How Do You Achieve Zero Fuel Consumption On Deceleration?

[Tordne]

The feel of engine breaking is the spark being withdrawn... Love the avatar

[N0DIH]

If you look at my tables, I don't change the spark on decel. The factory setting did, I leave it alone so it uses the Closed Throttle Spark table instead. I was having some anomoly that when it would go into DFCO, and the timing dropped, it would never come back up and my timing would be in the dumpster until I restarted. Puzzled me until I figured out it was DFCO triggering it. If I didn't allow DFCO, no issue. So DFCO Timing Retard is the amount of timing that is pulled out when DFCO is active. So whatever value in the Closed Throttle Spark table - DFCO Spark Retard = Total DFCO timing. So when I set DFCO Spark Retard to 0, then I leave my timing alone to the Closed Throttle Spark Table.

There is a significant difference in decel without the fuel vs with, and even factory you can feel the 45-48 mph point where fuel comes back on. I have tried and tried to get it significantly lower than 45 mph and although I can, the transition from fuel off to fuel on is too abrupt and my limited PCM wouldn't let me transition smoother.

The feel of engine breaking is the spark being withdrawn... Love the avatar

[Biggsy]

I havent touched my DFCO in my tune, so I decided to give mine a test today.
My car is VX Commodore LS1 Auto.
I can make the dash display 0L/100 if I go downhill and do a manual downshift to second at speed.

Cheers,

[dfe1]

When DFCO comes in on pulse width typically drops to somewhere between .200 ms and .350 ms (depending on the vehicle) and O2 voltage goes to .004 mv. With the stock cals I've looked at, the transition to DFCO is very slow because of a slow rate of spark adjustment. DFCO won't become active until ignition timing hits the value in B3336. (The description is not correct. This isn't the value to which timing will be adjusted when DFCO is active-- it's the value that activates DFCO. Spark will drop until it reaches the value in B5915.

Make sure that the value in B5919 isn't higher than the values in B3336 or you'll never hit the timing enabler for DFCO. Try values between .06 and .09 in B3334 to achieve a ramp in rate you're happy with. Values in B3335 (Ramp Out Rate) will be in the .4 to .7 range. Don't forget to adjust the other enablers (rpm, MAP, speed and throttle). If all else fails, send me your tun file.

[N0DIH]

Sorry for the n00b question, but I haven't got EFILive yet. What do you mean by the values in B5919 or B3336? Is this something in the datalog/scanner that is a specific location?

Love the sig! 1+1=10..... And FWIW the systems I used to work on 7+1=10.....

[dfe1]

I was begining to wonder if anybody got it. Sig used to be 7+1=10, then F+1=10. Figured it needed another change, so I went to the binary version. I used to work on octal systems as well. One of the best stories is the time we were installing an electronic cash register system in a department store and some electricians were on site. We were counting cable pairs coming into the system and you should have seen their faces when we counted 1,2,3,4,5,6,7,10, then went on to 16, 17, 20. They couldn't understand what happened to 8, 9, 18 and 19. Ever try to explain an octal or hex system to someone?

As for your EFILive questions, every table in the tuning software is numbered. B3334 is the DFCO Spark Ramp In Rate table, B3335 is the Ramp Out table. It's a little confusing at first, but all you have to do is enter the table number in the navigator window and hit search. The system will display he table for you. It might not be a bad idea to download the software from the EFILive web site and begin looking through it before you get your system.

[joecar]

Sorry for the n00b question, but I haven't got EFILive yet. What do you mean by the values in B5919 or B3336? Is this something in the datalog/scanner that is a specific location?

Love the sig! 1+1=10..... And FWIW the systems I used to work on 7+1=10.....

N0DIH,

No problem, feel free to ask questions all you like.

Download and install the software from here: http://www.efilive.com/download.aspx

Without a cable it still runs... you can view logs and view/edit tunes... you just can't log or flash;
real sample logs and tunes are included as are tutorial PDF's (see the Auto VE tutorial, for example).

Cheers
Joe

[joecar]

I was begining to wonder if anybody got it. Sig used to be 7+1=10, then F+1=10. Figured it needed another change, so I went to the binary version. I used to work on octal systems as well. One of the best stories is the time we were installing an electronic cash register system in a department store and some electricians were on site. We were counting cable pairs coming into the system and you should have seen their faces when we counted 1,2,3,4,5,6,7,10, then went on to 16, 17, 20. They couldn't understand what happened to 8, 9, 18 and 19. Ever try to explain an octal or hex system to someone?

As for your EFILive questions, every table in the tuning software is numbered. B3334 is the DFCO Spark Ramp In Rate table, B3335 is the Ramp Out table. It's a little confusing at first, but all you have to do is enter the table number in the navigator window and hit search. The system will display he table for you. It might not be a bad idea to download the software from the EFILive web site and begin looking through it before you get your system.

lol...

How about base 36 (...I think IBM did use base 36 a long time ago...)...

Base 36 uses the digits 0-9 and A-Z, so... Z + 1 = 10

[ringram]

Looks like you still have enable delay there!

[neil]

Hi dfe1,
I would appreciate if you could have a look at this tune and advise on the correct setting up of DFCO.
It doesn't seem to work no matter what I do.
I would really like for the engine to virtually cut all the fuel on deceleration.
It's just a standard non modified auto engine
Any help that you could offer would be greatly appreciated.
Thanks.

Regards,

Neil.