dfco questions

hey i have a couple dfco questions i cant really seem to find an answer to when searching

1) changing dfco settings dont seem to have an effect on entry speed for me upon coasting. even if i set the entry spark crank refs to 1 or 0, it still takes the normal ~1 second after letting off the gas to enter dfco and start engine braking, popping and decelerating. how can i make it so i enter dfco more quickly when coasting? ideally at lower rpms it would be instant or near instant.

2) what role does cfco play? i assume its pretty obvious in it being like dfco but triggered by the clutch, but there isnt a whole lot of discussion or information that i can find on how it works and interacts with dfco.

3) i want to make sort of a "progressive" exhaust pop tuning where lets say idle to 2000 rpm there is basically nothing, 2000-4000 it is about as intense as stock, and 4000-6500 its ricer in a golf r or audi a4. ive tried doing this just with the dfco table and it doesnt seem to work, it does go to a higher or lower intensity depending on if i add or remove timing, but not to the degree i want.

4) in the same vein as 3, how can i modify the duration of the popping? basically i want it to last about 1 maybe 1.5 seconds no matter the rpm but currently this happens only at lower rpm, below 3000 or so. as the rpm increases the duration decreases so i guess its a fixed number of something that determines it? especially over 5000 its just blblblpop and over in like a 10th of a second. this is all with 1 or 0 crank refs too.

I've found that if its the pop/burble noise you're after, modifying the timing table will achieve the best results. Setting the timing in that area close to zero (Best I remember, up to -10deg is okay, but I found it not necessary)... On the timing table, think higher RPM/low load (first 2-3 rows, and in the 2000-4000ish rpm columns) I've attached a quick example just for a visual. The example is not a final tune, just giving a visual on the area of interest. Attachment 108784

On a second note, the more timing you remove, the more aggressive the pops. If you want to "stage" it as mentioned above, be less aggressive 2k to 4k, and more aggressive above 4k, etc...... but all of your adjustments should be in the low load areas where if you are accel, and let off you can watch in the data when coming off the pedal it will track in the cells mentioned while the rpm is starting to fall on decel

Also note the less timing you have the more the engine will want to "engine brake" once you let off the accelerator. Less timing= more likely to pop, more timing= less likely to pop and less effects of engine braking. I have cfco disabled in my tune and I've noticed that the rpms will tend to hang a little bit more due to fuel still being sprayed into the cylinders.

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Originally Posted by davidchristian83

I've found that if its the pop/burble noise you're after, modifying the timing table will achieve the best results. Setting the timing in that area close to zero (Best I remember, up to -10deg is okay, but I found it not necessary)... On the timing table, think higher RPM/low load (first 2-3 rows, and in the 2000-4000ish rpm columns) I've attached a quick example just for a visual. The example is not a final tune, just giving a visual on the area of interest. Attachment 108784

On a second note, the more timing you remove, the more aggressive the pops. If you want to "stage" it as mentioned above, be less aggressive 2k to 4k, and more aggressive above 4k, etc...... but all of your adjustments should be in the low load areas where if you are accel, and let off you can watch in the data when coming off the pedal it will track in the cells mentioned while the rpm is starting to fall on decel

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thanks simple enough, ill start experimenting.

Quote:

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Originally Posted by sgod1100

Also note the less timing you have the more the engine will want to "engine brake" once you let off the accelerator. Less timing= more likely to pop, more timing= less likely to pop and less effects of engine braking. I have cfco disabled in my tune and I've noticed that the rpms will tend to hang a little bit more due to fuel still being sprayed into the cylinders.

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noted. ill have to mess around with cfco and see what happens. ive had it on and when shifting ive noticed theres basically 0 rev hang or lag which is awsome. my old car had HORRENDOUS rev hang that even a tune didnt fully get rid of.

Deacceleration Fuel Cut-Off

The snap-crackle-pop comes from the auto fuel cutoff feature
Minimum RPM disable: B2409 - sets the minimum RPM that DFCO can operate. This can be set pretty low but make it over idle PRM and have a bit of over head there.
Minimum RPM Enable: B2410 - over this setting, DFCO can work. Make it over the above setting and allow for some room.
Speed thresholds: B2402 - set to be close on the above settings for each gear.
These should help when DFCO operates and when it doesn't. To alter how quickly it comes into operation...

DFCO Entry Delay: B2401 - adjust to your desire. Don't make it come in too quickly though as it may make the car feel like it misses when releasing the throttle. Allow a little longer in low gears and shorter in high gears. Aim for between 1 and 2 seconds as a start.
The above settings will also change how long the crackle lasts when slowing down. If you want it to crackle for longer, add more time.

To change the "note" of the crackle, you need to work on the timing during DFCO entry...

. DFCO Enter Spark Timing: B5149 - lower numbers = more backfires, higher numbers = more burble.

For low backfires and crackle start at maybe a minimum of 0' and remove timing till it sounds "right". Follow the shape of the stock curve.

Hence this can be tuned out or increased to your liking. Note that it is a good feature though as it reduces fuel use.