Page 122 of Technical Information Manual - set the dwell meter to 4 cylinder scale. Harold McElraft - 3354 -- In dmcnews@xxxxxxxxxxxxxxx, "drdhdmd" <doctorDHD@xxxx> wrote: > 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/