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neutral switch issues??

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Hi all,

Just joined so keen to get amongst it.

I have a gu3 manual and the issue is when it is in gear(any gear), clutch in and engine warm the engine hunts between 500rpm to normail idle speed.

I have checked the shift switch and its good. This has only come on in the last few months. When rpm is over 1000 it not an issue. I know it tells the ecu its in gear when driving and has something to do with fuel when coasting TPS at zero but not sure about idle.

Any help would be good as I am smoking out the shoppers when reversing out of a car park!!

Sorry, 2001 zd30


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So when it idles in neutral it is all good but once you de-clutch and put it in gear it starts to 'hunt', am I correct?

What happens when you just de-clutch?

Is it dificult to engage reverse gear?

To me it appears that either the clutch is dragging so it loads up the engine or dual mass flywheel is so flogged out that when de-clutching the mass of the clutch is lost and flywheel just oscillates madly causing crankshaft speed to fluctuate which in turns causes the crank angle sensor to give false info to ECU, that would be my wild guess.

To follow this theory, I'd jack the Patrol of the ground and try, park brake off and repeat. If there is no load on drive train and it stops doing it then it is possible.

I can't see this being a neutral switch and you can check quickly by using 'engine warm up' switch. If  engaged RPM should be around 1100, as soon as you move gear out of neutral the revs should drop to idle. There is also brake pedal switch which when fault occurs it migh not give you throttle response because if ECU sees TPS % off idle and brake signal at the same time it has a 'hissy' fit.

You need to see what ECU sees from its sensors to narrow this down.


Edited by Rumcajs
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OK, Clutch disengaged, in gear it begins to hunt.

Heat switch on and same as above same deal, but the revs hunt from 11 rpm downwards.

4wd lever in neutral, clutch disengaged, in gear, same thing. 

Cant confirm on brake pedal theory at the moment.

I am looking at TPS fault but will need to look into it a bit further. Clutch & flywheel is being replaced next month so will see what happens?

Thanks for the reply will let you know what the outcome is.

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