DFCO Info

**TheApocalyptican** · 04-20-2013

Thanks for all the info and work on your part. The only thing I question about the image you posted is the MAP enter/exit. I read another thread on 3rd gen that RBob commented in about DFCO. He stated that the MAP enter/exit is opposite of the other two qualifiers. Basically said that for IE: in your bin info posted about that you need to be at 22.5 or lower in order to enter dfco, and when the MAP gets back above 40 it disengages. Maybe this is why DFCO is so hard to get into? Mine is set at 20 and 40, and I can just get down to 20, but not actually below when in OD. Was planning on trying it at 30 and 40, and to test this. Will post any info back afterwards.

Interesting in your post above that we essentially see 3 different sets of values between TC, TP, and the disassembly. This is why it's important for anyone wanting to change things to test and go little by little, and not just adjust something to 100% of where they think they want it!

**EagleMark** · 04-20-2013

I think your right, I switched Enter and Exit on MAP?

TC and TP could read differant if your using a differant bin then I am as well.

Another good point is always use the same definition mask, switching leads to issues you have discribed. Also some have Bias, like Spark Bias built into Spark Advance table and some do not. Meaning one with Spark Bias built in shows actual Spark Advance. One without Bias built in shows actual spark advance plus what ever bias is...

**TheApocalyptican** · 04-20-2013

Had to go to the bank. Couldn't really get into DFCO in the trip. Main problem seemed to be the fact that I was in OD and thus low rpms. I plan on checking it out more next week after I get my miss sorted out. I'll post back after checking it out some more. Looking for info on DFCO this time is the only time I've actually opened anything other than a $42 ASDU 7747. I think the TC vs TP value differences are due to just as you said, a conversion from hex. Especially with the enter and exit switched like I said, then the enter being lower in TC than in TP makes sense as to the activation of DFCO.

**chevmasta** · 04-30-2013

Any more info on this?

I have a hard time believing DFCO would turn ON at 16kpa and OFF at 33KPA as posted above?

**EagleMark** · 04-30-2013

Yeah it's right, but you have to look at everything else as well. This is for your $85 but it's very similar to $42.
First has to reach enable temp (I added it to xdf) at 0x310
Then it has to meet three qualifiers:
MAP enter 0x308
MPH enter 0x306
RPM enter 0x304
After all those qualifiers are met and then TPS value falls below 0x30E then it will enter DFCO and still have a delay at 0x30C

It will stay in DFCO until any of the RPM, MAP or MPH Exits qualifiers are hit.

The comments in disassembly don't describe it that well...

Code:

    	;---------------------------------------------
        ;  DECEL FUEL Cut Off
		; 
    	;---------------------------------------------
L8304   FCB  67     ; 1675 RPM, UPPER RPM LMT
L8305   FCB  48     ; 1200 RPM, LOWER RPM LMT
				 	;
L8306   FCB  10     ; 10 MPH, UPPER Vss LMT
L8307   FCB  7      ;  7 MPH, LOWER Vss LMT
				 	;
L8308   FCB  22     ; 18.5 Kpa, LOWER MAP LMT
L8309   FCB  64     ; 34.0 Kpa, UPPER MAP LMT
				 	;
L830A   FDB  0512   ; 7813 usec, FUEL PW WHEN DISABLING DFCO
				 	;
L830C   FCB  10     ; 1.0 sec DFCO TIME QUAL 
                    ; CAL VAL = Sec * 10
                    ;
L830D   FCB  32     ; 400 Msec, max after DECEL FUEL CUT OFF FOR PW
                    ; CAL = SEC * 80
                    ;
L830E   FCB  4      ; 1.6% DECEL FUEL CUT OFF TPS THRESH
				 	;
L830F   FCB  200    ; 78%  DFCO MULT STEP VALUE
L8310   FCB  152    ; 74c, DISABLE DECEL FUEL CUT OFF IF COOL  L.T. THRESH.
    	;---------------------------------------------

**TheApocalyptican** · 04-30-2013

16 is probably right. Mine used to be at 20 and I never really got into DFCO. I changed it to 30, and I can definitely tell when it happens. Especially in D instead of OD. It's a weird feeling, as it really causes you to decel quickly. I'd do a log and see what map # you are usually in when you let off the gas. Then you can adjust so that the number is above that.

