merc mefi 3 question
 

Anyone know who can remap mefi 3 computer?

Thanks

to a stock tune or custom application ??

Need custom tune,mild cam put in and lower vacuum is screwing up idle.

try Jim at Ozaek Speed and Marine,

Just having an issue with your idle? Whats happening? Tuning the idle can be a pain in them, I went through a bunch of **** setting my idle up. And that has to be done in the boat

Mark Boos @ Precision Marine or Dustin Whipple if you try and do it by mail. You would be better off if you could find someone that could tune it on the engine and in the boat.

Can't tune idle unless they have the engine or boat. I bought tuning software and tuned the idle myself with direction from Bob Radke. Bob did my actual tune, but you have to see what the motor is doing at idle to see what corrections need to be made to make it idle right. You have to sync your throttle blade percentage with your tps voltage, and you have to adjust your butterflys to get your IAC counts in the correct range. When we installed my 502mag mpi in my old boat we had to completely redo the idle cause of how the map was vs where the new motor wanted to idle with the cam etc... Its not really that difficult, time consuming yes, and have to have a general understanding of what does what. Great example is if the idle is set to 700 in the ecm and you have the butterflys open to say have it at 800 it will hunt around to find 700rpms buy taking timing away, adding timing, etc..If you tell me what exactly its doing I may be able to help, and also if you have a scan tool you take IAC, TPS voltage, and TPS blade percentage reading as well to see what they are doing.

Thanks for the response
Have a running rich and hunting at idle problem only
after lots of time determined that map sensor voltage is too high due to lower vacuum at idle
also injector pulse with is higher at idle dumping more fuel, believed to be caused by the map sensor.
If i remove the map sensor and supply 15'' of vac. it idles perfect at 600.

What is your water temp sensor reading? and what is your fuel enrichment set at? Fuel enrichment is like a choke, so what it does is say it is programmed to run a thermostat, your fuel enrichment may be set at like 40C, and its a graduated scale. Your map sensor is the main component that your ecu determines what to do, all the other things like throttle percentage, water temp sensor, etc... make small changes. What LSA is the cam ground on?

I will be the black sheep here but I found idle to be the easiest to tune. Assuming you didn't make changes to linkage, sensors etc and have base timing set change the BPW to get the AFRs in line. Once that is done see what the IAC count is. If you have a two stage throttle body getting the IAC dialed in is cake. I adjusted the second stage about 1/8th turn and it brought the count down. The second stage doesn't affect the TPS sensor so no calibration or tweaking is required. The big CAVEAT is that you have a two stage throttle body with independent adjustment of both stages. Change ONE variable at a time.

I wouldn't touch the fuel enrichment table at first since its a global parameter.