Timing pull for no reason

[morepowerjoe]

I talked about this in another one of my post but wanted to start a new thread because I'm getting no where. So, when I'm cruising along the highway my engine will suddenly drop timing usually at the same time my tcc line pressure drops. I'm going to post a older data log that shows what I'm talking about with a log I did yesterday that is newer just doesn't really high light what I'm talking about just for grins. Can anyone tell me what is happening? I have vvt still but don't see anything in the scanner to log that. I'm wondering if my vvt stuff is jacked up or my torque converter? Thanks

maf tune 4.hpl
last log.hpl

Camaro best tune.hpt

[Alvin]

Do you have a timestamp where your concerened?

[lablkv6z]

Do you remember if the AC was on during the log, I might have missed it if it was being logged. Possibly try zeroing out Torque Management/Engine/AC Torque reduction table.

[morepowerjoe]

Do you remember if the AC was on during the log, I might have missed it if it was being logged. Possibly try zeroing out Torque Management/Engine/AC Torque reduction table.

I always try to log with my ac off.

[morepowerjoe]

Do you have a timestamp where your concerened?

2:13:00 on maf tune 4

and 2:49:03 on latest log. It says spark torque management type; trans

[Cringer]

I talked about this in another one of my post but wanted to start a new thread because I'm getting no where. So, when I'm cruising along the highway my engine will suddenly drop timing usually at the same time my tcc line pressure drops. I'm going to post a older data log that shows what I'm talking about with a log I did yesterday that is newer just doesn't really high light what I'm talking about just for grins. Can anyone tell me what is happening? I have vvt still but don't see anything in the scanner to log that. I'm wondering if my vvt stuff is jacked up or my torque converter? Thanks

maf tune 4.hpl
last log.hpl

Camaro best tune.hpt

If you look at the log at 2:13, it shows your throttle starts slowly increasing and your cylinder airmass starts increasing as expected. If you then take the cylinder airmass and rpm from the log back to the high octane table in the tune, you see the ECM is doing exactly what you have programmed it to do.

.20 g/cyl @ 1600 rpm = 37.5* advance...your log shows 30*
.54 g/cyl @ 1600 rpm = 21* advance...your log shows 19.5*

You need to add more PIDs to your logging to show additional timing modifiers for both advance, retard, and torque management requests. This can also shed a lot more light into what is going on.

As for the TCC pressure, set the Adapt Min value to 0 (read more here) in Trans > Torque Converter > General. Right now you are allowing the TCM to decide to reduce pressure up to 150 KPA (21.8 PSI) for adapting TCC line pressure. Unless there is TCC slip though, a reduction in pressure is not a bad thing. However, you have not yet zero'd out the desired TCC slip tables. I would suggest doing that.

[morepowerjoe]

in my case I have a 3600 circle d single disc. Do you still recommend the adapt min value to 0? And could you explain a little more on how much pressure you should allow for the adapt max value because I've seen mine go over a 100psi on the tcc line pressure

[morepowerjoe]

Also I was referring to the dip in timing right before 2:13 where it goes to from 47* to 11* and then back to 43.5*

[Cringer]

in my case I have a 3600 circle d single disc. Do you still recommend the adapt min value to 0? And could you explain a little more on how much pressure you should allow for the adapt max value because I've seen mine go over a 100psi on the tcc line pressure

Wow...it would help if I was looking at the correct tune file...sorry! However, as far as timing goes I still think you need to log additional channels for advance, retard, and tq mgmt.

Yes zero out the min adapt as well. For reference, I run a 3600-3800 Circle D single disc converter on an SS3 cam. I don't see the channel for TCC Slip, you should log that and look for slip anytime TCC lockup is commanded. As long as it is not slipping when locked, the fact that TCC line pressure changes is irrelevant. Ideally you want to use as little pressure as needed to lock it and that is what the trans adapt is trying to do.

[morepowerjoe]

This is the log with the additional channels. It's a short log nut it still shows what I'm talking about.

last log.hpl

[Cringer]

This is the log with the additional channels. It's a short log nut it still shows what I'm talking about.

last log.hpl

OK I see TCC slippage <100 rpm. Try zeroing out the min adapt and if that doesn't help, then you are going to need to add more pressure to the TCC tables.

