help me out??

[CountryBoy]

I think under boost my car is suffering from knock retardation while under full boost. the car has a cold air intake,no catalytic converter,flow master mufflers,and a smaller pulley on the supercharger. I have an aftermarket boost gauge in the car that measures vacuum and boost. The guage measures 20" of vacuum under idle and at full boost it measures about 12psi. This is the second time the car has tried to kill itself when i try to do a top speed run,could it be becuase of the smaller pulley on the supercharger along with the other supporting mods? my other question is how expensive is a stock size pulley for the supercharger and would it be better for me to just go the route of a full aftermarket exaust from the headers on back?? help me figure this out???

[MoarkatsINmuhtrailer]

you have no supporting mods..what size pulley?

[Bio248]

define "kill itself".

sounds like you are hitting the limiter. and you shouldnt have a smaller pulley on the car anyway, you don't have anything done to it to support more boost.

[CountryBoy]

I believe its just one size smaller than stock,and when i let off the gas at the end of the run (117mph) the car just started to shudder and shake and it just runs like it has a nasty misfire. The last time it did this i had to replace the plugs and two of the three coils for the ignition system. would switching back to a stock size pulley and a better exaust system be a better way for me to go??

[Bio248]

your first problem is doing high speed runs.

[Nickell]

might have chipped a piston, or it ate a spark plug

[MoarkatsINmuhtrailer]

stock pulley yes..

the catback has nothing to do with it wanting to die

[DanPrixGTP]

Hopefully your engine isnt already toast.

First off, what size pulley is on there? Regardless, you should NEVER drop pulley sizes without flow mods.

What comes in, must come out.

Making 12psi with stock manifolds and stock everything else, when out of the factory they make roughly 7.5psi~... I wouldn't be surprised if you chipped a piston.

Lets says you're engine is fine though, you got two options.

1: Buy headers and get yourself a tune.

2: Put a stock pulley on (Which is the route you really need to go at the moment).

[CountryBoy]

I want to just revert the supercharger to stock and work on simple bolt ons to help flow,I got the car on a trade for my truck so I'm new to owning a boosted vehicle,I got the vehicle with all the mods already done

[Oxfire]

I got the vehicle with all the mods already done

First mistake. Second was not doing research prior to owning a boosted vehicle.


What everyone else said are all ways to go. Doesn't sound like that engine was maintained very well, you might be better off hitting up a wrecker and pulling a motor from there.

[dsmuts]

If you want to scan for KR I have a scanner.

[CountryBoy]

dsmuts,how far away from lima are you? that wouldnt be a bad idea for me to do. maybe you could help me figure out more of what my problem is

[dsmuts]

about an hour

[CountryBoy]

is a kr scanner something you just plug into the obd2 port like you would a scan tool? I'm familiar with the obd2 port and using a scanner to check trouble codes,I just finished my electronics classes for school at UNOH

[DanPrixGTP]

Put a stock pulley on there and then research.

You need to read up, lots of good information on this site.

Also, google does wonders as well.

Here, let me get you started, read this:
http://www.grandprixforums.net/safel...0-a-67580.html

[CountryBoy]

man i been basically living on this site in my spare time,read that article yesterday and i been researching on google too. I think I'm going to put a stock pulley on and then work on putting a good exaust system in it along with other supporting mods so i can really build this thing up eventually

[dsmuts]

It's a scanguage it'll read KR. Take a pic of the pulley you have.

[coolone]

Cheap mans scanner!!!


If you are using an Android based Smartphone. AND you get this...

Ebay - look for OBD2 Bluetooth thingy... Should be $17-$25 local or shipped direct from China.

Then download the app called Torque and register it $5 is well worth it. You can scan for KR and anything else, reset codes and record runs too. Only thing you can't do is program the PCM. Lol...

[Slick2500]

Don't waste your time on an exhaust system for a stock GTP.

[CountryBoy]

005.jpgthats the pulley on my car for those interested