View Single Post
JFairman JFairman is offline
Registered User
Join Date: Jul 2006
Location: S. Florida
Posts: 7,274
Lower your hot idle speed to around 800rpm and see how it goes.

There is also a small vacuum solenoid in the vacuum retard line.
On a cold start that solenoid closes so vacuum retard does not exist. The result is the ignition timing at idle is advanced a bit and that helps raise cold idle speed too.

When the K-jetronic box under the seat opens the vacuum retard solenoid after around 20-45 seconds depending on the year of your car and other variables the ignition timing retards and idle drops noticably all at once.
The aux air valve that bypasses air around the throttle body is closing around the same time but when you hear an abrupt drop in idle thats the timing being retarded.
That is another system to check and see if it's working correctly.

I've also heard that solenoid in the vacuum retard line also closes under boost via the throttle position switch at full throttle so the vacuum advance will become boost retard.
Old 11-05-2008, 10:18 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)