VCT Disabled State and Spark Jumping to different MP's while WOT

[trick76cj5]

Ok, again, thanks everyone for the help! I've learned a lot over the past month working on this tuning and I finally have things running pretty smooth. The truck is really starting to run good and feel smooth.

I had the opportunity to make some full throttle runs from 55-90 while passing. I've not pushed the tune that hard up to this point as I wanted to make sure it was safe. I had a few weird discoveries in the higher rpm's, and i'm hoping you guys can help shed some light on things:

1) My VCT is going to a "disabled" state, i can't understand what would drive that, but it happened on both pulls (4:47:03 and 4:49:34)

2) Additionally, I have OP turned on in the MP Configuration, but it doesn't appear spark is entering the OP table. And, it comes out of MP0 during the run and floats around (MP0 had been my full load table before OP was turned on). This drift appears to correlate with the knock event.

Let me know if anyone sees what may be causing my issues.

Thanks!

Attachment 145770
Attachment 145771

*Note: this was posted under an older thread I had created, but with no response I thought I should make it a new thread since it is a significantly different topic. I am deleting my other thread so its not in here twice. Thanks for understanding :-D

[trick76cj5]

Was able to make a longer run this morning, i pulled a little timing at 4500 to help with the knock, but its still there so will be pulling a little more. I'm clearly running into some toque reductions, but i'm not sure where to start.

Just after the VCT Disable my Driver Demand Limit Sources goes to Combustion Stability, and then eventually to Insufficient Fuel Flow.

My Throttle Angle source is tied to TQ Red. < Driver Demand and my toque source is TQ Based Decel while my throttle is at 99.5%.

I may be running into logging speed and events not lining up in such a short period of time, so i'm looking for some help.

Here is the latest log, the full throttle run is at 8:34:34:

53am.hpl

[trick76cj5]

Ok, one last data point, on my way home i got a run through 2 gears, it held until i went into 4th gear where the VCT disables while 3rd gear seemed to hold. I also made some adjustments on this tune for torque limits and driver demand back to what Sirius had posted previously.

53pm2.hpl
v3_Mod6.hpt

I know this is either weird, or i'm just missing something very obvious. Thanks for both your patience and assistance!

[SiriusC1024]

Instead of disabling VCT and your other changes, command MP0 at the Distance Tables.

[trick76cj5]

Instead of disabling VCT and your other changes, command MP0 at the Distance Tables.

Thanks for the response!

I actually didn't disable the VCT, the ECU disabled the VCT for some reason. The VCT should have been running off the schedule for OP which i had turned on in the Distance Tables based on your file. I'm running into a couple issues:

1) The spark source doesn't really go into OP, it will sometimes go 50/50 OP and MP0 sometimes, but not fully OP. On these runs, the spark source starts at MP0 but then drifts up to MP1 and MP2. This is problematic because MP1 and MP2 run more timing, and then i run into knock.

2) My VCT follows the OP timing until about 4500-4800 rpm and then drops to 0, shortly after my VCT Schedule mode changes from OP to Disabled. I think there is an error occurring here, but i'm not getting any codes when i check.

I'm not sure if the drifting spark timing is messing up the VCT, or if the VCT is messing up the spark.

I'm also not sure if my VCT is just going bad, or if i have a tuning issue.

I'm going to try a tune on Monday where i disable the OP setting and just set the MP for best drivability to manage the VCT angle at full throttle and see if that fixes it. Maybe my ECU doesn't like the OP settings for some reason.

Let me know if anyone else has any thoughts. Thanks!

[Pistol_91]

If the cam angles in OP are similar to those on any of your MPs. It will run or blend into that specific MP. For example, If MP 6 is 0,0 and you have cam angles 0,0 on your OP angles between 4-5k RPM, then between 4-5k you will see it using MP 6. The only way to have full control over which MP it will be using while in OP is to match whatever the cam angles are from that specific MP, into your OP angles.

[trick76cj5]

If the cam angles in OP are similar to those on any of your MPs. It will run or blend into that specific MP. For example, If MP 6 is 0,0 and you have cam angles 0,0 on your OP angles between 4-5k RPM, then between 4-5k you will see it using MP 6. The only way to have full control over which MP it will be using while in OP is to match whatever the cam angles are from that specific MP, into your OP angles.

Thanks, i was curious if something like that was happening. This is actually very helpful insight, I wondered what drove which MP it was using . . . so the distance tables determine the VCT angle and teh MP's are linked to the VCT angle. Am I understanding this correctly?

Why is there an OP spark table if it doesn't use it while in OP? Did I overlook a setting I needed to change, or do the vehicles that didn't utilize OP from the factory not use the OP spark table?

Any ideas why my VCT disables during the run?

[Pistol_91]

You're correct, if the vehicle doesn't normally use MP OP then it won't work even if you enable it. I have tried enabling MP OP to utilize under mapped points configuration but it doesn't do anything on my 2020 GT. The only OP table that is used is under the VCT tab for cam angles, hence why VCT schedule will say OP. Other than that everything else, spark, SD, Torque model will be pulled from mapped points related to the cam angles you have under the VCT OP table. Im on my phone currently so not familiar with your tune but if your MP 0 has cam angles 0,0 and you change your entire RPM range of cam angles to 0,0 under VCT OP, then under WOT conditions you will notice it will run in MP 0 100%. Thus pulling spark, SD, and torque model from MP 0.

