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Old 05-20-2008, 02:01 PM   #104 (permalink)
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Join Date: Jan 2008
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grnsat - '95 Saturn SL1

metro - '95 Geo Metro LSi
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(this is with code prior to tuesday morning's update)

dcb: could you (and everyone else, but since you have a saturn it would help me out) post what kind of instantaneous reading you're seeing at a certain speed?

Right now at a 60mph cruise, I'm seeing 34000uS injectors, and a 36 injector count. At 60mph, my car should be running 2165RPM, or 36 revolutions per sec. This shows I'm counting the number of pulses just fine. My VSS, MPH, MI are all still solid.

But as far as my uS display, I'm seeing a number that is far too low..

Here's what I would expect to see:

Suppose my car gets 45mpg at 60mph (I dont know exactly, but should be close). I would be consuming gas at a rate of 1.3333 gallons/hour.

With my car's 19lb/hr injectors, or 3.04 gallons/hr, times 4 injectors, I can spray 12.16 gallons/hr.

1.3333/12.16 is 0.109648849 or 10.9% time while injector would be on.

10.9% of a second is 109648uS.

With my current reading of 34000uS, i'm about 3 times less than what I'd expect to see. For the hell of it, I changed
tmpTrip.injHius += elapsedMicroseconds(injHiStart); to
tmpTrip.injHius += 3*(elapsedMicroseconds(injHiStart));

and got readings that, if you didn't tell me otherwise, i'd think were pretty accurate.

Is it possible we're losing quite a bit of microseconds on the pulses? losing 2/3 seems pretty unrealistic, but I thought I'd put it out there..

I'd really like to see your (dcb) uS at 60mph, to try to rule out a connection problem..
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