High reving Idle cold and hot. But why? 4.2 EFI

Mate, Arfa.

I can get low idle when I disconect the battery for about 30mins. Then restart the engine, warms up and Idles smooth as. Perfect.
But once I take it for a drive and the ecu wakes up It then goes back to high Idle when warm.which is around 950 to 1000 rpms.

I will have a look under the manifold and see if I can locate this extra sensor. I do have a etra black plug at the rear of the engine and cannot find where it goes. I was thinking maybe one of the water sensors maybe stuffed. First things first. check manifold sensor.

Is the "auxiliary air control valve" air operated or electric. A hint will be great.

Thanks
Kevin

Im back here.... lol.. I cannot find it. On the 4.2efi Blacktop. Its suppose to be on top of the rocker cover at the rear of the engine. I found the black plug that goes to it.....Its missing gone not there ... stolen by those UFO's. I need one. also there is a few other air hoses missing gone... last owner made a few changes... one of the hoses fron the rocker cover went directly to the air cleaner... No wounder the mass air flow meter was grubby.. hose no longer goes there just need to reconect it to its proper place......

the best thing i can suggest is try hunt through ebay ect for a gregorys manual for it, they give pretty good detail. but you are right it can be hard to find info on them

other things that can help is cleaning the aac valve and throttle body with carby clean, and if your consistantly having high idle you may need to manually set the idle screw at the back of the manifold, worst case could even be a vacuum leak

I going off to nissan to see if I can get pictures of the vacum system from there parts books. also check out other patrols ... If the owners will lift there bonnets for me..

been to nissan and got a picture of the vacum system for the 4.2efi. I have added the picture to this postAttachment 69397Attachment 69397 the part number thats circled is what is missing from my poor gq.

HI All.... I almost got this old Patrol Idling nicely thanks to all of the input from all of you. I removed both, aac valve and ficd and cleand them up But with the one with the spring in it and it has a valve in it. This spring and valve are loose and the valve stays open. Is this normal or not. I have attached a photo of it. Also can the orange bung be removed... Is there any adjustment for this valve. Or is it supose tobe like that.
to get it to Idle at around 650 to700 rpms I had to adjust the Idle on the, aac valve and ficd which ever one it is.
The next small problem is... when I push the excelerator the engine stumbles as if the Accelerator pump not working on the carby....BUT its a "EFI" So what causes this problem. Its been a problem ever since I have owned it.
Many thanks Kevin
Attachment 69863Attachment 69864

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Originally Posted by kbchez

HI All.... I almost got this old Patrol Idling nicely thanks to all of the input from all of you. I removed both, aac valve and ficd and cleand them up But with the one with the spring in it and it has a valve in it. This spring and valve are loose and the valve stays open. Is this normal or not. I have attached a photo of it. Also can the orange bung be removed... Is there any adjustment for this valve. Or is it supose tobe like that.
to get it to Idle at around 650 to700 rpms I had to adjust the Idle on the, aac valve and ficd which ever one it is.
The next small problem is... when I push the excelerator the engine stumbles as if the Accelerator pump not working on the carby....BUT its a "EFI" So what causes this problem. Its been a problem ever since I have owned it.
Many thanks Kevin
Attachment 69863Attachment 69864

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Clean & service the injectors and see if that fixes the problem.
Also check for any vacuum leaks with a can of WD40 while revving,spraying and looking/hearing the engine response.

Thanks Mate ... I have done the injectors. I will do the wd40 and get back to you..