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 Post subject: Help! Can't spin tires!
PostPosted: Thu Apr 27, 2017 2:34 am 
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Joined: Sat Feb 11, 2017 7:47 pm
Posts: 4
We've had the caprice for some time now and can't figure out why we can't do a burn out or spin the tires over. We've tried about every thing we could think of, changed motor mounts, some things in the tune, pulled the ABS fuse, nothing works. Anyone had this issue, what was the resolution?


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PostPosted: Thu Apr 27, 2017 2:56 am 
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Joined: Thu Aug 04, 2016 6:17 pm
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If it's a 2011, there's not much you can do. You cannot completely turn off the traction control on '11s.

If it's any other year, hold the traction control button for a minimum of 5 seconds. That supposedly disables the TC completely.

I've been doing a lot of experimentation in the code on mine the last few days. I've got it to bark the tires during WOT upshifts by slowly dialing back Torque Management, but still haven't been able to override whatever logic is keeping the tires from spinning during launch. I get just a small spin and protest from the rear tires from a dead stop, but as soon as they start to slip, the engine dials itself back until the car is moving a bit.

EDIT:

I just reviewed my latest data log. From a dead stop, when the car is floored, it initially responds by pulling timing to -6 degrees. It doesn't restore timing until the car is already moving several mph. I'm sure this leads to slightly quicker launches than spinning the tires, but they aren't nearly as fun.

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-2011 Caprice 9C1, 11k mile non-issue car
-1973 Firebird Formula, restoration in progress
-1986 C20 Suburban 454/5-speed, the toy hauler
-1991 BMW 325i
-2005 Jeep Grand Cherokee 4.7L, the wifemobile


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PostPosted: Thu Apr 27, 2017 10:46 am 
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Joined: Fri Aug 12, 2016 12:13 pm
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Location: Tampa, FL
Look at the Brake Torque table. Mine were limited to about 168 ft-lbs for all conditions. This table is probably the culprit that is commanding timing being pulled when trying to do a burnout. Also might look at the PE delay time. It is one of the contributors for the newer cars felling slow when you "punch it".

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PostPosted: Thu Apr 27, 2017 1:06 pm 
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Joined: Thu May 05, 2016 2:25 am
Posts: 99
Location: SW MI
RE not being able to completely turn off traction control on the 2011- on mine with "traction off" it will fry the tires if I want to. The stability system only seems to intervien if the car is sliding sideways. (No drifting allowed!!)
So I'm thinking it's something in your tune set too conservative.

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PostPosted: Thu Apr 27, 2017 1:29 pm 
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Joined: Mon Sep 12, 2016 5:18 am
Posts: 139
Location: Delmarva
I cannot powerbrake my 2014 unless i completely turn stability off.

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PostPosted: Thu Apr 27, 2017 7:19 pm 
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jackleg wrote:
RE not being able to completely turn off traction control on the 2011- on mine with "traction off" it will fry the tires if I want to. The stability system only seems to intervien if the car is sliding sideways. (No drifting allowed!!)
So I'm thinking it's something in your tune set too conservative.


It is a well established fact that from the factory, 2011 cars cannot turn off the traction control. I'm certain that there is something in your tune that has found a workaround, which is what I've been searching for, but have been unable to find. I've played quite a bit with the Torque Management settings to no avail. I also tried the max torque vs gear/rpm tables, and all that did was make for really harsh driving conditions down low, but it's still pulling a significant amount of timing when punching it from a dead stop. I've a mind to just keep turning things off until I find what's causing that. Ideally, I'd like to find a solution that allows tire frying with TCS off, and normal traction control with it off. Why the factory didn't do this in the first place is beyond me.

The brake torque table is only active with stability control on, so that's why you have to turn it off to powerbrake. You can increase those values, but TCS is still going to get upset if you try to powerbrake with it turned on.

I looked again in the Power Enable tables, and don't see a delay time or hysteresis for it. Maybe I'm looking in the wrong place, but this is all the options I have available to me:
Image

_________________
-2011 Caprice 9C1, 11k mile non-issue car
-1973 Firebird Formula, restoration in progress
-1986 C20 Suburban 454/5-speed, the toy hauler
-1991 BMW 325i
-2005 Jeep Grand Cherokee 4.7L, the wifemobile


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PostPosted: Thu Apr 27, 2017 8:06 pm 
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Joined: Thu Aug 04, 2016 6:17 pm
Posts: 94
My current thought is that I'm still missing something in the Engine Torque Management Tables. Here's what I'm currently working with:
Image

Basically what I've tried so far:
a) I raised the values in these tables to 487ft-lbs for all rpms. I can't tell that this did anything other than making post shift performance a lot more harsh. I had the torque management dialed in pretty well before changing these tables. Now it just feels overly harsh. I will likely decrease them way back towards stock again. The tables below show stock values vs what I am using now. My previous tune was set with these values at 150% of stock, and I liked the feeling of that quite a bit. Just enough to bark the gears under heavy throttle shits with 45% of the Torque Management removed on the transmission side.
Image

b) I disabled the ETC limit flag. My understanding is that this flag allows the computer to control the rate at which the throttle opens vs the rate at which you control it to open with the accelerator pedal. I noticed a lot snappier throttle response with this disabled, which I'm a fan of.

c) I adjusted these values to match the 2016 SS tune. I'm not entirely certain what they accomplish, as Fast Torque Exit is still a foreign concept to me.

d) Disabled the master switch for Powerhop. It was my understanding that by default this would also disable the Spark and Fuel Cut flags beneath them. Perhaps this assumption is wrong.

e) Brake Torque Limit Table: I increased these vales from the stock values of 42-98 to a flat value of 184 for all TPS and MAP points. I've only done one powerbrake event trying to set up for a launch, and was unimpressed with the overall feel of the car under these conditions. I may end up putting them back down to where they were. I have no desire to do brakestand burnouts, as that's just hard on equipment and tires.

f) Max Torque. I bumped this value up from the stock value of 479 to 550. I'm in no danger of hitting either value with a bone stock engine.

