KITT

Hey everyone.... I have a really annoying idle problem... Now let me explain this to you guys and I hope that I may find some help.

OK.... Its like this I go out to car and start it for the first time and drive as per normal on the freeway or just around toen and stop car is fine and idles properly... Leave the car for like 15 mins or even say 3 hours come back and drive the same again but when I stop and put car in neutral or Park it will idle at around 1700RPM!!??!!
Also I notice it when I slow down at traffic lights as its like the car wants to keep going even though I have my foot on the brake and the idle is high even though in gear. So I took the car to Nissan and they replaced the Idle Motor (Idle Step Up Motor thingy). But the car still idles high after the 2nd time car started?? its strange, it will continue to do this all day unless the car is left overnight or atleast all day. I had one guy say change fuel filter! I might do that but is that the problem? Does anyone know of this or had this happen?? I need help Please. Its like the throttle is like stuck on or something.I cleaned the throttle body but stil no luck! Any help would be great... Thanks...Sorry this is so long!

Entropy

iTrader: (1)

Well, the car should idle that way when it is cold or has been sitting for a while as it heats up. So, logically... if it does that when it is warmed up already then whatever sensor or wiring determines what it should be idling at for a specified temperature is faulty. That is the system I would check first.

The only other thing I could think of - would be the A/C system since the A/C should step up your RPMs when it is on. This seems less likely though.

Changing your fuel pump couldn't hurt, but I fail to see the effect it would have on your problem. Rough idle, hesitation, or rough starting maybe... but high idle - I doubt it.

There is always the idle adjustment - idle adjustment would be over-ridden somewhat when the car is cold - so it would make sense that; if the car is warm and the idle control has it set up to high then the car could be fine when cold and screwed up when warm.

Just trying to give you some ideas... for the record I know very little about VQ Engines.

iwannabmw

iTrader: (3)

My car started idling a little, about 1100 rpm, periodically. I found the throttle itself wouldn't always return to the closed position, the linkage was sticky. After spraying some grease on it and working it in, problem solved. Just an idea for you, make sure the throttle can move through it's entire range freely.

njmaxseltd

iTrader: (19)

Things to check"

Throttle cable adjustment - Is it to tight?

Throttle linkage on throttle body - Is it binding up?

Throttle linkage return spring - Is it weak?

Cold Idle helper - It's a plunger that kicks up the idle when the car is cold, is this hanging up?

False Intake Air - Check for leakes around the throttle body, any air that enters the intake after the throttle plate will increase your idle speed.

Perform an actual idle speed adjustment. Disconnect the TPS sensor and see what your car idles at.

Try this - When your car starts to give you the high idle, go under the hood and blip the throttle a few times manually. Then try to close the throttle plate by pushing on the linkage a bit. If you can push the linkage and obtain your 600 or so idle, your problem is linkage or cable related. Grease it up, WD40, check spring, cable adjustments ect...

Let us know what your findings are.

KITT

I forgot to mention that when the Idle is high...If I swtich the car off leave for say 10 secs or so and then start again it idles fine. But as soon as I drive off again and up the road or even onto a HWY then drive for say 15 mins at different speeds it will then idle high again after I stop!?! I checked the throttle cable its fine and I adjusted the idle but it will still do it again.Its totaly fine when the car first starts in the morning and I drive anywhere and stop it idles perfect but as soon as I drive for the 2nd time and I drive for a fair bit...bang it starts a high idle.I know when it does it even when Im driving because as I slow down I can feel the car down shift gears slightly noticble when comming to a stop...Even when Im at lights with the car in drive it wants to just go and will idle at just over 1000rpm even in gear! I noticed yesterday when it was doing it I left the car in park while it was idling high and after about 4 mins it stopped and idled normally....Its really strange...but as soon as I take teh car near a Machanic it behaves itself and they cant find anything wrong with it....No fault codes at all... I need help anyone had this before.....