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.

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.

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.

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

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.

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

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?

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.

Hard to argue that logic IMO.

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

This one data logs

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

Ahhh, I didn't realize their in-dash gauges also had data logging capability. I was looking at their handhelds.

Yep, it's relatively new, and has basically eliminated the lc-1 for most applications. And at this price even carb guys should have an AFR IMO. Great tuning tool.

I plan on putting a gauge holder right in between the hatches so they can be cracked to read the gauge for now. I need to keep it in the engine bay so I can log at the same time with the ecu software. I may get the extension cable and install twin sensors later, just need to find a place for them on my already cluttered dash.

I am heading out of town in a few minutes but I will post a few things and be back on here in a couple of days
1.Mefi3 to 4b-Bob at mefi burn will convert the programs for just a few dollars IF yu have a base program in 4b that you need.
2. Converting your motor from mefi3 to 4 or 4b ECU using your original harness, GM motorsports sells a adater harness that is plug and play, Tyler Crockett told me when I did mine that its easy to just repin, the problem we had was there were wires that did NOT show on the diagram, he couldn't figure it out either and I ended up with a butchered up mefi3 harness and buying a mefi 4 harness that did NOT fit right on, even more adapting.
3, IF you were starting from scratch, if I was starting from scratch and had to buy EVERYTHING including a ECU and harness, I would buy something ELSE with autotune. 2 years ago I converted a 600 hp PONTIAC to mefi 4a rail injection, scorpion throttle body. The harness and ECU can be had new from GM motorsports for only 620$, a STEAL BUT in retrospect when I add up the money I DIDN'T earn being at my own shop and the money I paid the dyno operator in the end I could have bought TWO or THREE auto tune ECUS and harnesses, but you learn , what can I say!
4. IF I was the OP and already owned a mefi3 boat with good harnesses, had the patience to tune , drive, record, tune, upload, drive etc I would probably buy the mefiburn again and do it myself. IF you don't have someone competent to help you, take notes, or drive while your doing it you are a better man than me IF you plan on doing it in the boat SOLO, I had my son who is one of the best wrenches I know (I TAUGHT him:evilb:) who ran keyboard, took notes while I drove when we did my boat , we would stop and I would calculate. I will say though TYLER CROCKETT dynoed the motor and set the original program for us, we just fine tuned it on the water. I would have actually had no problem paying him to tune it on the water BUT I had serious time constraints and its about impossible for me to spend a day during week in his neighborhood tuning. We did mine a little at a time. Mefiburn is a GREAT tool for self tuners, however, the program Crockett has uses something else called "slew" and he was able to change fuel PW while under a load and see what it did to the afr's and THEN stop and make changes where mefi burn users have to watch the afr meter, record, stop,calculate changes, upload, test drive and repeatIt is DEFINATELY time consuming
I will post more when I have time, Smitty

Perfect

My responsible side says: Pick a programmer, run his program with A/F bungs. Send it back with your data, get it updated and you are done. To properly do this, it is a 2-3 man job. Running down a lake/body of water at max speed with a laptop and wires strewn across the back seat isnt as fun or easy as it sounds. I've had the A/F laptop in the back seat a dozen times and you really arent cruising around, the bulk of the benefit & programming is at WOT so all you do is run around bare knuckeled for hours on end. 5500 RPM isnt the time or place for "trying out" your new software either.

My mad scientist side says: If you do it... make yourself a nice harness neatly taped where all the wires connect (Sensor, RPM, Battery leads, reset button) keeping them safe with a way to neatly pin the wires away from the belts & such. Also, long enough to run to the laptop on the floor where the laptop can be secured to something. I cant tell you how many runs I made and lost data because the freakin wires were flapping around at 85 MPH and the A/F had gaps due to the USB flopping around in the computer. Depending on the cam & where the A/F is placed you will get some moisture (not reversion) this pisses the A/F bung off (Innovate/Bosh Style) so, there isnt any fooling around idleing around. Start it and go! Just a few observations of wasted weekends playing with A/F....

fixx
 

Been using the Innovate data logging feature on the snowmobiles for a few years not so i dont think its that new..

This post may have changed my mind completely! You just painted quite a horror story for me. Maybe it is a better idea to go with a canned tune?

Remember, you don't HAVE to tune on the boat. You can log data from the AFR and then go back home, to the dock, etc to make the changes. Done in minutes instead of waiting days, weeks, etc for your MEFI to come back. Just a thought.

Thanks.

I've chilled out a little since then, I read and responded at 12am EST. I'm still going for it, my curiosity must be cured.

The locals are even more skeptical, a few so called "experts" have attempted tunes and failed. One guy convinced a friend to convert his 555cu ci 500EFIs to carb! :eekdrop:

I do want my boat to run, but I also want to know what the big deal is? Maybe I can help others in the future.

