Injector Setup

[97AWDTSi]

After speaking with the folks at EFI and getting NO WHERE. I figured I would pose a question to the MORE knowledgable crew in this forum.

Q: PMS's system, for our cars, is configured for 450cc or 550cc injector setting. I run on 750cc! Is it better to subtract a ton of fuel cross the board or create a new injector setup using their software for the 750cc and adding fuel?

The guy at EFI's exact words where "ahhh I don't know!".

[Rdy2race]

I'm almost worst

to answer you. yes no and maybe so.... :D

here is the deal

720's have shown that they do not like to run at a slow pulse with. The reason ... to long to go in to but it just doesn't run well. So you might have to ADD fuel in the lower load/rpm range so that the car will idle and get enought fuel to cycle. With tha being said at higher IPW numbers they will deliver much motr fuel then the other smaller inj will. So now in the higher RPM/load tables you will have to take away fuel.

The amount are not known as the mods that the car has will dictace what is needed. In most cases you will find a huge sweeping curve to make this injector work correctly. The biggest problem is that the system that is used is called Batch Fire. this means that it fires 1&4 and 2&3 plugs and inj's at the same time. So at one point your getting a wasted spark and fireing a inj on the back side of a closed valve. Nothing you can do about this with the PMS to my knowlage. This will make it rich and can be a problem at idle some times with very large injectors.

With the ECU programed for 550's will be the one to use. the curve will mostlikely have to go up in the idle range and lean out in the higer load /RPM range.

I hope this helps some
Good luck
BM-

[97AWDTSi]

Makes some'wot of sense. At least it is a starting point where as EFI had none. :( In this case the 550 setup with some fuel pull at the upper end of the fuel curve would be the way to go and dump fuel on the thing at idle / low rpms, if I am understanding correctly.j

This sounds backwards due to the fact that it is my understanding that the larger injectors run better at 60+ PW instead of slowing them down under 50. Something like sputtering fuel out of the injectors instead of blowing a fine mist into the engine like they were designed to do, correct?

Would it not make more sense to Add fuel at top end of the fuel curve and take out just a little at idle, for PW sake? (PW-Pulse Width, sorry folks for the abbv.)

thanks again.