Pelican Parts Forums - deceleration valve leaking?

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deceleration valve leaking?

1974 1.8, L-Jet FI: wondered why PO had idle air screw all the way in. I've replaced all hoses and Aux Air valve system is OK. So, last night I warmed it up and crimped off the deceleration valve air at idle, and the idle dropped from its usual 800 - 1,200 or so to about 600. Now I can do a fine adjustment of the idle air screw and have a steady 900rpm. Am I correct in thinking that the deceleration valve should only admit air for a few seconds after releasing the throttle from a higher rpm (the book says test by releasing the throttle from 3,000 and it should pull air through the valve)?

Yes, you are correct.

The deceleration bypass valve works on vaccuum from the engine which goes sky high when you snap the throttle shut. The second the revs are back to idle and not changing that valve should be shut.

Find a spare...

Sean

Is the decel vakve really needed?
Iam rebuilding my L-jet engine which the PO removed the decel valve.

Do I need to buy one or is it an over design my Porsche/VW