I was checking the just the mechanical advance. I had the vacuum line to the distributor disconnected (and plugged). So other than the 2 degrees off at 4000+ RPM, the mechanical advance seems to be working correctly. Base timing is also correct. I guess I'll have to get a vacuum pump to check the vacuum advance. I know the problem isn't bad gas or overheating. I'm assuming the spark plugs are correct, because they were installed by a DeLorean vendor. Though they're about 6 years old now. Any suggestions on what to do about carbon deposits? On Aug 15, 2006, at 11:26 PM, David Teitelbaum wrote: > Timing advance can be checked with a tachometer and a timing light. > Pinging can be caused by bad gas, carbon deposits, overheating, > running too lean a mixture, wrong spark plugs to name a few causes. > Total advance (with vacuum AND mechanical) should be 40, not 22. Make > sure you are getting ALL of your mechanical advance and all of your > vacuum advance. I have seen where the mechanical advance gets stuck > and you don't get any and I have seen problems in the vacuum circuit > and no vacuum advance. One of your timing advance systems is not > functioning. Very easy to check, disconnect the vacuum line to the > distributer and see if you get any advance. If you do then you know > the vacuum is the problem. Verify the markings for TDC on the scale > and make sure your initial (base) timing is correctly set @ 13 > degrees. Refer to M:01:04 in your Workshop Manual. A vacuum hand pump > is not expensive and would make it much easier to troubleshoot your > vacuum circuit. > David Teitelbaum > vin 10757 > > 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/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> 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/