I was adding more stuff to my ecu file and I found this. After adding it I opened it up to see what values were in my bin (originally ASDU). I noticed that most are the same for the 7747, except the manual trans bins have different values.

I assume this adjusts how the MAP works according to coolant, but why would they be different from manual to auto?

Also, I changed my table to the one that I found in ASDX (manual trans bin). I didn't really notice any difference.

 

Astro Captn', can you give a location for that term?

RBob.

 

The table in question is at 0x307 (MAP filter coef vs. coolant). Now in my search of the hack for "MAP filter" I found more stuff at:

0x00E (Normal MAP filter coef)
0x00F (Transient MAP filter coef)

I understand if you don't want to explain all of those. But I'm curious as to what a MAP filter coef does.

thanks again RBob

 

The filter routine is a first order lag filter. It is used for two things. First is to remove noise from the various sensor inputs. The second is to provide a delayed value. (please see the gmecm papers link for additional info).

The table at 0x307 is used to lag filter the current MAP value. The ending value has a greater lag when the coolant temperature is lower. The acceleration enrichment routine uses the delta of the current MAP and the filtered MAP to decide if and how much enrichment to provide.

A colder engine requires more enrichment then a warm engine. This is reflected in the table values. The table values (at 0x307) are the filter coeficients.

Note that this filtered MAP value is also used for decel enleanment.

Also note (twice now, have to stop this, lol), that the TPS is also filtered. However by the table at 0x31D. The lag filtered value from that is also used for accel enrichment.

RBob.

 

Great. Thanks RBob

 

SO the filters are used for AE, and is the map filter used for VE and spark values, or does the ecm use an unfiltered value for VE and spark delivery.

 

The MAP term used for the VE & SA lookups use these filter coeficients:

0x00E (Normal MAP filter coef)
0x00F (Transient MAP filter coef)

The normal is used during steady state conditions, while the transient filter is used during times of change. The transient filter coeficient is typically a faster term in order to get better engine response.

RBob.

 

I noticed in the 747 hack those to values were the same, myabe I'll try speeding up the transient. (that would be a bigger value??).

 

Yes, the larger the coeficient term the faster the filter (less filtering takes place and less lag).

RBob.

 

Thanks!