Walk me through measuring TPS voltage please.

[harrymaneuvers]

Ok so I am trying to iron out my TPS on the legacy. I still have a lumpy, spotty low end acceleration that comes on full power around 3500 RPM.

I cant for the life of me seem to be able to measure the TPS voltage to make sure it is between .45 and .55. I have tried it at the sensor with sewing needles in the back of the connector, at the ECU with that particular ECU plug unplugged, plugged in ect and cannot seem to either understand my multimeter or how to do this damn test.

This is the exact multimeter that I have:

https://sl-i.net/FORUM/images/imported/2013/09/0004217303320_500X500-1.jpg

I have been trying to measure the voltage with the setting shown (DCV) and with the black probe in the center hole and the red probe in the right hole.

If anyone can help me out with how to do that correctly it would be appreciated.

I have read and re-read the proceedures which are below:

https://sl-i.net/FORUM/images/imported/2013/09/TPSAdjustment-1.jpg

[harrymaneuvers]

Bump... figured it out. Rather than measuring at the ECU, I measured at the TPS by sticking two needles into the back of the connector like last time.

This time though I probed around with one of the probes touching one of the pins and the other probe touching the intake manifold.


BAM!!!!! Voltage starts to read between .20 and .80. Just dialed it into exactly .500. I am going to go home and see how the drive is... then I am going to disconnect my battery and see what happens when my ECU tries to learn with correct TPS voltage.

GETTING THERE!

[Garrison]

update us on the driving impression will you please? same issue here w/ acceleration

[Odycee]

BAM!!!!! Voltage starts to read between .20 and .80. Just dialed it into exactly .500V

Explain how you dial into exactly 0.5V - Slide TPS sensor along the loosen screws?

[harrymaneuvers]

Well it doesnt seem to have changed a whole lot. My car was idling between 1000-1500 RPM and then later in the day would be fine around 700-800 RPM.

In first gear from a stop... the acceleration is REALLY jerky if I try to floor it.... it doesnt smooth out until around 3000 RPM. If all of my shifts are in that range or higher, the car flys.


After I reset the ECU, it had a hard time staying started after a few start ups. Finally it started and kept idling although it was a little low and studdery.

After about 5 minutes the idle smoothed out but the jerkiness was still there.

My next move is to replace the front O2 sensor because it am pretty sure it is original with 250k miles on it. That and a grounding kit. Both items together shouldnt cost me more than $80 so I figure I will give it a try.

After that I am not sure what else.


No CEL's

[harrymaneuvers]

BAM!!!!! Voltage starts to read between .20 and .80. Just dialed it into exactly .500V

Explain how you dial into exactly 0.5V - Slide TPS sensor along the loosen screws?


Exactly.

Loosen the two screws, poke a needle in the second to the top wire on the back of the connector. Touch one of the multimeters probes to the needle and the other to the top of the intake manifold. It should show you exactly what the voltage is.

Then just rotate the TPS until the voltage is .500 and tighten the screws. You might want to check the voltage again after you tighten the screws because it will most likely change the reading slightly.

@ Garrison - here is a fairly helpful (although long) thread. I guess I didnt realize it but I dont think I had this jerkiness before the VSS Pro was BARELY working. Maybe the fact that it shows 5mph when I am actually accelerating up through 25 mph is contributing to the fuel injection system somehow?

http://www.rs25.com/forums/f13/t66391-h ... first.html (http://www.rs25.com/forums/f13/t66391-hesitation-look-here-first.html)

[harrymaneuvers]

Ok so more developments.


It looks like my high or normal idle is completely dependent on the cooling fans... which I have never seen before.

So with the temps (via scangauge) between 193 and 204 the idle is pegged at 1000-1100 RPM. As soon as the temperature gets to 204 and the cooling fans kick on, my idle goes down to normal.

With the cooling fans on, the temps start to drop until they get down to 193 at which point the fans turn off and my idle immediately goes back up to 1000 RPM.


SOOOOOOO... I am thinking it is either a grounding issue OR an IACV issue although I cleaned it thoroughly when I had the intake manifold powdercoated.