Idle is high when moving in neautral

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Gasher33

New member
Joined
Feb 11, 2017
Messages
29
I had some revving-related issues in the past and I managed to fix most of them but I am down to only one.

When the car is moving if I put it in neutral the idle revs jumps to around 1200 RPM and stay there until I get to a full stop. I also tested this on a hill, if I have my foot on the brake and not moving the idle is at around 800 but after I let the brake and start going down in neutral the revs go to about 1200 rpm.

Things that I did for other revving-related issues:
- New ICV
- New TPS
- Clean TPS plug
- Clean throttle body

Do you guys have some suggestions in order to figure out this issue?
 
All I can think of to initially check from past experience are;-

Check the rubber blanking plug on the throttle body - could be missing, badly fitted or leaking due to age.
Check the inlet pipes for cracks incase of unmetered air.
You say you cleaned the throttle body so assume the butterfly valve inside is carbon/crud free.
And finally - and damnit, Rick (YOG) beat me to it while I was proof reading this answer :lol: but saves me grabbing that picture - check clutch control switch above clutch pedal - can come loose.
 
Here you go YIP, beat you to the Air Blanking Plug pics: :lol:
[image]2150[/image]
[image]2151[/image]
 
Thanks for the amazing answers. I checked the Clutch Control Switch and it isn't loose (any guide to check it using a multimeter) and the Air Blanking Plug is there, mine is a bit different than the one in the picture and I can take it out quite easy but I don't know how to check if it's leaking. The pipes seem not to be cracked.
 
Could be a clutch hydraulic problem. Slave cylinder, master cylinder, or just fluid. I would expect other symptoms to go along with it, but maybe not.
 
Gasher33 said:
Thanks for the amazing answers. I checked the Clutch Control Switch and it isn't loose (any guide to check it using a multimeter) and the Air Blanking Plug is there, mine is a bit different than the one in the picture and I can take it out quite easy but I don't know how to check if it's leaking. The pipes seem not to be cracked.
The clutch switch should, when brake depressed, switch from open to close loop, IIRC (or other way around, but there should be a difference 1 to 0 or other way around from 0 to 1).
Leaks in inlet (unmetered air) you can detect by applying some brake/carburettor cleaner near suspected areas. It will suck in the cleaner and the revs will rise (as the cleaner will burn in the engine). The plug should be on snug, not to be taken ' out quite easy'.

Finally, when the car is rolling, the idle value will not drop to dead idle (825-875 rpm) but PCM will hold it at higher values (1200 rpm, possibly even more) to have enough brake assistance should it be needed.
 

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