Engine won't run without throttle help on startup

[Evan]

That just screwed up your TPS adjustment. Bad move.

Might try priming the FP several times before starting it (key to Run, pause pause while FP runs then shuts off, key to Off). Repeat.

I'm waiting to hear why tightening down the adjuster screw on the throttle body screwed up my TPS adjustment. Frankly, I don't think it did. I call bullshit.

 

[dgndngrngr]

^^^hahaha. the air charge sensor throws a different code. i forgot what it is though

 

[Evan]

The problem was the IAC.

 

[dgndngrngr]

good deal

 

[Earl43P]

Call BS if you like....

The setscrew you turned opened up the throttle plate "some" to keep it running with (we now know) a bad IAC.

Replacement procedure for a TPS has you "adjust" that sensor's mount until the output signal voltage is .96v with the throttle closed. Your throttle isn't fully closed if you turned that setscrew in, so your TPS signal is higher.

I'm sure it'll be fine if you turned it back the same amount. I just didn't want to see you add another problem to the issue you were already working on.

 

[Evan]

Call BS if you like....

The setscrew you turned opened up the throttle plate "some" to keep it running with (we now know) a bad IAC.

Replacement procedure for a TPS has you "adjust" that sensor's mount until the output signal voltage is .96v with the throttle closed. Your throttle isn't fully closed if you turned that setscrew in, so your TPS signal is higher.

I'm sure it'll be fine if you turned it back the same amount. I just didn't want to see you add another problem to the issue you were already working on.

Ok, I see where you're coming from. My "bullshit" accusation has been retracted. My apologies.

I did crank the throttle plate adjustment screw back, but I didn't mark exactly where it was. I think I'm close to the correct position, as the truck seems to run and idle perfectly.

EDIT: I should be able to crank the screw out until it's no longer pushing the throttle plate open. Then I know the plate is closed and I'm good to go, right?

 

[jasonl]

The TP sensor is an input to the tranny. If your voltage reading is off it can change the shift points or cause irratic shifts. Not sure how far it has to be out though. You should be able to unplug the TP sensor and us a digital ohm meter to back probe the sensor to see what it's reading.

 

[edgeofvision]

EDIT: I should be able to crank the screw out until it's no longer pushing the throttle plate open. Then I know the plate is closed and I'm good to go, right?

No. The factory position does not allow the plate to close all the way because it can make the plate stick in the bore in cold temperatures. You should adjust the TPS signal to 0.96~0.98v closed using the stop screw.

 

[Evan]

The TP sensor is an input to the tranny. If your voltage reading is off it can change the shift points or cause irratic shifts. Not sure how far it has to be out though. You should be able to unplug the TP sensor and us a digital ohm meter to back probe the sensor to see what it's reading.

What should the reading in ohms be, and which pins do I test?

 

[Earl43P]

Leave the TPS installed and connected.
Key to Run, engine Off.

Backprobe (or pierce the insulation of) the G/WH wire to get the .96 volts, using the TPS mount screws to adjust it (after you have the plate fully closed, but not sticking).

 

[jasonl]

Leave the TPS installed and connected.
Key to Run, engine Off.

Backprobe (or pierce the insulation of) the G/WH wire to get the .96 volts, using the TPS mount screws to adjust it (after you have the plate fully closed, but not sticking).

Thanks for clearing that up !! That is exactly what I had to do several years ago to adjust a new tps I put on my old Ranger. I just couldn't remember exactly how to do it without doing it. lol!!