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Discussion Starter · #1 ·
Back to work on the Shelby. Before I go back to troubleshooting electrical, I need to set the throttle plate to the original mechanical idle setting. The books I have show the throttle body assembly, but do not specify the closed / idle throttle setting. What is that setting? Is there a measurable gap between the blade and body like in carb settings, or is it to full closed position? If there is a gap setting what is it?

Thank you.
 

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Discussion Starter · #3 ·
Thanks for the info. Problem is this thing isn't running. I know the idle set screw is not to factory specs so I need to set it before I can begin troubleshooting the other issues, like high TPS voltage and idle through the roof.
 

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Discussion Starter · #6 ·
Hi NAJ. Thanks to you and Glhs60 for the responses. This is actually related to two threads from last year:

Erratic Idle, No Idle, High Idle. The car is possessed! and High Idle as Engine Warms. Mystery Vacuum Leak? '87 Shelby Charger T1, and probably Fault Code System Non-Op. '87 Shelby Charger T1.

I think I just need a new TPS. When I last worked on the car, looks like Sept 2021, I adjusted the idle control screw i back of the throttle body under the plastic cap. we were ruling out the high idle and high TPS voltage as tested. Then the faut code came up too. Right after I made the adjustment, the engine died. The OBD fault code system crashed again too. The engine restarted but would not idle at all.

I went back to the thing yesterday. OBD is working (at the moment) and it gives me fault codes, theyre only 11 and 55, but its working. I'd like to reset that idle adjustment screw back to the factory spec. I'm 99% sure it had never been played with until I touched it. It's been so long, I don't remember how far I changed it.

Any recommendations on setting it, or is it just start it and adjust while someone holds the throttle open?

It looks like the TPS part number was 4179849. I read elsewhere on here that that was superseded to 5227597?
So far I'm not locating a new TPS. Any idea where to get one?

Thanks
 

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Discussion Starter · #9 ·
What is closed throttle TPS voltage?
Here's the info the last time I worked on it. August 2021. It showed high and that day I got a fault code for high tps output shortly before everything crashed.
TPS Cold, ignition on, engine off. Closed= 1.163v WOT= 4.15v
TPS Cold, engine running poorly described above at 500 rpm Closed= 1.156v
TPS Hot engine running at idle after 25 minutes and rpm up to 900 Closed= 1.156v
Here's where everything crashed. With volt meter still back probed to TPS, I took rpm to 2500. TPS was 1.4v. When I released the throttle, idle dropped to 760 then after a minute, the engine died. Now it won't idle. I checked for codes. Remember there had been none before. After the engine died, I got Code 24 and Code 52. The volt meter was still plugged into the TPS.
 

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Discussion Starter · #10 ·
Screw adjustment screw in enough to get the car to start 1200 rpms is fine. Now remove hose from brake booster slowly which will cause the rpms to jump to about 3000. The ais should close. Placing a finger over the ais passage way on top of the TB with the elbow removed will tell you it's the ais is closed or not. One closed unplug it. Now hook hose back up and adjust idle screw to 900 rpms and turn car off. Plug ais motor back in, disconnect battery to clear codes and you should be good
Got it. Thank you. On the Base Idle Setting, which I did prior to turning in that setting screw, the AIS and TPS are on the same 5 wire connector. Unplug AIS and TPS is unplugged too. I wonder if that may have led to the high TPS output reading after I plugged it back in.
 

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Discussion Starter · #12 ·
HI and thanks again.

TPS readings as of today:
Engine off. Ignition on
Throttle screw completely backed out and throttle plate visually inspected as completely closed:
TPS output was 1.124v.
 

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Discussion Starter · #13 ·
Hello all. i bought a TPS that lasted about 30 minutes, No voltage readings, Zero volts, and codes 24 and 52, Lots of unburnt gas smoke.
Questions:
On base idle vacuum leak Idle controller set, the plug is 5 wire and controls the tps too. When I unplug the ais power. does that need to be done separately from the tps wires somehow?

Is there an electrical issue known that will fry a tps?

While it lasted, I had to reset the idle screw every few minutes. Hot idle was generally good at 900, but shut down and restart was 500 rpm until I gassed it a bit.

Any ideas?

Thanks
 
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