**EagleMark** · 04-30-2013

Right, you have to hit the low MAP number to enter while decelerating, you've already hit the MPH and RPM to enter. Then there is MAP, MPH and RPM can make it exit.

It is like a engine brake, it's nice to save fuel while getting off the highway but I find it does not help while light cruise, if you try and coast and it kicks in? You slow to quickly and have to accelerate.

**chevmasta** · 05-01-2013

For a haul rig, I love DFCO. Plus the ability to switch maps on the fly....I'd love DFCO.

Here's my questions.
I have ONE log where I entered DFCO. Flag turns ON.
In this log, I am at 21 KPA (note that in my mask it is LO 18.47). Then why did it turn on at 21KPA?
I was at 1800rpm. RPM limit HI is 1675. This is how it should be correct? above 1675 to enable dfco?
mph was 54. mph HI is set at 10. This is correct? above 10mph to enable dfco?

at

L830C in the above hac says "cal val" = sec * 10.

Does this mean the 1 second delay is acutally 10 seconds? (excuse my newB-ness).

Thankyou for the new .xdf Mark. You've helped me endlessly. Don't forget to post it in the 7060 thread. :)

The log-file attached shows the DFCO starting at an engine runtime of 514-515 seconds if you want to look.

**EagleMark** · 05-01-2013

I like working on the XDFs and reading disassemblies so it's my pleasure! The real talent is the guys who can make the disassemblies, even if they are not commented exactly or how we interrupt, they are the key to what we do!

I'll look at your log later.

**chevmasta** · 05-01-2013

Originally Posted by EagleMark

Yeah it's right, but you have to look at everything else as well. This is for your $85 but it's very similar to $42.
First has to reach enable temp (I added it to xdf) at 0x310
Then it has to meet three qualifiers:
MAP enter 0x308
MPH enter 0x306
RPM enter 0x304
After all those qualifiers are met and then TPS value falls below 0x30E then it will enter DFCO and still have a delay at 0x30C

It will stay in DFCO until any of the RPM, MAP or MPH Exits qualifiers are hit.

The comments in disassembly don't describe it that well...

Code:

        ;---------------------------------------------
        ;  DECEL FUEL Cut Off
        ; 
        ;---------------------------------------------
L8304   FCB  67     ; 1675 RPM, UPPER RPM LMT
L8305   FCB  48     ; 1200 RPM, LOWER RPM LMT
                     ;
L8306   FCB  10     ; 10 MPH, UPPER Vss LMT
L8307   FCB  7      ;  7 MPH, LOWER Vss LMT
                     ;
L8308   FCB  22     ; 18.5 Kpa, LOWER MAP LMT
L8309   FCB  64     ; 34.0 Kpa, UPPER MAP LMT
                     ;
L830A   FDB  0512   ; 7813 usec, FUEL PW WHEN DISABLING DFCO
                     ;
L830C   FCB  10     ; 1.0 sec DFCO TIME QUAL 
                    ; CAL VAL = Sec * 10
                    ;
L830D   FCB  32     ; 400 Msec, max after DECEL FUEL CUT OFF FOR PW
                    ; CAL = SEC * 80
                    ;
L830E   FCB  4      ; 1.6% DECEL FUEL CUT OFF TPS THRESH
                     ;
L830F   FCB  200    ; 78%  DFCO MULT STEP VALUE
L8310   FCB  152    ; 74c, DISABLE DECEL FUEL CUT OFF IF COOL  L.T. THRESH.
        ;---------------------------------------------

In the interest in learning, can you or someone else, explain to me these:

L830A FDB 0512 ; 7813 usec, FUEL PW WHEN DISABLING DFCO
;
L830C FCB 10 ; 1.0 sec DFCO TIME QUAL
; CAL VAL = Sec * 10
;
L830D FCB 32 ; 400 Msec, max after DECEL FUEL CUT OFF FOR PW
; CAL = SEC * 80
;
L830F FCB 200 ; 78% DFCO MULT STEP VALUE

I'd really like to understand how and when these are looked up and applied.
I could take a stab at it but then be totally off base.

