Idle adjustment issues

[A1218]

I was attempting to adjust the idle on my 97 Pathfinder. Started with a warm engine after driving and unplugged the brown connector to the tps then restarted engine. Gave the vehicle a few revs then let it settle. But with that tps unplugged it’s idling very low and rough, dipping below 500rpms. Something that didnt happen before when checking idle.

Plugging back the tps connector brought it back to a smooth idle. I let it rest for 20 minutes and then drove it around the neighborhood. I tried the procedure again and it didn’t misbehave during adjustment with the tps disconnected. What was up with that?

Should I mention that I had the a/c running while driving just prior to the initial adjustment procedure where it was rough.

[VStar650CL]

The TPS won't directly respond to temperature but the IACV will. Just a guess, but maybe your engine temperature was a tad elevated because of running the A/C?

[A1218]

The TPS won't directly respond to temperature but the IACV will. Just a guess, but maybe your engine temperature was a tad elevated because of running the A/C?

I guess it can be correlated because that may have been the only difference.

But how does the IACV respond to temperatures on the VG33E engines? I may be getting it wrong here but the VQ engines have coolant going to their IACV. I know the VG definitely does not.

Also, since I unplugged the TPS to do the adjustment is the engine relying on input now only from the IACV seeing that this occurred after unplugging it under my circumstances like elevated temps?

[MisterH]

I was attempting to adjust the idle on my 97 Pathfinder. Started with a warm engine after driving and unplugged the brown connector to the tps then restarted engine. Gave the vehicle a few revs then let it settle. But with that tps unplugged it’s idling very low and rough, dipping below 500rpms. Something that didnt happen before when checking idle.

Plugging back the tps connector brought it back to a smooth idle. I let it rest for 20 minutes and then drove it around the neighborhood. I tried the procedure again and it didn’t misbehave during adjustment with the tps disconnected. What was up with that?

Should I mention that I had the a/c running while driving just prior to the initial adjustment procedure where it was rough.

You're using a multimeter to set the TPS, right?

[A1218]

I was attempting to adjust the idle on my 97 Pathfinder. Started with a warm engine after driving and unplugged the brown connector to the tps then restarted engine. Gave the vehicle a few revs then let it settle. But with that tps unplugged it’s idling very low and rough, dipping below 500rpms. Something that didnt happen before when checking idle.

Plugging back the tps connector brought it back to a smooth idle. I let it rest for 20 minutes and then drove it around the neighborhood. I tried the procedure again and it didn’t misbehave during adjustment with the tps disconnected. What was up with that?

Should I mention that I had the a/c running while driving just prior to the initial adjustment procedure where it was rough.

You're using a multimeter to set the TPS, right?

I was trying to adjust the idle which calls for the tps bottom connector to be unplugged.

But yes when I did change the tps I used a multimeter and feeler gauges to set.

[VStar650CL]

I guess it can be correlated because that may have been the only difference.

But how does the IACV respond to temperatures on the VG33E engines? I may be getting it wrong here but the VQ engines have coolant going to their IACV. I know the VG definitely does not.

On the older 1-wire IACV's the ECM controls it with PWM, and temperature is the biggest parameter the ECM uses in deciding how far to crack it open. So it's an indirect response, but it still is one. That's why the VG's often run like crap when the ECT fails.

[A1218]

I cleaned the throttle body and maf this weekend and I notice that the idle has ticked up a bit after. It was previously 750-800 after I set the idle a few days ago. Now after cleaning it, it is now at 900rpms in park.

I used the appropriate sprays for each.