Toymods Car Club Inc: Tech & Conversions => 7m idle problems, and more...!!

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Mos
Occasional Poster

Toymods IT Secretary

Location:
Oz
Registered:
June 2002

Re: 7m idle problems, and more...!!	Wed, 17 December 2003 00:55

Hi Ed, There is an explanation for the "crazy" drop It's called idle speed cut. The ECU, when it thinks it's at idle (ie IDL and E1 or E2 shorted through the TPS), will cause idle cut when the revs are above a certain point (eg 1800rpm). Once they drop below a certain point (like 1000rpm) the ECU restarts fuel/ignition delivery. If the situation is not remedied it will happily bounce between those two values as was evident in Max's 1G years ago when the ISCV was fully open and wasn't shutting - block the air supply lines and everything behaves. You MUST set up the TPS. There's no such thing as mounting it at either extremes to see the effect For the idle circuit to operate correctly the TPS idle switch has to see the closing of the throttle, and the rpm has to be within tolerable limits. The factory procedure is to use two different sized feeler gauges between the throttle stop screw and the stopper to open the throttle a certain amount. With one thickness the IDL switch should be closed, with the larger thickness the IDL switch should be open. I have found that setting it up by "feel" (ie. determining the closed/open transition by hand) doesn't work as well as using the feeler gauges. In some cases you can set the TPS to a position where the IDL switch never closes; in such a scenario the ECU will think the engine is never idling, but running at a very small throttle opening. In some cases this is needed when the engine wont idle properly in the idle state (yours may fall into that category due to the standard nature of the components ) Your ECU does not have a stop light input so that can't affect the idle either (with some ecus all weird idling/roughness magically disappears after connecting that input). I actually don't know what the coolant lines do on cars with stepper motor ISCVs. With other types of ISC the water lines take care of cold start idle up, but I don't know for sure if this is the case with the stepper setups - the valve has plenty of range to allow enough air in. So set up the TPS correctly, and then diagnose from there. HTH. Mos. [Report message to a moderator]

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