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SSpdDmon
July 26th, 2007, 03:47 AM
2001 F-body M6
OS: 12202088
B3307 is set to 0.00

Is there a reason why it still takes 2 seconds for my DFCO to activate? When I let off in 3rd gear at say 3500rpm, it meets the TPS, RPM, MAP, and MPH requirements to enable DFCO. But, it still doesn't kick on for 2 seconds even with B3307 set to zero. :help2:
TAQuickness
July 26th, 2007, 08:19 AM
I don't have my software handy, but if memory serves, there is a minimum time that has to be met before DFCO can be reactivated in addition to the time you have to wait for DFCO to become active when the conditions are met. A deadband of sorts to keep you from teetering on the edge of the DFCO limits.

On initial decel, my DFCO takes about 1 second to activate. Subsequent decel's can take up to 2 seconds to activate DFCO depending on my right foot.

Is the problem you're having occurring every time you attempt to activate DFCO?
SSpdDmon
July 26th, 2007, 08:25 AM
I don't have my software handy, but if memory serves, there is a minimum time that has to be met before DFCO can be reactivated in addition to the time you have to wait for DFCO to become active when the conditions are met. A deadband of sorts to keep you from teetering on the edge of the DFCO limits.

On initial decel, my DFCO takes about 1 second to activate. Subsequent decel's can take up to 2 seconds to activate DFCO depending on my right foot.
I think you're talking about B3307.

IIRC...I think I noticed on my friend's '99 A4 SS that it went into DFCO as soon as I let off the gas. Wonder if there's something deeper in the OS (A4's vs M6's) that says M6's need a minimum of 2 seconds.
johnv
July 26th, 2007, 11:53 AM
There is M6 DFCO as well which you could play with,
It is disabled in most tunes - need to lower the enable temp.
SSpdDmon
July 26th, 2007, 01:40 PM
There is M6 DFCO as well which you could play with,
It is disabled in most tunes - need to lower the enable temp.
That's for when I put the clutch in. That works fine. It was enabled on my car from the factory.

It's when I'm cruising and lift my foot off the gas (while still in gear). The MAP, TPS, MPH, and RPM are all within the enable/activate ranges. It still waits a bit.
dfe1
July 27th, 2007, 04:36 AM
Your problem is timing ramp rate. Most stock calibrations remove timing very slowly. Change the values in B3334 to .100 and watch what happens.
SSpdDmon
July 27th, 2007, 04:57 AM
My log shows it drop instantly though. One frame will say 28* of timing and the next will say 2* of timing (when it kicks on). It really doesn't take more than a frame or two.

Realisticly, there are some 3,000 calibrations in our PCM from what I'm told. The great thing about EFI Live is they went through and selected a good 10% or so of them (the most relevant ones) so that we can tune our cars without being overloaded with tables. I think this might be something in the other 90% of the PCM we can't see.
dfe1
July 27th, 2007, 05:11 AM
My log shows it drop instantly though. One frame will say 28* of timing and the next will say 2* of timing (when it kicks on). It really doesn't take more than a frame or two.

Realistically, there are some 3,000 calibrations in our PCM from what I'm told. The great thing about EFI Live is they went through and selected a good 10% or so of them (the most relevant ones) so that we can tune our cars without being overloaded with tables. I think this might be something in the other 90% of the PCM we can't see.
What are the values in B5915? I don't think the problem is with tables that aren't accessible. I've done too many vehicles with no delay issues. I think you've got a conflict somewhere that's causing the problem.
SSpdDmon
July 27th, 2007, 07:12 AM
What are the values in B5915? I don't think the problem is with tables that aren't accessible. I've done too many vehicles with no delay issues. I think you've got a conflict somewhere that's causing the problem.
They're stock values in B5915. Again, I don't have a problem going into DFCO. It just doesn't want to kick over to DFCO until the enablers have been met for 2 seconds. Then, it switches over rather instantaneously. You can feel it when it does. Injectors go to ~0.4ms and timing drops to only a few degrees.
TAQuickness
July 27th, 2007, 08:38 AM
Jeff - could you email me a copy of the tune you're working on?
SSpdDmon
July 27th, 2007, 09:52 AM
Yup. PM me your email addy again? I can't remember which one is yours. http://www.motownmuscle.com/forums/images/smilies/lol.gif
TAQuickness
July 27th, 2007, 09:58 AM
pm sent...
SSpdDmon
July 27th, 2007, 10:07 AM
email sent... :)
TAQuickness
July 28th, 2007, 12:39 PM
Have any luck?
SSpdDmon
July 28th, 2007, 03:52 PM
Have any luck?
I increased the min TP% like you suggested. It still doesn't kick on for 2 seconds or so. Don't forget, it's B3317+B3316 that determines the where TP% has to be below. If you look at the logs I sent you, I don't think TP% is greater than 0.4% while waiting for DFCO.
TAQuickness
July 28th, 2007, 04:50 PM
Gotta new log?
SSpdDmon
July 29th, 2007, 02:24 AM
I'll get ya one later today. :)
TAQuickness
July 29th, 2007, 02:28 AM
Does DFCO behave as expected if B3307 is not 0?
SSpdDmon
July 29th, 2007, 06:43 AM
As long as it's greater than 2, I believe so. :) I used to have it set to 4 seconds and it would wait that long.
johnv
August 3rd, 2007, 09:39 AM
After doing some logging yesterday I noticed mine does the same:bash:
myfast70
August 3rd, 2007, 10:45 AM
What is DFCO? I'm new to the forum and am trying to learn as much as I can before I take the leap.
2002_z28_six_speed
August 3rd, 2007, 11:04 AM
2001 F-body M6
OS: 12202088
B3307 is set to 0.00

