jonalman

i have 30 pound injectors in my 93 mustang lx.i have bought a new MAF that is setup for the 30lb injectors. i have an A9 series ECU. What is the easiest/cheapest way to get my ECU tuned for the injectors?

thanks a lot for the help!

samseed101

The cheapest way is to just install it and ignore it. The injectors are 30# and the MAF is calibrated for 30# so the computer will supply the right amount of fuel via the injectors. It's not the best method because all it really does is trick the computer into supplying the fuel. Bascally, it does this by reducing the MAF voltage to represent an airflow that is about 27% less than how much air is actually flowing in (for 30# injectors.) So the computer thinks less air is coming in, and it thinks your injectors are still stock as well (27% smaller to be exact.)

The computer thinks everything is stock (27% smaller injectors) so the MAF lies to the computer and tells it that 27% less air is flowing in. The computer opens up the injectors with a long enough pulsewidth to supply enough fuel for how much air the computer thinks is coming in. But of course in the same amount of time, more fuel can flow through 30# injectors than 19# injectors. So in reality, roughly 27% more fuel will flow through. And of course because the MAF lied to the computer, there is actually 27% more air flowing into the engine anyway. So in the end, it balancs out and your engine gets the right amount of fuel even though the computer has no clue anything changes.

A better method is to get a chip / tune to tell the compuer the real figures. But that can be expensive and may not be worth it unless you have some other mods that require a good tune.

jonalman

yea i have read about how the ECU controls the pulse width of the injectors. would you suggest an actual dyno tune? or ahand held tuner to do the job? i do have manymods to the car. heads. intake. cam. exhaust without cats.

AdderMk2

no such thing

jonalman

no such thing as what?

samseed101

What's your full list of mods? Also, what else do you plan on doing? If you're pretty much done, then I'd get a dyno tune. Either have someone do it for you and burn a chip or tune it yourself with a Tweecer / PMS. But with an H/C/I , larger injectors, MAF, etc... then it's probably time for a tune.

I only suggest going to the dyno to do it because it's MUCH safr than trying to mess with it on the streets. You can do some of the tuning yourself without making WOT runs and without a wideband, but it will only really let you tune closed loop. You will eventually need a wideband controller and something that will let you hit WOT to redline.

jonalman

thanks, that makes a lot of sense. i do believe that i am just about done with engine mods. and i was afraid about doing the tuning myself, i thinka dyno tune would be good for me.

samseed101

If you're not comfortable doing it yourself, then take it to a pro and have them do it on a dyno for you. At the very least you'll want them to adjust your injector slopes, offset, breakpoint, and MAF transfer. Wouldn't hurt to mess around with the spark and fuel tables too if they have the time and you have the money.

jonalman

sounds good to me. thanks for your help