Tps still a problem

[bigred4x4]

OK so with the sensor (tps) plugged in it gets a 4.02v on the reference with it unplugged it gets 4.82v on reference and with grounding to something other than the ground in plug it reads 5.02v I've changed the sensor and the plug and still getting the same result I'm scratching my head trying to think where the voltage drop could be coming from tested the pcm ground and the engine ground and there fine don't really know where to look next besides just taking things apart and putting them back together.

I'm reading like 4.32v at WOT I believe some small issues are because of this(semi rough idle and some stumbling on very light throttle from a stop )not to mention the clunk coming to a stop which I've ruled out driveshafts etc.. because it goes away for a bit if I reset the pcm,I know a bad tps can cause this and would like to get it fixed I cringe when coming to a hard stop.

 

[swshawaii]

Any chance you installed a SOHC throttle position sensor on your '96 OHV?

Weird TPS issue | Ford Explorer and Ford Ranger Forums - Serious Explorations

 

[bigred4x4]

I doubt it I have a 95 engine in her and takes the older style square plug instead of the rounded kind I'm not sure was ever used for the ohc.

I'm losing voltage through a bad ground somewhere and I think what's even weirder is the voltage loss through the sensor itself

 

[boominXplorer]

I doubt it I have a 95 engine in her and takes the older style square plug instead of the rounded kind I'm not sure was ever used for the ohc.

I'm losing voltage through a bad ground somewhere and I think what's even weirder is the voltage loss through the sensor itself

Are you running the 95 harness or did you swap the plug over? Original computer?

 

[bigred4x4]

Well........ The guy that did the motor swap back when I first got the truck (within the first year..... Long story) got a low mileage 95 motor to swap in my 96 they used my original harness and computer but spliced in all the plugs on the 95 come to find out .... Again long story the IAC And plug didn't match and fried the PCM.... Took 4 different shops/dealers to figure that one out, any way the correct pigtail and computer was replaced but.... As far as the tps goes this is a new problem that just popped up when I got it back on the road again back in June.

 

[bigred4x4]

And even the 96 shows taking both styles of plugs I guess it depends on the manufacture date that determines whether you got the old style or new style.

 

[Turdle]

Have you tried disconnecting other sensor to see if the voltage goes up?

I think all the 5v sensors have one common 5v line source,

 

[J_C]

I may not be understanding what you're stating but the TPS is a resistive element (potentiometer) so with it connected, it's going to pull the voltage down a little by the amount of its resistance to ground.

I'm not so sure that TPS is your problem. At idle it shouldn't make it rough, but as far as stumbling on light throttle, you should be able to measure the resistance of the TPS and note whether it's a smooth resistance change or there is some error (open circuit or large deviation in resistance measurement) as throttle position increases. A smooth voltage change during its travel w/o interruption would also suggest it's gradually changing resistance without fault.

Is this a continuation of another topic you've posted or a new issue? Is the check engine light on, any codes set? If you have an OBDII scanner that can show live data, I'd look at the fuel trims and for misfires.

 

[bigred4x4]

I got the green light on my scanner no codes fuel trim is looking good,02 switch is good, bank 2 seems a little lazy though but not bad, tps % is 19 at idle and only goes up to 24.9 at 2k rpm....., also spark advance seems to be dancing around alittle more I remember not long ago it would usually be a little more steady, but I've literally have had no change in these tps values since I changed the sensor and the plug. Plus the reference voltage is about a volt low on the harness unless I ground to battery then it's 5.02v.

 

[bigred4x4]

I was tinkering around last night and noticed the small bolt that holds the throttle plate to cable linkage is very loose im going to tighten it up see what happens, also what effect would I get if I attempted to adjust the adjuster screw? Also going to try and adjust the tps I think it is a "non adjustable" part but it is because I've done it before you can make small adjustments to it by moving it with a multimeter hooked up and re tightening the mounting screws.

 

[Rhett]

I was tinkering around last night and noticed the small bolt that holds the throttle plate to cable linkage is very loose im going to tighten it up see what happens, also what effect would I get if I attempted to adjust the adjuster screw? Also going to try and adjust the tps I think it is a "non adjustable" part but it is because I've done it before you can make small adjustments to it by moving it with a multimeter hooked up and re tightening the mounting screws.

I guess you're aware of this thread (1st gen content):
http://www.explorerforum.com/forums/index.php?threads/adjust-your-tps-another-free-hp-mod.79362/

but the premise may be the same regarding moving the TPS while probing with multimeter.

