TPS readings goofy. Up dated

[Dave_J]

I am having CEL issues with this new to me 94 Touring wagons EJ22T. It is popping up code 41. I have checked all connectors, replaced the canster purge solenoid, replaced 90% of all vacumme lines and replaced the o2 sensor.

Today I went to "Pick-A-Part" looking for parts. I measured 5 different TPS units on 90-94 Legacy's. Every one ot them tested the same but not within the spec's in the book. And I mean they all tested just about the same readings. Tests between pins B and D I get around 10.5K ohms with throttle closed and 2.3K ohms WOT. Tests between B and C is 10.2K ohms thats does not change with throttle. What is the chanch that all these TPS's went bad in exacly the same way. The book says pins B and C should be less than 1K ohms closed and between 2.4K ohms WOT.

The one on my car reads between B and D is 22.5K ohms Closed and 6K ohms WOT, and 9.9K ohms between B and C.

A new TPS is between $210 and $325.

What do you all get as far as readings?

[Dave_J]

Looks like no one does this test.

I can not buy a new one ($325+) only to find out it was the MAF ($450+) or some other part ($$$). The Purge solonoid was $95 and the O2 sensor was $60. Throwing parts at a car is not the way to fix it, IMO.

Anyone local have an extra known good TPS, PM me please.

[Legacy777]

The TPS values should be "close" to the values in the book, but are not really going to be dead on. It's not a real big deal. It's more important that the resistance change smoothly.

Are you sure you're oriented the connector correctly when testing? The values you are posting seem pretty far off. Here are scans from the factory manual. They have a picture and show the connector orientation. The only real adjustment that can be made to the TPS is with the idle switch, and that's covered in scan 3.

http://www.main.experiencetherave.com/s ... sting1.jpg
http://www.main.experiencetherave.com/s ... sting2.jpg
http://www.main.experiencetherave.com/s ... sting3.jpg

[Legacy777]

Regarding your code 41.....that is the A/F learning control code. If all the sensors check out ok, the only thing left is the wiring and the ECU. If the wiring checks out, I'd suggest seeing if you can borrow or find a used ECU to try out.

[Mister Anderson]

I would check the wiring. I was getting a code 41. I checked the wiring and found the wire jackets cracked and in some places missing. I replaced the bad wiring and the code went away.

[Dave_J]

Update. Replaced TPS with a Pick-A-Part one, replaced three more vacumme lines, found two hoses loose on the pressure side. All is well. Pulls 20 inches of vacumme at idel and flash boosts up to 9 PSI and then relaxes down to 7.5 to 8 PSI steady all the way past 75 MPH when I let off. Runs fine on mid-grade with no pings.

Only code it sets at times, and not often, is the code for the nuteral safety switch.

The NGK plugs were gapped at over 0.045" so I installed new Iredumns gapped at 0.035". Did a cold compression test and #'s 1 - 3 were at 155 PSI and #4 was at 145 PSI. Did not do a warm or a wet test, Yet.

So far . Thanks all.

[91Beater]

The TPS values should be "close" to the values in the book, but are not really going to be dead on. It's not a real big deal. It's more important that the resistance change smoothly.

Are you sure you're oriented the connector correctly when testing? The values you are posting seem pretty far off. Here are scans from the factory manual. They have a picture and show the connector orientation. The only real adjustment that can be made to the TPS is with the idle switch, and that's covered in scan 3.

http://www.main.experiencetherave.com/s ... sting1.jpg
http://www.main.experiencetherave.com/s ... sting2.jpg
http://www.main.experiencetherave.com/s ... sting3.jpg

Hey Josh, After making adjustments, I'm getting a range of 2.0 to 8.2 k ohms, between 2 and 4. This is nothing near the FSM, but its more or less in line with the Chilton's.
Now, a concern I have is that when I set my meter to capture peak value and pump the gas from inside the car, it will jump to 12kohms. You can only see it when the meter is placed on peak capture. Is this normal behavior or should it be replaced?

[Legacy777]

What is the resistance doing when you smoothly open and close the throttle plate? Does resistance change smoothly?

I'll try and double check my TPS this evening to see what it's doing.

[91Beater]

What is the resistance doing when you smoothly open and close the throttle plate? Does resistance change smoothly?

I'll try and double check my TPS this evening to see what it's doing.

In resistance mode, it moves from 8.2 to 2.0 from closed to open. It's a digital meter, so you can't see the jump as you can on a needle analog type. There is a function on my meter that holds a peak value, so I activated that.

It will jump to 10.5 to 11kohm max while operating the throttle. This is a common behavior of a worn out potentiometer.

[Legacy777]

I know when I've tested TPS's in the past if you move the throttle quickly it will spike the meter. This occurred on multiple TPS's so I don't believe they were all bad, but more a function of the potentiometer used in the TPS.

If you think the TPS is bad, try and get a used one to check or replace your current one.