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Help! High Boost?

HardTail

HardTail

New member
Ok I bought a non running 2000 GTP. Replaced Fuel Tank, Fuel Pump, filter, fuel pressure regulator, MAP, MAF, TPS, Boost Bypass Solenoid and thermostat. Car sat for 4 years looking at the title and Mileage. Got it running. Here is my issue. When I start driving it if I give it any kind of gas the Supercharger Boost cranks all the way up and the car just wont go. If I feather the throttle and keep the boost from engaging it will run fine. It cranks and idles fine also. Just craps out (but not shut off) when you mash the gas. Any ideas? No error codes showing or in the system. Stock GTP right now till I can get this issue fixed.

Been looking over these threads but everything I read is low boost issues or trying to increase the boost.
 


Yeah I'd lean towards exhaust restriction if the car isn't misfiring or anything like that.

A temp gun on the cat could tell you. It would be crazy high at the front of the cat compared to the rear if the exhaust can't flow through it. Or it could glow red at night.
 
x2 on the clogged cat. you can pull the upstream o2 sensor to make an exhaust leak pre cat, if its runs better the cat is clogged up.
 
I was thinking maybe the converter but wasn't sure. I will unhook the exhaust in front of the cat this weekend and see how she does and if that fixes the issue. That makes more sense of why she is trying too run hot also.
 


While it's out you can go ahead and replace the probably rusted out resonator with a cheap glasspack, or replace the probably rusty mufflers with some QuietFlow or even Borlas. :D

If it's all rusty, there's some decent Ebay cat backs that are pretty cheap.
 
Probably will go with a cat backs if its bad. I have been just at a loss with it was almost ready to scrap it. I guess because it only had 83K miles on it I couldn't fathom that the exhaust would be plugged.
 


I know its needs one but trying not to sink to much in it before I know exactly what's wrong with it. If it will run without the Supercharger and at idle that shouldn't be a issue.
 
with those miles, and it sat for 4 years, tune up is "the" first thing id do, and a oil change. why did you change all that other stuff? that was the cost of a tune up i bet.
 
She wasn't running when I bought her. So I took a electric in line fuel pump bypassed all the other and she fired up. Old pump and tank was crap and I mean crap. so I started from there and worked towards the engine. Don't get me wrong If it is the converter then I will buy the rest for the tune up. I just want to make sure the motor and supercharger is working fine. If not then it will become a parts car and I will look for another GTP. Does that make sense? And yes I changed the oil already. Tranny will be next with the tune up if the cat is truly the case.
 
what im saying is it was due for a tune up before it sat for 4 years. they say 100,000 miles but lets be real here. plug wires also go bad. they are how many years old now? aka factory.
 


I agree and someone looks like they have changed the plugs at least cause they are autolights. But before I spend over 200 bucks in plugs, coil packs and wires I want to make sure the cat is the issue. If its running and ides fine then that shouldn't be the issue. I was thinking it was fuel type issue at first why I replaced all the sensors. Once I resolve the high boost issue then the rest of the tune up will follow plugs, wires, coil packs, tranny, vac lines, etc.. So recommendations when I get to the tune up stage? Stay with stock or MSD, Accel? Need to go back and re-read that thread you sent me in my new comers post.
 
tune up is less then $50. get some copper core plugs, 104's would work, those are like 2 bucks a plug. last set i paid 10 bucks from advance with a code, wires are like 35 bucks. any parts store brand will do. advance auto and a code once again. who likes to pay full price?

coils dont go bad to often.
 
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