As for the adjuster screw -- i've never done that on an OBD-II truck. i'd say as long as your TPS voltage is within range you would be ok BUT if your throttle body is anything like mine (I have a larger-than-stock one), it's definitely going to affect the idle rpm, and it's really finicky. I think if the screw were out of position, you'd know it with your idle, unless your OBD-II PCM is really quick to make those kind of adjustments.

Are you sure your TPS and IAC are working properly? The TPS voltage max and min may be right where they are supposed to be, but if the voltage change is unsteady or has a dip or slow point, it could cause the stumble.

 

[bigred4x4]

The signal voltage is .94 at close and 4.32 at WOT, it does seem to smoothly increase opening the throttle and no codes are being thrown but when I look at the live data it doesn't seem right it only jumps like 5% increase between idle (~700 rpm) and 2,000 rpm. And I'm pretty much experiencing every known symptom for a troublesome tps.

 

[bigred4x4]

It's like it's going bad but the computer corrects and learns from other sensors so the problems are brief and fairly small but would like to get it fixed especially for the clunk into first coming to a stop. Which I'm 95% sure is tps related.

 

[Rhett]

Is your '96 throttle still cable driven? I've seen the cable bind, that may explain why you're static throttle plate opening voltage test was fine, but your live data feed showed it not opening much when you were driving around.

If it's not cable driven then I'd replace the TPS at this point.

 

[CDW6212R]

Was any of the engine wiring changed or R&R'd at some time? If the voltage measurements at the TPS show figures that it should, and the engine runs like it's not right, I'd check the wiring from the TPS to the computer.

I'm not sure how tough that may be if the PCM connector would have to come off. I'd try to carefully stick the probe wire in the proper TPS terminal from the outside of the PCM connector. I'm wondering of the PCM is seeing the same voltages as the TPS is putting out.

 

[bigred4x4]

The engine throttle is cable driven, the tps is reading low on reference and signal when back probing while connected, I remember not long ago that it wasn't like that. The engine has been out twice since I've owned the truck but the last time I installed it I know the tps/voltage was not an issue. I'll play around with it alittle more today probably and report back.

 

[bigred4x4]

Ok figured one thing out thought I had it nailed but the search continues, when I had the engine replaced they spliced the wires in according to color which I guess was different from some reason I switched them to the correct positions but now I'm getting 5.02 on reference and .2 at closed and about 1.4 at wide open throttle between two different plugs and 3 sensors I don't get it the only thing that stands between the reference and signal is the sensor itself. Now my pcm recognizes a problem and is producing a throttle position sensor low voltage code.

 

[bigred4x4]

Here we go again .....lol come to find out the parameters other than the reference voltage that I had were fine (read more into acceptable ranges) the plug was not wired wrong. So i rewired the plug and guess what same results!!! Reading .2 at close and 1.2 at WOT what!!!!! I obviously damaged something when I switched the ground with the signal wire hopefully just the sensor as I'm reading a perfect 5.01 on reference and I'm getting a perfect .2v drop on ground ( reading into this this is normal and better than 0v supposedly it's ment to operate this way) I cleaned the PCM and main engine connector as well as the pcm ground which solved my high voltage drop but now I've screwed something else up I guess I'll buy a fourth sensor and try that if that doesn't work I'm absolutely clueless!!

So question of the day if the new sensor doesn't get me back to where I started then what next ? How do I test the PCM ??

And if all this goes back to normal but the the PCM isn't really picking up the signal even though it's fine at the connector then what test for short to ground in signal wire? And if that's good what next?

I can't believe this simple problem is turning into a seemingly endless night mare.

 

[CDW6212R]

Go slow and methodically at wiring tests and checks etc. Don't go probing any PCM connectors, the actual computer terminals. A multi-meter can damage circuits inside the PCM, test the wiring outside of the computer. Do you know which PCM terminals are for the TPS? If so, I'd start by checking resistance in those wires, from the TPS to the PCM connector. Those should be basically zero, so the PCM should see the same voltages that you get when testing the TPS normally.

 

[bigred4x4]

Ok so after replacing the plug and sensor with no change then I switch the plug back with new sensor then switch the wires then change the plug again then switch the wires back and then I buy yet another $40 sensor the 4th one thanks advance Auto for not returning " electrical" parts so I'm pretty much out $160 worth of sensors with old plug wired the original way with a new sensor im still reading 5.02v at reference,.02v drop on ground and a .2v on signal what gives!!!!!! Why all the sudden can I not for the life of me get back to ~1v - ~5v signal range. I'm getting .2 - 1.4 no matter what now I don't see how the PCM has anything to do with it when I'm getting these readings at the back of plug on the sensor.