Things I have left to try:

1 and 2) Disabling the Spark and ETC flags for TCS control. My understanding is this will remove TCS at all times, regardless of whether or not the TCS button is activated on the console. I don't really want that.
3) Disabling Powerhop via Spark. I thought that the master enable/disable would turn this off, but maybe not. Either way, I don't want it off all the time, just when I turn it off with the button.

All I'm really trying to get rid of is the 1-1.5s of stupid sloppy engine response that is resulting from the computer pulling 20+ degrees of timing out of my spark table when I punch it from a dead stop. If I want to spin the tires on a launch with TCS off, I should be able to do that. I still can't figure out what I'm missing in that regard.

_________________
-2011 Caprice 9C1, 11k mile non-issue car
-1973 Firebird Formula, restoration in progress
-1986 C20 Suburban 454/5-speed, the toy hauler
-1991 BMW 325i
-2005 Jeep Grand Cherokee 4.7L, the wifemobile


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PostPosted: Thu Apr 27, 2017 10:00 pm 
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Joined: Thu Aug 04, 2016 6:17 pm
Posts: 94
I just got back from a series of test drives and datalogging in which I tried disabling all of that stuff. It didn't help.

On one run, I set the Spark Minimum - TqMgt table to zero degrees, and set Max Torque Loss equal to 0 ft-lbs in the Engine -> Spark -> Advance table. It still wouldn't spin the tires from launch, but during the 1-2 shift, got a nasty cutout and lean pop in the exhaust. I checked the log file, and it had pulled timing to 0 degrees (not negative values like it usually does), but something in the TqMgt logic then commanded a throttle reduction down to 38.5% (Accelerator position read 99.6% throughout the event, but the TPS registered the drop, indicating that TqMgt stepped in).

Every one of my launches, even with the Spark Minimum - TqMgt table zeroed out, still showed -4.5 to -6 degrees of timing at the moment of launch. The shifts, on the other hand, only retarded timing down to zero degrees. This tells me the problem is probably not related to Transmission TqMgt or the Spark Limiters.

Then the kicker, if I start the launch on a dirt road and transition to pavement, it will spend the tires as long as your heart pleases on dirt, and continue to spin when you've hit pavement, all the way through the 1-2 shift. It was still pulling timing at the launch, but the -6 degrees of timing was not enough to keep the tires from spinning there.

I really need to find what table is causing this timing retard, only at launch, and only for the first second after launch.

_________________
-2011 Caprice 9C1, 11k mile non-issue car
-1973 Firebird Formula, restoration in progress
-1986 C20 Suburban 454/5-speed, the toy hauler
-1991 BMW 325i
-2005 Jeep Grand Cherokee 4.7L, the wifemobile


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PostPosted: Fri Apr 28, 2017 12:14 am 
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Joined: Fri Aug 12, 2016 12:13 pm
Posts: 185
Location: Tampa, FL
cal30_sniper wrote:


I looked again in the Power Enable tables, and don't see a delay time or hysteresis for it. Maybe I'm looking in the wrong place, but this is all the options I have available to me:
Image


cal30_sniper,

It's actually in front of you. The PE Delay disables Power Enrichment until the indicated RPM has been reached. In your example, PE will not happen until you reach 5000 rpm. PE rate is 0.100 which seems low but it will depend on your tune. Monitor your KR during full throttle. It is possible that your ECM is pulling timing if it is seeing knock.

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2014 Chevrolet Stingray Z51
2016 Cadillac ATS-V
2014 Jeep Grand Cherokee Limited


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PostPosted: Fri Apr 28, 2017 1:45 am 
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Joined: Thu Aug 04, 2016 6:17 pm
Posts: 94
Silversled,

Thanks for the heads up. I came to the same conclusion after pouring over my last couple of datalogs searching for the mysterious spark retard, and noticing that PE spark advance wasn't coming in until 5000rpm. I updated that in my latest tune, but haven't tested or datalogged it yet. I ended up setting the PE delay at 400rpm and a 1.0 Enrichment Rate Ramp-in. I also set the PE EQ Ratio at 1.190 to equate to a 12.35:1 AFR. Factory PE AFR was only about 13:1 until way up in the RPM band.

I did finally get the car to powerbrake and launch without pulling so much timing, although I'm not really happy with the way I had to go about it. After logging TqMgt and the other spark advance parameters, and finding that none of them were responsible for the strange -6 degrees of timing at launch, I went into the Spark Minimum table and set all of the Idle/Launch spark advance cells to 5 degrees. Something is still pulling the timing down to that limit every time, but at least now it isn't going negative. That led to a noticeable improvement, and no spark knock so far.

I'm antsy, I'm going to go log that last tune with the PE update and see if that helps solve it.

_________________
-2011 Caprice 9C1, 11k mile non-issue car
-1973 Firebird Formula, restoration in progress
-1986 C20 Suburban 454/5-speed, the toy hauler
-1991 BMW 325i
-2005 Jeep Grand Cherokee 4.7L, the wifemobile


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