At the recent PADMC Pittsburgh Fall Tech Session (thanks again Dave and Juley!), I successfully diagnosed a longstanding drivability problem. This turned out to be a bit of a tricky issue, so I though I would share: The symptom: Engine ran perfectly when cold and at speed, but at normal operating temperature exhibited an erratic but frequent hesitation off the line. Often it would nearly stall when accelerating from a stop light. The solution: I spent over a year checking and rechecking all of the obvious possibilities. Nothing helped. I assumed it must have had to do with the vacuum advance (since this only operates when the engine is warn), but the advance tested OK, and putting my finger over the hose showed vacuum at all the right times, proving that the idle switch and vacuum solenoid were operating properly--I THOUGHT! Finally, I borrowed Dave S's vacuum gauge and actually measured the vacuum at the output of the solenoid valve. It turned out that, although the valve was operating, it had a massive internal vacuum leak, resulting in only a few pounds of vacuum at its output port--enough to feel, but not enough to reliably operate the vacuum advance. Replaced the solenoid valve and all is well. Lesson learned: A fingertip vacuum test is no substitute for actual measurement. --Pete Lucas VIN #06703 [Non-text portions of this message have been removed] ------------------------------------ To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnewsYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/