ECU tech

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Aug 22, 2004 | 06:43 AM

#16

MalibuJack

EvoM Guru

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From: Royse City, TX

Quote:

Originally Posted by ShapeGSX

Shiv, no kidding? Is it just an addition/subtraction factor based on road speed?

What you mention about the two maps is also in the DSM ECU. One map is the high octane map, and the other is the low octane map. When the ECU wants to look up timing for a particular load and RPM, it reads the value out of both maps, and then uses an octane number, or long-term knock number to pick a value between those two map numbers. On a DSM, long term knock is usually zero, so the high octane map is used. The low octane map should only ever be used when someone pumps gas into the car that does not meet the factory's minimum octane requirements. The long term knock value (which Todd Day called octane) really shouldn't budge in a perfectly working DSM.

How does the Evo ECU choose a number between these two tables?

I'm fairly certain this hasn't changed much, though I think there's a short term and long term value.. Partly why resetting the ECU gives some people a perception that their engine runs a bit better. I do think the EVO ECU's knock algorithms are a bit better than the DSM's, in some cases and on some engines the ECU picks up alot of activity and of course, the car ends up rarely running in the primary (High octane) timing/fuel map. I think the big problem is once you drift out of the high octane map, it can take several run cycles before it comes back. (Picture an average of knock value over time and you'll understand what I mean)

Aug 22, 2004 | 01:16 PM

#17

shiv@vishnu

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From: Danville/Blackhawk, California

There is more info coming... but here's some stuff to tide y'all over until then:

https://www.evolutionm.net/forums/sh...5&page=2&pp=15

Aug 22, 2004 | 07:24 PM

#18

A418t81

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From: Birmingham, Al

Quote:

Originally Posted by shiv@vishnu

There is more info coming... but here's some stuff to tide y'all over until then:

https://www.evolutionm.net/forums/sh...5&page=2&pp=15

Great thread

Aug 22, 2004 | 07:36 PM

#19

Imyurturboluva

Evolving Member

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From: ATX

Quote:

Originally Posted by shiv@vishnu

There is more info coming... but here's some stuff to tide y'all over until then:

https://www.evolutionm.net/forums/sh...5&page=2&pp=15

No way...you can't get off that easy, Shivvy. We already know about the complex algorithms used to predetermine knock and stabilizing the knock threshhold. Give us some real meat and potatoes. No more suckling of the milk. Spell it out in hex if you have to.

BTW, that thread is getting on my nerves. What is there to not get? It's like my Mustang buddies who think I'm idiotic because I now have a 4 banger 4 door. What they are missing is that I can spank their asses and I can pull a G on the skidpad. I guess I just don't get it. For the street, tuning factory ECU's is the only way to run. Call me crazy, but that's what I see as the most logical conclusion. Any takers?
-chris

Last edited by Imyurturboluva; Aug 22, 2004 at 07:43 PM.

Aug 22, 2004 | 08:10 PM

#20

n00dle

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Quote:

Originally Posted by Imyurturboluva

Call me crazy, but that's what I see as the most logical conclusion. Any takers?
-chris

Standalones are nice and serve their purpose in some applications where they're absolutely needed and could benefit greatly from them, as in old school factory engine management system dating back to the '70's and early '80's. The Evo ECM and it's components have proven to be amazingly robust and even reliable with a good piggyback that allows adjustments to some of the parameters you need, while leaving the rest for the factory built in parameters to take care of ie; knock, cold start, air conditioning, hot/cold idle, barometric psi changes, etc. The Xede is by definition a piggyback, but it's capability is way more than your standard piggyback dating back just a few years ago. It's capabilities has revolutionized the meaning of piggybacks for me.