I need some help because I bet it is something small I am overlooking. I took my UIM off to replace the under TB coolant hose. Put it all back together and I noticed my TPS reading was off so I tried to reset it with the voltage method(engine fully warm). I couldn't get 1vdc to read, so I set it with the resistance method. My Rtek 2.1 said it was off though and I also tried to set the idle with the Rtek to no avail. I thought it was a shot TPS because it's very old and it just seemed that would fix it, well it didn't.

When I backprobe the green single wire coming out of the TPS plug it will only read Mv's like .75 and t moves around a little. Also when I backprobe the green wire I get a clicking noise at one of the solenoids near the oil filler tube.

It was all working just fine before I took the UIM off to replace that stupid coolant hose. What is going on? I have checked and rechecked and I am very frustrated. This is my only car right now so I really need to get it going soon. Any help is very much appreciated.

Also could someone please post a pic of the harness side of the TPS connector showing wire colors and locations please. I want to make sure everything is right.

 

Sounds a lot like what I am dealing with.
Have you isolated it to close loop mode only? That should help narrow down the components to check.
Is engine pulling good vacuum?
Have you checked that your BAC is working/plugged in?
Is there some slack in the throttle cable to allow some throttle body mechanism travel when adjusting the tps voltage screw (forgot the real name)?

 

I think yes to all of the above. I just know it has to be some little wire grounding or something. I have never had idle problems or hesitations until after I pulled the UIM to change that horrible coolant hose. It has to be something simple I'm just overlooking. Hopefully Hailers will show up sometime soon, he always has the answer for this crap.

 

Did you leave the inital set coupler in? I'm not sure what that does exactly if you leave it in, but it's a thought. Other than that, I'm tagging out and waiting for someone else to jump in.

 

No actually my Rtek controls it now and it's not even plugged in anymore. Thanks though. I have hope that I will get her running good again.

 

Just to add: I just checked to see if I had continuity to ground at the Black wire on the TPS connector. I do with the key off and I don't with the key to the on position. I don't know if that helps at all, but I am stuck and frustrated.

 

Odd. With a RTEK 2.1 or 2.0 you should be seeing 20 or 20 percent on the PALM screen when the car is fully heated up.

With a cold engine you will see a higher figure and it means nothing because of the throttle linkage being moved by the waterthermowax/fast idle cam etc when the water is cold.

The stk output wire on the harness (NOT the pigtail on the TPS) is green with a red stripe and it goes directly to the ECU.

Clicking of the blue or grey solenoids is normal in a sense. When the blue Relief should be getting a ground from the ECU to energize it. Should click on when the output of the TPS to the ECU is one volt dc (or 20% showing up on the Palm, same thing).

That's one function of the TPS.................opening and shutting the blue or grey solenoids when the throttle is moved. Emissions related thing. Those solenoids don't effect the actually running of the engine itself.

Don't try to read a ground wire with the key on. It will result in confusion. Read the gnd wires only with key OFF and meter on ohms.

With a hot engine you should be able to set the TPS just looking at the Palm screen . IF the screen shows other than 20% then just keep the engine at idle and turn the TPS screw one way or the other til the screen reads 20%. If it reads something like 19% or 21% you won't ever notice it when driving. There's some slack in what it reads.

Three wires on the connector. When the connector of the TPS is apart the brown/white should read approx 5vdc.........pure black should ohm out to ??? .2 to .4 ohms and if you read the green/red it would be meaninless 'cause the TPS plug is not connected up but when it is connected up and the engine hot, you could backprove the green/red and it should read approx 1vdc. But then again just looking at the PALM screen reading 20% would reflect that ( TPS has a full voltage possibility of 5vdc and one volt is.........20% on five volts. So that explains why the PALM would read 20%.

Sorry, I can't relate to the wires on the TPS pigtail, only the wires on the harness side of the TPS connector. I could go out and look but it wouldn't be productive.

 

Yeah I have read tons of threads on setting the TPS. It won't read 1vdc or anything above like 650-750 millivolts. I have set it before and it was fine. What could be screwing with the signal to the TPS from pulling the UIM off? I have gone through the idle setting procedure on the Palm and I have it idling, but if I drive it at low cruise speeds it bucks and hesitates which it has NEVER done before. I should be able to see 1vDC or more at the green wire with the key to on and the car fully warm, but it isn't reading that, so what could be causing that? Thanks Hailers. It also doesn't correspond to setting the ohms to 1k either. If I set it by Ohms then it reads like 14% on the palm and still doesn't drive good.

 

Have you ever just set the meter aside and just looked at the reading on the Palm? And when it read 14% as you say just above, just gone out and turned the TPS screw til the reading was 20%? That's what I'd do.

14% of 5vdc would be .7vdc. So that makes sense from what you wrote earlier when setting it using the ohm method.

 

In your first post you mention replacing the throttle coolant hose. How would that effect the TPS reading?

The water in that hose causes the water thermosensors plunger to extend when the water gets hot and this extension of the water themrosensors piston moves the throttle linkage via the fast idle cam etc which in turn moves the TPS's plunger. When the water thermosensors plunger is fully extended due to the water being fully hot, the throttle plates are now fully closed and the TPS plunger is now in the IDLE positon and that's where the output of the TPS is checked at.

The reading of a tps will be a higher figure when the water is not up to running temperature and there is no figure for what it should read with a cold/warm/tepid engine.

 

Replacing the coolant hose is when this whole problem started and means pulling a few connectors and wedging my arm in there to secure the fitting so I thought may be something in the area could have been bumped and causing my problems, that is why I mentioned it. I understand the thermowax system. That's not the problem. Yes, I have set it just by the palm to 20%. That is what I have it set to right now. It still hesitates and acts strange at low load. If I look at the voltage right now as it sits with the palm reading 20% it reads 650-750 millivolts at the TPS connector, not the 1Vdc that it should read, so that is why I am confused.

