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TPS Adjustment Procedure

NOTE: This entire procedure is simply a manual way of doing what the TPS Adjust wizard does for you automatically.

The ECU wants to see 0.63v from the TPS sensor when your foot is off the throttle and greater than, say, 4.6v when you're fully on it. You can datalog TPSvolts to see what the ECU is really getting. The value at idle (foot off the throttle) is probably more important than the value at wide open throttle. A value that's too high at idle can prevent the idle switch from activating or it will prevent the “simulate idle switch” functionality from working properly.


To adjust what the ECU sees, you can use the TPS Adjustment dialog. Start by disabling TPS adjustments. Then datalog RawThrotPos. That value is the real value datalogged from the ECU when you display TPSVolts or ThrotPos. Move the throttle from fully closed to fully open. Note the RawThrotPos at each point (fully closed and fully open) as follows.

Vc = RawThrotPos when throttle closed
Vo = RawThrotPos when throttle open

Next, solve for scale and offset as follows, using the values collected in the previous step.

Scale = 223 / (Vo - Vc)
Offset = 32 / Scale - Vc

Note that Scale will be a number like 1.05 indicating 105% in the DSMLink TPS dialog.

Lastly, enable TPS adjustments and enter the offset and scale values that you calculated.

dsmlinktpsadjustment.txt · Last modified: 2009/06/02 13:53 by twdorris