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2002 Grand Prix GT PCM Tune

Musclecarguy

Musclecarguy

New member
I have a 2002 Grand Prix GT which is mechanically stock with visual mods. I had a Mustang that was written off a couple of years ago that was A LOT faster than this car. I enjoy driving this car when its cold cause it is peppy. But soon as it warms up I loose all guts. Was looking into getting an aftermarket tuned PCM and am trying to figure out if it is worth it. Am I going to notice a difference? Don't want to spend a lot of money and the car is getting up there for mileage so I don't need a 10 second car, but want more pep all the time. Hopefully someone out there can clarify if its worth while and what brand is better. I've heard ZZP is hit and miss and that Overkill is decent, but I can't get on the overkill website. It says it won't open. All input is appreciated.
 


Really don't want to put lots more money into the car. Got house Reno's now and later on I want to get something else. Just trying to get some more pep from my car for now. Like I said when it's cold it's fun to drive. I want to replicate that.
 


Honestly a complete tune up would probably make it feel like a new car depending how long ago its been from its last one.

Sent from BFE
 
New plugs and wires a couple years ago. New filter this summer. Regular oil changes. I've been keeping up on maintenance.
 
Ya. Maybe 2 or so years. I don't put many kms on my car every year. And the car runs fine just loses some umph when it's hot outside. When it's cool weather or when car is cold it runs excellent. Noticeable power difference.
 
I highly advise you not to run it hard when the motor is cold. That is the worst thing to do to a engine.

The oil is not up to temp, the coolant is not up to temp, the engines fail safes are not alive yet. It's like pumping chocolate syrup when it's cold, thats not good for the bearings.

The reason is feels quicker is because when it cold like that, the engines knock sensors are not "alive" yet as the motor is still in open loop aka warm up mode. When they do come on, it will pull some power away when you give it the beans because it senses spark knock/ping and pulls timing to save the motor from damage.

You can run 91+ octane fuel to make it knock less and perhaps get a slightly better pep in it's step but without doing something intake wise like a HV3 and like a 3in downpipe, nothing will really do anything.
 


I've heard that the exhaust for gp are able to handle up to 300hp. And intake is an option. I thought the N/A cars were OK for knock. It was the S/C engines that were bad for knock
 
The NA motor knock more than a supercharged car, but N/A's don't have boost pressure to deal with. So really the knock isnt as bad but any knock can be said to be bad as it takes away power. It's nothing you can change as GM designs all stock motors to run this way, it's how they keep them safe for anyone to drive. They just pull timing to take away some power and keep things safe.

If you watch scanner with knock retard you'd likely see 8-10 degrees of knock with a L36 motor. Run some 91+ octane and will come down a little bit.

The exhaust AFTER the cat converter can handle 300whp easy. The factory downpipe is really small and the factory u-bend for the rear o2 sensor makes the pipe even smaller to like 1 and 7/8th compared the normal 2.25in pipe.


And you are right, the intake is a option but I was talking about a HV3 insert. It's a aftermarket part that goes inside the intake manifold to help with air flow into the motor. It's a good upgrade for NA cars.
 
How do you install the hv3 insert. Is it easy? I'm pretty hands on. Also I think I already have the U bend delete
 
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I don't know where you're getting the whole GT's knock more than GTP's thing at, really.

All cars tend to suffer from this at times, but I've never seen one do what you're describing.

I've seen cars that can net over 200 whp on a L36, so you can get power out of them.
 
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I'm assuming that the 200whp L36s you speak of have more mods than just a tune though? Otherwise share your secrets with me. :O XD
 


I didn't do the tune on it, but it had a cam with headers and HV3, I wanna say it was somewhere around 220 to be closer.

The point is, I they don't knock as much as stated AFAIK, if they did, you'd see a lot more 3800's in the scrap pile.
 
FWIW my N/A sees anyway from up to 7-13* of KR at WOT, but a lot of that I think has to do with my shot to hell lower mounts as at the top of 2nd i see little to no KR. But I see a decent bit of part throttle KR spikes once i hit 3rd up to 6* + at times. Which i believe to be false also. This is just what I've noticed.

Sent from BFE
 
I've read elsewhere that a guy put one on his car without any other mods and he said it felt slower. And that this mod is more noticeable if you do other mods
 
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