Is there a reason why it still takes 2 seconds for my DFCO to activate? When I let off in 3rd gear at say 3500rpm, it meets the TPS, RPM, MAP, and MPH requirements to enable DFCO. But, it still doesn't kick on for 2 seconds even with B3307 set to zero. :help2:


I have the same issue. COS5 or 2002 M6 OS. Never comes on immediatley.
Is it possible the PCM doesn't poll the requirements to enter DFCO fast enough?
SSpdDmon
August 4th, 2007, 04:55 AM
What is DFCO? I'm new to the forum and am trying to learn as much as I can before I take the leap.
Decel. Fuel Cut Off

I have the same issue. COS5 or 2002 M6 OS. Never comes on immediatley.
Is it possible the PCM doesn't poll the requirements to enter DFCO fast enough?
At least I know I'm not going crazy. http://www.motownmuscle.com/forums/images/smilies/lol.gif I don't think it's a 'slow poll' issue. I think it's the OS. My buddies '99 used to enter DFCO immediately. After I upgraded his OS to get to one VE table, his car doesn't do it anymore.
Haans249
May 19th, 2009, 05:05 PM
Has anyone found anything out from this? I'm working on DFCO as well, and I also notice the 2 second delay when entering once all parameters are met. I would like it to enter DFCO instantly once I'm off the throttle and still in gear. I'm going to try setting the timer to .05 and see if its set to 0 if it will default to 2 seconds.
WeathermanShawn
May 20th, 2009, 12:34 AM
2002 M6 here, does the same thing. Like SSpdDmon said, I think there are more functions either 'hard-wired' or tables not available than we know. I'm sure it is somewhat of an 'engine protection' feature. May not be wise to immediately cut off injector flow instantaneously.

I do not like my DFCO settings to be overly 'trigger-happy' to engage at every throttle letdown. Let us know if you can figure it out.
Haans249
May 20th, 2009, 03:41 AM
2002 M6 here, does the same thing.

Like SSpdDmon said, I think there are more functions either 'hard-wired' or tables not available than we know.

For me it is not an issue. I'm sure it is somewhat of an 'engine protection' feature. May not be wise to immediately cut off injector flow instantaneously.

But, that is total speculation. May be unique to our operating system.

Personally I do not want my DFCO settings to be as 'trigger-happy' to engage at throttle letdown. But, let us know if you can figure it out.

Regards.

..WeathermanShawn..


I will let you know. I want mine "trigger-happy" because if I let off the throttle while still in gear, its because I want to slow down haha. I have my parameters set that DFCO will turn on ONLY when I'm downshifting to slow down (coming to a light, slowing down on highway etccc) without having to hit the brakes. If I want to coast, I'll just push the clutch in :nod:
dfe1
May 20th, 2009, 04:29 AM
Take a look at Spark>DFCO. I've found that delays in entering DFCO once all parameters are met are usually the result of spark ramp rate. DFCO won't be activated until timing is reduced to the trigger value (in B3336). If the Ramp In rate is too slow, you'll have a noticeable delay. Change the values in B3334 and you should notice a big difference. Also note that once in DFCO, timing will be reduced to the value in B5915 under most circumstances. I have the values in B3334 at .04 and DFCO activation is almost immediate when I get off the throttle. Higher values obviously activate DFCO more quickly, but may make activation too harsh.
Haans249
May 20th, 2009, 04:30 PM
Thanks for the input! I will try that tomorrow. I put the delay to .05, but didn't notice a difference. I already have the values in B3334 set to .1, but I will put it at .6 to see if there is any difference. I also already have the values in B5915 set to 0 as well.