DFCO and Deceleration Eleanment.

[damanx]

I've been watching the blm/int numbers.

BLM's seem ok, with a few needed adjustments in the cells that I've not spent enough time in to get a decent idea of where they are sitting other than looking pretty rich.

But those are the cells that would be in the driving range above 65 mph and 2200 rpm.

Those seem easy enough to correct.

The ones that I am concerned with are the 20kpa and 30kpa cells that ALL show rich.

My truck idles in the 38-45 kpa range and cruise runs 45-55 range.

Those cells look good.

The concern are the cells in the 20 and 30kpa columns that only populate upon deceleration, and it's not so much the value of them being close to 128 as it is the spike in the INT dropping to numbers like 100.

It seems that my setup, when letting off the gas and just coasting and slowing down, the 30kpa column is pretty much where the engine stays.

When I let off the gas and then get on the brake, that is when the 20kpa cells populate.

Best I can tell, the Deceleration Enleanment plays a bigger part when you simply let off the gas for a few seconds and then either accelerate or apply to maintain the speed you have dropped down to, for a which a better example would be say dropping from 55-50, maybe 45.

If I understand correctly, and if what I am seeing applies to this thinking, then DFCO is more likely to be active from a deceleration to a stop. Like going from 45 to oh shit, I'm not going to make that yellow so I should go ahead and stop. I.E. Going from 50kpa to 20kpa in a short period of time.

Is my understanding of this as explained above correct?

If so, good, if not, please correct me before I tweak shit the wrong way.

As it stands, the Decel Enleanment Factor is valued at .371, and I'm not sure if this value should go up or down.

Thoughts, concerns, criticism and jokes welcomed.

(next episode will be the questions about the spikes in the INT going into the 150's when applying moderate amount of pedal.)

[RobertISaar]

INT shooting down with quick throttle closing and shooting up with quick throttle openings = not enough fuel being removed when in DE and not enough fuel being added in AE.

assuming the trims look good in steady-state, that is where you will be playing with stuff to get mixture correct during transients.

[EagleMark]

Where's the data log? Are you back to $42? Did you ever get a timing table close to your... 3.4L engine?

You should get the fueling VE tables close as a first step. But when you make big timing changes it will change your BLM/VE tables...

When data logging for initial BLM to VE adjustments disable DFCO (DFCO - CTS to Enable) and Decel Enlean (DE - Enleanment Factor to 0.000) Then do some manual smoothing of the VE table, sanity check in 3D so the table looks correct.

When done enable them and forget what BLM says when data logging. It won't be usable data. It's really not critical in anything except emissions. Very little help to MPG if any?

DFCO is hard to enter. Hard deceleration would be a situation when it does enter DFCO. Scenario would be highway speeds of say 75+ MPH and let off gas going downhill then the qualifiers can be met and wait for timer of about 2 seconds, most times you can feel it as an engine brake and when in DFCO the BPW should stop and BLM will be 128 IIRC?

(next episode will be the questions about the spikes in the INT going into the 150's when applying moderate amount of pedal.)

INT going up upon acceleration is a sign of needing more AE.

[damanx]

I decided to stick with the 7747 ecm and continue working on that.

Attached is the bin and datalog for the drive home this morning.

The original DE factor is .371

There are 2 parts, one is "test". That one is with the DE Eleanment factor set to .431 and the log marked "home" has the factor set to .300.

I wasn't sure which way to go on the factor, so I tried one with .06 higher and one .06 less, and why I picked .06, I don't know other than it seemed like a reasonable amount.

[damanx]

Everybody LOVES pictures........lol

Adding screenshots of the home.xdl monitors where the INT values are in question. (maybe seeing them all in one screen might help understand better where and why.)

[EagleMark]

I know your looking into and working on Decel fueling... but looking at your VE1 table I think you need to take a step back and clean it up first. It has some pretty big dips, spikes and a strange spot at 20 MAP 400 RPM. May be because of the way the VE2 table is set?

Also not a sign of knock counts anywhere... I know you've been working on MPG and I think there's some room here for more spark advance to increase MPG.

Also saw you INT rise and it does look like needing more AE.

So I made some adjustments and some smoothing to the VE1 table and spark advance as well as added a little AE, take a look at this bin and compare it to yours to see if you want to run it. If you do? You may need to do the BLM data and VE adjustments again, I'm worried about idle only really as that was a area way out of smooth as far as the 3d table goes.

As I said earlier the best way to get the fueling VE tables for decel area is to have the Decel and DFCO turned off. Then do your BLM data to adjust VE as normal. Turn stuff back on and see where numbers go... but normally it won't be the 128 your shooting for because of the Decel Enleanment...

BTW your BLM data in the home log was great! Your really splitting hairs trying to make that any better!

[damanx]

Thanks for looking at that Mark.

I'll run that BIN you posted tonight and tomorrow morning and get the logs.

As far as advance goes, I'm not sure that I have much more to go as one of the things I've been working on is getting the knocks down.

I think it's pretty close.

In regards togas mileage, I have pretty much accepted that 21-22 hwy is probably as good as it's going to get right now.

I don't know if it will get significantly better, even with a fresh rebuilt transmission.