My idle RPM in neutral or at idle in 1st gear has always been a tad on the higher side - 800RPM - 850RPM when the car is warm. However after Frank and I met and we did our tests, the last thing that we did was the OBDII self-diagnostic mode 3 and we did exit the diagnostic after we were done.

We went in, to grab a drink and when I came back out and started my car, it idled at 400RPM... which slowly climbed upto 600RPM - 650RPM. It drove fine, I thought, but ever since that day, everytime I start my car it starts off at 1200RPM or so (used to be about 1800RPM) and it gets warmed up, it settles back down to 500RPM - 600RPM (used to be 800-850). Sometimes when driving and coming to a stop, I pop it into neutral and use my brakes to stop, as I always do, and when I come to a complete stop, it is the nature of the RPMs to dip slightly and then go back to the resting idle RPM... but when it does do that dip, it gets between 400RPM - 500RPM! Stall RPM is 400RPM which makes me a little nervous.

What could have brought this about? All my vacuum hoses, etc are hooked back up properly. Did I not set the ECU back properly or something? Hope I can get some ideas from you guys here.

 

It should be around 700-800 in neutral. Turn the screw on the TB Counter clockwise till you get the right rpm...

 

yea, theres a screw to adjust idle RPM's ....try cleaning the idle air control valve!

 

Is there a "how to" on that anywhere?

 

umm my 97 Idles between like 650 and 550 and i was told that thats perfectly normal for a 5spd

 

I'd just do the basics, like resetting the ECU, cleaning TB and IACV, etc... before adjusting the idle screw.

Dave

 

Sounds like your base idle is off. If you haven't, do what other said and clean your throttle body. Otherwise, check your base idle by disconnecting the TPS and starting a warmed car. It should be in spec range which around 600 rpm. If not, adjust the IACV black screw or if it is off a lot, adjust the throttle plate screw.

My car was doing what your is to the tee and now problem solved...

 

My car idles at around 900RPM, but I thought this was just a Maxima thing. It must waste so much gas!! Is it supposed to be at 600?

 

The proper range depends on your transmission:
MT 575 +/-50 rpm
AT 650 +/-50 rpm

 

I have a manual transmission... What could be causing this high idle???

 

My tranny seems to behave normal (which is lower idle than my previous idle of 800-850) at times idling between 500 and 600. But when I come to a stop in traffic, sometimes it dips below to 400 - 500 which is definetly not normal. How can I try to rectify this?

Thanks!

 

My father's Max has a problem. After removing the throttle body and cleaning it the idle in Neutral is above 1k rpm's after EVEN AFTER it reaches operating temperature. It never did that before.

 

I already told you to check your base idle rpm. The reason why at times it is normal is that the ECU is constantly trying to correct your idle into normal range. You'll notice that when you brake coming to a light, the rpm's will dip but a moment later, it recovers. You can also check for intake leaks as that sometimes causes what you describe. I'm pretty sure you base idle is too low though...