LNF- Torque Management Inj Disable kills DFCO- WTF?

[oldskool]

So can anyone comment on the effect of going with 15 in all cells in this table?

Since i last posted in this thread, i've gone catless open downpipe. I disabled all rear O2 codes and have no MIL/CELs. The car seems to run great, except that with the stock inj disable table, my fuel cut is not working correctly now. with the cat/exhaust and rear O2 in place it would cut upon lifting the throttle and only resume well below 2000rpm. now it resumes fuel at higher rpm and seems to be random.

I'm thinking of going all 15s but i don't want to encourage misfires. I don't have GMS1 and i don't NLS for what its worth.

[Terminator2]

So can anyone comment on the effect of going with 15 in all cells in this table?

Since i last posted in this thread, i've gone catless open downpipe. I disabled all rear O2 codes and have no MIL/CELs. The car seems to run great, except that with the stock inj disable table, my fuel cut is not working correctly now. with the cat/exhaust and rear O2 in place it would cut upon lifting the throttle and only resume well below 2000rpm. now it resumes fuel at higher rpm and seems to be random.

I'm thinking of going all 15s but i don't want to encourage misfires. I don't have GMS1 and i don't NLS for what its worth.

I do not think setting it to all 15s would be a good idea because it tells all 4 injectors to cut in all of the different undefined modes.

[oldskool]

should i inch the first three columns up until my fuel cut is back to normal? I have a feeling it has a lot to do with not having a rear O2 - even though there are no codes/MILs, that is the only electronic that's changed. why would going catless cause a change in fuel cut?

Anyone running catless with no rear O2 experience this?

[Iam Broke]

Sorry, catless with rear O2, angled bung, no issues except an occasional too lean response immature on a long DFCO. No CEL.

My table is back to stock since running the MAF relocate.

[Terminator2]

should i inch the first three columns up until my fuel cut is back to normal? I have a feeling it has a lot to do with not having a rear O2 - even though there are no codes/MILs, that is the only electronic that's changed. why would going catless cause a change in fuel cut?

Anyone running catless with no rear O2 experience this?

Even if you put the table back to the stock settings it still does not cut the injectors on decel?

[gmtech16450yz]

Rear O2 tests are tied to DFCO, in other words the tests don't run unless DFCO is active or inactive. I would assume without a post cat O2, and disabling all rear O2 tests, that it might actually disable DFCO. They might have to have the rear O2 signal to monitor DFCO. I have a feeling you aren't going to get DFCO working without a rear O2.

On trying to figure out the cyl disable table...
I tried something with the far left column of all 15's, I put zero's one at a time in place of a 15, it looks like it needs ALL the 15's in the far right column for DFCO to work properly. I'm still thinking the rows are the modes and the whole far right column is for DFCO. If you take any of the 15's out, you loose DFCO in certain modes, like during shifts but not on decel. I've been running all 15's in the far right and everything else zeroed with no problems.

[kuprito]

What is better, everything 15's or stock?

[Iam Broke]

Far right column all 15's for DFCO, rest of the columns all zeros.

[kuprito]

I'll try it tomorrow.

Thank you very much!

[Ch1ck3n]

Good read guys, thanks for all the great info, definitely going to look into this stuff once I'm back home.. Being underway sucks. I seem to read all kinds of crazy good stuff as soon as we leave home port and I can't go out and screw with the car

[BackyardTurbo_FTW]

The 0's 15's method is really the best after playing with it a bit myself. Especially works good on cars with BOV's since it goes into DFCO almost immediately when you lift the throttle with any sort of load. Thanks GM Tech for the tip again

[CDNITE]

A buddy from Bosch sent me a ton of PCM/ECU info... When I saw this I remembered this Thread...

I hope this helps some:


INJOFFPATTERN Torque reduction by injection fade out. Different, repeating fade out patterns
can be defined for several full power strokes of the engine (720° crank or 2
full rotations). This prevents single cylinders from cooling down too much
and makes it possible to find optimal patterns.
Example 4 cylinder engine:

The cylinders are assigned bitwise, the lowest bit represents cylinder 1 in firing order (FO1), e.g.
injoff = 1:
- First power stroke 0°-720°: Cylinder 1 (FO1) is faded out
- Second power stroke 720°-1440°: Cylinder 2 (FO2) is faded out
- Third Power stroke 1440°-2160°: Cylinder 3 (FO3) is faded out
- Fourth Power stroke 2160°-2880°: Cylinder 4 (FO4) is faded out
- Fifth Power stroke 2880°-3600°: Cylinder 1 (FO1) is faded out

[Iam Broke]

Thanks, that explains it a lot.

[T-Man]

That's some nice info there. Do you have anything else that you could please share?

[CDNITE]

That's some nice info there. Do you have anything else that you could please share?

Yes I'm sure I do...

