DoD/AFM tuning Help Needed

[Dlanor82]

Hi Guys,

I am trying to tune my vehicle (Jeep wrangler JKUR with an L86/8L90e and 37" tires) for maximum fuel economy in city/highway driving.
The L86 has so much torque that in theory, with 4:10 gears, I should be able to have 4Cyl mode active during city/highway driving.
I currently have the DoD/AFM enabled and have tuned the transmission to stay between 1,400 and 2,000 RPM at low throttle.
Now DoD/AFM is enabling itself at at around 16 MPH and is on most of the time.

Here are my questions:

1- In general, will long term use of DoD/AFM affect or damage the engine in any way? Is it better to disable it for a heavy vehicle? I am concerned that the constant enabling/disabling of DoD/AFM will cause internal components to fail prematurely.
2- I use regular gas on my L86. I do hear some knock when the engine RPM is low and instead of downshifting, the engine tries to build cylinder pressure by phasing the cam to create more torque and pull the load. I will try to use premium and see if it makes a difference. But in theory isn't the engine supposed to adjust timing after getting knock feedback from the knock sensors and get rid of the knock ?
3- Is there a way to disable DoD/AFM until a certain RPM ? I would prefer it to engage after 1,500 RPM.
4- Is there a way to disable DoD/AFM until a certain speed? I would prefer it to engage after 40MPH. (Would Min VSS + Min VSS Hyst do it?)

Thank you!

[LSandlteditor]

Hello, Premium should be used...and yes in theory the engine adjusts timing by retarding it, however, it does still get detonation before it realizes it needs to pull some back. If i were you I would disable AFM all together.

[lucas287]

I like your approach! I, too, was hoping AFM could be disabled independently by gear but that's not an option. Only speed. I built an economy tune where I basically locked out 8 gear and enabled AFM by 45 MPH. It gets a solid 24-25 on the highway just by keeping it around 2000 RPM and in 4 cyl mode. 8th gear AFM is almost useless for steady state.

[lucas287]

Also knock learn factor. It will eventually learn not to knock in the load ranges, but, when you're constantly reflashing tunes I think the progress is lost!

I THINK there's a way to tune the SOI tables in the load ranges that you're getting knock but I haven't dabbled too much there.

[LSandlteditor]

Also knock learn factor. It will eventually learn not to knock in the load ranges, but, when you're constantly reflashing tunes I think the progress is lost!

I THINK there's a way to tune the SOI tables in the load ranges that you're getting knock but I haven't dabbled too much there.

Shouldn't touch those tables unless there is a big cam with lots of overlap. And I'm not even sure those tables are relevant in a Gen v setup.

[lucas287]

Shouldn't touch those tables unless there is a big cam with lots of overlap. And I'm not even sure those tables are relevant in a Gen v setup.

Are you referencing the SOI part or the knock learn factor part?

There's HUGE potential in tuning the SOI timing tables on the Gen V platform.

And I wasn't implying modifying the knock learn tables.

[LSandlteditor]

Are you referencing the SOI part or the knock learn factor part?

There's HUGE potential in tuning the SOI timing tables on the Gen V platform.

And I wasn't implying modifying the knock learn tables.

Hmmm....on a stock Cam that doesn't have a bigger fuel lobe?

[LSandlteditor]

Are you referencing the SOI part or the knock learn factor part?

There's HUGE potential in tuning the SOI timing tables on the Gen V platform.

And I wasn't implying modifying the knock learn tables.

I was talking about Start of injection. Yea, plenty to be gained but in this particular setup, DOD mechanical lifters are in the engine which tells me its a stock cam. To get rid of knock there is plenty of other areas to touch rather than SOI. Thats me at least, to each their own. Not stepping on toes brother and didn't mean to be.

[Dlanor82]

Guys, thanks for the replies.

Lsandlteditor: Could you please elaborate on why you believe that I should disable AFM all together? Will it damage the engine prematurely? And yes it is a stock L86 engine with the stock cam. Furthermore, the L86 recommends premium but does not require it. However you believe that premium would eliminate some of the knock correct?

Lucas287: Since I have 4.10 gears and 37" tires, 8th gear kicks in at about 55 MPH and still pulls the car wonderfully because my RPM is about 1400. Could you please let me know how you got the AFM to start at 45 MPH? Also does that mean that you rely on deceleration cut-off for fuel savings when the car is slowing down instead of AFM ? Are there settings that need to be modified for that?

Thanks guys

[LSandlteditor]

Guys, thanks for the replies.

