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Old 02-06-2009, 09:39 AM   #17 (permalink)
instarx
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Quote:
Originally Posted by dcb View Post
Hmm... the piezo fuel line tach sensor approach is looking better.

You can derive rpm. You can probably also tell how long the pulse was, which is a function of rpm and control sleeve position (effectively stroke). Still need to determine the range but should be able to get a relative reading anyway.

fuel delivered = rpm * pulse duration * k
But how are you going to measure pulse length? I think you are confusing new, OBDII engines (for which gauges are no real problem and determining pulse length is relatively easy to do) with older engines. The older diesel engines like the 190D, for which there are no gauges, just use mechanical injection timing.

If you have electrically controlled injection timing there is already an Australian company that makes a device that measures the length of the injection event to determine instantaneous fuel usage data. I can't remember it's name but I found it on Google a year or so ago. I posted about it on a 6.5L diesel engine forum, so if anybody is interested I can probably find it in their archives..., but it won't work on older diesels with mechanical injector timing.
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