2000 GT Hesitates Under Acceleration

[rhaltunen]

2000 Grand Prix GT with 110,000 miles. Car drives fine down the highway but has a really hard time getting up to speed when the throttle is pressed down. I can feel it trying to accelerate but it really labors to get there...with a lot of shuddering and hesitation along the way. The fuel filter was changed at 100,000 miles. Any idea's out there? Thanks-Rodd

[DJ JEFF]

There is another current thread that is going on this subect:

http://www.automotiveforums.com/vbul...d.php?t=694925

I have the exact same issue with my 97 GTP. After reading that previous thread one suggestion was to disconnect the MAS and see how your car drives. I just did that with my car and it seems to have made a pretty big difference. Although under hard acceleration it still stumbled but it did it a lot less. I just cleaned the MAS going to take it for a cruise to find out if that takes care of it. I'll post back here soon to see if it works.

[alfieferenzo84]

try a tune up and check your fuel pressure

[richtazz]

I agree with Alfie, have you tuned it up, and if so, what brand parts did you use?

Any CEL on or blinking when this occurs?

[DJ JEFF]

Originally Posted by richtazz

I agree with Alfie, have you tuned it up, and if so, what brand parts did you use?

Any CEL on or blinking when this occurs?

Sorry thread Jacking here, this original guy was a one hit wonder I think.

I have done fuel filter, plugs, cleaned air filter(KN), new MAS, pulled throttle body and cleaned. Fuel pump was changed about 3 or 4 months ago, pressure is good. My CEL has been on for random misfire, but here recently now it has started blinking more and more. I think my car is about to die. Somebody suggested to me that cam might be wearing out. Would this be a symptom of a worn cam on this motor? I have actually seen a Honda where the cam wore out and it caused the car to start losing power and not run very good.

Thanks for any ideas you might have.

[richtazz]

I know of people that have well over 300k that are still runnign strong. Unless there was another problem, I doubt your problems come from engine wearout Jeff. Same question to you as I asked the thread starter, what brand of plugs and wires did you use?

[DJ JEFF]

I do need to probably change my wires, I put in ACDelco plugs. The problem was there before I changed the plugs. What gets me is that it runs great without being under a load. If its in nuetral or park it doesn't miss a beat. I think it is something deeper then a tune up. I bought this 97GTP with a 110k on it I don't think the UIM/LIM have been changed yet but I haven't had any coolant loss, although last summer when it got hot outside, I notice my temp had started climbing to the 210 mark. Lookin around the manifolds they arn't exactly clean. I do have some seepage but not any puddles of coolant or anything like that. Probably what you would expect to see with 185k. One other guy a while back posted on here that he had this same issue but shortly after it started he started losing mass amounts of coolant and it ended up being the gaskets. Mine has been having the stumble for about 6 months and usually only noticable on the interstate. I don't know. I'll keep dinkin with it. I keep putting a $100 here and $100 there. It's still worth it. Cheaper then a car payment right now. I really appreciate hearin your ideas though. Thanks.

[BNaylor]

The SES light is blinking because you have a misfire condition which is most likely a secondary ignition problem. I agree with Rich replace the ignition wires. Stick with the AC Delco Premium silicone 7mm wires if you are stock. About a $55 investment. Also, the ignition coils pack can cause secondary ignition issues. Test the primary and secondary coil resistance.

Since you have a GTP the UIM issue GTs experience is not relevant. The supercharger is the UIM. However, it does have a gasket and o-rings for coolant passages that can go bad causing an internal loss of coolant and external. However, L67 GTPs are not immune from LIM gasket problems.