Lsandlteditor: Could you please elaborate on why you believe that I should disable AFM all together? Will it damage the engine prematurely? And yes it is a stock L86 engine with the stock cam. Furthermore, the L86 recommends premium but does not require it. However you believe that premium would eliminate some of the knock correct?

Lucas287: Since I have 4.10 gears and 37" tires, 8th gear kicks in at about 55 MPH and still pulls the car wonderfully because my RPM is about 1400. Could you please let me know how you got the AFM to start at 45 MPH? Also does that mean that you rely on deceleration cut-off for fuel savings when the car is slowing down instead of AFM ? Are there settings that need to be modified for that?

Thanks guys

Sure, your L86 has a 11.5.1 Compression ratio and a heavy vehicle which means in my way of operating that you need premium. I would also get a better spark plug in there that is more resistant to kr. AFM/DOD is the weakest point in all of these engines. Its not hidden information either, DOD lifters will fail...just a matter of when. I like turning it off altogether because many times a DOD lifter can been stuck compressed, this condition can be caused by the VLOM commanding activation or deactivation at the wrong point in the cam’s rotation, either in the ramp, or at the lobe peak. That is why I like turning it off altogether.

[Dlanor82]

Will disabling the DoD be enough to avoid DoD lifter failure or will it just happen anyways eventually?

[LSandlteditor]

If you upload any file, with any modifications, That alone can cause them to try to void your warranty.

[Dlanor82]

I am not eligible for a warranty because the engine/transmission were taken from a totaled 2015.5 Escalade.
I initially had the inherent transmission issues but GM refused to honor the warranty because the donor vehicle was totaled so I had to purchase a replacement from GM.
I am just hoping that the engine will not need the same thing due to lifter issues... Is there a way to avoid the failure in the future?

[lucas287]

I was talking about Start of injection. Yea, plenty to be gained but in this particular setup, DOD mechanical lifters are in the engine which tells me its a stock cam. To get rid of knock there is plenty of other areas to touch rather than SOI. Thats me at least, to each their own. Not stepping on toes brother and didn't mean to be.

Not stepping on my toes at all man! The SOI tables in general look like a complete nightmare and there doesn't seem to be much correlation to what's going on. I've followed many other posts by some of the big shots on here and GHuggins seems to be a big advocate of retarding (lowering the values) in cruise regions where detonation and fuel economy is a concern. In theory it makes sense too. If fuel is injected too soon it's more likely to preignite,...where as you retard the injection a bit closer to spark advance and it seems like it would be more stable. You'd also be injecting at a higher cylinder pressure too which, in theory, should have better atomization? However, what are the trade-offs? If it were that easy, why wouldn't GM do it that way from the factory? IDK. For the record, I couldn't make discernable differences messing with SOI beyond the placebo effect, so I just put it back to stock.

[lucas287]

Lucas287: Since I have 4.10 gears and 37" tires, 8th gear kicks in at about 55 MPH and still pulls the car wonderfully because my RPM is about 1400. Could you please let me know how you got the AFM to start at 45 MPH? Also does that mean that you rely on deceleration cut-off for fuel savings when the car is slowing down instead of AFM ? Are there settings that need to be modified for that?

Thanks guys

Yes, you can modify DFCO too, but it's already very aggressive. I've had mine turned off for a while and I, generally, like it more that way. I can actually coast now instead of slowing down so quickly. But, it makes freeway driving a bit annoying because you can't just lift throttle and drop speed quickly to follow traffic.

8th gear might pull wonderfully when all 8 cylinders are firing, but probably not in AFM mode at only 1,400 RPM. I lock out 8th on my AFM tune so I run more RPM which makes a bit more torque in AFM mode thus holding it much longer. You just have to change the enable speed to whatever you want and then zero out the hysterisis.

[azsteve01]

They have to prove your tune cause the failure...My dealer knows my truck is modified since I have a supercharger sitting on the engine that did not come with it. My fuel sender started failing a year after I put the supercharger on. Took it in, and they investigated and found that it was failing. The tech called me and asked if I had done any work on the fuel pump/sender at all. I informed him that I had not since my supercharger did not require an upgraded fuel pump or injectors. He told me he had to ask since I had put the supercharger on it. When I picked up the truck I let him know that I am honest about these types of things and that I would not claim a warranty on anything that I had changed and that I would warrant it first myself. I am running will within the parameters that GM stock motors that have superchargers on them and not pushing the limits of my engine waiting for something to break...it is just enough to play with....