Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

Photo
- - - - -

Testing a TPS 97 2.2L


  • Please log in to reply
6 replies to this topic

#1 mickytrus

mickytrus

    USMB Regular

  • Members
  • 137 posts
  • northeast

Posted 25 February 2014 - 10:29 PM

Hello,

 

I am interested in  testing a tps......

I have removed the TPS and have an ohm meter.

Basically, looking for the overall testing procedure...

testing resistance and resistence range....

  Also,  testing the voltage on the three wires

going to the TPS...

 

THanks, Micky

 

 Oh, symptoms......

   car Idles beautifully...........

try and accelerate and you would think the wires were crossed......

chuggs..... and doesn't even move...... press pedal to the metal....

and no difference at all..... so I am thinking either TPS or........

no electric getting to it........................

So when you describe.... use wire color if you can.... and reference pins by top pin of tps or middle or bottom...

etc etc..........   Thanks, Again,,, Micky......



#2 Fairtax4me

Fairtax4me

    Su bah roo'n

  • Gold Subscribers
  • 8,831 posts
  • Charlottesburg, VA

Posted 25 February 2014 - 10:49 PM

Overall resistance I don't remember offhand. But here's the basic.
Either outer pin to the center pin, you should have either high resistance, gradually sweeping to low resistance (or vice versa depending on which pin you choose. Switching top to bottom will reverse the resistance reading.) as you turn the TPS.
This is much easier done with the TPS still attached to the throttle body, so you can use the throttle lever to turn the TPS.
The reading should be a smooth change (easiest to see with an analog meter if you have one), if the resistance bounces around a lot and goes off scale the TPS is probably bad.

Wiring.
Center wire is the signal wire to the ECU.
Top and bottom will be either 5V reference feed from the ECU, or ground back to the ECU. Easy to tell if you unplug the connector and turn the key On, check each pin for voltage.

You should also check the TPS voltage signal back to the ECU while it is plugged in. You'll need a paper clip or needle to stick in the back of the connector.
Check the reference wire for 5v with the key On.
Check the ground wire voltage to be sure you have a good ground. Should be very close to 0V no more than 0.1V.
Check center wire voltage. Adjust the TPS until you have about 0.51V at the center pin. Then sweep the throttle slowly all the way to wide open. Voltage should climb steadily to about 4.2-4.5V.
If you have a jumpy (up and down) voltage reading, or voltage drops to 0 while sweeping the throttle open, the TPS is bad.

#3 mickytrus

mickytrus

    USMB Regular

  • Members
  • 137 posts
  • northeast

Posted 26 February 2014 - 11:14 PM

Thanks for the reply.... I just want to clarify so I better understand......

I bolded the topic.... and threw in a couple more words... Thanks, Micky

 

Overall resistance:

       Ok, that sounds good..... I understand... that.

 

Wiring

      Reference voltage, top and bottom pin while key is in on position ground to battery or any good ground....? (should be 5 volts)

 

Tps voltage back to ECU:

  this would be the center pin(wire)(while plugged in) stick a needle or paper clip in wire, run to ground, voltmeter reading should be 5volts?

 

Check the ground wire for a good ground. Should be close to 0v no more than 0.1volts(  not sure here what you mean)

    which wire is the ground wire( basically, place voltmeter between it and ground..... (should be close to zippo in voltage?) no continuity

 

Check center wire for voltage(not sure??? if you could clarify)

 

      Adjust the TPS until you have about 0.51V at center pin

          This would be key in on position..... using needle or paperclip..... throttle closed..... run to ground

                           Do the sweep thing  4.2 - 4.5 volts

                                   check your sweep quality.... should be fluid no drops



#4 mickytrus

mickytrus

    USMB Regular

  • Members
  • 137 posts
  • northeast

Posted 05 March 2014 - 10:42 PM

So ,,,,,,

Here is what happenend...

 

I have 5 volts with the key on. for the top wire in the plug.....

 

I don't have 5 volts on the bottom  wire in the plug

 

 So ..... I would like to know what to do next......

  I figure it would be good to check the wire to the other end for continuity

and I would also like to   know where it goes.......

 

       What are the next steps to trouble shoot this here?

 

  Thanks a bunch Micky

 

 

 

 

 

 

 



#5 Fairtax4me

Fairtax4me

    Su bah roo'n

  • Gold Subscribers
  • 8,831 posts
  • Charlottesburg, VA

Posted 06 March 2014 - 01:29 AM

Then the bottom wire is ground wire, so there should be 0v there. That means the ground is good.

The TPS signal at the ECU should be checked. You would have to get a factory service manual for the car and check which pin the TPS signal wire goes to in the wire diagrams.


Have you checked for split vacuum/ breather/ PCV hoses? Checked fuel pressure? Replaced air/fuel filters?

#6 mickytrus

mickytrus

    USMB Regular

  • Members
  • 137 posts
  • northeast

Posted 06 March 2014 - 12:53 PM

Then the bottom wire is ground wire, so there should be 0v there. That means the ground is good.
ok, that's great..

      I'll just test the sweep for voltage.... and adjust tsp....

The TPS signal at the ECU should be checked. You would have to get a
factory service manual for the car and check which pin the TPS signal
wire goes to in the wire diagrams.

 

Ok,    illl work on that.(finding out which pin)....    Where is the ECU located?



Have you checked for split vacuum/ breather/ PCV hoses? Checked fuel pressure? Replaced air/fuel filters?

    Not to any great extent......  I did pull off the air intake last night.... those hoses seem.... ok.....

 

I believe air filters.... fuel filters where already replaced......  (air filter is new)

 

 How do I check the fuel pressure.....

 I can go and purchase a pressure gauge/ fuel pressure meter.... etc if I have to .....

   which one should I get??

 

Thanks, Micky

 

 



#7 Fairtax4me

Fairtax4me

    Su bah roo'n

  • Gold Subscribers
  • 8,831 posts
  • Charlottesburg, VA

Posted 06 March 2014 - 09:02 PM

Most parts stores will rent fuel pressure test kits for free. You pay a fee to get it, but get all your money back when you return the kit.
You need a kit with a T fitting.
Hook up between the fuel filter and the engine.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users