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Car Forum / Honda Cars / September 2005What is a dwell meter?
Tegger's FAQs has references to dwell meters - e.g for testing the coil. I have never heard of a dwell meter before and they aren't widely available from what I can tell.. Wondering if my digital electric multimeter can do this diagnostic...? Starting Problems ... is this: Connect a dwell meter to the negative coil terminal and to ground. Crank the engine: No dwell, bad igniter; Dwell but no spark, bad coil. ... www.tegger.com/hondafaq/startproblems.html > Tegger's FAQs has references to dwell meters - e.g for testing the coil. I > have never heard of a dwell meter before and they aren't widely available [quoted text clipped - 6 lines] > Crank the engine: No dwell, bad igniter; Dwell but no spark, bad coil. ... > www.tegger.com/hondafaq/startproblems.html unless it's the automotive variety, probably not. but don't worry about it. if your car has electronic ignition, it's irrelevant because "dwell" is all determined by the ecu or ignition module. all that matters is that the igniter switches, that the coil fires, and that the plugs spark. use of the word "dwell" is a throwback to the old days of contact breakers where the contacts had to "dwell" for long enough to energize the coil. too little dwell, not enough spark energy, especially at high rpm's. too much, coil ran too hot. >Tegger's FAQs has references to dwell meters - e.g for testing the coil. I >have never heard of a dwell meter before and they aren't widely available >from what I can tell.. In the old mechanical breaker points ignition systems, dwell angle is the angle of rotation of the distributor through which the mechanical points are "closed. The points must remain closed for a sufficient time to store energy in the coil sufficient to produce a good, hot spark at the plug when the points open. In a four cylinder engine, dwell angle is typically around 60 degrees. There is an equivalent measurement in an electronoic ignition system that is usually called dwell, but it is not properly dwell in the old contact points sense. This quantity is electronically controlled. I am not sure what an old fashioned dwell meter would be measuring in a modern electronic ignition engine. However, I do not think it would be useful information. There is typically no way to make adjustments on most electronic ignition systems anyway. Hope this helps. Elliot Richmond Freelance Science Writer and Editor > >Tegger's FAQs has references to dwell meters - e.g for testing the coil. I > >have never heard of a dwell meter before and they aren't widely available [quoted text clipped - 19 lines] > Elliot Richmond > Freelance Science Writer and Editor The 'Old' Dwell meters were usually based on continuity testers. I suppose you could measure continuity with it. I have seen articles in the electronic trade magazines about using Volt-Ohm (V.O.M.)meters for measuring point dwell. This was back in the late sixties and early seventies. I know I'm showing my age here. Randy >The 'Old' Dwell meters were usually based on continuity testers. I >suppose you could measure continuity with it. I have seen articles in >the electronic trade magazines about using Volt-Ohm (V.O.M.)meters for >measuring point dwell. This was back in the late sixties and early >seventies. I know I'm showing my age here. Young whippersnapper! My dwell meter scale read in degrees. I never took it apart but my guess was that it was some sort of RC circuit (or maybe IRC) with a voltmeter reading the potential across the capacitor. The longer the dwell, the more charge the capacitor would accumulate, and the higher the voltage, which would then read as a larger dwell angle. Elliot Richmond Freelance Science Writer and Editor >>The 'Old' Dwell meters were usually based on continuity testers. I >>suppose you could measure continuity with it. I have seen articles in [quoted text clipped - 9 lines] > dwell, the more charge the capacitor would accumulate, and the higher > the voltage, which would then read as a larger dwell angle. That's how I would build one - dead simple :) --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0535-3, 09/02/2005 Tested on: 9/3/2005 7:52:57 PM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com > >The 'Old' Dwell meters were usually based on continuity testers. I > >suppose you could measure continuity with it. I have seen articles in [quoted text clipped - 12 lines] > Elliot Richmond > Freelance Science Writer and Editor Some of them would simply let the longer the dwell be indicated by the lower resistance read. Letting the mechanical inertia of the meter integrating the pulses into a smooth reading. Randy >>>The 'Old' Dwell meters were usually based on continuity testers. I >>>suppose you could measure continuity with it. I have seen articles in [quoted text clipped - 15 lines] > Some of them would simply let the longer the dwell be indicated by the > lower resistance read. There should be no change in resistance - either it's infinite (points open) or near-zero (points closed). > Letting the mechanical inertia of the meter integrating the pulses > into a smooth reading. That's how almost all tachometers work. > Randy --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0535-3, 09/02/2005 Tested on: 9/4/2005 4:44:13 PM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com > I am > not sure what an old fashioned dwell meter would be measuring in a > modern electronic ignition engine. However, I do not think it would be > useful information. A dwell meter can measure fuel injector's richness, although the correct way is to measure current. > Tegger's FAQs has references to dwell meters - e.g for testing the coil. I > have never heard of a dwell meter before and they aren't widely available > from what I can tell.. Replace the dwell with a spare bulb from the taillights. > Wondering if my digital electric multimeter can do this diagnostic...? Yes/No. If the coil is severely dead there is no load. And no load = no signal. That's why the bulb works. >> Tegger's FAQs has references to dwell meters - e.g for testing the coil. I >> have never heard of a dwell meter before and they aren't widely available [quoted text clipped - 6 lines] >Yes/No. If the coil is severely dead there is no load. And no >load = no signal. That's why the bulb works. dwell is the number of degrees the points were open, for an ignitior it's faster to use a common test light. Chip |
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