tickover too high

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barker746

New Member
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20
Location
darlington co,durham
hello peeps, my 97 v8 auto 3.9 disco tickover is 900 rpm in neutral, in gear driving round town i end up riding the brakes cos idle speed now at 1250 rpm . anyone know how to bring the tickover down as i cant see any way of doing it . cheers steve:confused:
 
the ecu has been replaced with one from a 95 v8 3.9 es after both heads had to come off + be skimmed my old ecu decided to retire itself . where would i find the plenum chamber + the stepper motor? cheers steve
 
The Plenum its the alloy top with 3.9 on it and the idle control valve is at the rear with the blue & orange wires, so unplug and unbolt it and spray the working parts with brake cleaner and put back carefully.
 

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Ok still keeping it simple, is your air filter clean? also look for any air leaks, splits in hose's going to the plenum, hose clip joints, also the seam that goes around it where the top meet the bottom and also the large AFM hose. Any additional air leaking in will upset the tickover.
After that you will be looking a faulty items like the air flow meter AFM that's the lump just after the airfilter, you should get the engine pluged into the diagnostic kit (testbook of similar) to confirm.

If you also post in the it's a V8 mate, engines forum u may get a few more responces and may get it sorted for u :)
 
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all hoses are okay replaced some iffy looking jubilee clips . air filter is a cone shaped k+n one cos the lpg regulater sits where the air box use to . idle the same on lpg or petrol . the seam of the plenum ok . will have to get it plugged in , thanks for your input , cheers steve
 
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