TPS adjustment help

Deuce Cam
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Joined: Sun Jan 13, 2013 2:41 pm
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TPS adjustment help

Postby Deuce Cam » Thu Nov 03, 2016 2:40 pm

My ecu throws code 11. It's been this way for years and the engine has always ran good and passed emissions. In lieu of much talk about code 11/tps recently on the forums I decided to attempt adjusting my tps to spec via the procedure in the service manual, but was unable to do so, i think...

TOYOTA TPS Part #: 89452-28010

All testing was done with tb assembly off the car.

Initially, I checked the resistance specs between tps terminals from the chart in the service manual, and all were to spec except IDL-E2 w/ 0.35 mm feeler (no continuity).

Then I followed the manual's adjustment procedure. Between IDL-E2 I now have continuity when testing w/ 0.35mm feeler, and no continuity w/ 0.59 mm feeler.

However, when I go back and test resistance measurements between tps terminals - like I did at the start - IDL-E2 w/ 0.35mm feeler is out of spec. There is continuity (14k ohms), but listed range is 2.3k or less. I tried a few times, and it was the lowest I could get that specific resistance measurement without any of the others being out of spec.

Is this normal operation?

Any thoughts or insight? I haven't put it back on the engine yet.

EDIT: I also added service manual screenshots below for reference.

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jondee86
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Re: TPS adjustment help

Postby jondee86 » Thu Nov 03, 2016 4:44 pm

Basically, the ECU is monitoring for a change in state, from continuity (low resistance)
when the throttle is closed, to no continuity (high resistance when the throttle is open.
With 12V applied to that circuit, I expect that 12 kOhm still allows the ECU to see 12V
vs zero volts, and it will recognise the change of state.

I have not seen anything that says the actual resistance is crucial, and the fact that your
car ran fine would tend to bear this out. On the other hand, it is important that the VTA
and VCC resistance values are within spec, as the ECU will be making changes to fuel
based on the values and their rate of change.

So I say... put it back the way it was and be happy :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

Deuce Cam
Posts: 1346
Joined: Sun Jan 13, 2013 2:41 pm
Location: AZ

Re: TPS adjustment help

Postby Deuce Cam » Thu Nov 03, 2016 5:06 pm

Hey thanks for the feedback.

I've been editing the original post to make it more clear/concise.

To clarify, before adjustment IDL E2 had no continuity on both terminal tests. After adjustment I now have continuity where I'm supposed to but perhaps too much... (It probably doesn't matter.) All the other terminal resistance tests are within spec (before and after adjustment).

I want to try and get it right because although my engine runs good, there are small nuances with the idle and throttle response after cold start in cold weather that I don't think are normal. I'm curious if getting the tps right changes anything.

EDIT:I went for a quick drive, got the engine up to temp, then checked for cel's (nothing yet :)). I also noticed that my idle seems rock solid so far; before it would often bounce/hunt within roughly a 50 rpm range.

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jondee86
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Re: TPS adjustment help

Postby jondee86 » Thu Nov 03, 2016 9:15 pm

If you had no continuity on both tests, that would mean that most likely the ECU
never saw a change of state when the throttle closed, and never switched into
"idle" mode (fuel and ignition both change for better idle). Rough/unsteady idle
is because the engine always had "run" fuel and ignition settings. Getting the
changeover from "run" to "idle" is important for on and off idle transitions.

So good job :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.