Don't wanna get anyone in trouble though...

Maybe if you asked very specific questions I could "paraphrase"...

Know what I'm saying... Chris are you picking this up?

[Pandion]

A buddy from Bosch sent me a ton of PCM/ECU info... When I saw this I remembered this Thread...

I hope this helps some:


INJOFFPATTERN Torque reduction by injection fade out. Different, repeating fade out patterns
can be defined for several full power strokes of the engine (720° crank or 2
full rotations). This prevents single cylinders from cooling down too much
and makes it possible to find optimal patterns.
Example 4 cylinder engine:

The cylinders are assigned bitwise, the lowest bit represents cylinder 1 in firing order (FO1), e.g.
injoff = 1:
- First power stroke 0°-720°: Cylinder 1 (FO1) is faded out
- Second power stroke 720°-1440°: Cylinder 2 (FO2) is faded out
- Third Power stroke 1440°-2160°: Cylinder 3 (FO3) is faded out
- Fourth Power stroke 2160°-2880°: Cylinder 4 (FO4) is faded out
- Fifth Power stroke 2880°-3600°: Cylinder 1 (FO1) is faded out

I'm not sure I understand this correctly. I think its saying that it cuts cyl 1 on its power stroke then after so many degrees of rotation it cuts cyl 2 and so on. Is that right? And thats only how it works if set to 1's? So 15's means it cuts all 4 at the same time?

[fr0stb1t3]

Yeah, zeros and fifteens down the right column cleared up a ton of my NLS issues from the stock tables.

[rnjmur]

I'm not sure I understand this correctly. I think its saying that it cuts cyl 1 on its power stroke then after so many degrees of rotation it cuts cyl 2 and so on. Is that right? And thats only how it works if set to 1's? So 15's means it cuts all 4 at the same time?

1111 = 15 which means all cylinders are cut. The way I understand is that stock there are 4 "profiles" which fade injectors on different cylinders in a repeating pattern to prevent specific cylinders from cooling more than the others. For example:

DFCO begins:
Powerstroke 1 - cyl 1 cuts; Powerstroke 2 - cyl 1 & 2 cut; Powerstroke 3 cyl 1, 2, & 3 cut; Powerstroke 4 - cyl 1, 2, 3 & 4 cut; Powerstroke 5 - cyl 2 cuts; Powerstroke 6 - cyl 3 & 4 cut;, Powerstroke 7 - cyl 1, 2, & 3 cut; Powerstroke 8 - cyl 1, 2, 3 & 4; Powerstroke 9 - cyl 3 cuts; Powerstroke 10 - cyl 1 & 2 cut; Powerstroke 11 - cyl 2, 3 & 4 cut; Powerstroke 12 - cyl 1, 2, 3 & 4; Powerstroke 13 - cyl 4 cuts; Powerstroke 14 - cyl 3 & 4 cut; Powerstroke 15 - cyl 3, 4 & 5; Powerstroke 16 - cyl 1, 2, 3 & 4 cut; Powerstroke 17 (the pattern starts over) - cyl 1 cuts ... etc

[rnjmur]

Yeah, zeros and fifteens down the right column cleared up a ton of my NLS issues from the stock tables.

If you put a zero it will NOT cut any cylinders during those powerstrokes.

[CDNITE]

I'm not sure I understand this correctly. I think its saying that it cuts cyl 1 on its power stroke then after so many degrees of rotation it cuts cyl 2 and so on. Is that right? And thats only how it works if set to 1's? So 15's means it cuts all 4 at the same time?

Maybe this helps?

A cylinder individual injection cut can be done to reduce engine torque for functions such as traction control, speed limiter and rev-limiter. This requested cut off level is made via the signal injoff.

The values in XXXXXXX represent 10-bit binary values where each bit corresponds to a cylinder. The first cylinder in the firing order is the
least-significant bit (or right-most) position.

To cut injection for a cylinder, place a ‘1’ in its bit location. The number
of cylinder injections cut should be made to increase as the cut off value injoff increases.

This cut pattern is switched every 720 degrees of crankshaft angle.
When changing used cylinder number you have to readjust injection cut.

Example INJOFFPATTERN for a 4-cyl engine:
injoff - - - - >
y/x 0 1 2 3 4
0 0 1 (=0001b) 3 (=0011b) 7 (=0111b) 15 (=1111b)
1 0 2 (=0010b) 12 (=1100b) 7 (=0111b) 15 (=1111b)
2 0 4 (=0100b) 3 (=0011b) 14(=1110b) 15 (=1111b)
3 0 8 (=1000b) 12 (=1100b) 13(=1110b) 15 (=1111b)

injoff = 0 : no cylinder injections are cut

injoff = 2 : cut cylinders 1 and 2, then after 720 degrees cut cylinders 3 and 4, and so on

injoff = 4 : all cylinder injections are cut


--Christian