How to- 2.9 idle adjustment

[rusty ol ranger]

I am also facing the issue of me touching something I shouldn't have. My 1987 B2 will start and run fine for 30s before flat-out dying. This was after I had messed with my TPS. Hopefully, this fixes it. What do I do if I can't get it to warm up because it keeps dying?



I'm worried about this too. Does anyone have any recommendations if I come across this? Can I adjust the voltage of the TPS without touching the the Idle screw?

Will it stay running with your foot on the throttle?

id make another thread for this issue itll get more attention.

 

[Nelson and Hudson]

Update: I cannot stress this enough, DONT TOUCH THE TPS. I finally fixed my problem. Before, it was struggling to stay at 45, now I can do 75 up a hill no problem. It felt as if it wasn't able to change gears. I probed the ground and the signal wire from the TPS and measured it to be ~0.74v. I loosened the screws on the TPS and tilted it until I couldn't turn it any farther to increase the voltage to ~0.84v, after tightening the screws and resetting the ECU by unplugging the battery for a few minutes it ran like new! I'm gonna try to the get the voltage 0.9v and the idle RPM to 700 and see if that improves it any further.

 

[SCOTTY]

I know the oil weight is wrong on this label but is the Idle RPM correct ? (1990 2.9, AT)

 

[alwaysFlOoReD]

I know the oil weight is wrong on this label but is the Idle RPM correct ? (1990 2.9, AT)

View attachment 105366

oil is correct for the year. rpm is in range.

 

[franklin2]

I will add to this thread. I just swapped in a 2.9 where a carbed 2.8 resided. It wasn't easy, new fuel tank, sending unit with pump, had to mount the frame rail pump and run all new supply and return lines. Then there was the computer. Had to add all that in with all the wires for the fuel injection.

After I got done, I went to start it, it would not idle correctly. When it was cold and idling high it was fine, when it started warming up and the idle speed came down, it would start hunting. I could adjust the throttle screw and get it to idle smooth, but touch the throttle to rev it up and it would start hunting again. When you tried to move it around the yard, it truly was a Bronco, bucking and jerking.

After much experimentation I found out that the early 2.9's (this was a 1986 system) did not have a speed sensor. They had different idle strategies for idling stopped and running down the road, and this was determined by switches on the transmission and the clutch pedal. When I did all this wiring, I had left this idle switch loop open, ungrounded. It goes to pin 30 of the computer. I found out if I grounded this pin, everything settled down and I was able to drive it.

In fact it drives better I think than it ever did when it was in the truck with the switches supposedly working. Maybe they were not working that well, it was always a challenge to get going without stalling the engine. I permanently ground pin 30, and have been a couple of trips so far. I will have to see if leaving this grounded affects fuel mileage or driveability.