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

HI All,
Now when the engine is cold the idle is at about 1500 RPM.
As the engine warms to normal temp it slows to about 800 RPM. Which is good.

But when I start it when its warm, it starts at 1500 RPM, and finally slows to the 800, mark this may take about 5mins.
I would of thought that a warm engine would start at normal Idle of 800 RPM. Not the 1500 RPM.

I have never had a car that carries on like this Patrol.

Is this normal for these GQ's 4.2 EFI..... Or do I need to adjust some stuff.

All info would be great.
Thanks
Kevin

My sons RAV4 did that idle prob I cleaned the Maf senser with the proper cleaner and it fixed it. I was told if that didn't work to clean the throttle body also. Hope this helps it didn't take long so it was an easy fix $20 for the spray tho

Can you please tell me what the Maf sensor is. I think its on the intake side of the manifold??

HI,
I just found it, on utube. Mass air flow sensor,. Also found how to clean it .... Off to auto one and get a can of cleaner for MAF.
Thanks Drewstar.

I have finally done it.. Taken out the Mas air flow meter and body .. What a lot of dirt stuck to the senors There was so much dirt I had to us a soft brush to clean the dirt off. Now its shinny clean and the body is spotless as well. Only have one problem with it now and that is the wire mess is missing not there when I removed the MAF body.

I disconnected the battery for a while so the ECU resets, so I been told.
The engine now Idles at about 650 RPM... Never done that since I have owned it.. 6mths. Adjusted the timing from about 30 deg to 10deg.
Hopefully the fuel consumption will improve. motor sound so smooth now.
Time for test drive later.

mate theres a procedure to set the timing on a tb42e if you just set it to 10 deg at idle it will be retarded and perform poorly, the procedure is to disconnect the aac valve and ficd at the rear of manifold. then you can set the timing to 10 deg,

if you must just do it the lazy way at idle make sure its up to temp and set it to 15 deg with everything connected as normal as thats what i get as a digital read out on my ecutalk unit at idle after setting it using the correct procedure

Ohhh thanks mate.... I forgot to take off the vac hose from the dissy... But whats the other one then.... FICD whats that... Your help is great..

there is no vac hose on a tb42e dizzy, the aac and ficd are the 2 units with wires at the back of the manifold, they allow the ecu to raise/lower the idle speed as required

Thanks Billyj,
Since there is very little and almost no info on the 4.2 EFI.. I would be lost and stuck without this forum. Everyone is a great help to me.
Now I can take them wires off and do the timing properly.

Many Thanks
Kevin

Quote:

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Originally Posted by kbchez

Thanks Billyj,
Since there is very little and almost no info on the 4.2 EFI.. I would be lost and stuck without this forum. Everyone is a great help to me.
Kevin

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Likewise Kevin.
I'm sure the TB42E was a joint development between Nissan and "Area 51" - using classified conspiracy theory UFO technology.
Tempted to backward engineer it to a TB42s just to have some info on it.

The high idle could also be due to the "auxiliary air control valve" located under the inlet manifold, sticking open or being unplugged.

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

Quote:

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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..