"Smurf" wrote in message
...
I am suffering from a very erratic idle on a 2.5ltr sve lpg converted car,
currently 58,000 miles. The car is an automatic, and seems to function fine
in all other manners, but, when put into neutral the revs jump up and down
from 1500 to 2200rpm making the kind of noise you would get from
deliberately revving the engine. The car functions in all other ways ok,
when in drive, with the brake on, there is no rev problem, but then the
engine is engaged... There is a consequence of this, at speeds of low revs,
the car gets a slight jerk forward as it pushes up from the 1500 to 2200.

This happens whether or not the car is running on lpg or petrol, but
doesnt happen when the car is first started up, ie it runs for a short
while before the problem happens.

A general mechanic who has done work for me in the past, said his fault
finding equipment couldnt pick anything up and suggests i go to dealer and
see if their system can locate the fault.

I dont know much when it comes to cars, but have read about lpg messing up
some valves, and i do know that it has some 'valve saver' fluid bottle
fitted.

Any help would be greatful.

Two things spring to mind on the xtrail 2.5 - throttle body fault, idle
adaption needs to be re-learnt (google for this), or you have a split hose
in the PCV system.

Check those in reverse order (£ to ££££)

Tim.