[cwebster]

DO NOT DO THIS!

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Update 20170707: Launch will result in an immediate nose-dive. Yes, you will be able to exceed the 4000 RPM idle limit but some kind of fail-safe kicks in and immediately pulls timing.
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Ever since I started bringing my new ZL1 to the drag strip it's been a trade-off between spinning the tires or bogging the motor. I managed to get my ETs down to 11.6 on stock tires by minimizing wheel slip. Then my new rims and drag radials finally arrived. I thought this would solve my problems... well, yes and no. It solved the wheel slip problem but I found that the ECM or one or more of the control subsystems would not allow me to get enough torque off the line to obtain a decent 60-ft time (under 2.0). With the DRs I'd need to launch and maintain a higher launch RPM - I figure between 4500-5000. The 4K RPM idle limit was imposed regardless of what drive mode I was in, even when I "disabled" Traction Control (TC) and Stability Control (SC) by holding down the SC button 5-8 secs. It also seemed to be robbing me of power when it bogged.

I had heard before that the "ABS Fuse Pull" worked on the 5th Gen Camaros to improve launch speed but the 5th Gen did not have the 4K RPM idle limit. Apparently, it did pull engine power at launch though. There's not a lot of detail describing exactly what this fuse pull disables or what subsystems are affected. It's even difficult to find the exact fuse numbers to pull. Then trz174 said in a post to one of my recent threads that he's done it on the 5th Gen and 6th Gen ZL1 and it appears to work the same. I decided to do some more digging... Some threads said that the (5th Gen) ZL1 no longer went into the familiar "nose dive" on launch. Here is a post that describes it well: "Line lock for a ZL1.... help please (Post #17)" 10-18-2015

Key phrase:

This is a great no-tune way to run DRs or slicks because it shuts off the ABS sensors and prevents the computer from reducing power when it hooks hard - the good kind of hook, not a dead hook. This is one reason why you see stock tune M6 ZL1s nose dive after a hard hook on DRs or slicks at about 40-50 ft out. The 8 second method does not shut down all the traction nannys, the ABS fuse pull does.

This is exactly what I want, it would seem. I went ahead and pulled both ABS fuses (F1 and f22) to document exactly what happens. The two annotated photos at the bottom show which fuses I pulled.

WARNING: I should warn anyone attempting this to proceed with caution. Be mindful that this will completely disable the Anti-lock Braking System (ABS). If you press to hard on the brakes you could loose traction and loose control of your vehicle. This also COMPLETELY DISABLES Stabilitrak (Stability Control - SC), Traction Control (TC), and the electronic Limited Slip Differential (eLSD). You will essentially be driving the car full-manual in every respect. I do not recommend this fuse pull for stock/street tires. It's way too easy to loose traction without the controls in place. In no case should this fuse pull be used while driving on public roadways.

I intend to try this during tonight's test-n-tune at a local drag strip... I'll let you know how it turns out.

--Cal


Observations with ABS fuses pulled:

Indicators after engine start:

1. In the tachometer display (left), the ((ABS)) & Stability Control Off Icon indicators are illuminated
2. In the speedometer display (right), the word "BRAKE" appears.
3. In the Driver Information Center (DIC):
- An "Information" dialog apears stating "Rear Axle System Off".
- A "Service" warning appears: "Service Rear Axle"
- Near the top, the "SC Off" icon appears.
- After a while the "SC Off" icon is replaced by a new icon ((P)) with wrench under it, apparently warning to service parking brake.

What stops working:

1. Idle RPM limit. While stopped, any throttle setting up to redline is possible. I only tested to about 5500 RPM.
2. Competitive Driving Modes. No competitive modes or features are available, including line-lock launch control, and no-lift shift. Only main drive modes can be selected. This does not appear to affect the default suspension settings for each drive mode.
3. Anti-lock Braking System. See warning above.
4. NPP does not open baffles while idling, even in "Track" drive mode. It does open up once you hammer the throttle, though.
- It's not possible to change "Engine Sound Management" in Infotainment "Settings". I went ahead and changed this to "Track" after replacing the fuses. Hopefully, once set it will retain these settings after the fuse pull. Didn't check this yet.

What still works:

1. Parking Brake
2. Drive Mode selection
3. Normal braking
4. No hesitation on acceleration.

Engine Compartment Fuse Block:

Pull and stow fuses: F1 and F22

Cover Diagram:



Fuses:

[1slowssm6]

Any update on how this worked out for you? Curious if this will help all the m6 guys even in ss trim

[PRAY]

Great post and great research as usual. I did a skim read and you may have covered this. Does this effect the A8 guys as well. I am thinking that a converter simulates clutch slip and TM/TC could see this as wheel spin and do the same thing.

