Voltage on Throttle Sensor
 

I have had problems with my cars idle for the last two years and have tried everything possiable to fix. I borrowed the Subaru computer anlyser and then compared the differences between my car (390K)and the wife (130) wht I found was that my throttle sensor was reading .48V as opposed to my wifes at .16V. A couple of years ago I had my throttle sensor changed and it seems it was not put in right. I think the manuel is wrong because it said it should be .4v at idle and max 4-4.5, my max is 3.7V.
Any one got a suggestions on this issue.
Tony

My service manual states that at idle, the voltage between the middle pin of the TPS and ground should be between 0.4 and 0.6 V.

At wide open throttle, that voltage should be between 3.6 and 4.3 V.

If your idle speed is incorrect, I would suspect the Bypass Air Control Solenoid Valve (sometimes called the IAC).

My idle speed would sometimes rise to over 1500 RPM - it was the IAC causing this, as it had stuck open. I had to remove it, and thoroughly clean it to fix the problem.

The other possibility is that the Auxiliary Air Control Valve is sticking open.

This valve allows extra air to bypass the throttles when the engine is cold. It consists of a bi-metallic strip, driven directly from the output of the fuel pump relay, so that it should close within minutes of the engine being started from cold.

This valve may also require removal and cleaning.

:)

Jason.

Jason have you adjusted your TPS and if not have you measured the voltage on it?

Yes - my TPS is adjusted in accordance with the service manual.

Jason.

Tony,

It would appear that your wife's car is set incorrectly. Please check my info in the how too section.

Hi Trevor I think may be that the Subaru test unit I am using reads differently to a voltage meter which I will check today. I also have the TPS unit on a throttle body from a half cut and I plan to see what it reads. Since winding it back the car has run smother and th idle has not screwed up once. Considering I have tried every thing I can think of to fix the idle in the past I want to investigate this in more detail. I am sure that you have found that the manuels can be wrong some times so lets see what readings I get today.
Tony

Okay tested the TPS from the half cut and it was .4V I need to get Matt to test his and see as his car is only 7 cars differnet in chassi from mine so we will see.
Tony

Tony, on this one, be sure that the manuals are absolutely correct. There are many members who have the TPS set as per instructions and there is no reason to have any doubts.