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Help needed after head gasket replacement

3K views 11 replies 4 participants last post by  adrian 
Adrian,

Won't turning the throttle stop screw affect the point at which the 'Throttle Position Switch' detects the 'closed' position? It's a while since I had the ICV version of engine (on a 1994 2L ECO), but I found unless there was enough 'travel' to ensure the throttle position switch was clearly triggered, when parts get warm and/or worn the 'stop position' may not be detected, and the floating rev scenario (as per your description) occurs.

In summary, the throttle stop screw should not be adjusted, without ohming out the closed and open positions of the throttle position switch and ensureing correct resistances/switching occurs. Haynes manual describe test method/values.
 
Turning throttle stop screw back would be the easy test/solution - after checking error codes.

To adjust throttle stop position switch is easy too. Just loosen locking nut, and rotate the unit slightly clockwise and retighten locking nut. Best to check switch resistance against haynes manual figures before and after - and ensure a spare 'degree' of rotation is included to allow for any play in the mechanism when unit is hot under running conditions.

I leant this process the had way when an 'Indie' Saab specialist in south west tried being smart, by turning throttle stop screw to reduce tickover - at least he did it free of charge!! My guess was he didn't even know what a throttle position switch was! I had to set it back when the 'floating rev' scenario occured - itermittently - mainly when engine was up to temp, etc.
 
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