MikeScarab28XLT

Hello
have someone a spark advance Tabel from a 502 EFI ?

In the Mercruiser Service Manual 16 i can only see the advance from the voyager distributor module. But i can nowhere find something about a advance tabel from the ECM Modul ??

I drive today a 500EFI it makes total at over
2000 RPM total are in diacom 28*. Real 36* 28* + 8* = 36*

My 502 EFI
makes 2800 RPM 30* in diacom and real
than 3100 RPM 33* in diacom and real ( No Nock retards 33 + 8 = 41 this is not real and can not work)
than over 3200 RPM 28* in diacom and real
With real i mean showen with light gun timing tool.

Have someone a Tabel from this Engine ??
Ore now what advance this engines make ??

92nsx

IIrc it is in the Merc manual 16, and also 23.

EDTI: Yep it is in # 16. Page: IGNITION SYSTEM - 4B-4

MikeScarab28XLT

I have read this 4B-4 but i dont read anything about EFI only 502 MAgnum.
Its the same Distriburor but the EFI have a advances tabel in the ECM. The Distributor curve are only use for driving home in save mode i have read.

MikeScarab28XLT

This is what my ECM do.

Is it normal ??

http://www.offshoreonly.de/phpbb/dow...e.php?id=23626


http://www.offshoreonly.de/phpbb/dow...e.php?id=23629

Trash

Your timing is fine. The Merc tables are strange as I alluded to in another post. If you have the TB-V it will also incorporate Mean Best Timing (MBT) and advance timing under static cruise throttle until it either detects knock or nor RPM increase.

The ignition advance at 40kPa (basically throttles closed) during heaving deceleration is 40 degrees on several Merc packages!

MikeScarab28XLT

Thanks Trash for both replays.

You say it is normal, but what can i do to correct it. The hp500 dont do it.
Is it not better to stay at 36" at over 3200-4950 rpm i can drive ?

Trash

You need to change the Spark Advance/RPM/MAP table or timing table in the MEFI 1. Merc most likely reduced timing at the upper rpm and MAP points to minimize detonation potential. The Merc black motors (502 EFI) are more conservatively set up compared to the HP (blue) motors.

If your motor is running fine I wouldn't worry too much. If you are looking to experiment, then you need to alter the timing table. You would need MEFI burn software or get in contact with your previous tuner or one of the many other capable people on this forum.

MikeScarab28XLT

I have no nock retards with 33* under 3200 RPM. Du you think i became nock retards with 36* over 3200 RPM ?

Can i run 16 Base Time to bacame 36* Total on WOT. What than are with under 3200 RPM with 16+ base time ?

Do you think someone have a fitting programm for the black old 502 EFI from 1993 that make what im looking for ?

Trash

If you have no knock under 3200 rpm and the ECM commands 33degrees timing then that's ok. I can't say if you will experience knock with 36 degrees of timing above 3200 rpm. It just depends on too many variables.

In order to test it you would have to adjust the timing table in small increments. MEFI Burn software will allow you to do this. If you are uncomfortable doing this then I would suggest talking with a tuner. Some of these guys can tune remotely which may be of some benefit due to your location. If the stock ECM is reducing timing at the upper rpms I would not worry about it as long as it's not due to knock. The factory timing tables in most cases reduce overall timing in the upper MAP and RPM spectrum.

You could, but I would NOT do this. You are trying to fix something that is NOT broken.

If your boat was tuned before I would talk with them.

If they didn't modify the MEFI 1 timing table I would leave it alone.

The timing curve you are seeing is most likely normal unless you are experiencing some significant performance degradation.

IF you are still unhappy with the timing the only answer I can give you is to get it remotely tuned by MEFI Burn, another tuner, or buy the software and change the timing table.

MikeScarab28XLT

Thanks for als anwsers and help.

I think i buy the mefiburn solution.
I recorde and save the standart ecm hex9550 and the modifyed ecm hex9334.
Than i record and save the hp500 file.

Than i inspect all files and look what i can change.

If i see something are very difficult i can allways go back ore take a remote tune.