My 1999 nissan has a erradic idle it idles at 1000 rpm and then jumps up to 2000 rpms and then back to 1000 rpms. this go on and on. please help me thanks.

how did you adjust a pre-programmed ECU idle settings ??? please be more specific

the vehicle's ECU is pre-programmed to run higher than 1000 rpms while in "open loop mode" then idle back down to ~750 rpms once the engine reaches operating temperature "closed loop mode"

did you tap into the OBD 2 port and used a laptop to change the settings?

Idle air control valve would be causing this issue. You got it right

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_677dced97ad9bddf

-Yes most car prefer at 750 to 800 Rpm.

Mai Lor

I would check the idle air control valve that is the what controls rpms

correct rpms should be ~800rpm ac off, and ~1000 rpm ac on.
idle up switch is broken or vacuum hoses attached to idle up switch has leaks.

Check out related help links to troubleshoot these problem:----Click the link below:---Idles Fine but RPM jumps in drive mode? http://technoanswers.blogspot.in/2012/07/idles-fine-but-rpm-jumps-in-drive-mode.html
---------Mitsubishi Lancer rpm needle bounces? http://technoanswers.blogspot.in/2012/02/mitsubishi-lancer-rpm-needle-bounces.html
--------How to adjust rpm on 2009 dodge charger SRT8?

http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
---------
Engine cuts out at 3000 RPM? http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html

---------

Cold start problem and vehicle shudder around 2500 to 3500 rpms
http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html

---------
High rpm in neutral? Inconsistant high RPM in neutral? http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html

-----------
Jetski Sputters and Low RPM? http://whatisbyme.blogspot.in/2012/07/jetski-sputters-and-low-rpm.html

--------
Fuel Injection Problem And RPM suddenly increases http://whatisbyme.blogspot.in/2012/07/fuel-injection-problem-and-rpm-suddenly.html

----------
2005 Toyota Highlander: Engine runs hard RPM below 3000? http://whatisbyme.blogspot.in/2012/05/2005-toyota-highlander-engine-runs-hard.html

---------
1987 Toyota Camry: RPM Drops going Up hills? http://whatisbyme.blogspot.in/2012/05/1987-toyota-camry-rpm-drops-going-up.html

-----------
Cruise Control stops working, Excessive cranks to start the engine and RPM goes max 2500 http://whoisbyme.blogspot.in/2012/07/cruise-control-stops-workingexcessive.html

----------
1990 Toyota 4Runner: Engine cuts off when reaches 2000 RPM?

http://whatisbyme.blogspot.in/2012/05/1990-toyota-4runner-engine-cuts-off.html

------------
1999 Toyota Camry: Erratic stalling and high engine RPM at idle?

http://whatisbyme.blogspot.in/2012/05/1999-toyota-camry-erratic-stalling-and.html

---------
1995 Toyota LS: Misfire at idle or low RPM http://whatisbyme.blogspot.in/2012/04/1995-toyota-ls-misfire-at-idle-or-low.html

-----------
Lexus RX: Tapping noise under Valve Cover At Low RPM? http://technoanswers.blogspot.in/2012/04/lexus-rx-tapping-noise-under-valve.html

----------
These will help.
Thanks.

How long has it been since you replaced everything? These cars have a "learning" feature. It may be readjusting itself.

Are you certain you used the recommended plug? These cars do not like anything but.

when the car is cold the comp turn on the idle valve to be 1500 rpm normal but 2000 rpm too high may be a leak of air into the intake

ok a couple of things to try one is loosen the throttle cable so it has a little play in it and then you can check for vacume leaks using carb cleaner if rpms change you have a leak

its becouse the cars computer tries to heat its self for it not to work when it is too cold
so just leave it there for a while till the rpm go to normal




by kevin