7.4 MPI, MEFI 3 odd timing problem
#11
Registered
iTrader: (1)
Had which problem ?
The following users liked this post:
SB (10-14-2021)
#13
Registered
iTrader: (1)
Thanks for clarifying :thumbs
#14
Registered
Thread Starter
Join Date: Mar 2008
Posts: 206
Likes: 0
Received 0 Likes
on
0 Posts
Correct, the MEFi 3 tries to test the knock sensor on first throttle up after re-start. It advances the timing fully to make it knock. If it doesn't see it, it retards timing a bit. This can happen from using 93 octane instead of 87 gas. Mine was doing that running 89, so I went in a turned it off using MEFIBurn
#16
Registered
VIP Member
dt21
Ive got twin 502's Mefi3, but had same issue, very low timing. I will attach the timing chart. But if you look at orig specs that is what it is supposed to be for your motor. I guess for engine safety - old gas, over-prop'd , etc. Anyway i attached a timing chart and sure enough your advance is exactly where the specs say it should be.
Around 16.9 deg advance in the 2nd column from the right which is about where you'd be running near WOT mid/upper rpm.
I used mefiburn and advanced mine 4/5 deg more than chart said where the timing was low at mid/upper rpm and lower MAP. Basically the mid/upper right section of chart. It felt like a different motor, peppier. Gained 3mph also.
But i have always run premium, occasionally 89, and fresh gas.
Ive got twin 502's Mefi3, but had same issue, very low timing. I will attach the timing chart. But if you look at orig specs that is what it is supposed to be for your motor. I guess for engine safety - old gas, over-prop'd , etc. Anyway i attached a timing chart and sure enough your advance is exactly where the specs say it should be.
Around 16.9 deg advance in the 2nd column from the right which is about where you'd be running near WOT mid/upper rpm.
I used mefiburn and advanced mine 4/5 deg more than chart said where the timing was low at mid/upper rpm and lower MAP. Basically the mid/upper right section of chart. It felt like a different motor, peppier. Gained 3mph also.
But i have always run premium, occasionally 89, and fresh gas.
The following users liked this post:
articfriends (10-16-2021)
The following users liked this post:
articfriends (10-16-2021)
#18
Registered
VIP Member
With the orig timing i could only turn 26 Bravo one 4 blades, 5200rpm. 76mph. Now with more timing i can turn 28's, but just barely. 5050 rpm, 79mph.
FYI my motors are stock except for air filters, roller rockers only because the orig where worn out, and Eddie Marine standard log type exhaust - but they flow well over stock, gained another 3 mph with them also.
FYI my motors are stock except for air filters, roller rockers only because the orig where worn out, and Eddie Marine standard log type exhaust - but they flow well over stock, gained another 3 mph with them also.
The following users liked this post:
articfriends (10-16-2021)
#19
Platinum Member
Platinum Member
iTrader: (1)
With the orig timing i could only turn 26 Bravo one 4 blades, 5200rpm. 76mph. Now with more timing i can turn 28's, but just barely. 5050 rpm, 79mph.
FYI my motors are stock except for air filters, roller rockers only because the orig where worn out, and Eddie Marine standard log type exhaust - but they flow well over stock, gained another 3 mph with them also.
FYI my motors are stock except for air filters, roller rockers only because the orig where worn out, and Eddie Marine standard log type exhaust - but they flow well over stock, gained another 3 mph with them also.
#20
Registered
stock cal id is FE28 for the 454 mag EBC4
stock cal for 500EFI is DA02
the table shown is even low timing for stock 454 MAGMPI
table looks like an L-29
stock cal for 500EFI is DA02
the table shown is even low timing for stock 454 MAGMPI
table looks like an L-29
Last edited by tunertech; 10-26-2021 at 01:22 PM.
The following users liked this post:
articfriends (10-26-2021)