Throttle position sensor
Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
Make sure you set it when you install it, you can't just screw it on and call it a day.
I prefer to take the throttle body off, put the sensor on and leave the screws snug. Plug it into the harness, slide some paper clips into the ground wire and signal wire, then turn the key on and check the voltages.
You need to set the signal voltage to be about .96v at idle and it should go to about 4.5v at WOT. Make sure that when you open the throttle there are no voltage spikes.
Tighten the screws and install the throttle body, re-check voltages to make sure it hasn't moved.
Don't let the paper clips touch w/ the key on.
You'll have a ground wire, a signal wire, and a 5v reference wire. I forget which color goes to which, black is obviously ground.
I prefer to take the throttle body off, put the sensor on and leave the screws snug. Plug it into the harness, slide some paper clips into the ground wire and signal wire, then turn the key on and check the voltages.
You need to set the signal voltage to be about .96v at idle and it should go to about 4.5v at WOT. Make sure that when you open the throttle there are no voltage spikes.
Tighten the screws and install the throttle body, re-check voltages to make sure it hasn't moved.
Don't let the paper clips touch w/ the key on.
You'll have a ground wire, a signal wire, and a 5v reference wire. I forget which color goes to which, black is obviously ground.
Elder User
Joined: Mar 2004
Posts: 500
Likes: 1
From: Penndel, PA
ok, its been a while, but i'll give it a whirl...
the TPS screw holes aren't perfectly round. they are slightly ovaled to allow for very little adjustment. basically as Mustang said, with the key in the on position engine off, probe the ground and signal wires, rotate the TPS every so slightly until the proper voltage shows up at idle position. tighten the screws down. check it again at idle position, if still good, check it a wide open throttle.
haynes or chitons should be able to tell you what color is what.
the TPS screw holes aren't perfectly round. they are slightly ovaled to allow for very little adjustment. basically as Mustang said, with the key in the on position engine off, probe the ground and signal wires, rotate the TPS every so slightly until the proper voltage shows up at idle position. tighten the screws down. check it again at idle position, if still good, check it a wide open throttle.
haynes or chitons should be able to tell you what color is what.
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Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
One of the TPS sensor holes is an elongated hole to allow you to move it. The voltage output to the computer at closed throttle should be around .95ish volts. There is some variance there - but the computer likes that voltage the best...between .9 and .98 volts. If you look at SCT computer tuning software, they tune for that voltage as well.
It should be about 4.5v at full throttle and there should be no voltage spikes throughout the movement of the TPS sensor. It's a potentiometer so when they go bad sometimes they do that.
The TPS has three wires, ground, 5v reference, and signal. The signal wire will have the .95-4.5v, the 5v reference wire will always have 5v, and the ground is ground.
Attach a voltmeter to the pins at the computer 60 pin connector corresponding to the TPS signal wire (haynes manual has them, or many other sources) and check it's voltages.
Your not really suppose to just slap a TPS sensor on the TB and drive it w/o setting the voltages right, or atleast checking to make sure they're right.
Now there are tolorances where the TPS would work ok even at say .80v at idle...but like I said the computer seems to like the .95v-ish area the best.
The TPS is a very important sensor so it should be set right.
It should be about 4.5v at full throttle and there should be no voltage spikes throughout the movement of the TPS sensor. It's a potentiometer so when they go bad sometimes they do that.
The TPS has three wires, ground, 5v reference, and signal. The signal wire will have the .95-4.5v, the 5v reference wire will always have 5v, and the ground is ground.
Attach a voltmeter to the pins at the computer 60 pin connector corresponding to the TPS signal wire (haynes manual has them, or many other sources) and check it's voltages.
Your not really suppose to just slap a TPS sensor on the TB and drive it w/o setting the voltages right, or atleast checking to make sure they're right.
Now there are tolorances where the TPS would work ok even at say .80v at idle...but like I said the computer seems to like the .95v-ish area the best.
The TPS is a very important sensor so it should be set right.
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Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
Originally Posted by 96f150
I believe the only 5.0 throttle bodys that were adjustable, were in the mustang. I have never seen one on a Mass-Air setup either.
SCT tuning software is for MAF and they have a specific point in their software for adjusting the idle TPS position.
It's not the throttle body that provides the adjustment, it's the TPS sensor.
It only takes a smidge to change the voltage, and when I say smidge, I mean a real smidge...