[cwebster]

Originally Posted by 1slowssm6

Any update on how this worked out for you? Curious if this will help all the m6 guys even in ss trim

Originally Posted by PRAY

Great post and great research as usual. I did a skim read and you may have covered this. Does this effect the A8 guys as well. I am thinking that a converter simulates clutch slip and TM/TC could see this as wheel spin and do the same thing.

It went horribly wrong! Don't waste your time... While the fuse pull did remove the idle RPM limit, completely disabling SC and TC, the engine computer appears to have a failsafe that pulls timing immediately upon launch whenever it deems that there is too much clutch slip.

After 2 launches resulted in a complete nose dive I put the fuses back in. I was so thoroughly disappointed that, after a few more "normal" passes I quit and spectated for the rest of the night. I haven't been back to the track since then.

Pulling the fuses also seems to disable the engine sound management, preventing the baffles from opening on the dual-mode exhaust except for hard acceleration. It's like it stays in Touring mode.

I'll post the videos and notes later but I'm preparing to venture out again tonight. I gotta get seat time in the MT DRs.

--Cal

[PRAY]

Sorry it didn't work out brother.

[cwebster]

Originally Posted by PRAY

Sorry it didn't work out brother.

Sokay, I'll still have fun with it - just not as much fun at the drag strip as anticipated. I've still got a few tricks up my sleeve, though.

For example, next time I'll try a few passes without any burnout on the DR's. This should result in some wheel spin at launch. SOMETHING has to slip to get into the power band where the useful torque is available. If GM will not allow me to slip the clutch then I'm forced to sacrifice some rubber. My best time (11.6) on stock rubber was with moderate wheel spin at launch. Only problem there is that it's much more difficult to accurately and consistently control tire spin than clutch slippage. Too many variables - track condition, temp, humidity, throttle pressure... Still, it's worth a shot.

I'm convinced that the main problem with poor launch and low 60 ft / ETs in the 6th Gen ZL1 M6 is the always-on "Manual Transmission Protection" feature described in the document below. It cannot be disabled without a targeted engine tune.

I described my rationale in these two posts on another thread:

eLSD Wheel Slip % on M6 - post 151
eLSD Wheel Slip % on M6 - post 161



GM Doc ID 4733151 "Manual Transmission Protection Description and Operation"
(First posted by dcosta here)

[BlaqWhole]

I take it you M6 guys are mainly having trouble when trying to launch the ZL1...is that true? I'm just curious if any of you have tried just going off idle and how that went for you.

[cwebster]

Originally Posted by BlaqWhole

I take it you M6 guys are mainly having trouble when trying to launch the ZL1...is that true? I'm just curious if any of you have tried just going off idle and how that went for you.

Not sure what you mean by "just going off idle". All launches with the M6 require some combination of clutch and throttle. All combinations I've tried result in either wheel-spin or ECM intervention.

[Getinthur]

So. I went to the track last night and been having the same problems, a few Vette guys told me to launch at idle as well. I tried and it worked, I started adding some RPM's to it, I launched at 2k RPM's for 5 passes and the car took off like a rocket twice, got sideways the other 3 times. Trail and error and tons of practice I think we could figure this out

[trz174]

I had a different experience during Friday TnT. I was first car in the gate and ready to do as many runs as the night would allow. However, racing luck reared it's head and I was only able to get three runs due to continuous water seeping into both lanes at half track.

All runs were with a bone stock ZL1 M6 with 28" Hoosier drag slicks. 3/4 tank of gas. Stock front tires at 40 psi, rear at 18 psi for each run. Rears adjusted for temp at starting line before each run. All shifts were right at redline with not stutter.

First run was a baseline with the car in track mode, stabilitrak off, and using launch control. After the first run, the track shut down for several hours so I did the fuse pull for the second and third run. First run was the typical nose dive at launch that makes you feel like a spectator. I ran the second run the same way as the first but with ABS pull. I launched just under 5000 with no nose dive but not a particularly good launch due to wheel spin. Third run was the same (with ABS pull) but with a 4000 launch - car hooked hard and nose dived because I didn't feed power and manage the clutch slip (missed it by that much). Probably could be fixed with a controlled clutch slip + power + practice.

My intent was to make as many runs as possible and thrash out the different fuse pull, clutch and other launch combos with the slicks and learn something useful. When the track finally re-opened, I got in two additional runs before they shut down at 11PM. Track was well prepped as always at SGMP and there wasn't much they could do about the water since it rained for 3-4 days straight that week.

Tough to draw any conclusions without comparative runs. There is a lot more in the car no matter what combo is used. I just have to figure it out and make it repeatable.

Since consistency is out the window at this point, I'll bring the ZL1 M6 to CFest and race the road course and do some drag strip runs but will focus on brackets with the bone stock 16 SS Auto on the original tires.

