DFCO Clarification

[L83Crazy]

What I am experiencing is on decel I am very rich at .73 lambda.

After driving for approximately 10-15 mins it finally shuts off my injectors on decel like DFCO is designed.

My research is revealing a possible catalyst setting or it's a hidden parameter we don't have access to and this is normal.

For whatever reason I have never had this problem in the past.

Only thing I have changed prior to noticing this is dialing in my MAF calibration.

Once it was dialed in, I switched back to closed loop and started noticing this.

I tried changing MAF parameters in the 2400-3000hz which is where I land on decel but did not change my a/f. However it was a small adjustment.

If this is normal, is there a way I can at least get this to command 1.0 lambda instead of just pouring gas into my engine during decel?

Or am I missing something here?

I am attaching logs from the same drive. About 5mins apart. One showing how my injectors stay on during decel and then injectors disabling during decel.

[GHuggins]

It's usually the lower end of the airmass model. I didn't look at the log, but that's if dfco itself isnt working. Just make sure it's not evap purge or something like that.

[DSteck]

You’re right that it’s a catalyst related situation which means there will likely never be a publicly defined way to fix it.

[smokeshow]

Its probably trying to run POPD or something similar...but you've stripped out too much shit for it to accomplish anything. So it gives up after a number of attempts and gives you DFCO back. There's a ton of stuff just switched around willy nilly in this file...SOME diagnostics have to pass before others can run. If it were me I'd go back to stock and start again...

[GHuggins]

Yeah, Smoke's not wrong. There are a lot of things in there that don't make any sense at all and honestly some of it like the weird hump in the torque model probably isn't helping any. SOI is most likely costing you some power on its own. There are certain things that need to take place with "certain delete's" as to what the ECM's routines are looking for and will run test for. Without being able to alter said items it will keep trying to light the cats off and run rear O2 and cat test. This is why I was saying to make sure it's not evap earlier. I see evap purge take place a lot on decel for some of this that will always throw things off if not corrected. Best to have the cats and let it do it's thing...

[L83Crazy]

The tune is a Whipple provided calibration with their kit I installed. I did some power enrichment and trans adjustments. Yes I have heard plenty of bad things about their tune.. It worked well with whipple kit plus long tubes. All I have done is put on a 4" intake and re-calibrated the maf and now I am encountering this problem. The end goal is a proper tune, but I'd love to learn as much as I can til then. I keep going back to the whipple intake tube and factory airbox. At least works lol. Figured I could get away with the intake and a maf re-cal but obviously not if the tune is bad to begin with. Might be time to hang it up and let you professionals step in. I appreciate the help and patience for a rookie like me.

[TriPinTaZ]

Since this wasn't an issue before your MAF recalibration and change in intake tube diameter, the solution can potentially be found in the virtual torque tables. It's possible that this is actually a torque related issue.

HPTuners bent a knee to the EPA and removed some important settings and won't define others. I've even sent them some specific things and they won't add it. EPA overreach at it finest. They need to worry about much greater issues than us race car folk.

[GHuggins]

This is a whipple tune? They must be doing them differently now because I've never seen one from them that had the VE or torque models changed. The 5.3's have that hump, but not as pronounced as it is in the posted tune. I've also never seen the injectors changed like that before. The SOI makes sense now coming from them. Whipple's always just jacked the "boundaries" through the roof like that.

[DSteck]

This specific issue is something HPT never had defined and never will. It's an annoying thing that makes even a bone stock car run like crap on decel.

[L83Crazy]

I am going to adjust my VT in that area and see what happens. Changing tq model had no effect. I had random rapid throttle issues when I first installed the kit. I went back and forth with whipple and by the 5th tune the issue was at its best but still present from time to time. I posted about that issue when it came up again with a larger throttle body. I have since gone back to factory throttle body and now just trying to iron out this new situation with an intake. Then I was hoping to ride this out til I get a proper tune.

DFCO does begin to work at the same spot of my drive home from work.

I may swap my factory air box and whipple tune back on and run the whipple tune back in to make sure it's not related to something else.

I still need to test my purge valve.

[L83Crazy]

Verified my purge valve is not pulling vacuum when commanded sealed. I have access to GDS2 and MDI.

The fact DFCO begins to work at the same spot on my drive to and from work has me believing the vehicle is waiting for some sort of test to pass or its temperature related.

A couple of things to note..

First, I changed over my intake right as the weather outside went from 30-40deg to now 0 to -5deg. Maybe this is normal when ambient temp is this cold?

My attached logs show coolant temp around 180 when DFCO did and did not work on same drive. DFCO set to operate after 86deg ECT. Which has me thinking it could be ambient.

Second, (stupid but curious question incoming) I have had my cats deleted for some time and codes ignored. I have left them plugged in and ziptied up out of the way. Didn't want the connectors getting full of crap or try and cover them up. If they're under the truck, in these cold ambient temps, could it be taking a real long time for them to heat up in which is not allowing dfco? Clearly I have a lack of understanding all that is needed for DFCO to operate. Still figuring that out..

If I decel and place trans in manual mode and make the engine brake the truck it will activate DFCO. I can watch the wideband go from .73 to full lean once I force a downshift.

[DSteck]

Check your PMs.