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2. Determine injector firing method for the complete 4 stroke cycle. Let's say this is a 360° bank-fired, meaning an injector fires each and every crankshaft revolution. 3. Determine how many times the injector will fire at the specified engine speed (600 RPM) in a fixed time period. We will use 100 milliseconds because it is easy to use. Six hundred crankshaft Revolutions Per 4. Determine the ratio of injector on-time vs. off-time in the fixed time period, then figure duty cycle and/or dwell. The injector fires one time for a total of one millisecond in any given 100 millisecond period. One Weaknesses of Dwell/Duty Meter The weaknesses are significant. First, there is no one-to-one correspondence to actual mS on-time. No Second, all level of detail is lost in the averaging process. This is the primary weakness. You cannot see the Here is one example. Imagine a vehicle that has a faulty injector driver that occasionally skips an injector pulse. A connected dwell/duty meter would see the fattened pulse width but would also see the skipped pulses. It This situation is not a far-fetched scenario. Some early GM 3800 engines were suffering from exactly this. The As you might have guessed, a lab scope would not miss this. RELATIONSHIP BETWEEN DWELL & DUTY CYCLE READINGS Dwell Meter (2) Duty Cycle Meter 1° 1% 15° 25% 30° 50% 45° 75% 60° 100% (1) These are just some examples for your understanding. It is okay to fill in the gaps.
1998 Chevrolet Pickup C1500 GENERAL INFORMATION Waveforms - Injector Pattern Tutorial
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