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Re: Megasquirt 2 EFI and Vintage Air A/C in a 74 Challenger
[Re: 2011GrabberGT]
#1658685
08/18/14 11:46 AM
08/18/14 11:46 AM
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Joined: Jun 2008
Posts: 1,822
Colorado
denfireguy
top fuel
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top fuel
Joined: Jun 2008
Posts: 1,822
Colorado
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Quote:
Exactly. The whole point of sequential is to time the injector pulsewidth with the intake valve opening events so that fuel is only sprayed when the valve is open and taking in air.
At mid and high RPM's the intake valves will be opening and closing faster than the injector opening and closing events since the pulsewidths have to higher to deliver the necessary fuel quantity.
The end result is that the injectors cannot open and close fast enough to match the valves while still metering enough fuel, so even sequentially fuel injected engines essentially operate in batch fire mode above a certain RPM.
Direct injection is really the only way to get around that.
If I couldn't get a clean idle or my car still made my eyes burn like Testor's Model Glue I'd have considered making the jump.
Being able to independently tune each bank resulted in the largest impact for me. I was able to drop my idle kpa down by 5-7 just from tweaking the VE tables to get the AFR's even and correct.
The other caveat is that if you run sequential and don't take the time to find the ideal injector timing you can actually induce problems with shaky idles and excessive emissions that may not be present in normal batch fire mode.
That all makes total sense. I know the on/off time of an injector is not real short and at high RPM it would be much like valve float, not enough time to totally open or close.
It also makes sense that the ideal injector time would be critical to get the fuel through the valve at the exact time it would be needed and again would be variable with RPM.
Next question: Did you start with setting up the ignition timing first or the injection? Or did you do all of it at once? I was going to start with timing first since it was the easiest and then add fuel injection.
Craig
Last edited by denfireguy; 08/18/14 11:50 AM.
2014 Ram 1500 Laramie, 73 Cuda
Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango
Only previous Non-Mopar: Schwinn Tornado
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