It was a beautiful almost "Spring" day so I couldn't resist. I connected my scope to the diagnostic port to "see" what was going on. According to my calculations the frequency of the signal was 70 Hz which I believe is correct. The problem is the duty cycle ON was only 38.8% with the WOT switch closed. The manual says 50 - 60. Something did not seem right so I went back to the DeLorean Workshop Manual and checked all the "Pulse Ratios" on page D:04:15. Everything seemed to be inverted, that is, the lower part of the square wave pulse signal got bigger when the WOT switch was closed. I tried all the test configurations and the all were right except they were inverted. Attaching a known voltage and polarity to the scope proved that + was indeed up. I was confused. It was getting dark and I had to close up shop. Now sitting here something I read popped into my head. It talked about connecting the dwell meter to the pinS on the diagnostic plug. A quick check of the schematic revealed the problem. I had connected my dwell meter and scope to one pin on the diagnostic plug and ground. (They way we used to check dwell on a car with points.) It seems that the other pin of the diagnostic plug is not ground but rather positive 12 volts. Thus all my measurements were off and I guess I adjusted the CO to around 60 instead of 40. Now I have a project for next weekend! I believe this has been address in the past but none of the answers I have found seem to make sense...to me. When using a DWELL meter to measure these "ratios" What scales and setting do you use? Since we are talking about something that in theory can go from 0 to 100 percent, it doesn't seem correct to use even the 4 cylinder range because that maximum is only 90%. Does anyone have an answer with an explaination? (I know I am asking alot but remember what the old wise man said about giving a fish vs teaching someone how to fish...) When all else fails Read The Manual. Fortunately when I was flying Pipers I ALWAYS used my checklists and went by the book carefully. Thank you, Dave and 6530 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/