Solved 98 Ranger Help

I been searching the internet for an answer, but still a bit complexed. My 98 Ranger 2.5 has an issue, P0122, high idle, no other codes thrown. I bought this truck with this issue, I did however put a new TPS sensor on the truck, but the idle remains the same. I did test the TPS sensor and connector with a multimeter to make sure it was receiving voltage and ground, and I did the TPS sweep test with the throttle also. There was no spikes or dead spots, and the idle was about .96-.97 volts to 4.5 volts wide open.

I know however that the throttle plate screw was messed with, which I am not sure how to reset correctly. I believe that may be what's causing the issue, I know the truck is suppose to idle at like 750 rpm, but unfortunately my truck does not have a tachometer to read the rpm. Right now when it starts it idles so high it sounds like your cruising down the freeway when in neutral (it's a manual)

Is there a correct way to rest the throttle plate screw to the factory setting?

That throttle plate adjustment screw is basically used to keep the throttle plate from binding at the idle position. The throttle plate should be fully closed at idle to let the by-pass Idle Air Control valve control the idle. You could also have a problem with that by-pass IAC valve. It can cause a high idle if it gets stuck. Sometimes cleaning it resolves the problem and sometimes it requires replacement.

If the throttle plate is being held open with that throttle plate screw you can adjust it closed but make sure it is not sticking. If you can feel it sticking a little, adjust it up until the sticking stops. Changes in temperature (usually cold) can change the point where it sticks and you may have to readjust again until it is free all the time.

I don't have a tachometer but I do have a scan tool and multimeter, so I removed the IAC even though it is almost new and cleaned it, and set the TPS voltage to .98 at idle and that seemed to fix the problem and clear the code.

Well the problem is back, it was idling high again, so I did the idle set procedure by letting the truck warm up, disconnecting the iac, and setting the throttle plate screw down to about 600 rpm. With the iac unplugged the truck would idle smoothly around 600 or so rpm, but if you touched the throttle even a little bit the engine would immediately die. So I went ahead to plug the iac back in to allow it to bring up the idle and same result the engine immediately died.

It seems even with or without the iac the engine dies if any extra load is placed on the engine whether touching the throttle or plugging in the iac. Also the P0122 code has returned, circuit to low.I should add even when the engine idled high if you unplugged the iac the idle did drop and if you plugged it back in the idle raised, so I know its working. I also tested the tps connector, to make sure it was receiving the 5 volts, as well as checking the ground, and the input wire and they were good.

I guess this means the new tps sensor I bought is possibly bad then? Any ideas?

Got it fixed it was the new standard t157 tps sensor, when I put a new motorcraft tps sensor on took care of the problem.

Thanks for posting the solution!