawa

Bob, the reprogrammed computers (PCM) for the Grand Prix have the speed limiter removed.

Reply to
Nascar24Rulz

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