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91 ranger 2.3 tps and idle screw adjustment


jonathand579

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I need help with new tps adjustment
 


scotts90ranger

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You're supposed to adjust the TPS to be .9-1V and or the idle about 500rpm with the IAC unplugged if memory serves.
 

jonathand579

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Thankyou. Up until about 2 weeks ago I didn't know what a TPS was. I'm trying to dial this thing in so it'll run halfway right.
 

RonD

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The TPS(throttle position sensor) doesn't do that much, but is needed

There is no "idle screw" on a fuel injected engine, can't be, there are no idler Jets
There is an anti-diesel screw, that does adjust throttle plate, so same function as idle screw, but not used to set idle so...........

The TPS gets 5volts, along with most other sensors from computer, they share this 5volts
When closed the TPS will send back .69-.99v under 1 volt is spec, to computer
When throttle is Wide Open(WOT), TPS should send back 4.5-4.9volts, 4.5v or higher is spec

The computer "learns" the TPS voltage so if you install a new one it will take a few drive cycles(warm up cool down) for computer to re-learn the new TPS voltage

The anti-diesel screw can be use to set the low voltage on TPS........IF TPS does not have slotted screw holes
You test TPS voltage with throttle closed and then at WOT, under 1volt and 4.5v or higher is set right

The TPS's main function is as the "accelerator pump" was on a carb, it gives the computer a "heads up" to quickly add more fuel and adjust spark timing for quicker acceleration response
Its secondary function is as a comparison to check MAF or MAP sensor data, computer "knows" the size of the engine is operating, so it "knows" exactly how much air should be flowing in at say 1,000RPMs, its just math
So with TPS at XX, and RPMs XXXX air flow should be XXX


Yes the anti-diesel screw should also be set, this is done with engine fully warmed up and idling
Fuel injected engines must use an air valve to set idle, Ford calls theirs the IAC(idle air control) Valve
It has 2 wires connected and looks like a can laying on its side

After engine is fully warmed up and idling
Unplug the 2 wires on the IAC Valve
RPMs should drop to 500 or so or engine may even stall, either is GOOD, no adjustment needed, if TPS is set already

If RPMs do not drop then try turning anti-diesel screw counter clockwise(unscrew), if RPMs start to drop then keep turning until engine is barely running 500-600RPM, its now set

If turning anti-diesel screw doesn't lower idle, turn it back to where it was, your higher idle is a Vacuum Leak
 
Last edited:

gw33gp

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I have learned to adjust that throttle plate adjustment screw so the plate is just above the point where it does not bind in the throttle body. This may not be the correct way but it has worked for me.

Actually, I only had to do this one time on my 89 STX with the 2.9L engine. For some reason the throttle plate suddenly started sticking at idle. I could see this was a factory set adjustment and had a soft glue type material on the adjustment screw to keep it from moving. I adjusted it up just enough to free up the throttle plate with the engine off. I then took it for a drive and all was good again. I applied some material again to keep the screw from moving and never had a problem with it again.
 

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