Reprogramming the MEFI 1 ??
 

What parameters if any can be altered on a MEFI 1?

MEFI Burn you can change almost anything in the MEFI EUU's, Whe I did a custom plenum and cam swap I used a Split Second PSC1-003 to alter the MAP signal voltage. It worked a lot better than I was expecting, I was able to get it to idle pretty good and still use the IAC to control the idle in gear.
Before altering the voltage signal the MAP was showing 2.80 volts at idle with the new cam so was super rich, I ended up at 1.7 volts which it really liked. Using a wide band lambda I was lean from 3500 up but show 4.5 volts on the scan tool, so was at the limit of the injectors. I installed larger injectors and pulled a % out of the VE table on the PSC1 and started to alter the 3500rpm up, I ended up with a WOT lambda of 12.3 to 12.50 A/R and showing 4.3 volts with the scan tool so still have a little more if needed.

So for around $300 US you can alter the fueling for any MAP controlled fuel system with surprising results.

MEFI Burn will let you alter anything you need to on a MEFI 1. There are very few tables you actually need to play with. MAP/BPW/RPM and Spark/MAP/RPM are the two of most importance. Install a wideband for AFR readings. The vast majority of the other options you don't need to touch when tuning.

Okay ,I just sent my MEFI 1 over to be altered and this is a quote of the reply i received.

Sounds like BS, a 454/502 WITH mefi1 stock has a iac in throttle body, why anyone would say it has no provision makes no sense. For injector changes, tuner would revert to the bpw tables vs rpm map. Now, mefi 1 DOES suck and makes giant rpm and map jumps in tables (poor resolution) and what that means is between certain areas and above certain rpms, there is no as adjustment so you have to richen fuel somewhere else to be safe and it ends up being rich somewhere you dont want it to be

Okay,
I sent this to who i thought was one of the leaders in doing these reprograms if i can call it that.
Where do i go from here?
Do i argue it can be done?
Have it returned to me in Australia then send it to someone else?
Who should i send it to?

I started with a 502 mpi fitted 525 intake with injectors,crane 168741 cam and CMI's.
I asked for the idle to be lifted to 750.Rev limit to 5600 and whatever else they thought necessary
given the changes i had made.

Who did you send the MEFI to?

CP.
Who should i send it to?

Where do i go from here?

needs to go to mark boos at precision marine or eddie young, id do it but i havent set up a mefi1 for a 525 intake so id only be guessing at your fuel tune, mark boos has prob done this setup

Get your MEFI back from those individuals. They do not know what they are talking about.

Rev limit increase on a MEFI 1? Super easy to do.

IAC control? Super easy do to, but this is actually a mechanical throttle blade adjustment to get the IAC count in the proper range for idle control.

Idle change? Easy.

You could try the two individuals mentioned, but Mark didn't do a lot of MEFI 1 work from my last conversation with him.

More motor specifics would help us help you.

What size injectors? What fuel pressure? What compression ratio? etc. etc. More data the better?

The MEFI 1 is MORE than capable to do what you need it to do. True it does have some fidelity limitations but splitting those hairs are transparent to the end user. In other words, you can't tell nor does your motor care if you are at 12.8 AFR and 3000 rpm or 13.3 AFR at the same RPM. On a dyno squeezing for a certain HP perhaps, in the boat, no.

most so called Pros, arent

Thats why I got all the MEFI burn stuff myself, same thing I had to do in the car world do it right myself guess Ill start doing for the boat world

Just as a note, it appears the OP is from Australia....so, shipping back and forth is more troublesome than us.

Australia is huge into performance everything, so, ,makes you wonder if there is someone that can do programming for the OP over there - live is always better.

Nobody over here doing it.
Motor is still just a basic 502 Mag MPI.
8.75 comp,502 MPI ignition and fuel system,525 injectors.Okay so I have to get it from CP to either of the 2 you mentioned.

send them (CP) a pre-paid shipping label (thru e-mail) to wherever in the states you are sending it to...or ask if they will since they can't help you.

Just sent them an email.
I know Eddie Young has been around for ages.
Is that who i contact.

k

Eddie is a straight shooter. He will let you know if he can do it or if he sees any problems. He is on OSO so shoot him a pm or email. If that doesn't work I can send you his email or telephone number.

Padraig

Ok thanks.
Doing it now.