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

[kbchez]

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

[drewstar]

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

[kbchez]

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

[kbchez]

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.

[kbchez]

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.

[billyj]

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

[kbchez]

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..

[billyj]

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

[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.
Now I can take them wires off and do the timing properly.

Many Thanks
Kevin

[Arfa Brayne]

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

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.