[Fraxum]

Hmm, I think this limitation is only the case with the ZL1 and not with the standard SS. While it took some practice I can now get to a 1.82 60' with only NT555Rs. And I think I can do better once my tune gets sorted out.

No nose dives, but some bogs, and spinouts, along with one smelly clutch run.

I think Chevy is protecting the ZL1 drive train. Is it any stouter than the standard SS?

[cwebster]

Originally Posted by trz174

I had a different experience during Friday TnT. I was first car in the gate and ready to do as many runs as the night would allow. However, racing luck reared it's head and I was only able to get three runs due to continuous water seeping into both lanes at half track.

All runs were with a bone stock ZL1 M6 with 28" Hoosier drag slicks. 3/4 tank of gas. Stock front tires at 40 psi, rear at 18 psi for each run. Rears adjusted for temp at starting line before each run. All shifts were right at redline with not stutter.

First run was a baseline with the car in track mode, stabilitrak off, and using launch control. After the first run, the track shut down for several hours so I did the fuse pull for the second and third run. First run was the typical nose dive at launch that makes you feel like a spectator. I ran the second run the same way as the first but with ABS pull. I launched just under 5000 with no nose dive but not a particularly good launch due to wheel spin. Third run was the same (with ABS pull) but with a 4000 launch - car hooked hard and nose dived because I didn't feed power and manage the clutch slip (missed it by that much). Probably could be fixed with a controlled clutch slip + power + practice.

My intent was to make as many runs as possible and thrash out the different fuse pull, clutch and other launch combos with the slicks and learn something useful. When the track finally re-opened, I got in two additional runs before they shut down at 11PM. Track was well prepped as always at SGMP and there wasn't much they could do about the water since it rained for 3-4 days straight that week.

Tough to draw any conclusions without comparative runs. There is a lot more in the car no matter what combo is used. I just have to figure it out and make it repeatable.

Since consistency is out the window at this point, I'll bring the ZL1 M6 to CFest and race the road course and do some drag strip runs but will focus on brackets with the bone stock 16 SS Auto on the original tires.

Nice job on that 2nd pass (11.767). Was that with the fuse pull? I couldn't get close to that. I've given up on the fuse pull. It dives for the ground every time for me and I don't like how it handles either. Those 60 ft times are killing us and it's all from the always-on "protection" mechanism. I'm going to try just running cold DR's next time to allow some wheel spin at launch. That way I'll be in the power band when it does hook.

Have fun at the CFest. Wish I were going...

[cwebster]

Originally Posted by Fraxum

Hmm, I think this limitation is only the case with the ZL1 and not with the standard SS. While it took some practice I can now get to a 1.82 60' with only NT555Rs. And I think I can do better once my tune gets sorted out.

No nose dives, but some bogs, and spinouts, along with one smelly clutch run.

I think Chevy is protecting the ZL1 drive train. Is it any stouter than the standard SS?

If you've had an ECM tune, the tuner may have programmed out the protection feature. Seems to me it's main purpose is to prevent warranty claims. If you've already voided the warranty with a tune there shouldn't be a problem.

Yes the ZL1 has beefier drive shaft and half-shafts at least. I think the diff might be stronger too. Still uses the TR-6060 tranny but it's the MJK variant instead of your MM6.

[Dubchitts]

Originally Posted by cwebster

Sokay, I'll still have fun with it - just not as much fun at the drag strip as anticipated. I've still got a few tricks up my sleeve, though.

For example, next time I'll try a few passes without any burnout on the DR's. This should result in some wheel spin at launch. SOMETHING has to slip to get into the power band where the useful torque is available. If GM will not allow me to slip the clutch then I'm forced to sacrifice some rubber. My best time (11.6) on stock rubber was with moderate wheel spin at launch. Only problem there is that it's much more difficult to accurately and consistently control tire spin than clutch slippage. Too many variables - track condition, temp, humidity, throttle pressure... Still, it's worth a shot.

I'm convinced that the main problem with poor launch and low 60 ft / ETs in the 6th Gen ZL1 M6 is the always-on "Manual Transmission Protection" feature described in the document below. It cannot be disabled without a targeted engine tune.

I described my rationale in these two posts on another thread:

eLSD Wheel Slip % on M6 - post 151
eLSD Wheel Slip % on M6 - post 161



GM Doc ID 4733151 "Manual Transmission Protection Description and Operation"
(First posted by dcosta here)

Attachment 883702

Wheel spin off the line works best so far for mine with m/t Drs. but then again I don't have near the power you do. I don't get much seat time to experiment, but what I've figured works best for me is just slipping the tires through the water, then 3500 clutch dump. Doesn't seem to bog down there but still only a 1.9 60'