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Old 11-18-2018, 10:11 PM   #51
lummert
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Starting to notice that these injectors work better at 2.7 Bar fuel pressure. Engine idles rough until it warms up at 3 Bar fuel pressure. Duty cycle is nearly the same at either fuel pressure. Idle: 60% compared to 58%. Engine off : 82% compared to 79%. So I take it that the fuel pressure difference has little effect on the duty cycle. So go with the fuel pressure that works best for the injectors?

Info that I found on Mustang Cobra site about running injectors that are too big:
* Lower fuel pressure and increase injector openings.
* Run richer at idle.
* Run a less aggressive injector if ECU allows it.
* Raise the idle speed.
* A combination of a few above...
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Last edited by lummert; 11-18-2018 at 10:21 PM..
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Old 11-19-2018, 01:04 PM   #52
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Swapped to a second BMW 2.5 Bar FPR because car was hard to start this morning (35* F) with the Buick 3.0 Bar FPR. Now to wait for it to warm up a bit outside to do a pressure test with this other BMW FPR.

Looking through my FPR's to see if I have a good OE Volvo type FPR.
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Old 11-22-2018, 02:54 PM   #53
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Today I found a different dwell to duty cycle conversion chart. I retested with the dwell meter on a warm engine and got 36 degrees on 6 cyl scale. According to this chart 36 degrees on 6 cylinder scale = 40% duty cycle. 40% duty cycle at idle in closed loop makes much more sense.

Ground controlled circuit @ 36 degrees on 6 cylinder scale = 40% duty cycle
Feed controlled circuit @ 36 degrees on 6 cylinder scale = 60% duty cycle

Not sure about the voltage reading that I was getting. With dwell meter at voltmeter connected at same time between test point and battery positive showed 5.95 VDC. 5.80 VDC corresponds to 60% duty cycle on same chart.

Last edited by lummert; 11-22-2018 at 04:10 PM..
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