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Registered
Join Date: Mar 2005
Location: London,England
Posts: 14
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Stupid Cds/ignition Question, Guys But......
Hi All,
Can someone tell me how to wire up my engine diagnostic multi-meter to the engine, so that I can measure the engine speed without:- Blowing up the CDS/Voltage transformer units Blowing myself/the meter up Running to the cock pit to read the cars tach. every five minutes No probs measuring the dwell. Various Manuals have put me off shoving the probes in and seeing if I can get a tach reading. Would like a suggestion of how to measure tach. whilst being around the back of the car with my head in the engine bay (metaphorically speaking) I know this is a dumb ass question so please be gentle with me in your answers....
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Neil Keegan. 1970 911T-for fun 1987 Diahatsu FourTrack-for terrifying Taxi's |
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08-17-2005, 12:03 AM
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Join Date: May 2005
Location: Bothell, WA
Posts: 239
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garage,
If your engine diagnostic multi-meter has an RPM setting, just hook the positive wire to the positive terminal on the coil, and ground the negative wire. This should give you RPM on the engine diagnostic multi-meter. Rex
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1975 911s 1997 Saab 900s |
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08-17-2005, 04:34 AM
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Location: London,England
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thanks ..just got a bit nervous over this as the meters instructiions for measuring rpm say only use on older, non-electronic ignition systems and I didn't know how close the CDS system came to this and didn't fancy blowing the cDS unit.
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Neil Keegan. 1970 911T-for fun 1987 Diahatsu FourTrack-for terrifying Taxi's |
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08-17-2005, 05:06 AM
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Hilbilly Deluxe
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Don't hook up anything to the coil, without spending some time looking through the archives. This subject has come up before, and IIRC the answer was "Don't do it".
Use the Search function Tom |
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08-17-2005, 06:20 AM
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Registered
Join Date: Dec 1999
Location: TX USA
Posts: 9,804
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Neil,
If you want information about theory of operation of the CDI system, here is a thread with an official Bosch document: Perma-tune CD or Bosch CD? For checking rpms or dwell ... a meter is connected to the Black/Violet wire at the distributor, and to ground. Your meter will see a 12 - 14 Volt pulse train ... unless you already connected it to the coil and roasted the meter input circuit with +460 Volt pulses from the CDI unit!
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Warren Hall, Jr. 1973 911S Targa ... 'Annie' 1968 340S Barracuda ... 'Rolling Thunder' |
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08-17-2005, 07:30 AM
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Location: London,England
Posts: 14
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Thanks Warren,
I figured there was a way to do it it's just finding the right connection. Nope haven't fried the meter yet as I read the CDI description in the workshop manuals last night..the bit about 400+volts at high cycle amplitude put me right off. Will read the thread and report back on further adventures if I haven't blown myself up...
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Neil Keegan. 1970 911T-for fun 1987 Diahatsu FourTrack-for terrifying Taxi's |
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08-17-2005, 07:53 AM
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Join Date: Jul 2001
Location: Wilmington, NC USA
Posts: 635
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If you are reading the dwell just move the switch to RPM and you are there. Its the same connection for both.
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69 911 2.3Ez 85 928S |
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08-17-2005, 09:02 AM
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1982 Porsche 911SC Coupe 3.2
