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One more Injector Question

Posted: January 14th, 2012, 5:08 pm
by WJ 2000
Ok , so me and my buddy where talking about fuel Injectors, so I have a 4.6 stroker with 24 # pound injectors, the arument is . Just how are these injectors working / with the stock PCU
my 2000 Grand Cher, had 22# pound injectors, and stock PCU, and now I put in 24# pound injectors, would'nt my stock PCU still think there 22# pounders . I dont really know ??
I think my motor mite be running to lean, and if thats the case . Holey sheep dip .

Re: One more Injector Question

Posted: January 14th, 2012, 5:26 pm
by Muad'Dib
If you have a higher pressure flow rating at a given pressure then more fuel will be put into the cylinder within the same injector pulse.

The Computer doesnt know and cares less. All it does is open the injector for a certain amount of time (pulse width). Again, during that time if you have a higher flow injector in there then more fuel will end up in the cylinder.


You need to get a wideband if you think your running lean so you can really see how its running.

Re: One more Injector Question

Posted: January 14th, 2012, 5:42 pm
by SilverXJ
Yes, the engine doesn't know or care. What it cares about is what it sees through the various sensors. MAP and O2 being the most important. It uses the O2 sensors to modulate the AFR to 14.7:1 in closed loop. In open loop it relies on the MAP sensor values and crosses them to a map(chart sort of) to determine how much fuel to add.

In closed loop your injectors are with in the correct size to achieve the 14.7:1 (stoich) afr. However, in open loop you need a wideband O2 sensor gauge to see whats it is doing.

Re: One more Injector Question

Posted: January 19th, 2012, 8:53 pm
by WJ 2000
Thanks Guys .