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Mike23386 12-01-2006 03:07 PM

'88 GT throttle sticking problem
Has anyone had this problem before? I have an '88 GT with stock 5.0 in it and I seem to have a throttle problem. When it had the stock throttle body on it I don't recall it ever doing this. I put a Proffesional Products 70mm throttle body and spacer on it not to long ago. When the engine is not running you can push the gas pedal down and it goes down nice and smooth. When the engine is warm and running it is very hard to push the gas pedal down at first. It is like it is frozen when you first try to push it down and once it breaks free it goes right to the floor smooth but when you let it up it sticks again. This causes me to do burnouts on the street that I really DONT mean to do. Seriously. As soon as you turn the engine off this problem goes away completely. The pedal becomes nice and free until you start the engine again. PLEASE HELP I NEED TO DRIVE THIS CAR ON THE STREET AND DONT WANT TO GET STOPPED FOR UNNECESSARY BURNOUTS!

Mike23386 12-01-2006 08:45 PM

New Problem #9,999,999!!! My car is now backfiring out of the exhaust as well as through the intake! I tried turning down fuel pressure-nothing changed. I tried turning up fuel pressure-no change. I tried adjusting timing both advanced and retarded and.....yes, you guessed it!.....NO CHANGE! As you can see I am very P.Oed about this whole situation. So I do not know what to do now. Too dangerous to drive on the street because of the gas pedal sticking and it has no power now due to all kinds of backfiring. I am in dire need of peoples help, suggestions, opinions, ANYTHING! PLEASE HELP ME!!!!!

codmac 12-02-2006 12:27 AM

i know you said that you adjusted the timing, but backfiring is a tell-tell sign of a timing issue. just to be sure, tell me about the heads, valves, camshaft, lifters and intake. did you do the work your self or did someone else do it?

Mike23386 12-02-2006 07:50 AM

Yes, I did the work myself. Almost everything is stock on the motor. What I have is Hooker Headers, offroad X-pipe, Flowmaster 40 series catback, MSD cap+rotor, MSD Blaster Coil, FRPP 9mm wires, Bosch platinum 2 plugs, Smog pump delete, 255 lph fuel pump, adjustable regulator set to about 50psi, Proffesional Products 70mm throttle body+spacer, and a Paxton SN-92 Supercharger. Everything else is stock. But the gut I got it from said he had someone pull the motor and do the top end in it. But I have had the intake off and the valve covers and everything is stock so I dont know what he was talking about.

88FOXLX 12-02-2006 10:54 PM

OK, funny mine does the same thing, but only after a friend adjusted the throttle. Thereís a screw on the back of the throttle that you can tighten up to give you better response but I think if is tightened to much it sticks...let me know because my problem didnít start until he tightened it up. Maybe just back it of a half turn might help.

Mike23386 12-03-2006 07:30 AM

I forgot about that screw. I adjusted the idle when I first got the new throttle body but never thought to readjust it. I believe I know how to fix this whole problem. As you know if you turn the distributor one way it idles faster if you turn it the other way it idles slower. (Still get confused as to which way is advance and which way is retard.) Obviously the timing was set too much ?ed (advanced,retarded?) and I had to loosen the screw way too much to make it idle down. So if I adjust the timing to where it needs to be I should probably have to tighten the screw to make it idle higher so it wont die on me and the butterfly in there shouldnt get stuck against the bore anymore. I will try this today and let you know. If it doesnt work then Step 2??

quick5pnt0 12-03-2006 12:37 PM

As for the throttle sticking, try letting it warm up and get it to stick (preferable in neutral/park to be safe). Once you got it to stick then try disconnecting the throttle cable completely from the TB and seeing if it'll still stick (by giving it throttle right at the TB with your hand). This might give you an idea of whether it's the TB or throttle cable.

It could be that the throttle cable is kinked somewhere causing it to stick. OR maybe the throttle body itself is faulty and sticks when it's hot.

quick5pnt0 12-03-2006 12:46 PM


Originally Posted by Mike23386
(Still get confused as to which way is advance and which way is retard.)

Clockwise to advance. You should be able to tell if it's advancing or retarding when you turn it because the engine revs usually go down when you start retarding it. Are you using a timing light?

Mike23386 12-03-2006 04:08 PM

Yes I was using a timing light but it is very hard to see the numbers so I will have to clean the balancer and put chalk on #14. When you move it to 14 is that advancing or retarding. One day I tried advancing it all the way then I retarded it all the way and each time I never got a knock or ping out of it when I drove it.

codmac 12-04-2006 01:08 PM

do you get any kind of change when you advance and retard the timing? if not, then either your doing something wrong or something is wrong with the car. oh and i would get rid of those bosch plugs, there primarily made for import cars that are running a higher compression ratio. the good old autolight or motorsport sparkplugs are great, i know your using a supercharger so just set the gap to about 35-40.

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