Nope.

 

Nope; at least not directly through the E6K/E6X programs. However, I'm interested in seeing if it's possible to modify a file directly and change the two split tables and then see if the ECU actually fires the trailing ahead of the leading. Plan on working on it today.

B

 

Whats does that mean... The software is whats holding it back?

 

I think so. I think its the user interface on the older programs that's disallowing it. I'd be willing to bet (not a lot, mind you!) that the ECU itself will work just fine firing trailing ahead of leading. It's just a matter of getting the data into the map by going around the user interface and modifying the file directly.

B

 

Got it all fired up. Found where the trail split stuff starts in the raw file (around Offset 800). Looks like it's a no go for negative split from what I can tell. The hex data in those spots bottoms out at 00. Don't think it's possible to go to a lower value than that. This would require a firmware revision w/ an updated user interface.

 

The firmware in the ECU might be bounds checking it or using it as an unsigned number. That would really kill any chances without a firmware update.

Of course, how familiar are you with negative numbers in binary? Your negative numbers are from 80 - FF where FF is -1. Or if its a 16 bit value, then FFFF to 8000 where FFFF is -1.

 

Really! I didn't know that. I might have to give that a try. I wonder if the ECU would actually fire it -1 from Leading if I set the rows in vacuum to FF each bar.

B

 

Just tried taking a test E6K map and, via hex editor, changing the first 11 bars in the 0-2krpm split map from 00 to FF. Forced a change of 255 which actually showed up in the editor.

 

Do me a favor and test this out by manually spinning the CAS though. I would hate for it to fire 255deg advanced on you.

 

Neg split is running your trailing timing more advanced than your leading. Correct? I am running a megsquirt Ms1, is this possible with the ms1?
Thanks
Keith

 

only ms2 and ms3 can run negative split. this is an excellent thread btw.

 

So, I read through this thread, and am impressed with the amount of actuall information in it. A thought came to my mind, and I'm not too sure how well it would work in the upper rev ranges, but for those that don't have an ecu capable of running negative split, how would just switching the wires around work? Put your trailing on the leading, and the leading on the trailing. Obviously this would only be for an n/a application though.

 

Negative split is designed for low vacuum/load levels. Fact...Mazda uses it for better emissions and fuel economy. It will also quiet down the exhaust pulses a bit. I heard you should not run negative under heavy loads as it may cause detonation.