Question about 2002 Pontiac Grand Prix

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I have a 2002 Grand Prix GTP and i am having trouble with the supercharger. Most times only getting 1/2 boost on the guage and it runs like a regular 3.8l - the supercharger will ocasionally kick in but always sporadic. Plenty of oil in the supercharger and the belt tensionner is fine. Any ideas as to what the probelm might be?? Sometimes I am only getting a 1/4 boost

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Check the vaccuum lines to the super charger boost control valve located on the back of the supercharger closest to the air cleaner opposite the pully. If you are not getting vaccuum to the boost control colenoide follow the vaccuum hoses back to the boost control switch and check for engine vaccuum at the switch.

Posted on Aug 02, 2009


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Transmission Compatibility

As you see I provided you the models you can apply the transmission :The 4T65E-HD (code MN7) is a heavy duty version of the 4T65-E used with more powerful engines such as the LS4 V8 and L67/L32 supercharged V6. Applications: 2.93:1 MN7 Pontiac Bonneville SSEi L67 Chevrolet Impala L67 Chevrolet Monte Carlo L67 Pontiac Grand Prix GTP/GXP Buick Regal GS Buick Riviera L67 (97-99) So ,yes you can!

May 28, 2013 | 1998 Pontiac Grand Prix

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I got a 2000 pontiac grand prix gtp the car runs well but the boost level will not go more than 1/4 on the gauge, one mecanic said to change the spark plugs because they are 4 or 5 years old (iridim...

The spark plugs have absolutely nothing at all whatsoever to do with boost levels.

However; change them anyway because new plugs are always better. In the GTP, don't use the iridium plugs, use copper core. I highly recommend Autolite 605's, gap them to .055"

In the GTP, spark knock is a common, performance robbing issue because of the supercharging. You'll lose 5-6 horsepower for every degree of timing ****** that the engine computer will employ to prevent the spark knock. If you use copper core plugs though, this problem will be less likely because copper dissipates the residual heat much faster than iridium, so that only the electrode spark alone can be hot enough to ignite the fuel. The only other difference between the plug types is how long they last. Iridium plugs were the originals only because they last longer...they offer no performance benefit to the GTP.

Now on to your actual question.

There only a few causes for loss of boost pressure in the GTP, all of which are an easy fix.

Supercharger belt slip, disconnected or damaged boost bypass valve hoses, or maladjusted boost bypass valve linkage.

The easiest thing to do first is the boost bypass valve adjustment. This will produce results even if you DO still have belt slip or a leaking hose.

Locate your boost bypass valve. You will find it mounted directly in front of where the throttle body bolts into the intake plenum.
You will see that it is held in place by three bolts. Loosen them in this order; left, right and rear. You will find that you'll need a 4" extension socket to reach the rear one. Hold your socket on that one while you push down on the valve body. As you may notice the mounting bolt holes are elliptical, allowing for the height adjustment. You can use this as a visual reference for how far to push the valve down. You shouldn't push it down all the way, only about a half an inch will suffice.

What the adjustment does is reduces the amount of throttle opening needed to produce boost, by shortening the travel length of the valve lever that is attached to the throttle. When properly set, it will allow about 11 to 11.5 PSI at wide open throttle, or just short of wide open throttle. In any circumstance you may also notice that your GTP is a little quicker from a standing start after the adjustment.

Jun 26, 2011 | 2000 Pontiac Grand Prix

1 Answer

Would replacing a power steering pump in a 2002 Grand Prix GTP Supercharger cause the SuperCharger belt to break.


The supercharger belt is on the main drive, the water pump is on the accessory drive. Provided that they are both properly installed of course.

Jan 14, 2011 | 2002 Pontiac Grand Prix

1 Answer

I have a 2002 Pontiac GTP.I have noticed today on the Interstate that the booster is not performing when i give gas to pass somebody,any idea what the problem could be?


Oct 06, 2010 | 2002 Pontiac Grand Prix

1 Answer

2000 Grand Prix GTP supercharger fluctuates when accelerating

There is no wastegate.

Change the spark plugs and pay special attention to the plug on bank 3. Look for physical damage on the electrode...cracked, bent etc.
Use Autolite 605's copper core gapped to .055" and NEVER run less than 92 octane.

Apr 02, 2010 | 2000 Pontiac Grand Prix

1 Answer

Supercharger troubleshooting????

Check for a vacuum leak from the inlet and outlet hoses on the boost bypass valve and especially the boost solenoid.

Aug 03, 2009 | 1999 Pontiac Grand Prix

2 Answers

Boost issues

No leak, it may be time for a service to your supercharger. There is maintance that most people don't know about and the bearing to the supercharger's wear out and then has play. The bad things is with the play the lobes in the supercharger starts to rub against the housing and then the tolerace clearance is larger then when the car was new. Long story short, time to have your supercharger rebuilt before it fails and kills the engine too. There is an other way you can look in too, here is there web page Good luck

Apr 07, 2009 | 1998 Pontiac Grand Prix

1 Answer

Serpertine belt diagram

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Oct 19, 2008 | 2002 Pontiac Grand Prix

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