DFCO setting for more mileage?

[Tran2la]

I have HP Tuners and would like to tune the DFCO to give me a tad more fuel mileage under deceleration.

I have the 2013 L99/LS3 with an automatic. I also have a wideband and I have seen that sometimes it does the fuel cutoff under decal and other times it does not. I have had it tuned as well.

I would like to have it cut fuel till it drops down to somewhere around 1500 rpm but in HP Tuners, it seems that the enable and disable is through TPS.

Is that where I do the adjustments? And what would you guys recommend?

[Tran2la]

Figured it out. Changed CylAir to a higher figure and now it works. Guess with the new cam, stock figures were too low and engine CylAir never went that low to enable.

[acammer]

There are a few different things you can do to extend the range of DFCO. I have mine come in fast, and stay on all the way down to 1200rpm. If you drive with DFCO in mind you can definitely pick up some MPGs.

[Tran2la]

Originally Posted by acammer

There are a few different things you can do to extend the range of DFCO. I have mine come in fast, and stay on all the way down to 1200rpm. If you drive with DFCO in mind you can definitely pick up some MPGs.

What things can you do? How do you have it set up to come on fast? Not much info revealed from your post. Do share.
As for enable and disable rpm settings, I have mine set at 950/850. And even with that low of a Rpm, it will still shut down around 1100ish due to MPH settings. And it works out to never stall.

Hope others chime in to reveal their settings.

[acammer]

Originally Posted by Tran2la

What things can you do? How do you have it set up to come on fast? Not much info revealed from your post. Do share.
As for enable and disable rpm settings, I have mine set at 950/850. And even with that low of a Rpm, it will still shut down around 1100ish due to MPH settings. And it works out to never stall.

Hope others chime in to reveal their settings.

Here is a screen shot of all the settings I have changed. I could bring my disable values up a few hundreths to get it to run down even further. Those cylair values for the enable and disable will depend on camshaft profile, I pull less vacuum at low rpms, so my values may not work work your setup.

Mine never has any issues coming out of DFCO, whether in gear or stepping on the clutch at just off idle. A well tuned idle will ensure this.

[Tran2la]

You wasn't kidding with the entry speed!

[acammer]

Originally Posted by Tran2la

You wasn't kidding with the entry speed!

It still doesn't happen as fast as I'd like - there must be a preset delay that works on top of the settings you can adjust.

[Tran2la]

Originally Posted by acammer

It still doesn't happen as fast as I'd like - there must be a preset delay that works on top of the settings you can adjust.

I did see a DFCO delay setting but mine is zeroed out. On my car, sometimes, it dos not go into it even though all the parameters are met. I think that the engine load has to be low or something (I'm running Automatic 6l80e). Going downhill it activates every time but uphill, at times it just does not go into it for a while. I did not see any other delays that can be adjusted.

[acammer]

Originally Posted by Tran2la

I did see a DFCO delay setting but mine is zeroed out. On my car, sometimes, it dos not go into it even though all the parameters are met. I think that the engine load has to be low or something (I'm running Automatic 6l80e). Going downhill it activates every time but uphill, at times it just does not go into it for a while. I did not see any other delays that can be adjusted.

I'm sure with an automatic there is an added layer of complexity with DFCO. I know with several other automatic late model vehicles I've driven it seems pretty hard to get the full DFCO and engine braking I would like to see. My wifes 2012 Town & Country for example - it takes FOREVER to actually go into a full DFCO, even when downshifted and at a point where it should be strongly engine braking. I believe it has a lot to do with the PCM still manipulating the throttle - even though I have my foot off the accelerator. I'm not sure, but there may be other trans or throttle parameters you could tweak to further change the response.

The DFCO delay setting is zero on mine as well - that seems like an additional time you can apply to add a static amount of delay time for DFCO entry once all other parameters are met. I've never messed with it.

For me, I want DFCO to be just like it is with my old mechanical diesel truck - when I roll out of the throttle if the driveline will keep the engine turning then the fuel shuts right off.

[ABM Camaro]

Personally if it was me, Thats not where Id look to improve MPG. Id look at the threshold where I can go into power enrichment.

In you HPT, go under your Fuel tab/ Power Enrich/ throttle/ Hot. Stock its about 30% throttle to enter PE. From zero to 3000 RPM range bring that up to 50%. This will tell the computer to look to go into power enrichment above applying 50% throttle in your lower cruising range.

[acammer]

Originally Posted by ABM Camaro

Personally if it was me, Thats not where Id look to improve MPG. Id look at the threshold where I can go into power enrichment.

In you HPT, go under your Fuel tab/ Power Enrich/ throttle/ Hot. Stock its about 30% throttle to enter PE. From zero to 3000 RPM range bring that up to 50%. This will tell the computer to look to go into power enrichment above applying 50% throttle in your lower cruising range.

Concur - I have that strategy in place as well - I have a falling curve from 1000-4000rpm on TPS threshold for PE. It requires 65% at 1000 rpm and then is down to 15% by 4000rpm - so, as the RPMs rise it's easier to get into power enrichment.

[xc_SS/RS]

Originally Posted by acammer

Here is a screen shot of all the settings I have changed. I could bring my disable values up a few hundreths to get it to run down even further. Those cylair values for the enable and disable will depend on camshaft profile, I pull less vacuum at low rpms, so my values may not work work your setup.

Mine never has any issues coming out of DFCO, whether in gear or stepping on the clutch at just off idle. A well tuned idle will ensure this.

Holy crap that cuts in fast lol I'm gonna adjust mine to come on sooner. Interesting seeing your settings!

[acammer]

Originally Posted by xc_SS/RS

Holy crap that cuts in fast lol I'm gonna adjust mine to come on sooner. Interesting seeing your settings!

It doesn't though, I really haven't felt much of any change in the entry time, even with it that aggressive. I kept on halving and halving the values - it seems like it has a good 0.5-1 second delay still to come in.

[xc_SS/RS]

Originally Posted by acammer

It doesn't though, I really haven't felt much of any change in the entry time, even with it that aggressive. I kept on halving and halving the values - it seems like it has a good 0.5-1 second delay still to come in.

What are your spark settings? I know on other E38 pcms (LS7 comes to mind) there are decay settings for dfco which is the ramp rate to your desired dfco spark value. Wonder if the guys at hp tuners could make that available on our cars. Might be the setting you're looking for

Edit: I emailed hptuners support to see if there are additional settings for dfco