HaxbySpeed

Yes, auto tune is your friend. Then turn off auto tune and closed loop function and run open loop with the new map the CMD created.

HaxbySpeed

It's not actually a Merc computer, it's an antique GM unit that is extremely limited when compared to modern aftermarket EFI ststems. If you don't mind driving around with a note pad and a laptop, looking at 2 different screens, then stopping, downloading, and then waiting 5+ minutes for your changes to upload and then repeating... Then it's not a bad deal. It is fairly easy though because the system has such limited resolution there isn't much fine tuning. Just be careful when you start the wot tuning. I'd start conservative on the timing in case you're a little lean. Also, sometimes it's easier and more intuitive to tune with the graph instead of the cells. Make a percentage change on one cell that you know needs to be adjusted and then go to the graph and try to blend everything around that peak, or valley. Once you get started you'll get lots of help here. Shoot Articfriends a PM, or ask him to post here. He's got a ton of good MEFI tuning info and experience.

abmotorman

Next winter i'm plan on pulling my motors to port heads, bigger cams...general refresh. Unless the stock tune is extremely rich I will need to adjust fuel i'm sure. In preparation, this summer I plan on capturing A/F data using some type of wide band setup??? I'd prefer to have something that gives me gauges for the dash, way to record an hour of events and maybe compatible with someones autotune function like Dynojet's. The graph tuning is something I prefer. Question, does anyone know of a A/F system that will give me the gauge, recording and compatibility I desire. The first 2 are probably more important since the MEFburn really doesn't scare me that much.

4bus

iTrader: (4)

I'm confused. I was under the impression that the CMD system simply read A/F and adjusted the injector pulse width at the injector. This is the email I got from Keith after I asked about my engine last fall

Hello Ron. While I haven’t specifically tested a 575SCi, the beauty of our system is that it’s basically universal. As long as we know what injector connector is on the injectors, and know the polarity of them, then we can figure out which of our units will fit and work on the engine. We have several units available for other applications, but unfortunately, the 575SCi was a relatively short run engine platform from what I can find, which is why we don’t already have a plug-and-play solution lined up for it. However, it’s likely that we already have something that will work!



It’s my understanding that the 575SCi uses dual throttle bodies with two fuel injectors per throttle body. The electrical connectors for these may be the same EV1 injector connector as used in the CMDM-5011 application for the spread-port big block applications.



Are you familiar with the throttle bodies? If you look at this diagram from mercruiserparts.com, you can see the throttle bodies and the injectors down the center of the throttle bores, and the wiring harness that connects them to the throttle bodies. http://www.mercruiserparts.com/images/COMMON/10543.png



If you have access to your engine, can you locate these plugs and take a picture of the plug, then unplug one of them and take a picture of the inside of the plug on the harness, and then the connector that it plugs into on the throttle body? This would enable us to determine if it’s a connector we already have in stock. Once we determine that, we’ll know if we can make a harness to fit that engine.



Keith Lockliear

Technical Support Manager

Dynamometer & Performance Products

Dynojet Research Inc

Free: (800)992-3525

Fax: (702)399-6385

4bus

iTrader: (4)

I do understand that! I did search for a couple of MEFI4B's over the winter so that I could have the live write info, however the only ones I found were quite pricey and had an unknown history. Honestly, I also don't want to change too much at once. As tedious as the burning may be, at least I know what is there works.

I plan to data log the afr on the same computer, hopefully there is some kind of time line in the software that will allow me to align the files relatively close. I do know that if I have fast throttle transition, or idle shifting issues that my antiquated ECM will become a major pain. However, the bulk of the tuning will be steady rpm. I also will have step files to fall back on.

I am going to see if I can get articfriends to chime in thanks for the lead.

Steve H

I finally got the boat out for the first time with the Holley HP system and could not be happier. After an hour or so of running at various speeds and configurations: fast cruise, slow cruise, heavy accel, light accel, drives and tabs up, or down, etc. etc. I am relatively confident that it is 95% tuned.
I did not have to stop the boat to up load or down load, no notebooks to track AFRs vs RPMs. No guessing the amount of change needed for the values in cell on a map grid. Then load modified tune to other engine and double check it with the innovate meter. Just drive the boat and watch the system do its thing on my laptop. I was just an observer!
I purchased the HP system from Alex Haxby, with his knowledge and experiance we had my engines up and running after about five or ten minutes on the phone (thanks Alex).


If my positive experiance continues, I can not imagine any reason to mess around with the MEFI Burn.


Steve

HaxbySpeed

I've got a bunch of MEFI boxes I've replaced. I'm sure I've got a couple 4b's kicking around you could have if you want. I'll dig them out if you're interested?

4bus

iTrader: (4)

absolutely!

Funny thing is 575advantage has a tune for this exact engine and cam setup, however it was done on a 4b so it cant be used on my 3.

You would be a life saver, let me know what you find.

onesickpantera

iTrader: (1)

Hard to argue that logic IMO.

Where did you find a data logging Innovate AFR for $155???

4bus

iTrader: (4)

This one data logs

http://www.ebay.com/itm/Innovate-MTX...aac005&vxp=mtr