MSefi.com read only forum (Jan.15,2018)

hey guys, i am currently making a tune for my nissan exa, and was wondering what would happen if i entered a larger flow rate for my injectors? would it just end up starving the engine of petrol? or would it actually work? Im sure its a dumb question but it had me thinking

ctchme wrote:hey guys, i am currently making a tune for my nissan exa, and was wondering what would happen if i entered a larger flow rate for my injectors? would it just end up starving the engine of petrol? or would it actually work? Im sure its a dumb question but it had me thinking

injector flow rate=injector flow rate

Nothing is ever going to change your injector flow rate, short of changing injectors themselves!

Ken

EDIT: Although increasing fuel pressure could increase flow within certain limits.

ctchme wrote:hey guys, i am currently making a tune for my nissan exa, and was wondering what would happen if i entered a larger flow rate for my injectors? would it just end up starving the engine of petrol? or would it actually work? Im sure its a dumb question but it had me thinking

Changing the req.fuel does the same thing in effect.

If you lie to the ECU and tell it the injectors flow more than they actually do, it will use shorter pulses resulting in less fuel flow.

The ECU doesn't actually measure the amount of fuel injected. It calculates the duration of the pulse width based on the flow rating that you enter. If you tell the computer you have 50 pound injectors, it will use a pulse width 25ms (numbers I made up).

If you then tell the computer you've installed 25 pound injectors, it will use a pulse width of 50ms, in an attempt to get the same amount of fuel. But since you didn't really change the injectors, the engine will be getting twice as much fuel as it needs.

what would happen if i entered a larger flow rate for my injectors?

ctchme,

This is not as simple a question as I think you would like it to be. Firstly, for the most part the codes don't have a injector flow setting (the newest model based code do have such a setting), instead they have a req_fuel setting (and the injector flow is part off the req_fuel calculation).

If you put different number in the req_fuel calculator AND you adjust the VE table to match, then you will get the same fuel as before, and all will be well (assuming it was properly tuned in the first place).

If you put different number in the req_fuel calculator AND you DON'T adjust the VE table to match, then you will get different amounts of fuel. Putting a larger value for injector flow in the calculator than you actually have will lean out the engine, putting smaller value will richen up the engine fuelling. HOWEVER, if you have EGO feedback enabled, then this will compensate up to its limits under the conditions ego feedback is active (so probably not always).

None of this changes the actual physical flow rate of the injectors, as other have said.

The best and simplest thing to do is to use the most accurate number you have, and leave it at that.

Lance.