This advice from HS can save alot of time. I was too focused on each cell when I started tuning, vac/rpm/bpw/afr, Bob showed me exactly what HS described which is to use the graphs to make smooth changes to multiple cells. Other than that, there were a few initial hours in the boat using the laptop to make changes. Once I got the hang of it, as Arctic has said, to make changes in the garage or to have multiple test tunes ready was much easier.
Starting with a tune that is close shouldn't be a problem. Bob will council you not to touch 90% of the tables.

I'm coming in way late here, but just ran across it. To address your questions:

1. While an O2 sensor must be present during tuning, you can remove it once you are happy with the tune and turn off the AutoTune feature. It will then run in open loop with the adjusted tune you created.

2. If the O2 sensor fails, the AutoTune will stop running and adjusting, but any trims already created will still be active.

If you are considering the possibility of running a CMD Marine unit in the future, you may consider our Wideband2 device to monitor you air/fuel ratios. The Wideband2 device has 4 gauge options which will show you your air/fuel ratios, or you can connect our LCD-200 touchscreen device that has logging capability. With the LCD-200 and a 1gb SD card, you can record up to 186 hours of data from the wideband device. The Wideband2 also has a digital input for seeing RPM and an analog input for one 0-5v signal (I'd suggest MAP, as that is likely what you will tune by later). This gives you the ability to log air/fuel ratio with RPM and MAP pressure for graphing ease.

If you decide to add the CMD Marine unit later, just connect the Wideband2 to the CMD Marine unit using a CAN to CAN connection cable (#76950145) and then you can enable the AutoTune feature with the hardware you already have.

Just a note here, in the MAP vs RPM table in the CMD Marine unit, the pressure value break points are user defined and allowed up to 51 break points (every 0.1v from 0 to 5v if you so choose).

Some days later, im on the same point to order mefiburn. Something new in this projekt ?

I haven't been on this site for quite some time, curious why all the misinformation. The mefi 3 and 4 can be programmed real-time without stopping and shutting down the engine. The mefi 4 can run closed loop wide band. I had pondered a couple of years ago to write a strategy for internal self-tune but I really don't need it and got bored with the concept. Mefi1,2 require a shutdown for a few seconds then takes a few seconds to download changes.

Neither have much resolution but will still work in plenty of applications. Mefi1 can't do boost, mefi2 can do boost although just as archaic as mefi3 as just a multiplier based on boost xy and not rpm/kpa xyz like a mefi4. Sheesh, never understood the bashing of mefi computers. The mefi1 first showed in boats in 93 but is almost identical strategy code wise to an 87 chev truck computer with the addition of EEPROM. The mefi4 can do almost anything the aftermarket would want. I've done 1500hp blown marine with it years and years ago. It can run 8 coils, just about any crank/cam trigger you want including a std gm distributor. I generally use it with 60-2 crank and 4x cam and dual knock sensors so the ecu can retard ONLY the cylinder that is knocking. The only real downfall of the mefi4 is it doesn't have the capacity to do sequential fuel. The mefi5,6 does.

It seems alot of people don't know the huge power a mefi controller has. example mefi4b, 8 coil drivers/sequential spark, boost tables to 200kpa(~15lbs) adjustable to 9000rpm fuel and spark, dual fuel available, accurate and complete knock control programmable to allow at what point you want to enrich to aid in controlling runaway detonation. Fuel pressure monitoring to enrich in case you are starting to clog a fuel filter or lose a pump and programmable limp mode so you can look at datalog or gauges to see. Oil pressure vs rpm safety similar to fuel pressure settings. EGT, etc etc.

Anyway, sorry to bore y'all.

I'll ask this again. Anyone near Milwaukee have experience with this program?

I'm getting ready for my winter project. I plan on ordering the MefiBurn software. My ? is about the O2 bings. I contacted CMI about welding the bings in the tails. Do I need bings in all 4 tails? Do I need just 1 O2 setup and after I tune 1 engine put O2 in other engine? I plan on using live and then closed.

I would do 1 per engine, trick is to get them to live...much talk about that...we killed 3 in 2 hours run time...just the exhaust system/cam combo and revision...get it tuned then remove them...

any news? you give up or have a success story to tell?

4bus....any updates on your experience with Mefiburn?

Yes.

I have now the the MefiBurn Software and Hardware.

Very Cool and simpel to work with it.

MefiBurn load the Files from the ECM to the PC. 10sec.
TunerPro modify the Files.
MefiBurn load the Files from PC to the ECM. 10sec.

ScanPro are like Diacom not for twin, but the display for singel are bigger and nicer.