Don't let all the opinions get to you. If you're interested in learning how to tune, how to get your boat running to YOUR satisfaction, and having the ability to say "I did this myself!" then go for it. I can tell you first hand.... it may be a bit intimidating at first but it can be done and the satisfaction in the end is well worth it, IMHO. I upgraded to a mefi4a in 2010, went the mefiburn route and am still fiddling with it a here and there. I'm not sure why some believe it should be "one and done." I learn something each and every time and for me, is why I do it. To each their own I suppose.

Go out and get an A/F program, get bungs welded in (pain in the a$$) and get yourself the data. Its nice to be able to see where your A/F data is all thru the RPM range. Then, after a dozen WOT runs make the call if its worth buying the programming software. The whole software kit thru Innovate is $299 http://www.innovatemotorsports.com/products/kits.php
All you do after you get the data is convert the graph to CSV in Excel and you have A/F data by the second at every RPM range.

...maybe you dont need changes.

I already did the bungs, and purchased the innovate mtx-l with data logging but haven't played with it yet.

My stock tune is safe, however it is prob the worst tune that merc has ever put out.....correct that, it is. The cold start tune is so rich it instantly blackens anything around it. Many know the 575 came way off from stock. And I do need the burn software to at the very least change the rev limit to 6k


My plan from the start is to change the cold start on the hose, raise the rev to 6k then start datalogging. Very good chance it will still be a little rich with the stock tune across the rest of the range, which I am ok with. It was safe stock, but not so rich that I was getting wash or deposits.

I will share my data collection with screen prints on here and with Bob from mefi burn, and take all your advice.

I am not trying to squeeze every last pony out if this engine with a tune, I am trying to clean it up and insure it is safe

-Been following this tread with great interest as I've got a few upgrades in mind also.

FWIW, when my 575SCI's were upgraded a few years back, the mods we did were flat top pistons, minor port, custom ground hyd roller cams very similar to the 525EFI, Whipple intercoolers and smaller pulleys (6.5lbs @ 5600)

The ecu's were sent to AZ Speed & Marine for re-cal and rev limiters bumped to 5600. Fortunately, they nailed it on the first try, the boat runs fantastic, much cleaner than a stock 575SCI, no soot on the transom at all. -In fact, been running the same plugs for 3 seasons...

I've just recently received a new pair of TBS billet blowers and thinking hard of upgrading the outdated throttle bodies to the new FAST four barrel dual 4150 style four barrel TB's. AZ Speed offers a complete kit to convert the old system, retaining the MEFI 3. At what point do you can the antiquated MEFI system and start fresh with an entirely new system??

-Here's a shot of the AZ Speed kit.

http://i817.photobucket.com/albums/z...ps2545a962.jpg

Wow that is sexy :D

What size TBS? Have you seen the threads with guys converting to 8-71?

Did you find my pulleys yet? :lolhit:

I still run the same AFR unit as you, the MTX-L. Works great.

Since you have a tune that works but isn't optimized you are in great shape. Start simple and in the idle range as you stated. Keep the changes small and make them one at a time. In other words don't make a bunch of changes to the timing table, coolant vs bpw and MAP/BPW table all at the same time.

Often times the rpm/MAP points lie in between 2-4 cells on the table. In this case you may need to adjust the 4 cells appropriately to get the desired results.

I've done what you are going to do so feel free to PM me.

Does anybody know why the MEFI 3s and 4's take so long to load? The MEFI 1 takes about 2-3 seconds max.

Great advice, and thank you.

I have some options for dropping the stock thermo down. It runs at 150 factory, I can get 140, 130 and 120. A few tuners I talked to run the 120 for best charge no chiller. Is this 30 degree drop going to cause a tuning nightmare? Or should I choose a higher temp like 130 or 140?

I here the mefi4b loads fast as well. I am not that concerned with loading time...I have lots of time :D

It was mentioned earlier, why not use an automotive ECU that you can buy at any junk yard for $85 and program it with HP Tuners? I already have HP Tuners software for my cars and trucks. The ECUs are more than capable, and dirt cheap. There are several companies that make harnesses for them to fit any application. I was toying with the MEGA Squirt idea, but then I needed the HP Tuner software anyway, so why not use it for the boat also? It doesn't support self tune or live tuning, but the data logging is decent.

My sentiments exactly. I love doing it even when I scratch my head at times.

It will not cause a tuning nightmare. Adjust the coolant temp vs. bpw table or equivalent so that the multiplier is 1.0 at your thermostatic temperature. Any tabulated temp below your thermostat temp should have a multiplier greater than 1.0. The table is in Celsius so you have to do a little math.

