how to increase idle speed
08-02-2005, 10:11 PM
#1
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how to increase idle speed: FIXED Thanks John S.
I have been playing with the throttle cable but it doesnt seem to increase the idle speed. It doesnt decrease it either. I searched nuchols site and also rennlist but got no matches.
Last edited by perrys4; 08-13-2005 at 02:34 PM. Reason: UPDATE
08-02-2005, 10:21 PM
#2
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Idle speed is determined by the LH magic box and regulated by the ICV ....the cables have no impact ( unless the throttle body cable is too tight only and prevents the butterfly valve from fully closing). The early 16v cars have idle (air bypass ) screws on the throttlebody.
If I misunderstood, what is it you are trying to adjust?
If I misunderstood, what is it you are trying to adjust?
08-02-2005, 10:37 PM
#4
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Perry.............as Garth correctly points out the idle on your car is non-adjustable. The LH eprom adjusts idle for all conditions through input from many sensors. If your car is an auto and I assume it is (1990 S4) correct idle is 675 rpm. There is a possible cure for low idle by adding lubricant (WD40 or such like) to the vacuum line that feeds the idle stabilzer valve...........there's good write ups in the archieves. Also, the MAF may be causing issues..............easy check if you have a buddy with a similar car............swap the MAFs and see how yours run. I assume all regular maintenance items are in good condition?; spark plugs, ignition wires, air filter etc etc.
08-02-2005, 10:45 PM
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Car is in great shape and current on all maintenance. I will take it in to Precision next week and see what Greg can find. I thought maybe there would be an wasy fix. Thanks
08-03-2005, 06:32 AM
#7
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Incorrect idle can also be an early sign of LH ECU failure...
Greg will be able to put a diagnostic tester on the car. Using actuator tests it is possible to quickly analyse this type of problem. Idle speed should be 675rpm under all conditions. It is temperatuyre compensated etc.
Regards
Greg will be able to put a diagnostic tester on the car. Using actuator tests it is possible to quickly analyse this type of problem. Idle speed should be 675rpm under all conditions. It is temperatuyre compensated etc.
Regards
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08-03-2005, 11:58 AM
#9
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Hi Stirling,
If you are referring to the MAF idle mixture pot, then this is not in circuit on S4 and later cars. (even on non-cat cars).
The idle speed adjustment is automatic, the control ciruits are in the LH ECU and are not adjustable.
If you are referring to the MAF idle mixture pot, then this is not in circuit on S4 and later cars. (even on non-cat cars).
The idle speed adjustment is automatic, the control ciruits are in the LH ECU and are not adjustable.
08-03-2005, 01:07 PM
#11
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There is an adjustable stop for the throttle body closed position which is set lock nutted and paint marked at the factory but as was mentioned it should never need adjustment and is not in the workshop manuals as I recall.
08-03-2005, 01:16 PM
#12
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It is not possible to alter the idle speed manually on a S4 engine. Any change in air entering the engine, ie: increasing the tplate adj, will just cause the idle air act to close down to get the idle back to program.
Marc
DEVEK
Marc
DEVEK
