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nissan
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Discussion Starter · #1 ·
Hi guys

My 04 GU 4.2TDi has been doing something strange recently. The last couple of times I have used my aircon ( for demisting at this time of year where I'm from ), when I come to a stop the idle RPM is higher. About 11-1200 RPM. I can also notice it coming down a hill when off the pedal. The engine breaking isn't normal I assume as the throttle isn't backing off. When at idle if I give the pedal a quick tap the RPM (after rising for a second obviously) drops down to normal idle speed until next time you stop. This doesn't happen when I first turn aircon on. It increases slightly as normal.

Could it just be a sticky cable like the old days? Surely if it was it would do it with the aircon on or of. I know the aircon does increase your RPM's somehow. Is this operated mechanically ( cable to IP )? I assume so on a 4.2TDi.

Any ideas guys.

Cheers.
 

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nissan
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Hey Franky the idle up is on the top of the IP. It's not common but I guess it could get dirty and stick. Have a squizz you'll see it easily from the top.
 

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nissan patrol
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There is a vacuum pot on the outer side of the injector pump that pulls another stopper onto the throttle shaft to increase rpm with the AC on.

I have never seen it happen, but I guess its possible the control solenoid (that is up on the firewall) could be leaking and supplying vacuum to the pot.

I would just start by checking the throttle cable has 3-4mm of freeplay on the side of the pump.
Then making sure the air con idle up pot isnt pulling on the throttle stop also.
 

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nissan
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Discussion Starter · #5 ·
Thanks heaps guys I will check it out after the missus gets home and I get a leave pass to the shed. An hour or so I reckon if I plan it right.

See how I go. Will update in a while.:D
 

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nissan
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Discussion Starter · #6 ·
Hi back again. Didn't get a leave pass but got kicked to the shed anyway. Oh Well.

Just had a look at all the linkages and cables. Top cable has spec play in it. Bottom cable has too much play. I do however suspect this is the cruise control cable which might explain why it surges.

Can someone tell me what the module on the very top of the IP and the mechanism it is attached to are for. Is this what you were talking about timo_ed?

At the very bottom of the IP there is a what looks like a vacuum diaphragm linkage. What is that for. I always want to know what I don't know about my girl.

Cheers again
 

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nissan patrol
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The vacuum pot at the bottom is the air con idle up I explained earlier.

There is an adjustment on the rear of that vacuum pot to move that diaphragm.
Wind it in for less rpm on activation, and out for more rpm.

But to see if this is what is actually causing the problem, pull the vacuum line off it and see if it changes rpm.
 

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nissan
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Discussion Starter · #8 ·
The vacuum pot at the bottom is the air con idle up I explained earlier.

There is an adjustment on the rear of that vacuum pot to move that diaphragm.
Wind it in for less rpm on activation, and out for more rpm.

But to see if this is what is actually causing the problem, pull the vacuum line off it and see if it changes rpm.
What would you expect to happen to the RPM pulling the hose off and on?

Cheers
 

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Can someone tell me what the module on the very top of the IP and the mechanism it is attached to are for. Is this what you were talking about timo_ed?



At the very bottom of the IP there is a what looks like a vacuum diaphragm linkage. What is that for. I always want to know what I don't know about my girl.



Cheers again

The module on the very top is the throttle position sensor. DieselTuners description was better than mine...the vacuum diaphragm at the bottom is the correct one.
 
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