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Throttle linkage - 2.8 by notaguru
Started on: 04-03-2014 01:10 AM
Replies: 8 (116 views)
Last post by: notaguru on 04-05-2014 07:15 PM
notaguru
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Report this Post04-03-2014 01:10 AM Click Here to See the Profile for notaguruClick Here to visit notaguru's HomePageClick Here to Email notaguruSend a Private Message to notaguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
'88GT, 2.8

Somewhere in the connection between the accelerator pedal and the throttle body, there's slop. When depressing the throttle, response is very poor until the pedal makes it to the floor - then the car functions properly.

I am pretty sure it's linkage. Fuel is good, new filter and screen, 40+ pounds fuel pressure, new ignition wires and plugs, no codes, etc. But the car doesn't GO!!

???
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mcguiver3
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Report this Post04-03-2014 08:31 AM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Edit/Delete MessageReply w/QuoteDirect Link to This Post
Are you sure there is slop in the linkage?
Have you been able to actually look at things as they are moving?
Could be the TPS out of adjustment for one thing.
The only areas of possible slop would be the throttle pivot and cable to the pedal as long as the cable anchor points are OK. IMO
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notaguru
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Report this Post04-03-2014 10:05 AM Click Here to See the Profile for notaguruClick Here to visit notaguru's HomePageClick Here to Email notaguruSend a Private Message to notaguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
When I depress the accelerator pedal, it must go most of the way down before there is any engine response.

When I simply turn the pulley on the throttle body, response is immediate.

So, I conclude that somewhere between the PEDAL and the PULLEY there is another of Pontiac's design faults. Perhaps the same designer did the dew wipes and the parking brake...
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Gall757
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Report this Post04-03-2014 12:55 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
There is a plastic bushing on the pedal mechanism that may be to blame.
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mcguiver3
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Report this Post04-03-2014 02:22 PM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Edit/Delete MessageReply w/QuoteDirect Link to This Post
The cable is non adjustable so if there is any slop in the cable something is grossly wrong.
Have you watched the TB end while someone depresses the peddle?
I can't imagine that the cable has stretched that much.
As long as each outer sheath end is anchored properly and the throttle peddle mechanism is not loose or worn.
Then it has to be the inner cable.
Are you sure it is routed correctly to the TB?
Not sure if it's possible to screw that up but if it's possibly routed where the cruise control cable goes?????
Have any pics?
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Indiana_resto_guy
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Report this Post04-03-2014 07:59 PM Click Here to See the Profile for Indiana_resto_guyClick Here to Email Indiana_resto_guySend a Private Message to Indiana_resto_guyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Did this just start?
Is the car new to you?
Got a pic of the engine bracket where the cable is mounted?
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notaguru
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Report this Post04-03-2014 10:10 PM Click Here to See the Profile for notaguruClick Here to visit notaguru's HomePageClick Here to Email notaguruSend a Private Message to notaguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
This '88GT has 40k miles on it, but spent most of its life stored unprotected, in the sun. I got it running, and it passed CA smog. There are many small problems still to be resolved, including this throttle issue.

I compared the visible throttle linkage (throttle body) to drawings, and at that end of the cable it's correct. I still have not figured out how to reliably post photos here.

Tonight I plan to recruit my wife to push the gas pedal as I observe the linkage. That might identify the source of the problem (as opposed to the TPS, etc.).

Thanks!
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mcguiver3
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Report this Post04-04-2014 08:14 AM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Edit/Delete MessageReply w/QuoteDirect Link to This Post
Wives are a great help with car problems.
I use mine to test for spark from time to time.
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notaguru
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Report this Post04-05-2014 07:15 PM Click Here to See the Profile for notaguruClick Here to visit notaguru's HomePageClick Here to Email notaguruSend a Private Message to notaguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
On this low-mileage '88GT, there's slop in the throttle linkage.

The accelerator pedal must move more than one inch before the pulley on the throttle body begins to move. However, when the pedal is all the way down, the butterfly in the throttle body is fully open.

What could be the cause of that inch of play?

Does anyone have an illustration of the throttle linkage assembly?
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