All tests have been done with a fully warm engine. FYI. Thanks again for your help.

 

I can't account for the 650-750.

You might have loosened an injector plug on the primarys????

If it was tps related mabe you could remove the tps plug and drive it to see if it acts the same or not. OR watch the 20% on the palm as you slowly step on the pedal (engine on or off) and see if the voltage rises like it should or if it rises and suddenly drops down (bad tps) as you step on the pedal.

Does the DIAGNOSTICS show a fault for TPS??? I mean after it's set for 20%? When you set the idle using the PALM does it show a message saying the TPS value needs to be set?? or does it show the 20% as it should?

 

After I set the idle and set the TPS to 20% on the palm it shows 20% as it should and there is no fault on the diagnostic screen. The % rises just right as I step on the pedal. It was difficult to set the idle with the palm though so it seemed something was different or wrong. I will go take it for a drive with the TPS disconnected and report back. Also the TPS is brand new today from Mazdatrix.

EDIT: The car will not even stay running with the TPS unplugged, so I couldn't test if it acted the same.

 

I just had my UIM off last weekend, and ran into a couple issues that could be related to your problem.

1) I created a vacuum leak between the UIM & LIM by tightening the nut on the TB end (at the TMIC support) before tightening the 4 nuts/long bolt along the intake runners. Loosening everything, and then tightening in the correct order fixed it.

2) The variable resistor setting in the Rtek just stopped working, and I could no longer adjust the idle mixture at all. You mentioned that the idle was hard to set, so maybe you're having issues too? I downloaded the latest pocketlogger software to the Palm, and it fixed it.

Between the vac leak and not being able to adjust idle mixture (I just switched to 720/880cc injectors), I ended up with a really crappy idle and lots of hesitation at part throttle. I'm not saying rule out the TPS as a problem, but I'd say it's worth trying anything. For what it's worth, my TPS sits at 26% at the lowest, and everything works just fine.

 

I'd remove the intake and look around a bit. I'm guessing a vacum leak. Line off the primary injector air bleed? or hard injector grommets or bad connection on a injector.

At one time or the other I've reinstalled the intake and messed up something under there when reinstalling that water hose to the intake. Usually knocked off a primary or secondary injector plug or a hose offf the top of one of the oil injectors and caused a vac leak.

I don't see the TPS being the problem or else the Palm wouldn't read 20%. Couldn't do that if it didn't see the output of the TPS being approx 1vdc.

Brand new TPS. Whew, big bucks there. Nice to have a new one though.

 

Well I have ziptied all of my vac connections under the UIM so I don't think it's that, it also pulls the same vacuum it did before according to the palm, and my boost gauge, but I will most likely take the UIM off again and see. Sometimes I just want to push this car off a cliff! I feel like there is some electrical connector or loose random wire that is causing this problem. How can the ECU see 1vDC when I cannot at the connector, doesn't it just go straight from the TPS to 2G in the ECU? What would cause the readings to be different?

 

Shoulda read the same. Someday I'll go set my TPS to read someother figure like maybe 15 or 25 and then backprobe 2G (green/red) . But not today.

 

Where does the voltage coming into the plug come from? Main relay?

 

On a series four car ............brown/white is ref voltage and comes from the ECUs guts..........black or brown/black is gnd from the ECU gnd on the rear rotor housing........green/red is output from the TPS to the ECU.

So called ref voltage is five volts made by the ECU and that is as high a voltage you'll ever see from a TPS and I doubt you'll ever see that high a voltage.

Brown/white is spliced to a few other sensors in the engine bay and goes back to the ECU on pin 2A.

Green/red is a straight run back to pin 2G on the ECU

Black is spliced to several other sensor gnd wires and terminates on the top of the rear rotor housing and also is spliced to pin 2C of the ECU (ECU guts gnd wire).

Just about what you see on the 88 wiring diagrams on page 50-25.

 

Once again I feel like such an idiot. I have a setting on my digital meter called "battery load test." I was using that which I guess simulates load on the battery and it was giving me a false reading. I am sorry for wasting your time Hailers! I get .997 volts now as it should be. I imagine my slight hesitation was due to a vac leak, I will see if it still hesitates and investigate more. Man I love spending over $200 for **** I don't need.

 

By the way, make sure you BAC plug is on the BAC.

So I went out to the 87 turbo that hasn't run in a week and put a PALM on it and backprobed 2G at the ECU with a Fluke.

Engine cold but weather about 90 degrees plus minus a bit.

TPS read 34% on palm in the beginning which was 1.74 vdc on the meter.

33% read 1.71 on the meter

32 % read 1.64 on the meter

30% read 1.56 on the meter

28% read 1.45 on the meter

25% read 1.29 on the meter

23% read 1.22 on the meter

21% read 1.11 on the meter.

Sorry, my TPS is set to 21% and I'm not going to screw the screw to get it to 20%. It won't make a bit of difference in life.

TPS are curious things. They identify ZONES OF OPERATION for the ECU. Those zones of operation are in the training manual online and that gives one sort of an idea what the zones are.

IMHO seeing 18 or 22% means it still sees the idle zone of operation in my very humble opinion. Just an opinion.

 

Thank you many times over Hailers. Not many people would do something like that to help out a fellow 7 owner. I am still getting a hesitation, especially at full throttle it will hesitate, then keep going, it idles fine though. I did find a slightly loose hose and tightened it down, but it probably is my UIM gasket leaking now or something. It isn't very old though, maybe 6 months. Time to go vac leak finding.

 

hailers2 is pretty good at helping out if he can. try to reset your whole electrical system with the battery disconnect method. sometimes this helps.