Do your initial BPW/MAP changes with the motor up to operating temperature. Then adjust the coolant temp vs. BPW multiplier table to adjust for cold start/warm up enrichment (akin to a choke). That's how I did it, others may have more eloquent methods.

It will not cause a tuning nightmare. Adjust the coolant temp vs. bpw table or equivalent so that the multiplier is 1.0 at your thermostatic temperature. Any tabulated temp below your thermostat temp should have a multiplier greater than 1.0. The table is in Celsius so you have to do a little math.

Do your initial BPW/MAP changes with the motor up to operating temperature. Then adjust the coolant temp vs. BPW multiplier table to adjust for cold start/warm up enrichment (akin to a choke). That's how I did it, others may have more eloquent methods.

I forgot about this thread, posted real quick while waiting to leave to go snowmobiling. It sounds like what the OP wants to do will be pretty straight forward. Last year Onesickpantera had his motor freshened, a little bit of porting, he installed 02 bungs in his exhaust. His hp 500 tune was close but not quite perfect, he drove around and wrote down his afr's and vacuum readings at various rpm's, texted me and emailed me the info-ie- 4400 rpm's-3 "vacuum/14.2 afr. I took all his readings and converted the vacuum to MAP (vacuum x 3.333), graphed out where his afr's were and needed to be,lets say he wanted to be at 13.0 and was at 14.2, I then divided 13 by 14.2 and got 91.5%, 3" vacuum= 9.99 , 100 map minus 9.99 puts you right at 90 map table,lets say his pw was 5 ms at 4400 in 90 map box, I then took 5ms x .915=4.575, I would round it UP slightly to account for deadband to lets say 4.6 ms. We straightened out his rich idle, a stumble he had off idle, a fuel tuning booboo in his tables down low that had been that way for ever. During initial testing boat went lean from 3800 up progressively worse which validated that his porting actually did something. When he started I copied down a un-molested version of his tune and then modified a COPY , loaded it on a spare mefi3 I had laying around and sent them back and forth making slight tuning changes. In the end his boat ran clean, rpm's higher and had good looking afr's all the way up and down the rpm range. I think it was FASTER and EASIER for me to do the tuning sitting at my desk at home then if I had been on his boat because the stress of bouncing around trying to make changes/calulations was removed from the equation and Scott simply drove his boat and jotted down a few quick notes and AVOIDED sustained running in the 4000 rpm up range at first because it was pretty lean, I think we swapped ecus back and forth 3 times plus the first time of him initially sending it to me to raise the rev limiter and copy it. When I tune my boat again I plan on taking some readings then going and parking while I make changes like I did for Scotts. Something else I did while dynoing the Pontiac that I mentioned earlier is I would modify/write several tunes ahead of time while sitting around at night to try on the dyno the next day so the MONEY clock wasn't running as much while I decided what to change next, instead I could keep uploading tunes until I reached the point where I needed to do specific modifications to tunes that I had tried. Tuning can be fun if you can take the stress out of it, and like I mentioned before, if I already owned something with MEFI I wouldn't go out of my way to change it at great exspense just to have autotune, I would just buy mefiburn and tune it IF you are mechanically saavy. On the other hand, I would NOT go buy another mefi harness and ecu and build sonething around it especially of you are going to be tuning something that is a MILE from a existing tune, Smitty

On my duramax I set the ECM up with what efi live calls "dsp5" and I would right 5 tunes each slightly different when I was doing the initial tuning. That way I had 5 different tunes ready to go on the fly with notes of what was different in each one.

Smitty, if he was lean at 14.2 and wanted to target 13.0 then you wouldn't decrease the BPW from your example of 5ms to 4.6ms, but rather increase the bpw? I believe you made a simple clerical mistake in your post but wanted to make sure I'm not out to lunch.:ernaehrung004:

I think you would add about 9% to the bpw in your example (5.45ms) to target 13.0.

Your exactly right, was tired when I wrote that and thinking backwards!!

No worries, I've made those types of mistakes too often.....I was scratching my head doing the math thinking what trick has this Smitty come up with here!?:ernaehrung004:

http://mefituning.com/contact
Ben probably has a tune for you.

Is that for me? I don't want a canned tune :D

Didn't you tune your own boat with the help from Bob at mefiburn? Anything you want to share? Did you have a thread going?

I'm gonna order the software later today, should be able to start tuning soon

Yes, for you. Call Ben. He can help. Bob knows Ben because we were one of the 1st to use Bob's stuff so there is some knowledge there.

4bus, as Smitty said he helped me with mine last year. You're doing something similar by starting with a "close' stock tune so I think you'll be okay. If you were starting from scratch that would be a different story.

Thank you for the words of encouragement! The software will be here Friday. Looking forward to getting started