Pontiac GTP Help

Z

ZNix

Young-Gun
Joined
Jun 17, 2009
Hey Guys, I haven't really been active these days. I bought a Pontiac GTP that needed some help, and the Buick has been on the back burner. Its coming along, just not in enough time to get on the road for my license (which I have! Woo!). Anyways, I am still being plagued with a hard start issue and a little bit of a rough idle. I have replaced plugs, injectors, battery (which was needed anyway) and the wires look and seem to be new. If anyone can think of what could be causing a rough idle and hard start let me know. Other than that, car pulls pretty hard :D. And its supposed to be slow compared to the Buick! Can't wait to get it done :D :D..

Thanks
ZNix

P.S. it also seems to have a vibration at times going up hills and even sometimes just normal driving. Any ideas?
 
Is it

The turbo version or just injected what size motor any other mods .could be simple as a vacume leak
 
Clean the MAF with maf cleaner, clean the throttle body and IAC.
 
Okay, sounds good Pronto! It is the supercharged model with a 3.8L v6. Kind of like our turbo buicks!
 
Watch out for a leaking intake manifold that floods the cylinders with coolant. EGR passage melts the plastic intake manifold and then allows coolant into the motor. Ask me how I know.

This was in a 98 NA Grand Prix GT. Car started running a little weird progressively getting worse, had it floored and was only going about 20 mph. Made it home OK, started doing it about 2 miles from home. Smelled the coolant coming out the exhaust pipe so knew things were serious. Did a little research on the internet and saw this was a common problem. Pulled the plugs and they were filled with coolant! Pulled them all and cranked the motor over until no more coolant came out. Drained the oil right away and half of it was coolant!

New plastic intake from Dorman and a new intake gasket set and was back in business. Car ran great for about another year and then sold it. Don't know how it didn't bend a rod!
 
TR Custom Parts said:
Watch out for a leaking intake manifold that floods the cylinders with coolant. EGR passage melts the plastic intake manifold and then allows coolant into the motor. Ask me how I know.

This was in a 98 NA Grand Prix GT. Car started running a little weird progressively getting worse, had it floored and was only going about 20 mph. Made it home OK, started doing it about 2 miles from home. Smelled the coolant coming out the exhaust pipe so knew things were serious. Did a little research on the internet and saw this was a common problem. Pulled the plugs and they were filled with coolant! Pulled them all and cranked the motor over until no more coolant came out. Drained the oil right away and half of it was coolant!

New plastic intake from Dorman and a new intake gasket set and was back in business. Car ran great for about another year and then sold it. Don't know how it didn't bend a rod!
Click to expand...

Getting coolant in the oil was a common problem with these cars.
 
Do what the "non-car person" that owned the car previously neglected: change the fuel filter. When I worked at the dealership, you'd be surprised how many used GM cars came in with the original fuel filter still installed.
 
There's also a recall out on Supercharged cars for Valve cover gaskets
 
gsgns4me said:
Do what the "non-car person" that owned the car previously neglected: change the fuel filter. When I worked at the dealership, you'd be surprised how many used GM cars came in with the original fuel filter still installed.
Click to expand...

Done. I have replaced: Plugs, fuel filter, injectors (made the car run 100000x better), and I think that is all for the engine.. I do not smell coolant in the exhaust, though It could possibly be one. The plugs smelled like fuel, nothing else.
 
Those cars are supposed to start real easy due to the more triggers on the crank damper. Is the crank sensor and its wiring in good shape? Might be cheap insurance to replace it. It's one of those things good to have on hand any way cause if it goes bad its a "No start" issue.
 
Don't those cars have the Series II 3800 with the insanely stout bottom end? That would be fun to tinker with...
 
When I had I think that same problem with the GS it was the stock plug wires, I replaced the coil packs at the same time also, both MSD.

Your vibration is most likely one of your axle\wheel bearings going or possibly your tie rod going out, mine vibrates above 65mph. I just ordered both for my drivers side front.

Here a link to change it yourself
DIY Hub/wheelbearing replacment - RegalGS
 
Do what pronto said. And also check the plug wires going to the packs and make sure there not rusted and have s good connection. Also when u take the intake off make sure there's s screen infront of the maf that smooths out the air for idle. But some people take them out thinking it helps
 
CHARGED said:
When I had I think that same problem with the GS it was the stock plug wires, I replaced the coil packs at the same time also, both MSD.

Your vibration is most likely one of your axle\wheel bearings going or possibly your tie rod going out, mine vibrates above 65mph. I just ordered both for my drivers side front.

Here a link to change it yourself
DIY Hub/wheelbearing replacment - RegalGS
Click to expand...

I just replaced both the right CV Joint and Hub Assembly. Should I replace both sides? It seems like a waste because both on the left side are in great condition. Though the car does have high mileage.. Ill resistance check the packs and wires to see if they need replacement. I really do not want to pull the intake off. Really don't lol.
 
Sorry I should have been specific. Not the manifold the air intake comes off with one flathead I believe Takes 5min
 
Jack that side up and see if there is any play in the wheel, I know on mine I have much more play on the side I'm replacing then the other side where the bearing and tie rod was done over a year ago, but sometimes its hard to tell just by doing this test.
If its original and your car has higher miles(mine is at 130k) its only a matter of time anyway.
 
ZNix said:
Hey Guys, I haven't really been active these days. I bought a Pontiac GTP that needed some help, and the Buick has been on the back burner. Its coming along, just not in enough time to get on the road for my license (which I have! Woo!). Anyways, I am still being plagued with a hard start issue and a little bit of a rough idle. I have replaced plugs, injectors, battery (which was needed anyway) and the wires look and seem to be new. If anyone can think of what could be causing a rough idle and hard start let me know. Other than that, car pulls pretty hard :D. And its supposed to be slow compared to the Buick! Can't wait to get it done :D :D..

Thanks
ZNix

P.S. it also seems to have a vibration at times going up hills and even sometimes just normal driving. Any ideas?
Click to expand...

What kind of plugs did you put in car? I forget but I think they are Nippon denso/ac delco. dont run any other plugs. I get those in for running rough and Im always taking out bosch platinum plugs. I get plugs right from the dealer.Check that regulator also.pull vacuum line and start it and watch for fuel. I install a clear line between line and regulator when I check them. does car start run and die? It could be resistor for fuel pump. If it is updated it should be mounted to firewall and not down on passenger side frame rail.Gm sells the updated kit to relocate it. hope this helps
 
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