Neutral idle high until I stop

[soldave]

Strange little problem here that I've known recently. When I come to a stop at a junction or a set of lights, I will often go into neutral and just slow down gradually. When I do this, the idle will go to 1,200-1,400rpm. But then when I reach a standstill, after a couple of seconds the idle will drop down to 850rpm (it's normal level).

Not a big issue, but would be curious as to whether anyone knows what could be causing it. Thanks in advance

 

[Twistaye]

Had this problem on the Stealth we had before it was wrecked, the IAC (or ISC) on the throttle body was out of adjustment, opened it up and adjusted it and re-installed it and it idles fine again (I believe we turned it all the way counter-clockwise to where the spring is the furthest out). This was on an a/t dodge stealth with the SOHC v6 (turns out the IAC was the same on the stealth and eclipse, it was interchangeable). Whenever the car was in gear or neutral it would sit around 1500 rpms, but that was the problem with it. Might not be the same in your case, but maybe a possible lead to check into!

 

[andy4g63]

Try to adjust the BISS screw, then check the throttle stop. Make sure everything is connected. Like Twistaye said check ISC motor. It should measure between 0.028-0.088 oms. Check this info on VFAQ.

 

[soldave]

Will get hold of a multimeter and check out the ISC sensor, and try to do the BISS thing too. Thanks

 

[greddy_1700]

Please post back your findings, my car is doing the same thing.

Thanks!

 

[stockfornow]

My car is doing the same thing, but turns out that the O2 sensor is dead..... I'm still waiting on the part to replace it, but it could be that your O2 sensor is going.... And don't buy Bosch ones, they're junk as I found out, get Denso one. Good luck!

 

[eclipsegsx1736]

I know this is an old thread but I accidentally came across this. I'm posting this for anyone in the future coming across this thread in a search.

This is completely normal and correct behaviour of the ECU and ISC. It does this to maintain sufficient RPM to the power steering pump to help with turning the steering wheel while moving when you are in neutral.

As a side note, you should NEVER be coasting in neutral while moving. This is illegal in some states (yes it actually is) and is actually potentially dangerous as you do not have proper control of the car.