Discussion
Been having a quite bad idle problem. I was using a sealant on the stepper motor. Changed to PTFE tape as the sealant was spacing out the motor a tad, after a comment by Streaky I think? Then the connector to the air flow thingy on a hot wire was a tad slack so tightend up the connectors. Seems to have worked.
Question's. How does the stepper motor etc all control the idle? What does it do? And the screw in the plenum all fit together with the above? Is there a definitve description on how it all fits together?
There is also a screw detent under the throttle linkage. I assume this affects the throtle pot and its position (well obvious when you look at it) but how do you set it?
Question's. How does the stepper motor etc all control the idle? What does it do? And the screw in the plenum all fit together with the above? Is there a definitve description on how it all fits together?
There is also a screw detent under the throttle linkage. I assume this affects the throtle pot and its position (well obvious when you look at it) but how do you set it?
The throttle plate (or butterfly if you know it as that) is normally set (on the non-hotwire at any rate) by putting a 2 thou" feeler gauge under the edge of the plate and setting the stop so that the blade can only just move.
The stepper motor (aka idle stabilisation valve)responds to a control voltage from the ECU that is in turn repsonding to RPM info. The stepper motor opens a valve that admits more or less air, bypassing the throttle plate, to compensate for varying factors such as the PAS pump loading up at full lock and trying to stall the engine.
The throttle pot needs to be set so that at idle, a specific voltage (within a narrow range) is being sent to the ECU so it knows what idle 'looks like'. On the non-hotwire, its about 300mV. On the hotwire, the ECU relies more on the pot info than does the non-HW, which can actually run quite happily with the pot disconnected (dunno about the HW setup though!).
Ian
The stepper motor (aka idle stabilisation valve)responds to a control voltage from the ECU that is in turn repsonding to RPM info. The stepper motor opens a valve that admits more or less air, bypassing the throttle plate, to compensate for varying factors such as the PAS pump loading up at full lock and trying to stall the engine.
The throttle pot needs to be set so that at idle, a specific voltage (within a narrow range) is being sent to the ECU so it knows what idle 'looks like'. On the non-hotwire, its about 300mV. On the hotwire, the ECU relies more on the pot info than does the non-HW, which can actually run quite happily with the pot disconnected (dunno about the HW setup though!).
Ian
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