3.9 idling waaay too high - Land Rovers Only

igould · 08-03-2005, 06:09 AM

My 3.9 manual has been idling recently at around 2400rpm. It seems to occur at random from start up, either on gas or on petrol.
Sometimes it will drop in stages back down to normal if I get stuck at a red light for a long time, but mostly it just continues idling high.
This is not too good around town, but a real pain on muddy down hill descents.
Any clues?

Thanks,
Ian

LANDY96 · 08-03-2005, 09:11 AM

Well first of all, I had that problem after I replaced my stepper motor, and some other electronic goodies. I replaced them without unplugging the battery, or something like that,

. I was told the only way to fix the idle was to have the adaptive memory purged. Also check your pcv hoses, they could be clogged!..... BUT....... that was about 10,000 miles ago! She has done this twice to me in the last 1000 miles. Only for a short time, and when I turn the engine off, and start back up, she is all normal. I do have a check engine light on again, that was after a misfire, not sure what caused that, I have changed the speed sensor, could be ecu fuel prom. I would have your local independant rover shop put it on a diagnostic!

texasrover · 08-03-2005, 11:38 AM

Your misfire, make sure you dont have an injector going out. This can cause the idle to act funny when it trys to compensate... so I have been told.

I have idle issues and the injectors are the only thing left to be changed... I have changed the IACV serveral times with and without the trottle sensor, adjusted the trottle cable to the point I dont know what is right anymore.

The idle issue never ends. My main problem is low idle... then it dies. Some times, it idles fine other times it is low, it use to idle high or low. Now, mostly low. The low idle is more annoying because I have to restart the stinking thing ever time I get out to open the gate.

LANDY96 · 08-03-2005, 03:21 PM

To clear a few things up..... I did have my adaptive memory cleared, took about 2 min. and she ran perfect. They are able to check out your whole sensor system, and it only cost me $75.00. It was worth all of the headache!!!!!!!!!!!

TerryS · 08-03-2005, 04:44 PM

Sounds like you need to reset you base idle speed. Not real complicated.
First thing, clean the IACV.
1.Start the engine.
2.Pinch off the hose between the IACV and the throttle body, using a pair of needle nosed vise grip or other clamp pliers.
It's important that you completely close off this hose.
3.Disconnect the IACV plug

4. adjust the base idle set screw on top of the throttle body to 600-650 rpm
5. shut of engine, and disconnect battery for a minute or two.
6. Reconnect IACV plug, remove vise grips, reconnect battery and restart.