Throttle position sensor - Voltage on output wire

[Heavyopp]

Just a shot in the dark,but sounds like an injector or more running to rich.Did it do this before the change

I've never driven this jeep -- came to me with "needs"

When I 1st started playing around I did get some bad injector codes so I upgraded them all to the ford upgrade injector - I forget the part number


I'm trying not to just replace parts and figure out what is going on but this voltage on the Tps output wire has me stumped

I do keep getting Tps voltage low p0122 also -- guess it's time to dump another $71 into a new mopar TPS

If this thing wasn't so clean I'd go find a 99 to play with

 

[Waynerd]

I never figured out my issue. I did confirm on another of my Cherokees that runs well and has no CEL lit. There is voltage at the signal wire cavity when unplugged from the TPS. On the 98 that was throwing codes the voltage was much higher with the 3 fuses I pulled installed.
When I turned my wheels sharply the jeep would sputter and stall until I removed the fuses. Only explanation I was able to find for the signal wire having voltage when unplugged from TPS was that it was for if the TPS failed the vehicle could be driven still. Found that on a non jeep website.
I tried several TPS from my various jeeps and I still kept getting high and low voltage codes. I kept messing with the connector and finally got the codes to clear and stay away. I actually drove it at one point and had forgotten to plug the TPS in and it ran fine but didn't shift correctly so that just proves its getting a voltage signal from someplace other than the TPS.

Good luck. I've given up on mine for now until I can afford a clockspring then I'll try again.

 

[Heavyopp]

New TPS did nothing -- I don't get the P0123 code much but I get P0122 every time I clear codes -- Low voltage from TPS

New PCM changed nothing last week -- I don't know where to look anymore

I still get a glowing red rear pre-cat -- on the bottom of the cat and for a few inches of the pipe

I also have a lot of fuel disappearing -- I've put over 10 gallons of fuel in this jeep and never driven it -- There are no leaks in the tank or that I see or smell -- where is all my fuel going? -- It's ran at idle for a few hours, rough idle at best -- never should use all that fuel -- I would think if all that fuel was getting burned in the exhaust I'd have had meltdown and a fire by now

Also put new NGK plugs in last week although the new champions where black, wet but uniform from cylinder to cylinder

Runs OK cold at idle -- OK above idle but once it's hot it barely idles, runs rough, and stalls eventually

There has to be something I'm missing with the p0122 code -- Thats my only constant code

My clock spring is unplugged too although my issues don't seem to be coming form there

 

[90xj06]

can you read live data with your scanner? or just codes? also check that sensor ground Brown w/yellow has a good ground it does join with the coolant temp and air intake sensor. so it may be chaffed or broken before the join as you have no codes for that sensor.

also assuming you have an auto trans. the transmission computer connects to the signal return line too. and that P1694 would be from the Trans Computer. so that could have failed and is shorting your signal return line. from the tps.

 

[Heavyopp]

Can read live data with scanner -- what am I looking for?

Air intake sensor? Is that the MAP sensor? where do these all ground? My coolant sensor is fine.

Yes auto trans -- I have tried it with the TPS unplugged -- No change in the way it runs and voltage on wires

1694 seems to have gone away for the moment

 

[90xj06]

see what the tps reading is during the live reading. engine does not need to be running. it might list as a % or a voltage. and did you try with the tcu unplugged?

 

[Heavyopp]

I get a % as live reading from TPS -- Starts out at idle with TPS around 15 or 16% and goes all the way up to full throttle to 100%

Yes I did try with TCU unplugged -- No change

 

[90xj06]

so from that data is seems to be reading correctly. does it also show a voltage range?

 

[Heavyopp]

No voltage on my scanner -- It's a module that plugs in and send data to my iPad -- seems to work pretty good

A friend has a real scanner at his shop -- I just have to get the jeep there and he'll scan it for me -- says he can get more data than I can -- Just a PIA to trailer over to him...

 

[Bobbie]

I put two tps in one of my jeeps.Chased this problem like you and finly had enough and returned it back to parts store.Parts man said this part is a used mopar part but they took it back because they know me .Someone brought it back and got a refund on a junk part.Owner said it happens all the time.My jeep runs like new now.

 

[Heavyopp]

I ordered a mopar TPS from amazon -- Sure looks new and seems like both my original and the new replacement are working properly -- I can't imagine a 3rd TPS would change anything for me

 

[Bobbie]

I ordered a mopar TPS from amazon -- Sure looks new and seems like both my original and the new replacement are working properly -- I can't imagine a 3rd TPS would change anything for me

Check the power plug to the tps for a good snug fit.May not hurt to clean it with electric cleaner.Have you every cleaned the throttle body and changed the gasket.

 

[Heavyopp]

No never removed throttle body -- I was thinking about that lately

How do you clean it? -- just spray throttle body cleaner or do I need to poke out holes like a carburetor

 

[Bobbie]

No never removed throttle body -- I was thinking about that lately

How do you clean it? -- just spray throttle body cleaner or do I need to poke out holes like a carburetor

Yes, clean all hole and use an old tooth brush with body cleaner.Last thing if you have air,blow all holes out.Be sure to replace gasket.Remove the tps and fast idle switch before cleaning.

 

[Heavyopp]

I'll assume by fast idle switch you mean Idle air control

Local advance auto has the gasket -- Felpro -- $2.09

I think I'll do this today and see what happens

 

[Waynerd]

I did read where someone was getting false TPS codes and it ended up being their MAP. What about troubleshooting your MAP? It's free.

 

[Waynerd]

Apparently on some vehicles the TPS and MAP are compared by the by the PCM. Also the MAP is one of the sensors the PCM uses to define timing and fuel trims.

 

[Heavyopp]

I did get a MAP sensor code a few times -- Found a Vacum leak and that went away

I'm pretty sure I pulled the MAP sensor and did troubleshoot but I'll double check it

I don't recall the procedure at the moment, Have to look it up and refresh my memory

Yesterday I didn't get to the throttle body but I did a few things in between working on a Vibratory plow for work

1st off I reset the PCM -- Positive battery cable off, ground to AC compressor for a few minutes

Battery back on, key on, headlights on headlights off, key off

I also took apart the positive connection at the Power distribution block and cleaned everything, coated with copper never seize and assembled

I changed my oil -- Turns out that the XJ was probably 1.5 quarts overfull -- I don't know why I missed this -- I have checked the oil, never noticed how overfull it was -- So I changed out the oil with 1 quart of Marvel Mystery oil and 4 quarts of Rottella 15-40 diesel oil -- This jeep has 225,000 miles and has been sitting for at least 3 years

The oil that was in it was thin, like water -- I don't know what weight it was but really thin -- It was black, not milky just thin -- I had always been fighting oil pressure -- got a ton of pressure now with real oil in it

Keep the suggestions coming -- Still runs like shit but no P0122 code after an hour of run time yesterday -- Maybe cleaning the throttle body will help -- gonna find out soon

 

[Waynerd]

Testing map requires a vacum pump. Or there's a procedure to test it with the vehicle running. Not sure of the specs off hand. I have read that if the map is unplugged and nothing changes then the map is bad. Not sure how accurate that could be though.

At the least you could test for voltage, ground and continuity. Until you figure out the voltage range with vehicle at idle. And since I've been thinking about this I realize that maybe I should test my MAP.

 

[Waynerd]

Oh and the oil capacity for the 4.0 is 6 quarts. And the dark thin oil may be contributed to excess fuel washing past the rings. Did the oil smell very much like gasoline?