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Roland@pcmtec

HOWTO: Launch Control / Rolling Antilag via Cruise Control Paddle

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First see this thread to setup your Multi Flash Tune (MFT) Custom Operating System.

This launch control system is activated whilst he cruise control paddle is held in. As you can see it goes from 2psi without launch control to 9psi. This is on a large frame GTX42 style turbo.

The launch control maps are activated by holding down the cruise control paddle. The goal here is to build as much boost as possible and reduce torque to stop the vehicle braking through the torque converter or revving too hard.

WARNING This system can destroy turbines, valves and anything not heat shielded that is near the turbo if you do this for an extended period of time. It is recommended to be used for a few seconds at a time at the drag strip. If you have a cracked exhaust manifold, housing or snapped exhaust studs this will amplify the problem in a very short period of time. If you have weak valve springs this may also cause the lifters to pump up and cause a lumpy idle immediately after using the launch mode. If you use this system then immediately turn the vehicle off you may cause the turbo bearing shaft to droop (due to it being so hot it bends) this will then destroy the turbo next startup. Ensure you cool the turbo and engine down for at least 5 minutes after use. This can also melt catalytic converters possibly blocking your muffler, ensure it is only used with an aftermarket exhaust.

This system should only be set up for customers vehicles who have been explained the risks and know when to use it, similar to using a 2-step or transbrake.

First ensure your TPS threshold is setup such that the vehicle will go into open loop when in launch control

image.png.35cc227a7e80496e2508f41d0da96a44.png

Next we can start modifying the launch control spark maps. For an aggressive spark map that causes the maximum boost to be generated you could use the following. Note you would need to change the minimum spark clip to -20 to actually see these spark values.

auF16593_LaunchTune_Fuel1

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Now if you want to ensure the vehicle cannot stay in this region for an extended period of time you could just add a spark hole instead. In this example once a certain amount of boost has been made it will either break through the converter, or if in a manual vehicle it will just rev to redline.

auF16593_LaunchTune_Fuel1

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For an automatic it is recommended to set the -20 column just before the converter slip limit is reached, this way the car will reach the converter slip limit at 2500 (for example) rpm, hit -20 degrees, lose torque and drop rpm, when the rpm drops the timing will increase bringing it back up. This will cause the car to bounce between say 2400 and 2500 rpm like a limiter. If you set the timing negative too early, the car will not get high enough on the converter and will not build boost.

For the launch fuel map you can go fairly rich, I found the engine will misfire much below 0.74 lambda, when cold even 0.78 will cause a misfire at times.

auF0172_LaunchTune_Fuel1

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Regarding cam timing we can use a fairly aggressive overlap of 30-35 degrees. Ensure you set both Max Overlap tables

auF16492_LaunchTune_Fuel1

auF16503_LaunchTune_Fuel1

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For the wastegate duty cycle we recommend zeroing the duty cycle at high revs to ensure you do not overboost.

auF0307_LaunchTune_Fuel1

image.png.4945a40caed21aa73b2e31e5a66218d9.png

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Just a question about activating the launch tune.  When the car is driving, and you hold in the cruise does it just switch to the 'launch tune' tables or do you have to be at a complete stop.

If it can be used anytime, it be used as a scramble button. Yes/no?  i.e. keep all the tables in the launch tune the same as a the tune you are running except for the boost table.  Then you could theoretically hold in the cruise when you 'need' slightly more boost?  Just thinking out loud.

Could be useful for those bracket racing etc.  Or even just for being on a low boost tune but being able to induce high boost tables when wanted without restarting car?

 

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It works under all scenarios so you can use it for rolling anti lag or an overboost/scramble button.

Maxx put a video up showing how it works as rolling anti lag. I use it in my car as well and it is amazingly good fun. You can load up the car at 2000rpm in 4th and get full boost. Let the button go and it is like a sling shot. Great fun!

Live high low boost switching we will have soon via some combination of holding the cruise buttons down all at once without requiring the car to be off.

You can also wire in a rotary dial into the rear o2 sensor and couple this with the multi tune for variable boost on the run. This would then interpolate between the 98 and e85 maps which you could set up to only have boost tables in giving you variable boost.

edit: Live tune changing with the engine running is now possible. This means boost/ghost cam etc can be toggled at any time.

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On 8/7/2019 at 2:53 PM, Roland@pcmtec said:

Live high low boost switching we will have soon via some combination of holding the cruise buttons down all at once without requiring the car to be off.

 

I know ive asked before and you have said no one else has really requested it, but its been some time so i was wondering if anyone else has request boost maps based on transmission modes? L/h boost for D/P modes?

 

+ is activation of the launch control mode possible when your on the brake and touching accelerator > instead of holding cruse control?

Edited by BeerTurbo

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1 hour ago, BeerTurbo said:

I know ive asked before and you have said no one else has really requested it, but its been some time so i was wondering if anyone else has request boost maps based on transmission modes? L/h boost for D/P modes?

+ is activation of the launch control mode possible when your on the brake and touching accelerator > instead of holding cruse control?

The multi tune basically covers all scenarios for boost control now so it's unlikely we will change it. You can change the boost map (or anything really) with the car running now.

We could change the launch control setup, but it takes us weeks to test new changes especially to ensure backwards compatibility so it is unlikely we will change it in the future now. The testing required means it would be close to 10k in R&D to make a change like that.

Basically we have to design something that caters to the masses, if we made every combination possible you'd end up with an aftermarket ECU and then we would have to charge the same to make it profitable.

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17 hours ago, bos330 said:

Hi can launch control function/tune be used for boss 5.4 and miami v8s?

Yes it can. You can still use a spark hole or a rev limiter (for a manual).

Obviously there is no turbo to spool so the system will be a lot simpler. In the case of the 5.0 supercharged you probably actually want it to reduce power so that you don't turn the tyres. All comes down to the use case and the goal as to what the tuner will do.

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On 4/9/2020 at 10:35 AM, Roland@pcmtec said:

Yes it can. You can still use a spark hole or a rev limiter (for a manual).

Obviously there is no turbo to spool so the system will be a lot simpler. In the case of the 5.0 supercharged you probably actually want it to reduce power so that you don't turn the tyres. All comes down to the use case and the goal as to what the tuner will do.

beauty thanks Roland yeah i was basically asking for drag strip situations. Should help heaps having finer control.

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