3.9 idling slightly erratically

My Disco is idling slightly lower than it should and can very occasionally cut out whilst coming to a standstill, the revs also sometimes start to rise to just over 1000RPM until I blip the throttle and then everything seems to return to normal, I have just replaced the accelerator cable as it was sticking but the problem still remains.

I unplugged the MAF sensor and it made absolutely no difference to its running, I was going to clean it but don't really know where to start or what to use.

Also one of the wires from the lambda sensors was touching the manifold so I moved that back.

It runs the same on petrol as it does on LPG.

Any ideas before I take her to my indy and spend more money?

Clean the crank case breather and stick a can of injector cleaner into the petrol works for me, or keep away from supermarket petrol.

I would say clean and check all crankcase breathers as discool says, try spraying brake cleaner around the plenum and see revs rise, if so could be a minor plenum leak, I doubt if it is a stepper motor problem if it doing it on gas as well as petrol, single point lpg systems have a separate lpg stepper (well mine has), also worth checking and cleaning the throttle butterfly, once I had done all of the above and adjusted base idle speed, mine has ticked over beautifully for ages, can barely feel it's running at junctions etc. It also stopped the irritating problem of revving to 2000rpm on startup for a few seconds (which made me sound like a moron in car parks!) now only goes to about 1300 for a couple seconds.

I have exactly the same problem on petrol (d1 3.9 V8) BUT when I switch to LPG it runs fine????

@zaky31 - try cleaning your stepper motor and it's housing, there's plenty of write ups online

somersetsparks said:

@zaky31 - try cleaning your stepper motor and it's housing, there's plenty of write ups online

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