Fast Idle After Replacing TPS

[sdkhalsa]

Just replaced the TPS on my 94Q, and now have an idle of about 1500. I believe that the system needs to relearn the closed throttle position. How do you do this, or is there another problem? There do not appeaar to be any intake manifold leaks, and the idle worked fine before changing out the TPS.

[Q451990]

My understanding is that it is very difficult to properly set the sensor without a Consult. Might be worth having done professionally. Otherwise your best bet is to set using the voltage method (read at the ECU) after a 15-20 minute warm up. The fast idle cam will change the "closed" position if the throttle body is at all cold and throw everything off. And be sure not to mess with any of the little screws on the throttle body or take too much slack out of the throttle cables.

Good luck!

Heath

[sdkhalsa]

Heath:

Thanks for your response about setting up the TPS. Finally have a bit of time to work on it again, having diverted my energies to putting in upper links on the the rear suspension. Where can I find a description of the "voltage method", having been unable to locate it in the shop manual.

[squeefoo]

PS: For your own sanity don't screw/adjust/playwith with anything on the fast idle cam or you'll be sorry...

I did once....................... once.....

[Ozzie]

A genuine Nissan Consult can do it, and so can a home consult with a laptop..

[elwesso]

You can probe the ECU and do it that way.. as long as its close to .4 volts (meaning .4 volts read at the ECU pins) it will be fine. Youll notice a definite change in the engine as it no longer thinks it is at idle.

[sdkhalsa]

Where can I find some instructions on probing the ECU? Today disconnected the negative post of the battery for 30 minutes trying to force a reset, but nothing seems to have changed.

[elwesso]

You can probe it on the TCU (yes trans control unit) on pin 34 and 35