Aftermarket TPS vs. Motorcraft

Flavadave4 · May 1, 2011

I have had a check engine light on in my car since the h/c/i upgrade a few years back, the car ran ruff when it was cold but fine when warm so I just lived with the light. Now I am trying to get everything perfect so pulled the codes and got a code 23.

It has a cheapo TPS from Autozone on it and I can only adjust it as low as 1.65vdc, slotted out the holes and could get it down to 1.19 vdc, slotted it out a little more and got it to 1.10 but the on the road test the engine revved right up the first time I touched the throttle and I had to shut it off and roll it back into the parking lot (my slotting work slopped out the holes and jumped it past the tab insde)

My question is this; Do you think or have experiance with the better units having the holes closer to where they should be to get it in the operatiing range of .6-1.1 volts?

tb9050lx · May 1, 2011

Flavadave4 said:
I have had a check engine light on in my car since the h/c/i upgrade a few years back, the car ran ruff when it was cold but fine when warm so I just lived with the light. Now I am trying to get everything perfect so pulled the codes and got a code 23.

It has a cheapo TPS from Autozone on it and I can only adjust it as low as 1.65vdc, slotted out the holes and could get it down to 1.19 vdc, slotted it out a little more and got it to 1.10 but the on the road test the engine revved right up the first time I touched the throttle and I had to shut it off and roll it back into the parking lot (my slotting work slopped out the holes and jumped it past the tab insde)

My question is this; Do you think or have experiance with the better units having the holes closer to where they should be to get it in the operatiing range of .6-1.1 volts?

auto zone sells nothing but **** parts . start with a motorcraft tps if possible.then retest the voltage your getting is way to high.should never be over a volt .

2000xp8 · May 1, 2011

I think autozone parts are engineered to last 6 months.
Replace it with a ford unit.

Flavadave4 · May 1, 2011

Thats what I was thinking, just needed some reassurance.

Mustang5L5 · May 1, 2011

Yes, most motor craft ones I've bolted on have been in the correct range right off the bat just by bolting down.

Auto parts store crap...I always have to slot

larrym1961 · May 1, 2011

I had a high peformance mechanic tell me any time I replace any sensor on my Mustang use only Ford Motorcraft parts. Nothing else seems to work as good!

Flavadave4 · May 4, 2011

So there are 2 different ones offerd by Motorcraft, how can I determine the correct one?

jrichker · May 4, 2011

Before you spend money on parts, spend some time with a quality multimeter and check out the ground signal on the TPS.
It is not the same ground as the engine block.

Be sure to check out the TPS sticky at the top of th forum. See http://www.stangnet.com/mustang-forums/825424-adjusting-your-tps-0-98v-not-necessary.html

Code 23 - Throttle sensor out of range or throttle set too high - TPS needs to be reset to below 1.2 volts at idle.
Keep in mind that when you turn the idle screw to set the idle speed, you change the TPS setting.
You'll need a Digital Voltmeter (DVM) to do the job.

Wire colors & functions:
Orange/white = 5 volt VREF from the computer
Dark Green/lt green = TPS output to computer
Black/white = Signal ground from computer

Always use the Dark Green/lt green & Black/white wires to set the TPS base voltage.

Do the test with the ignition switch in the Run position without the engine running.

Use the Orange/white & Black white wires to verify the TPS has the correct 5 volts source from the computer.

When you installed the sensor make sure you place it on the peg right and then tighten it down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the front screw enough so you can move it just a little in very small increments. I wouldn’t try to adjust it using marks. Set it at .6.v-.9 v.

1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

2. When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

If setting the TPS doesn’t fix the problem, then you may have wiring problems.
With the power off, measure the resistance between the black/white wire and battery ground. You should see less than 2 ohms. Check the same black /white wire on the TPS and MAP/Baro sensor. More than 1 ohm there and the wire is probably broken in the harness between the engine and the computer. The 10 pin connectors pass the black/white wire back to the computer, and can cause problems.

See the graphic for the 10 pin connector circuit layout.

Diagram courtesy of Tmoss & Stang&2birds

Flavadave4 · May 4, 2011

jrichker said:
Before you spend money on parts, spend some time with a quality multimeter and check out the ground signal on the TPS. It is not the same ground as the engine block.

Be sure to check out the TPS sticky at the top of th forum. See http://www.stangnet.com/mustang-forums/B25424-adjusting-your-tps-0-98v-not-necessary.html

Code 23 - Throttle sensor out of range or throttle set too high - TPS needs to be reset to below 1.2 volts at idle. Keep in mind that when you turn the idle screw to set the idle speed, you change the TPS setting.
You'll need a Digital Voltmeter (DVM) to do the job.

Wire colors & functions:
Orange/white = 5 volt VREF from the computer
Dark Green/lt green = TPS output to computer
Black/white = Signal ground from computer

Always use the Dark Green/lt green & Black/white wires to set the TPS base voltage.

Do the test with the ignition switch in the Run position without the engine running.

Use the Orange/white & Black white wires to verify the TPS has the correct 5 volts source from the computer.

When you installed the sensor make sure you place it on the peg right and then tighten it down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the front screw enough so you can move it just a little in very small increments. I wouldn’t try to adjust it using marks. Set it at .6.v-.9 v.

1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

2. When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

If setting the TPS doesn’t fix the problem, then you may have wiring problems.
With the power off, measure the resistance between the black/white wire and battery ground. You should see less than 2 ohms. Check the same black /white wire on the TPS and MAP/Baro sensor. More than 1 ohm there and the wire is probably broken in the harness between the engine and the computer. The 10 pin connectors pass the black/white wire back to the computer, and can cause problems.

See the graphic for the 10 pin connector circuit layout.

Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Thanks, I have read through previous postings of yours and did the procedure as you suggested. I had 4.95 vdc on the Orange VREF using my ground probe on the black wire of the TPS. Key on engine off with ground probe on black wire, I could adjust the TPS and get the voltage down on the Green wire but only down to 1.1 vdc. Is this not the correct way to adjust the unit?

BTW- That first link you posted is a dead link...

jrichker · May 5, 2011

Sorry about the dead link, I must have missed something copy& pasting it. Try this: http://www.stangnet.com/mustang-forums/825424-adjusting-your-tps-0-98v-not-necessary.html

Your procedure is correct. What I was encouraging you to do is to check the resistance between the black/white signal ground and the negative ground connector on the battery. A higher than normal reading (.2-1.5 ohms) would cause problems getting the TPS setting in the correct range.

Flavadave4 · May 5, 2011

jrichker said:
Sorry about the dead link, I must have missed something copy& pasting it. Try this: http://www.stangnet.com/mustang-forums/825424-adjusting-your-tps-0-98v-not-necessary.html

Your procedure is correct. What I was encouraging you to do is to check the resistance between the black/white signal ground and the negative ground connector on the battery. A higher than normal reading (.2-1.5 ohms) would cause problems getting the TPS setting in the correct range.

Okay, I will check out the ground resistance this afternoon. I want to replace the TPS unit anyway seeing how it fits on there sloppy after I slotted the holes but am finding 2 part numbers from Motorcraft, will the Calibration code sticker in the door jam lead me to the correct part number?

FourEyed · May 5, 2011

I keep one of these connected to my TPS, eliminates all doubt at a glance, and its kinda cool too.

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