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Yes, you are crazy. Our season is way too short to go down the path you are headed.
Those motors don't need much to run real good. Go with a reputable shop that has a proven cam/tune recipe that is known to perform and be reliable. Keep it simple and go boating ! |
Originally Posted by Kelly O
(Post 3884737)
Yes, you are crazy. Our season is way too short to go down the path you are headed.
Those motors don't need much to run real good. Go with a reputable shop that has a proven cam/tune recipe that is known to perform and be reliable. Keep it simple and go boating ! Wish I could have kept it simple, a scared lobe caused me to have to upgrade from flat tappet to hyd roller. The reputable shops I have talked to do not have enough confidence to say the tune will be right for this area based on my cam choice. Further tweaking will be mandatory. As I read it doesn't look to be rocket science, however a dyno would make this much much easier. The bottom line is if can not get it right I can always try one of the "canned tunes" later, First week of May is my deadline. And if that doesn't work I will bring the boat to Lake George for a prop shaft dyno tune. :D How hard can it be? :lolhit: |
Originally Posted by Trash
(Post 3884165)
Ok, you have a MEFI 3 with a stock tune but a modified 575 correct?
I believe, but am not sure but the MEFI 3 ECMs were locked by Merc with a password. I can't confirm this but you will know when and if you try to download the file using MEFIBURN. I have a MEFI 1 and it was not locked. I was able to download and save the stock tune and go from there. Made my job much easier. It is true that the AFR readings would be logged separately from what Scanner Pro logs. However you can wire and set up Scanner Pro to log AFRs as well. It takes a little extra wiring and some tweaks on ScannerPro. Not insurmountable but extra work. To date I've simply logged them separately and taken time hacks on the recording to along with a series of throttle inputs to align the playback. I also do some steady state simple paper/pen notes and that has worked well. Much of the idle and warm up can be done on the trailer with a hose attached. This is good for cold start to warm idle no load tuning. Do you know the stock motor cam specs and boost? What modifications did you do to the motor? Cam? Heads? Both? Injector mods? PM me for more details. I wish you the best of luck. Thanks for the tip on the cold start tune I do know the stock motor cam specs and boost, they are off the shelf merc 575sci. Engine mods are just hydr roller conversion, 120 degree stat from 150, boost upgrade from 4.5 stock to 6 psi, and cp performance adjustable fuel regulators. 7.5:1 stock comp, and a lower end that will support huge HP are stock and untouched. Many will tell you this engine came in need of a tune more than any other efi engine from merc. It is beyond rich, has chronic IAC issues, throttle blade issues, and the cold start table will kill a manatee. It uses 4 large injectors in a tbi setup that works much like a 4 barrel carb set up. I have been told this set up make it easier to get close, but difficult to fine tune. |
Save yourself the mailing option and have them remote in live for the extra $50! :)
---- Remote tuning We can tune your controller remotely, anywhere in the world, if you have purchased our MEFIburnTM software and you have a high speed internet connection while connected to the vehicle you want tuned. You will be able to watch your laptop's screen as the MEFI calibration parameters are changed and saved. Clear descriptions of what is being done will be explained as it is happening. Our price for remote tuning is $250 |
Originally Posted by Optimus Prime
(Post 3885110)
Save yourself the mailing option and have them remote in live for the extra $50! :)
---- Remote tuning We can tune your controller remotely, anywhere in the world, if you have purchased our MEFIburnTM software and you have a high speed internet connection while connected to the vehicle you want tuned. You will be able to watch your laptop's screen as the MEFI calibration parameters are changed and saved. Clear descriptions of what is being done will be explained as it is happening. Our price for remote tuning is $250 |
Originally Posted by Optimus Prime
(Post 3885110)
Save yourself the mailing option and have them remote in live for the extra $50! :)
---- Remote tuning We can tune your controller remotely, anywhere in the world, if you have purchased our MEFIburnTM software and you have a high speed internet connection while connected to the vehicle you want tuned. You will be able to watch your laptop's screen as the MEFI calibration parameters are changed and saved. Clear descriptions of what is being done will be explained as it is happening. Our price for remote tuning is $250 Honestly I don't know why so many make such a big deal out of fuel air metering when it comes to efi vs carb. Sooner or later we have to learn this stuff, no time better than now! |
I purchased the MEFI Burn program a few years ago. It works very well, and works exactly as advertised. However, I found it needing more tuning time and expertise than I had to give.
I recently purchased the Holley HP EFI system. Why? "Self-tune" You just set the basics, such as engine size, max timing, desired AFR etc. The 02 sensor is connected directly to the ecu (closed loop) enabling the ecu to learn the settings needed to achieve the desired afrs. After the base maps have been built by the ecu during closed loop operation, the 02 sensor can be removed and the system will operate strictly from the base maps (open loop) that it has learned. No more manually changing fuel curves or spark advance cell by cell. I'm not saying that tuning the MEFI systems is wrong, or not worth it, it just wasn't for me. I have it installed, and both engines are running but have not had it out on the water yet. I will be glad to report back as soon as I have some real data to share. Steve |
Originally Posted by 4bus
(Post 3885183)
That won't work with my mefi3 computer which doesn't accept live changes. Decent idea however.
Honestly I don't know why so many make such a big deal out of fuel air metering when it comes to efi vs carb. Sooner or later we have to learn this stuff, no time better than now! |
The best way to start is on the dyno set the brake at given rpms say 2000,2200,2400 on up to your rev limit,sweep the throttle at those rpm from zero to full watch your afr adjust as neccessary,make full throttle runs on dyno and also check your cruise speed on dyno ,when you think you got it right install engine in boat and check your afr at all speeds adjust as needed,we have done several efi projects using mefi burn and it works real well never done a 575 sci,it does require alot of time and patience
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Originally Posted by 4bus
(Post 3885052)
mefiburn.com supplies the unlock passwords
Thanks for the tip on the cold start tune I do know the stock motor cam specs and boost, they are off the shelf merc 575sci. Engine mods are just hydr roller conversion, 120 degree stat from 150, boost upgrade from 4.5 stock to 6 psi, and cp performance adjustable fuel regulators. 7.5:1 stock comp, and a lower end that will support huge HP are stock and untouched. Many will tell you this engine came in need of a tune more than any other efi engine from merc. It is beyond rich, has chronic IAC issues, throttle blade issues, and the cold start table will kill a manatee. It uses 4 large injectors in a tbi setup that works much like a 4 barrel carb set up. I have been told this set up make it easier to get close, but difficult to fine tune. You can still data log even on a locked ECM. You just can't save or change the .bin file without zeroing out the controller. You don't want to do that. Building a tune from scratch would be a PITA. From my limited experience extremely rich idle conditions will cause the IAC to surge. I nearly doubled my injector size and prior to trimming out fuel the IAC was surging full tilt from open to closed trying to keep the idle under control. Motor sounded cool but it was completely impractical. Trimming your idle and cold start fuel values "may" help the IAC issues. |
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