Bad TPS???

2933 Views 25 Replies 8 Participants Last post by cheappower82, Feb 3, 2005

MKIIBeater

Discussion Starter · Jul 3, 2003

Well further testing shows that the TPS is cosntatntly putting out 5 volts. I do not understand why but I just assume its broken. At leist I hope. Im hoping thats its not doing that because of some type of constant ground somewhere or something. Im going to try and replace it and if that doesnt work then Ill now I have to chase some damn wires down. Thanks much...

PS- I wonder what this is doing for my fuel trims...consdiering the EFI runs the injectors and timing according to TPS, and the AFM. Although the AFM is functioning fine I wonder if the TPS is making things screwy. If anyone knows of anythign that this might be please chime in. THanks,

Austin

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cheappower82

· #17 · Jul 19, 2003

Looking at my Toyota 5M-GE/6M-GE engine repair manual, I noticed the voltages are as followed:

up to Aug. '85 -
Throttle valve open: 4-6V; (IDL - E1)
Throttle valve fully closed: 4-6V; (Psw - E1)

Australian vehicles and 6M-GE from Sept. '85 -
Throttle valve open: 4-6V; (IDL - E1)
Throttle valve fully closed: .1-1.0V; (VTA - E2)
Throttle valve fully open: 4-5V; (VTA - E2)

These are voltages at ECU wiring connectors

Not sure if this applies to our case, but it does show significant differences that will affect the S-AFC. The S-AFCII manual has 3 TPS settings; none of which applies to the 3-wire sensor :bad-word:

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cheappower82

· #19 · Jul 20, 2003

MKIIBeater said:
Well i sont know what you mean about the 3 wire o2...that doesnt have anything to do with it.

Three wire TPS.....I have the same rectangle TPS

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cheappower82

· #21 · Jul 20, 2003

Well if you still want to keep the S-AFCII, the hardest things to come by is the harness and the ECU ('85).

The throttlebody and TPS that came with my 6M-GE will work. So if you can locate the '85 harness and ECU, I'm sure that someone will sell you their 6M TB and TPS cheap (I may have extras laying around in storage).

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cheappower82

· #26 · Feb 3, 2005

SlimFastSupra said:
if you have an on/off type of TPS, you can add a MAP sensor from just about any car and use the vac to zero reading as the TPS input.. this way you can have varying conditions instead of off/on.

What he means about the on/off TPS is this: 85 and newer uses a variable voltage (true throttle position) tensiometer type TPS. As you depress the gas pedal, the sensor sends a different voltage per position (prorated). Some TPS's go from low to high voltage (0-5V), and some decrease with TP (5-0V).

The 84 and older (square TPS) act as an on/off switch. As the pedal is depressed, the TPS goes from no voltage to max (usually 5V).

That's the way it was explained to me.

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