Weird dip in timing - E38

[Justinjor]

Hey all,

I have this strange dip in the timing when just starting off from a dead stop. I have a twin disk clutch in the car and I have to feather the throttle at take off, and sometimes I let off all the way and the car falls on its face. Is there any way to make it transition more smoothly with the timing?

Any help is appreciated.

Thanks

[Bill@HPTuners]

log:
-RPM Limit Type
- Spark TqMgt Type
- ETC TqMgt Type
- FuelCut TqMgt Type
-ETC source

Might just be M6 spark smoothing though

[Justinjor]

Spark smoothing is disabled in the tune. At least, it should be. I'm pretty sure all the torque management is turned off as well but I'll log just to be sure. Thanks Bill.

[Justinjor]

Ok, I don't see RPM Limit Type in the list of parameters anywhere. I have all the others. Where is that one hiding?

[Justinjor]

Also, I see those pids(except the RPM Limit type) in the Table view, but when I try to add it to the Chart view, none of them are visible. What am I missing? What is the proper way to log those parameters? I thought I could just add a series in the chart display and select the PID..

[Justinjor]

Ok so I figured out it's the CFCO set at 4mph and 5* timing that is doing it. Does anyone have a recommendation for how they have theirs set? I was thinking about setting it to 25mph instead of 4 as by 25mph the car is well on it's way.

[IDRIVEAG8GT]

Ok so I figured out it's the CFCO set at 4mph and 5* timing that is doing it. Does anyone have a recommendation for how they have theirs set? I was thinking about setting it to 25mph instead of 4 as by 25mph the car is well on it's way.

Are you sure it's CFCO? Haven't heard of or had a problem with that before.

[Justinjor]

Well I'm not 100% sure, but I feel pretty confident given the scan and the settings for CFCO. The log shows timing immediately dropping to exactly 5* and the CFCO timing table is set to 5*.

I know it happens when I try and feather the throttle/clutch. I'm thinking that because I have an adjustable master cylinder, the 'clutch pos in' needs to be relearned as perhaps the computer thinks the clutch is in or something. Perhaps the sensor is just at the cusp of 'clutch in' and as soon as I put any pressure on it, the computer thinks the clutch is all the way in and it refers to the CFCO table.

I didn't get a chance to mess with it last night but I'm going to try the relearn process in the scanner and see if that helps. If not, I'll up the minimum mph for CFCO to 25mph and see if it goes away.

[IDRIVEAG8GT]

Well I'm not 100% sure, but I feel pretty confident given the scan and the settings for CFCO. The log shows timing immediately dropping to exactly 5* and the CFCO timing table is set to 5*.

I know it happens when I try and feather the throttle/clutch. I'm thinking that because I have an adjustable master cylinder, the 'clutch pos in' needs to be relearned as perhaps the computer thinks the clutch is in or something. Perhaps the sensor is just at the cusp of 'clutch in' and as soon as I put any pressure on it, the computer thinks the clutch is all the way in and it refers to the CFCO table.

I didn't get a chance to mess with it last night but I'm going to try the relearn process in the scanner and see if that helps. If not, I'll up the minimum mph for CFCO to 25mph and see if it goes away.

Yep that'll do it. Try the relearn first thing so the ECM sees proper clutch in and out travel. There is a chance you may have to disable CFCO completely.

If that doesn't do it, I'm willing to bet you have a false Torque Management source coming from somewhere. Do you have your Tip-In and Fast Torque EXIT tables disabled? If your tune has them, get rid of them.

[Justinjor]

Tip-in is disabled under the torque management section and fast torque has some settings still enabled.

[Justinjor]

This look right?

[IDRIVEAG8GT]

Tip-in is disabled under the torque management section and fast torque has some settings still enabled.

Fast Torque is "Driver Demand" reference. Although these computers aren't near as in depth as the E39/E78 they still receive torque calculations from engine output and whatnot.

Depending on how you have your RPM control set up, this could also be causing an issue. Everything else working as it should?

Just trying to lend different options in case one change doesn't get the job done.

And yes the attached images look just right. As long as the Fast Torque is maxxed you should be fine.

[Justinjor]

Everything else seems to be working just fine. It's just that weird 'fall on its face' behavior at very light load.

[IDRIVEAG8GT]

Everything else seems to be working just fine. It's just that weird 'fall on its face' behavior at very light load.

Only when letting out on the clutch or does it do it at very light throttle conditions when the clutch is fully engaged as well?

I'm on mobile or else I'd look through your tune n log. Sorry.

[Justinjor]

It's only during take off when trying to feather it. The clutch will be at least half way out or fully engaged. I wish I could log clutch position PID. Is there such a thing that will show the % engagement from 0-100%?

[IDRIVEAG8GT]

It's only during take off when trying to feather it. The clutch will be at least half way out or fully engaged. I wish I could log clutch position PID. Is there such a thing that will show the % engagement from 0-100%?

Not sure. Definitely try the relearn first though.

[Justinjor]

Relearn was unsuccessful. I'm not really sure what it wants me to do or how to make it work. I logged the clutch pedal pos, clutch raw, and clutch pos in PIDs and they actively move when i push the pedal in/out. I tried to do the relearn but it stayed at 20% no matter which way I tried it.


I set the CFCO to kick in at 30mph instead of 4mph and the car drives 100 times better. The issue is gone.

[frans96ss]

I have a car doing the same thing... Spark is very irractic when it does it though... my CFCO is turned off though. Spark smoothing is also off.

[LEDbetter]

I'm getting the same symptoms.... but for an automatic. E38 computer. Could the CFCO tables be an issue in my situation too?

[10_SS]

It's only during take off when trying to feather it. The clutch will be at least half way out or fully engaged. I wish I could log clutch position PID. Is there such a thing that will show the % engagement from 0-100%?

I dont have problems, however I have a 2010 Camaro LS3 Manual, stock clutch/pedal, but with a Whipple, but I do log Clutch Pedal Position %.

One difference I noticed was you have the "Spark" enabled for Traction Control System, whereas I changed mine to only use "ETC". Not sure but might be worth disabling that too.