**EagleMark** · 05-01-2013

I didin't see it come on at 514-515, that looked like a data glitch. But it does come on at about 8:35 when you cruising and went 0% TPS and guess what? Took 10 seconds to enable DFCO flag! Looks like it stayed in DFCO till 12xx RPM was reached?

EDIT: DFCO timer fixed in XDF.

**EagleMark** · 05-01-2013

Hey next time you do a log will you do a WOT run? What ever you feel safe with. This data stream has BPW and Async BPW, man does Async BPW do weird stuff when it comes on, I'd like to see what it does at WOT high RPM...

**EagleMark** · 05-01-2013

Originally Posted by chevmasta

In the interest in learning, can you or someone else, explain to me these:

;
L830C FCB 10 ; 1.0 sec DFCO TIME QUAL
; CAL VAL = Sec * 10
;
L830D FCB 32 ; 400 Msec, max after DECEL FUEL CUT OFF FOR PW
; CAL = SEC * 80
;
L830F FCB 200 ; 78% DFCO MULT STEP VALUE

I'd really like to understand how and when these are looked up and applied.
I could take a stab at it but then be totally off base.

L830A FDB 0512 ; 7813 usec, FUEL PW WHEN DISABLING DFCO = the Fuel PW when DFCO is disabled/turned off, it needs something to get going again.

L830C FCB 10 ; 1.0 sec DFCO TIME QUAL ; CAL VAL = Sec * 10 = I think your right and this should be the 10 second delay, not 1 second after all DFCO qualifiers are met, it still has a 10 second delay.

L830D FCB 32 ; 400 Msec, max after DECEL FUEL CUT OFF FOR PW ; CAL = SEC * 80 = I think this is commented wrong, we've talked about this before and this is an added PW before going DFCO, your log shows .5 before DFCO. I can see this on my WB and it goes rich before DFCO.

L830F FCB 200 ; 78% DFCO MULT STEP VALUE = Have no idea?

**chevmasta** · 05-01-2013

Originally Posted by EagleMark

I didin't see it come on at 514-515, that looked like a data glitch. But it does come on at about 8:35 when you cruising and went 0% TPS and guess what? Took 10 seconds to enable DFCO flag! Looks like it stayed in DFCO till 12xx RPM was reached?

EDIT: DFCO timer fixed in XDF.

am I an idiot? why don't I see the DFCO timer in that last .xdf?
yes, it stayed in till 1200rpm.

the 514-515 was the "engine runtime" parameter. which parameter where you looking at that shows minutes and seconds 8:35?

Originally Posted by EagleMark

Hey next time you do a log will you do a WOT run? What ever you feel safe with. This data stream has BPW and Async BPW, man does Async BPW do weird stuff when it comes on, I'd like to see what it does at WOT high RPM...

This is probably the best one I have when we were going over the last BPC stuff.

"engine runtime" of 367 seconds has me WOT.

(it's not often I do that)

**chevmasta** · 05-01-2013

Originally Posted by EagleMark

L830F FCB 200 ; 78% DFCO MULT STEP VALUE = Have no idea?

The adx has this as DFCO BPW multiplier step.

I'm wondering if this multiplies the BPW from:
L830A FDB 0512 ; 7813 usec, FUEL PW WHEN DISABLING DFCO

or

L830D FCB 32 ; 400 Msec, max after DECEL FUEL CUT OFF FOR PW ; CAL = SEC * 80

im just thinking out loud (on a forum) lol