Hi guys,

I hooked up my OBD II scanner the other day to my new-to-me '97 4Runner Limited with the 3.4 to check the readings of the engine's sensors. With the engine off and ignition on, I noticed that the TPS was registering a value of 11.8% with my foot completely off the gas. When I depressed the gas pedal all the way, it registered 76.5%. I opened the throttle body all the way by hand and it still returned a value of 76.5%. This doesn't seem right to me; do I need a new TPS?

 

And how does that compare to acceptable stated readings in the FSM?

:wabbit2:

 

I currently do not have a FSM for this vehicle, so I do not know.

 

With my scangauge ii, it reads 10 at 700 RPMs.

Are you getting a code indicating that the TPS is problematic? If not, don't sweat it.

If you want to check it though:

http://www.ncttora.com/fsm/

 

GOOD QUESTION!!


Per my '99 FSM, p. DI-169:
Throttle valve fully closed: 7-11%
Throttle valve fully open: 65-75%.

You are high on both by a smidgin. The FSM goes on to say:

...sounds like you're good. This is a GREAT page and I had never seen it before. I'll post a link if I can find it on line.

EDIT: See page DI-11 here: http://www.ncttora.com/fsm/1996/SIL/...zfe/preche.pdf

Note: All these specs are the same in '99, except that there are no #2 fuel trim items in '99.

 

Hmmmm... I don't really understand why it would be "normal" for the TPS to register a value ~25% less than what the driver is asking for. But if that's the way it's supposed to be then I won't worry about it.

 

Beats me, too. That TPS is used on other engines as well so maybe one of those has different geometry that allows for a wider angle of arc on the butterfly. It's also more precise to keep a resistance type sender a bit within its extreme range. But I'm sure the ECM is designed so that it regards anything 65%+ as WOT. In any case, the butterfly is what counts as far as volume of fuel/air mixture, the TPS just affects fuel trim and ignition timing. Those probably hit their extreme values somewhere before WOT, like maybe 50%+ (just going by how old-time mechanical distributor advances work).

 

So strange to see TPS issues, all of a sudden at the same time mine is having issues. I've changed my TPS and I still get no acceralation..wish mine would get resolved i'm not enjoying my Runner right now. 235k and this is the only thing to ever go wrong.

 

your tps will never read 100% or 0% because it uses those values for diagnostic purposes. and it associates those percentages with voltages, so if it sees a certain voltage(percentage), the ecm knows that there is a problem