As for VCT disabled, I have experienced this before near idle conditions but I am not exactly sure why or what it means. The only thing I can think of is it is "hunting" for the correct table to use during certain conditions and is unsure to use, OP, OS, Best fuel economy etc etc. So during that time, at those specific cam angles it is at in that moment, it is hunting. That's why I have my tune set up under WOT to run 100% on a given mapped point and not blend. It also makes it easier to tune for spark. That is my theory behind disabled. Hope this helps.

[trick76cj5]

You're correct, if the vehicle doesn't normally use MP OP then it won't work even if you enable it. I have tried enabling MP OP to utilize under mapped points configuration but it doesn't do anything on my 2020 GT. The only OP table that is used is under the VCT tab for cam angles, hence why VCT schedule will say OP. Other than that everything else, spark, SD, Torque model will be pulled from mapped points related to the cam angles you have under the VCT OP table. Im on my phone currently so not familiar with your tune but if your MP 0 has cam angles 0,0 and you change your entire RPM range of cam angles to 0,0 under VCT OP, then under WOT conditions you will notice it will run in MP 0 100%. Thus pulling spark, SD, and torque model from MP 0.

As for VCT disabled, I have experienced this before near idle conditions but I am not exactly sure why or what it means. The only thing I can think of is it is "hunting" for the correct table to use during certain conditions and is unsure to use, OP, OS, Best fuel economy etc etc. So during that time, at those specific cam angles it is at in that moment, it is hunting. That's why I have my tune set up under WOT to run 100% on a given mapped point and not blend. It also makes it easier to tune for spark. That is my theory behind disabled. Hope this helps.

Thanks so much, that helps.

With this new understanding, i went through my MP's today and matched the MP's where Best Fuel Econ and Best Drivability meet to help keep the engine from hunting when its really close to both of these tables. This seems to have smoothed the engine performance with less small "jolts" felt as the engine was changing tables that were too far apart.

All this seemed great, but i'm just checking my log from the way home. I had a chance to get on it on a back road (traffic was brutal tonight!), anyway, everything ran fine, no CEL and truck seemed to pull just fine, but now i'm seeing the VCT still transferred into OP and then disabled . . . but it stayed disabled the whole way home.

First, i figured by disabling the table in the Mapped Points Configuration table, it would shut it off . . . evidentially that was an incorrect assumption. So, i went and set the rest of the triggers for OP back to stock, but left the safe tuning in the spark table just in case.

Second, the fact that VCT never re-enabled makes me think this may be a hard part issue. I put solenoids on when i put this engine in . . . not saying the replacements couldn't go bad, but it doesn't seem likely. Anyone ever run into this?

I'll run it again tomorrow with the updated tune as mentioned above, but I hate unsolved mysteries lol.

Here is the VCT, its showing OP Power and its starting to add retard as i get over 4000 rpm. It shouldn't be running OP, but i'll get that fixed:
VCT_OP.png

It looks like the VCT's turn off before they are commanded . . .this could be the lag associated with the signal refresh, or it could be the VCT's inability to hold the timing under full load (doesnt' sound feasible, but it's all i got) Also, i noticed the torque request is 663 ft/lbs at this point:
VCT_Before_Failure.png

Right about the time the VCT goes to the disabled state, the torque request also drops to 575:
VCT_Disabled.png

The VCT stays disabled this time, almost like it is in a limp mode of some sort, it also stays in MP0.

Did i hit a torque limit that i've overlooked? Any thoughts?

56pm3.hpl
v4_Mod1.hpt

Thanks again everyone for all the help, just about the time I think i have stuff figured out pretty well, i learn a ton more! You guys have all be such great help!

[Pistol_91]

I personally would just disable one or the other and use 1 distance table for normal driving. Your OP and PE are set exactly the same and take both of them a good second to enable WOT. I would lower them a bit or play around with them to see when they enable after you go full throttle.

Looks like what may be the culprit is the "Trans shift mod" in torque source right before it goes into Disabled. Right after that happens your lambda goes very rich for a split second, Spark is cut to a negative value, and the VCT schedule goes to disabled. Not exactly sure what that is but seems like a torque reduction under transmission when upshifting. Maybe someone else can confirm. It's definitely some kind of limit

[trick76cj5]

Ok, thanks for that! I tried to make OP turn off on this last tune, but i missed something. The tune I run this morning will hopefully turn OP back off.

The trans shift mod is torque reduction on my shift. It is interesting that those happen at the same time, I've been thinking i need to dial that way back as the truck really seems to take a second to recover from a shift.

I think you pointed out something I have been missing too, from a stop, when i hit the throttle hard, it is really feels like it bogs . . . this could be related to the delayed PE. I will adjust that in this tune this morning too and see if that helps out.

[trick76cj5]

Quick update!

I pulled codes this morning and I have a pending code for Bank 2 Cam Position Sensor. So, i think this is the culprit for the disable VCT status!

I'll check the wiring and replace the sensor when i get back from my next business trip and I'll report back if that cleared up that issue.

Regarding the rest of the tuning. I finally understand what people were talking about the tables jumping around, and now that i've smoothed out the VCT tables, my reading is very steady while cruising, I have much more low end torque when throttling in while on the interstate w/o driving a down shift, its a significant improvement.

Also, I pulled my Power Enrichment in much sooner so its kicking in on the interstate when i'm under more load and that is helping keep me out of knock.

Thanks again everyone! I'm finally starting to see the light at the end of the tunnel.

[Pistol_91]

No problem. It's perfectly ok to have VCT schedule use OP. It's also ok to disable it. It's up to you.