Need help setting baseline idle 1993 K1500 350 TBI

[TruckBFT]

Hey all - been struggling getting my baseline idle set on my 1993 Silverado.
85,400 miles.
I set the timing....which was off. I cleaned the IAC valve.

I followed the steps below:

Turn off engine and leave ignition key in "Off" position. Unfold paper clip and bend it into a "U" shape. Push the ends of the paper clip into the "A" and "B" terminals of the ALDL (Assembly Line Diagnostic Link) connector, diagnostic connector. In GM vehicles that use this TBI injection, the connector is a black plastic rectangular connector located under the driver side of the dash. "A" and "B" terminals are located on top right of connector.

Unplug the IAC valve located on the passenger side, rear of the throttle body.

I did wait until I heard the IAC click.

Start the engine.

- at this point, the RPMs rev out to ~1,500 and turning torx doesnt do anything. It seems like IAC valve is stuck open. I also tried a new IAC valve, same thing.

Insert a T-30 size Torx driver into Idle adjustment screw that is located behind the plug removed earlier. Turn the screw to adjust the idle speed to 650 RPM +/- 50 RPM.

Turn off engine and disconnect the negative battery terminal from the battery. Reconnect IAC valve. Reinstall air cleaner and remove the paper clip from the ALDL connector. Reconnect the battery terminal after 5 minutes and test drive the vehicle.


Thanks for any help. Current idle is low - like ~200-250, which is reason for trying to reset.

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[PlayingWithTBI]

Push the ends of the paper clip into the "A" and "B" terminals of the ALDL (Assembly Line Diagnostic Link) connector, diagnostic connector. In GM vehicles that use this TBI injection, the connector is a black plastic rectangular connector located under the driver side of the dash. "A" and "B" terminals are located on top right of connector.

After you jumped pins A & B did you turn the key on for 10 seconds to reset the IAC then turn the key off and then disconnect the IAC?

 

[TruckBFT]

After you jumped pins A & B did you turn the key on for 10 seconds to reset the IAC then turn the key off and then disconnect the IAC?

Hmmmmm - I definitely turned key on, reset IAC but I DID NOT turn key off prior to unplugging the IAC. Thats probably it........

 

[PlayingWithTBI]

Sorry, you did it correctly, my bad. Just going by my feeble memory. I know you have a set of instructions but here's another one to look at.

TBI tuning-website - Tuning the TBI.pdf

 

[TruckBFT]

That PDF is an awesome document!! Thanks!

 

[skylark]

Did you disconnect the wire for setting base line timing?

 

[TruckBFT]

Did you disconnect the wire for setting base line timing?

Yes, the Tan/Black Electronic Spark Timing (EST) by-pass connector wire

 

[someotherguy]

Current idle is low - like ~200-250, which is reason for trying to reset.

200-250? Where are you reading this from? The factory tach starts at 500.

Richard