In your new log...the only timing dips I see is where you let off the throttle and are coasting, which is normal. The throttle position is 25% which is consistent with idle (if you log accel pedal position this should show 0%). There is also a channel you can log called Idle SC mode and that will toggle between Idle and Coast. During Coast my understanding is that the ECM references the Idle Coast down table [12614] for the desired timing and the airflow final minimum [12087] to maintain the idle RPM as defined in the Idle Min Set Point VSS table [12104]. Idle adaptives (engine > idle > adaptives, proportional, follower, integral) kick in to attempt to maintain that coast down idle RPM (which means opening/closing throttle) and using the over/under idle timing advance tables [12670] and [12671]. In short, I don't see anything wrong here.

[morepowerjoe]

What TCC table do I increase the pressure on if I need to? Apply ramp or max pressure? Thanks

[Cringer]

What TCC table do I increase the pressure on if I need to? Apply ramp or max pressure? Thanks

Start with [TCM] 15235 - TCC Apply Pressure Ramp (applying in small amounts).
The [TCM] 35050 - TCC Max Allowed Pressure is just a cap on the max allowable pressure. Since it is 138 psi across the board you shouldn't have to increase this.


You also have these two options which I do not have, so I have not experimented with them. But I believe these may come into play. Try upping the ramp first and see where that gets you.

[TCM] 35050 - TCC Max Allowed Pressure
[TCM] 5671 - TCC Pressure Regulator Offset

BTW you need to prevent TCC lockup at WOT, it will ruin your TCC single disc clutch. Right now you have set to engage on 5th and 6th gears in the WOT tables. I would also release it in the normal tables around the 69-75% throttle opening.

[morepowerjoe]

Thanks for your help!

[morepowerjoe]

Ok so I did another log and at all of my rpm peaks you will see it pull timing just for a second but sometimes all the way down to where I have the lowest minimum spark base 12701 timing set to which is 5* and when it does that it says under spark torque mang type - trans. Why and what makes it pull timing like that? Is it the TCS method where I have spark enabled 290? Thanks

last log 3.hpl

[GHuggins]

This should make the tcc engage a lot harder and hold better if it's not just toast already. Flash engine and trans then test easy at first to make sure things aren't hitting too hard. I didn't do the other mentioned changes as you might want to do that too.

To me it looks like in the log it tries to engage the tcc - tcc slips too much then it goes to tm and aborts line pressure to it - drive a little more then repeats. That's what I'm seeing anyway. Circle D's are ALWAYS the worst to get into full lockup.

[morepowerjoe]

On this screen shot this is what I've been referring to as timing pull. It does basically every time I get on the gas.

2023-03-10.png

last log 3.hpl
Camaro best tune.hpt

[morepowerjoe]

I will go and test it without the tcc engagement and see if it's still happening but I'm assuming it will. This all started after I rescaled my maf and changed my exhaust around. Once I changed my exhaust (removed cats and put in a true x-pipe) I must have picked up a decent amount of hp because all of the sudden my fuel pump was maxed out so then I rescaled my maf and that's when I noticed the timing pull under throttle. So I did add a pretty decent amount of airflow to the maf because it was so lean and like I was saying I'm now wondering if it has something to do with the virtual torque. On the screenshot from post #17 you can see exactly what I'm referring to.

[morepowerjoe]

This should make the tcc engage a lot harder and hold better if it's not just toast already. Flash engine and trans then test easy at first to make sure things aren't hitting too hard. I didn't do the other mentioned changes as you might want to do that too.

To me it looks like in the log it tries to engage the tcc - tcc slips too much then it goes to tm and aborts line pressure to it - drive a little more then repeats. That's what I'm seeing anyway. Circle D's are ALWAYS the worst to get into full lockup.

Just for educational purposes I tried out the tcc setting you gave me and the timing pull is still there under spark torque mang - trans 2023-04-14 (2).png

[Cringer]

Just for educational purposes I tried out the tcc setting you gave me and the timing pull is still there under spark torque mang - trans 2023-04-14 (2).png

Looking at the last log 3.hpl file at time 10:07:07 AM (09:49 in)...it shows that

• The throttle goes up and hits 49.8%
• As it is going up you see the transmission downshift 6-5
• Then the PID for "Spark Torque Management Type" goes to "Trans" during the drop.
• Then you see timing hit 5*.

Looking at the tune file Camaro best tune.hpt:

• You have tq mgmt applied based on [TCM] 423 - Tq Red Enable Power Downshift
• And when I check the [ECM] 12701 - Minimum Final Spark table...it needs work...
• However, the [ECM] 12704 - Minimum Final Spark TqMg table shows 5* as expected and is overriding the values set in 12701.

So basically, it appears to be working as expected. Hit gas, downshift, torque management is applied.