I have used it on my twin 502EFI from 1993.

I modifyed only the Spark and the Fule Tabel upper end.
I have no Dyno in Germany, so i modifyed only the tabel over 4600 RPM. The rest of the fuel tabel are stock.
And i reduced all the lower RPM high spark advance 40+ to only 35*.
The total Spark are now higher than stock.

Boat runs 9kmh faster now.

Im happy with this small changes in the software, and the big changes in speed.


This are my best performance upgrade for the $.

Um.....yes! One of the best investments I have made to date.

I agree with every thing MikeScarab28 has stated, plus I would add the support from Bob is simply amazing. He was on the phone with me for an hour on a Saturday morning.

The software is easy to use, uploads fast IMO.

I got my AFRs in check for idle and no boost cruising, 13 at idle mid 12s cruising. I am still rich under boost running high 10s (stock). I know she has more, but time is a factor. Really should get my cruising in the high 12s and boost up in the 11s.

After playing with the cold start enrichment I simply wiped it out.....yep, wiped out! Starts perfect, runs great and doesn't turn the transom black or load up as it did stock. It still amazes me how rich this tune was from merc, dangerously rich IMO

I lost my o2 sensor last year leaving it in the boat in the water, maybe moisture. I never touched the tuning since that, but I am ready to go again. Waiting for slightly warmer temps to start

Quick ?....Was your Mefi3 locked? If it was does the software unlock it?

My MEFi3 was stock and locked with the merc code, MEFIburn provided the code to unlock. He also has the stock files if your ecm has been modified and locked with a unique code from the tuner. Basically just wipe it and start from stock as the only option if the tuner has locked the ecm.

By quick I meant uploads took seconds after files were modified. You can not write live unlike some aftermarket systems. Fastest tune would be a system that referenced an 02 and makes adjustments on the fly, like what haxby was recommending.

I had a stock tune to work from, the engines have been modified but not re-engineered completely. If I was building from scratch, or after huge power I would have went with a system like haxby suggested.

Great info 4bus...I changed the blowers out to Dyers 8-71's. Everything else is stock. I went up to 32 pitch props and hitting the ref limiter. I want to change the rev limit and also I want to use 120 degree thermostats. I will give Bob a call this morning and order. Thanks for all the useful info. Next winter I plan to change cam's to roller like yours and I might be getting with you as how you like your setup.

I think you are safe to spin those stock cams up to 5500 rpm and still make power. How old are your valve springs?

You have may have to change the bpw vs ect enrichment table slightly with the colder stats, I had to lean mine out a little. At 130 ect my afrs were in the low 11s no boost.

Can't say enough about the full roller conversion and upgraded cams, peace of mind full roller, and more air in/out is always a good thing. The stock merc cam is very conservative The sound at idle is noticeably more healthy next to a stock 575sci.

Talked to Bob this morning and ordered. Let the fun begin......:fear:

Get some o2 bungs welded in the exhaust, and buy a good wide band afr.

Ive been lurking on this thread 4bus and decided to buy MEFIburn a few weeks ago.I have an interesting project a 1968 vdrive flatbottom with a Mercruiser 7.4 MPI MEFI3. Bob helped me out unlocking it as well i was suprised to see only 13-15 degrees of timing at WOT and i hooked my LC1 wideband up was playing around in the driveway with water hooked up no water going through headers my AFR at startup was 17:1 for a good 20 sec before it trimmed down to 14:1 or so Did you zero out the cold choke tables??

I am testing out new version of Datamaster for MEFI3 pm me if you wanna check it out.

Does the software tell you what optimal setting are for each table? If not where can I find the info to educate myself?

I have 2 poker runs in June and after that I will send my tails to CMI to weld in the bings. On second thoughts I'll call them this morning to see what their turn around time frame is. 4bus where did you weld your bings at?

I did zero out, but you are lean on the choke side...I would add. 17:1 is crazy lean for cold. Mine would run in the low 10s with the stock "choke" table. Without the cold table it still starts in the high 11s and ect vs bpw leans it out as it warms up to 130, at 130 it idles at 13.5:1 afr

??

The software tells you nothing, basically. You need an AFR for a "target". Basically go out and record a movie on scanner pro using the software, at the same time run an afr either recording or have someone take notes. Key marks should be as follows-

AFR Readings-

Cold start up-
Warm idle, cleaned out-
Cruise no boost, 3000 rpm
" " 3250
"" 3500

Then hit some boost points as well, 4000, 4500, 5000 WOT. You need to sustain each rpm range for a short period of time and let the AFR stabilize.


