Sorta, when i dynoed 502 mpi i was making 540 hp, motor would be two to 3 points lean from 3000 to 4200 or so on 1 bank of injectors, match up from about 4200/4400 to about 5000 then would invert to opposite batch of cylinders/injectors. When i un-set the flag in programming like a 500 efi has to staggered injection/skip double fire problem went away, had to add about 1 ms to most injection tables to pw to acct for the double dead bands. Ended up making over 560 hp once tune was right. This motor has more even afrs with it ON, go figure!!
The problem i have NOW is quite different, after motor warmed up the green black batch of 4 injector leads would lose all power and motor would drop down to 4 cylinders and refuse to fire those injectors. just solved it after alot of pissing around. Hooked up msd tester to spare 7 pin ign module, made a heat sink so it wouldnt go up in smoke. Plugged it all in, fired all 8 injectors at 4000 rpms with a vom in each batch, ***** sat there firing all 8 injectors and dummy coil plug flawlessesly for 2 hours. Heated air intake temp sensor up to 60c, no affect. Heated ect sensor up to 65 c, no effect.
Meanwhile i scoured thru tune on lap top the whole time, comparing bins from stock 500efi, stock 502 mpi, previous blower motor tunes, etc. FINALLY found it.
1. One injector bank for rpm reduction turned ON
2. ECT OVER TEMP CAUSE RPM REDUCTION TURNED ON
3. Over temp threshold in constants and scalars was set to 69.9c (we only heated it to 65c but it runs about 68/69 on dyno)
4. Overtemp clear was set to 66c
Turned them down to 20 c, uploaded the file and bam, green black batch of injector leads quit firing!

Adjust tune and upload, plug everything back in right on motor andvremove all test equipment,go get another 10gallons 89 octane, warm her up and im back in business!!

Smitty, this is all in MEFI 3 correct? I had a conversation with you regarding this (Well kinda - regarding fuel vs spark rev limit rpm reduction) on facebook few days ago. Can you simply crank up the rpm reduction temperature vs ECT, or turn off? And where is the one injector bank rpm reduction located? Excuse me if its obvious, I do not have my laptop with me today to see. Thanks -Chris

[QUOTE=articfriends;4540223]Sorta, when i dynoed 502 mpi i was making 540 hp, motor would be two to 3 points lean from 3000 to 4200 or so on 1 bank of injectors, match up from about 4200/4400 to about 5000 then would invert to opposite batch of cylinders/injectors. When i un

Yes, definately set yours to spark only and now that im aware of this ect overtemp set it to 95 c, i went ahead and turned it off too but just in case there is a hidden table turn temp up. All the other causes rpm reduction i always leave turned off on my own stuff anyways. I just missed this one!

Please forgive a stupid question, but why use the mefi when there are aftermarket options?

I have 6 or 7 mefi harnesses and 10 mefi3/4 ecus laying around, no reason to spend another 5000$ on two aftermarket ecus/harnesses. If you read the whole thread too i sm movi g forward to extensive testing of two different 500efi intakes and various modified 500 efi parts, some of my harnesses are drop ons for them. Keep in mind too, a aftermarket efi isnt magic either, you still have to set targets, sort out glitches, etc plus im a glutton for punishment! Gimme fuel had a magic holley efi on his 548, it auto tuned a hole in one of his pistons!!

AUTO TUNE.... Works great for EDM. Electronic dance music. Lol! Under the hood of a car or hatch of a boat I'm not sold on it. I'm sure it may work flawlessly for several but I can't even do an AUTO download on my laptop or iPhone without something failing. I forgot about gimme fuels piston. That sucks!

Ok, I found overtemp clear and also overtemp set. Both set to 68*C which is only 154.4*F. I will turn this up. Where is the enable/disable for this??

Disregard, found a flag/switch "Engine over temp causes rpm reduction". It was set (checked)

Keep in mind, there IS a reason for these safetys, in my case though the dyno runs close enough in temp to trigger it, im going to have to go back and look at a stock 502 tune at THAT temp, a 500efi has it set at 98.7c or something. Personally on a single engine boat i would not want ANY saftey parameters that could reduce power to point you couldnt get off water and you watch temp/oil press resl close. On a twin engine boat having some of the ssfety oarameters turned on, at least oil pressure and temp would be a good idea, i will prob turn some of this stuff on when im almost done with this project , set thresholds pretty high, Smitty