Injector Duty Cycle

Q&A regarding engines, turbos, and intercoolers and power upgrades

Injector Duty Cycle

Postby 5speedGT4 » Sat Oct 23, 2004 10:25 pm

Well ive been messing around with my new AVC-R boost controller and upped the boost on my ct26 to 1 bar for the time being, since my stupid ct20b went south on me.... And ive been watching my injector duty cycle quite a bit. It seems to get very close to 100% if not at 100% at higher rpms and full boost. Now my question is, what can i do to bring this back down to a more sane percentage. Right now all i have done is a walbro 255 pump on my fuel system, but i have a aeromotive fpr coming hopefully today or monday.

I know im running slightly higher fuel pressure right now because of the pump (it sure smells rich as hell) but I dont like the idea of it hitting 100% duty cycle on my ct26. Especially when i plan to run a td06 at 10-12 psi on stock injectors with some more fuel pressure and less timing on race gas.
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Re: Injector Duty Cycle

Postby Trance4c » Sun Oct 24, 2004 4:17 pm

5speedGT4 wrote:Now my question is, what can i do to bring this back down to a more sane percentage.

Get some 550 cc injectors.. only way to bring that down is to throw more fuel at it. The stock 440's won't be liking that kind of duty cycle for very long, nor will your engine.. I would watch out, you might be near conditions to lean out!
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Postby silverarrow » Fri Oct 29, 2004 5:27 am

Not to hi-jack this thread but which model # of walbro fp do you guys order/buy? I don't want to buy the wrong one.

But yes anyhow, whatever Clayton said.
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Postby SeanGTS » Fri Oct 29, 2004 6:03 am

I also need to know that part # :shrug:

On topic though, i think your thinking is incorrect on this. Im not to savvy when it comes to injectors, pulses, duty cycles, blah blah, but i know a bit about the ECU.

I believe that when you raise the boost above the factory limits (11.8psi), and as little as 1 bar of boost, the ECU is not adequately equipped to handle this situation. Instead, it goes into a frenzy and dumps in fuel at the maximum possible rate, even if its excessive.

So, this is why i believe your seeing 100% duty cycles. The RC ECU has maps up to 17psi i believe, which would mean you would be running those predetermined maps at the current boost level that your on. This would ease the rate at which your injectors are firing, and insure your car has the right recipe for the boomstick. :D
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