After you have all that info Bob will help you make changes. The software does have the ability to reset the curve after a spot change is made, which is great. Make sure you save current file before you make a change. I keep all mine in folder dated, with what changes I made. I also have different tunes for the different sides, that may be overkill for you.

You need to go back out with the afr after a change is made. The computer compensates off the coolant vs bpw table. Example, the boost table is simply a multiplier based on the coolant vs bpw number. So you will see numbers (example) 1 psi may show up as 1.05 on the table. Meaning it is the base fuel (1.xx) plus the additional based on the boost (x.05). the same is done across the board for all, including the choke.

Just make sure you look at the afr before and after, it is key.

The stock spark table should be ok, I wouldn't mess with it unless you have a specific issue you are trying to address.

I have my rev limit set at 5850 /5950 it is two stage. Make the lower number your rev limit. With your cam I would set it at 5600/5700 and prop it to run 5500 cool weather

If you have hanging IAC issues you can mechanically adjust down watching the IAC count on the software, slick. I have mine set at 15 and no longer have hanging idle issues.

4bus, what i want to do first is set the rev higher to 5600. Also I want to use a 120 thermostat. Your right I always get the hanging IAC and have to turn off and restart to bring the idle down on the port motor. I might be asking you a few more questions after I get the software Friday.

Getting the IAC count to between 0-10 should be done first. This is typically a mechanical throttle blade adjustment unless you are extremely rich at idle which can cause the IAC to cycle wildly.

Any competent welder that can stitch stainless can do this, it's very simple.

For what it's worth, I'm pretty handy with mefiburn myself.

I had mine welded local by the best welder I know, he is an artist. Blew the hole with a plasma, welded in and out without peening down metal, then polished. Looks factory.

I agree no reason to send to cmi, however make sure you have a good clean welder. Leaks in the wron spot can cause reversion or loss of 02 sensors, or both. Bungs should be in 10 or 2 o'clock position and have welded on the hot side (cyl 1,3,5,7) tuning from the even bank can cause lean conditions on the odd bank side in a bbc

Thanks for the info. I do know a welder that does SS and he has done work for me before. Do you happen a photo of your bings? I just got off the phone with Bob and he asked me to send him my .bin files. Both of my were locked but he was able to unlock them. Have not changed anything yet.....too scared...

We call them "bungs" around here :D

I don't have any pics, but I will take some next time I think of it.

The only change you should be making rev limit without an afr. You can also wipe out the cold start, it is not needed on that engine, trust me. So much better without it. There is a fuel purge table that shoots fuel out of the injectors based on ect at key on, leave that alone.

I am sure bob won't let you with out and afr, but do not make any changes to fuel bpw without one, especially with the extra air you have coming out of those 871s

Troper - Pm your email address - I'll send you some pics of bungs welded into Stainless Marine risers.

PM sent...thanks

I decided to get the bungs welded local. What does everyone thing of these bungs...correct ones?

http://www.ebay.com/itm/4-Stainless-...-/370380542321

Those will work, you do not need 4 however, just do the 1,3,5,7 bank side.

When they come go to an auto parts store and ask for an 18mm copper gasket for a Honda car drain plug, use that gasket to seal the 02 bung when plug is installed.

I figured for the price it was cheaper to get 4. Hardin wants $85. each.....

Do you have a wideband, Troper? I use a Fast dual sensor unit. Would be willing to help you tune a bit as I'm not too far away, if you're interested.

Absolutely would like some help and some schooling. I do not have a wideband sensor unit, I was going to have to buy one, but if I can drag the boat over to you I'd rather use that money to pay you....

Take him up on this offer. It is not hard once you know, but the learning curve take a lot of time....and fuel :D I would have saved about 5-10hrs having someone with experience by my side during the learning process. Bob is great, but the phone only goes so far. Great offer IMO

I'm just PM him with my phone#. I think this is a good route to learn.

OK did my first cal change this morning....kind of nerve racking. Bob helped me setup my rev limit to 5500rpm's. I had to unlock the Mefi 3's and then download the .bin files. Cleared the computers and reloaded with the new .bin. I will test it out this afternoon on the lake....

My rev limit was set at 5800 with stock cam/valvle train and I never had an issue @~9.5 boost, 120 tstat, whipple cooler. Just throwing it out there as my cat went faster even though HP may have been falling off. This also lets you keep lower prop pitch for getting out of the hole.

OK. Im right about to start this DIY myself. I have the Mefi burn software, welded bungs in both risers.

What is the most cost effective AFR setup to buy ? Do I need a dual channel and run dual o2's or just one on the 1,3,5,7 side ?