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Input for activating Launch Control

Launch Control

Discussion and questions related to the course Launch Control

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I'm trying to set up a ground speed launch control system however I don't have a clutch switch - is there any way to activate the launch control limiter while my speed reads 0km/h? The reason why i'm trying to avoid the clutch switch activation is because i'm wanting to ride the clutch and handbrake prior to launching so my drivetrain is preloaded. I saw that when you were programming your ground speed control is you still had your clutch switch as the input source. Is there any way to proceed as I would rather not release the clutch so harshly. Cheers!

What ECU and car?

I've got a Link G4+ in an Evo and turn mine on by using the inter cooler spray button. I configured it as a GP input and set the latch option to on. Launch control then activates and it will hold that RPM until I exceed the speed I've set, as far as I can tell!

Hope this helps,


Hey Ads, It's a Link G4 and an R32 GTR - I'm using the high/low boost (GP input) switch to toggle the launch control mode for the time being, the subtle differences between the G4 and the G4+ can be frustrating! I'm sure I'll adapt over time and get the hang of it - persistence is key.

With the ground speed based launch control option you don't specifically need a clutch switch. Set the mode to 'Always On' and then adjust your launch rpm vs ground speed table to suit. Just make sure your speed channel is correctly selected. This may not be overly effective on a GTR though as the 4WD system will still provide torquer to the front wheels when wheel spin is detected from the rear. This could result in front wheel spin and then you don't have a valid ground speed channel.

Just further to my last, I've been refining my settings and as I increase the ignition retard I get substantial amounts of black smoke rather than a bang or a fireball as I'd commonly see in other set ups. If I increase the ignition retard too much I get an overboosting effect. Does this sound like it is incorrectly configured?

You'll need to datalog your launch control situation. When you review it look at the area of the map that your reaching, it may be reaching an area that hasn't been tuned yet and is overly rich, or you can use Link's launch fuel trim. Check your normal fuel map and if it has been tuned then edit the launch fuel trim, you don't want to pull fuel out of your main map for launch control only to have it run lean when your driving.

When your retarding timing during launch you will generate boost, if you retard it too much you will reach a point that you'll begin overshooting the boost you want.

*Picture attached is for example, it has not been tuned.

Attached Files

Cheers for the reply Chris, unfortunately I don't have a wideband sensor to see the mixtures changing. Do you think it would be good practice just to trim fuel from the launch control table in the increments you have shown in your attachment? I can always just try it and use the exhaust for my indication.

I never tune without a wideband, if you think of it this way, what is cheaper, a wideband or a new engine?

During launch control the AFR's aren't a true reflection of the AFR's due to the cut from either the ignition or the injectors which allow the ECU to hold the requested RPM. This is covered in the course so it might be worth going through it again.

Sorry but I find that a bit contradictory, if a wideband sensor is not accurate in this instance then what would be a good alternative to measure the adjustments to the fuel trim table?

There isn't really a perfect way of checking the AFR while a launch control system is active. As Chris mentioned, any time you have an ignition cut occurring, the wideband reading is essentially useless as it will be seeing a full cycle of unburnt fuel/air passing through the exhaust which reads lean due to the oxygen content.

The usual reason for black smoke would be that the ignition retard is building enough boost to have you operating in an area of the map that you haven't been able to access in your normal tuning and is overly rich.