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When is DFCO on 06+ Civic AT?

I've read online:
910 rpm above 21 mph
1200 rpm
870 rpm

Can anybody with a SG confirm any of this?

Hi Boston Man:

___You can feel it. From about 30 mph, let off your accelerator pedal and keep shifting your gear selector down. By the time you are in first gear and traveling maybe 10 to 15 mph, you will feel the surge as you pass through ~ 1,100 RPM (or whatever the actual RPM is) when fuel cut is released. The transition will feel like a strong deceleration to an almost glide like feel and that is exactly the RPM where the injectors came back online to preserve idle.

___Good Luck

___Wayne

I watched for DFCO this morning. On my 08 Civic AT, it appears that DFCO occurs when you let completely out of the gas, then the Grade-logic of the trans keeps it in DFCO as you lose speed by downshifting as the engine reaches 1000-1100 rpm. It will keep downshifting and keeping it above 1000 rpm (and in DFCO) until about 12-15 mph.

But it's not always 100% of the time when you lift off the gas that it will go into DFCO. I noticed this AM I was doing about 30 mph, lifted off the gas and it stayed out of DFCO. At least that once. So I'm not sure what the logic is, but the scangauge definately shows when it's in. 9999 mpg and open loop.

Now if I could just figure out when the fuel-economy I-vtec mode is active....

I watched for DFCO this morning. On my 08 Civic AT, it appears that DFCO occurs when you let completely out of the gas, then the Grade-logic of the trans keeps it in DFCO as you lose speed by downshifting as the engine reaches 1000-1100 rpm. It will keep downshifting and keeping it above 1000 rpm (and in DFCO) until about 12-15 mph.

But it's not always 100% of the time when you lift off the gas that it will go into DFCO. I noticed this AM I was doing about 30 mph, lifted off the gas and it stayed out of DFCO. At least that once. So I'm not sure what the logic is, but the scangauge definately shows when it's in. 9999 mpg and open loop.

Now if I could just figure out when the fuel-economy I-vtec mode is active....

Thanks man!

I'm finding this is varying for me. At least from a Scangauge standpoint; I think the civic is working fine.

A short while ago, I noticed my scangauge was showing cutoff occuring every time I let go of the pedal...even if I was at a complete stop, idling. Obviously that was wrong and screwing up my counters. So I unplugged and replugged in the scangauge (from the device...not the ODBII port) and that went away. So I figured it was a momentary glitch.

But now it's not showing at all the cutoff. I have the TPS cutoff set at 18 (I idle at 14), and no matter what happens, the gauge doesn't register the cutoff. I do think the car is doing it, as when it hits ~1100rpms or so it feels like it kicks back in. But the gauge still doesn't show it. And I unplugged & replugged again to no avail.

I'll post this in the scangauge forum as well, but anyone have any ideas?

Thanks
-Mike

I'm finding this is varying for me. At least from a Scangauge standpoint; I think the civic is working fine.

A short while ago, I noticed my scangauge was showing cutoff occuring every time I let go of the pedal...even if I was at a complete stop, idling. Obviously that was wrong and screwing up my counters. So I unplugged and replugged in the scangauge (from the device...not the ODBII port) and that went away. So I figured it was a momentary glitch.

But now it's not showing at all the cutoff. I have the TPS cutoff set at 18 (I idle at 14), and no matter what happens, the gauge doesn't register the cutoff. I do think the car is doing it, as when it hits ~1100rpms or so it feels like it kicks back in. But the gauge still doesn't show it. And I unplugged & replugged again to no avail.

I'll post this in the scangauge forum as well, but anyone have any ideas?

Thanks
-Mike

Hope you get that figured out lol. Must be frustrating trying to get the correct readings.


When you guys with a SG adjust the TPS #s (18, 14, whatever), does it change stuff on the car or is it just to calibrate the SG?

It could affect some of the MPG calculated readings but I think its only for our visual benefit. If the engine is DFCO, it will still DFCO whether or not the SG is reporting it. If its bothering you, just turn it off by setting the CUTOFF to 0.

It's not bothering me. I just want it to be accurate. It used to work; it just doesn't now, and that's what bothers me.

The fact that I get a reported 120mpg as opposed to a 9999mpg really doesn't bother me much either, and for the short amount of time that I am in DFCO, it probably wouldn't throw it off too much. (we're talking about .30 gph vs 0.0 gph for a few seconds here and there) I just want to make sure it's working right.

-Mike

Update:
It seems to show the 9999 ONLY when I have the LP gauge up. If I remove the gauge, then it doesn't show 9999 (or even 0.0gph). Putting the gauge back up makes it work properly again.

This blows my mind. How does it figure out gph then?

-Mike

It seems to show the 9999 ONLY when I have the LP gauge up. If I remove the gauge, then it doesn't show 9999 (or even 0.0gph). Putting the gauge back up makes it work properly again.

Same story here. I just got a SG2 a month ago. It was indicating DFCO just fine. Now it doesn't show DFCO (i.e. the 9999) unless the LP guage is showing. This seems to be a SG2 problem (as apposed to a Civic problem) since it can properly identify DFCO when LP is showing.

Does Linear-Logic know about this problem? Are they working on a fix?

It's not a major problem but it does limit me to just 3 useful gauges since I would not normally choose the LP gauge.

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Definitely annoying.

The LP Gauge to me is useless. To some, it might be useful, I don't know.
I could understand if the sgii wasn't monitoring the sensor if it wasn't chosen as a gauge...but as digi just pointed out, along with me, it has to somehow because it used to work without the LP gauge up!

For me, I don't have a 4th gauge that I really need up, so it's not that big of a deal. The two I mainly use are MPG (obviously!) and TPS. I haven't yet figured out how to properly use LOD and some other one (TGT?) that someone mentioned in another thread.

-Mike

I sent a email to service@linear-logic.com yesterday regarding this. No reply so far.

After posting about the SG2 DFCO problem here, I ran across another thread called "No more DFCO" in the ScanGuage forum. Seems to be a common problem for 8th gen Civics:

http://www.cleanmpg.com/forums/showthread.php?t=14754

@phlack, I see you've posted there.

I'll post on that thread if Linear-Logic responds to my email since we're straying off-topic here.

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From the factory service manual, fuel cutoff occurs over 800 rpm (AT) or 820 rpm (MT). From personal experience (as reported by SGII), it seems to be just a bit higher than this. Also, it won't engage when it's too cold. I haven't been able to correlate this to a specific engine coolant temp, which makes me think it's tied into transmission temp.

I found that DFCO engages under the following criteria:

water Temp above 150F
MPH: 30-33, 37-above (can occur at lower speeds but is hit or miss depending on grade-logic)
TPS: ~14 (sometimes it'll engage at 15, but generally you're not depresseing the pedal)

I have also found (like others) that 9999MPG is only displayed with the LP gauge OPEN.

What does open and closed loop mean?

What does open and closed loop mean?

A good question but always remember that google is your friend :) : http://www.google.com/search?q=open+loop+closed+loop+engine
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