Reckless32

Not that I'm going to, but I'm curious should I ever have it done or come across someone who wants to do it. Also, what's the ballpark expense?...

Goodfella

First off we need to know what engine you have. We have seen approx a 3 mph gain with remapping the ecm raising fuel psi and running a K&N filter on a 502 MPI Arizona Speed and Marine is a good company to do this modification.

99baja342

Goodfella
Recently I have added EMI exhaust, K&N filter, and Crane Cam's Ignition box on my 502 EFI's. Why would I need to remap the ecm and raise fuel psi?

BillR

Good question:

Reckless & I have 496 HO's. They have the 555 ECU.

Bayley

I've talked many people, a number of times, about re-programming ECU's for various conditions. What sucks about all these ECU's, is that they are speed density, open loop operation. They work fine at WOT, but driveability often suffers.

Hey, it's marine... who cares about economy, right? The other down side is a sooty transom whenever the ECU is recalibrated for more power (i.e. large displacement, blower, etc.)

The new 496 motors are an even bigger monster. There is a lot more computing that is involved with this processor (32 bit vs. older Merc EFI 16 bit systems, I think). I've been trying to find anyone with leads on the source code or calibration files for either one of these two processors for a long time now and have had zero luck. You definitely need to know somebody on the inside.

Back to the Original question;
I know Tyler Crockett has been checking some new calibration tables for the 496 series. Not sure if he comes up with the table values, or our sources that work and just tests the results. Either way, he could help you out. Also, I know AS&M has been looking in these processors, as well as the boys at Whipple.

Good Luck

Goodfella

99Baja342,
Always remember Mercruiser builds and sets there engines
up VERY VERY FAT! fuel wise. Thats why
you see a noticeble gain when you remap and also get rid of the sooty transom Contact the people at Arizona Speed and Marine.

crmax

if they are set up rich to start with wouldnt they get a little leaner with any intake or exhaust changes?