keis

Hey just wondering if you need a remap for the ecm if installing 24lb injectors. (Car is l98 with 22lb injectors 1990 with MAP)

-keis

sofakingdom

iTrader: (1)

More than likely. You could try em and find out, not too hard to backtrack.

ULTM8Z

Couple of things...

The injectors are ~10% bigger than the originals, so you're very likely going to have the ECM trimming out a lot of fuel delivery to try to maintain 14.7:1 during normal operation.

However, during non-closed-loop operation where the ECM is just shooting in a pre-programmed amount of fuel (i.e, cold starts, power enrichment, accelerator enrichment), you're going be be running very rich.

The other thing is if these 24's are Bosch-III style, you may end up needing to get what's known as the voltage offset data for them. Injectors have a particular profile of flow vs input voltage, and there's a table in the calibration that has that curve. Different injectors will often have different curves. So the ECM needs to know this curve so it can adjust it's commanded fueling according to what it sees as the operating voltage of your car (which is basically what your alternator is putting out).

I hear that Fuel Injector Connection is now giving that data out electronically with the purchase of injectors. Might want to give them a call.

Also, are you sure you have 22lb? Those were for 350's. If the car is a 305, than it's likely 19 lb.

sofakingdom

iTrader: (1)

...

ULTM8Z

That's right... L98 =350

Vader

Technically, the ECM was designed to operate injectors for a given duration of time under given conditions. That had no direct control over the amount (volume or mass) of fuel applied. It operated solely on the assumptions of the flow rate of the original injectors and at an assumed fuel pressure, and also considered the propagation delay of that injector. The (then) Delco Electronics boys and girls allowed themselves some latitude in making the system adjustments available within the programming so that different OEM injectors could be used. No one knew if Bosch was going to be purchased by Hitachi and closed, or if Rochester was going to develop their own injectors (like Multec), or what market variables would require them to install a variety of injectors, but they could configure the system to use those and burn half a million PROM/Memcal modules to make it run without completely redesigning the system.

Fast-Forward 40 years, since the '165 was under development in 1984, we can use that latitude by reprogramming, and/or also by adjusting pressure. Keep in mind the ultimate goal of applying an appropriate mass of fuel.