Earlier today G3po mentioned an idea to me to create a launch controller for the VQ35 cars. Basically, this module would monitor wheel spin and if it detects slip it will proportionally decrease throttle position. This type of system has the ability to electronically 'perfect' luanches in the the Z/G. Does anybody else thing this would be a good idea?

We also discussed having the output control boost in turbo applications....



This type of system, of course, would only work when VDC was switched OFF.

 

I'm in. I'd like to see something like BMW M3 launch control. Next time I'm at a light with an M3, I'd like a fair start.

Cal

 

Sounds interesting.

 

I'm having a hard time finding out exactly how the wheel sensors work. The service manual is typically very thorough, but it gives little to no information on the wheel sensors. So far all I can find is that there are two wires to each sensor and one of them should be above 8vdc, so I would assume the other wire is the signal coming back? The other thing I need to figure out is how many pulses per revolution we are dealing with. The service manual hints that the signal is a square wave, but who knows. It also looks like you can pick up all four wheel sensors under the drivers dash.

The accelerator pedal actually has two signals. I would imagine if I scale them both at a certain % that they will always be in the proper relation to each other. These are 0-5VDC signals. I could then scale the 0-5VDC stuff to 0-16VDC for boost control

Does anyone know anything more about these wheel sensors?

 

Interesting and cool idea, if perfected I would be interested. Will this be for both 6mt and 5at? Also, would you be able to adjust it, like have different modes or would this be a self adjusting just point and launch and it controls everything?

Could a module be built that would hold rpm at a preset level, then when clutch is fully released give control back to the driver? Dunno if I am making sense or not. Basically the driver would hold the pedal to the floor, but with this module turned on the car would not rev past a certain limit that is set by the driver. As soon as clutch is fully released then control of the pedal will be given back to the driver. Hmmm now that I think of that, it may cause too much wheelspin if the driver holds the pedal down and you all of the sudden get full throttle. Maybe throttle % could be given back in increments. Forgive me if this sounds stupid I am thinking out loud here.

Maybe, I am not understanding exactly what your module will do. Or I am just too dang tired to make sense.

 

I know I got you thinkin bout this , but I know squat as to waht the sensors acutally report. I guess you'd need to hook up a an O-cope and have a look see.

 

haha I've thought of that. That is a terrible idea.

The wheel sensors won't display anything unless they are moving. So, I will need to get an inverter, and my o'scope isn't exactly small. An O'scope requires complete user control, so I won't be able to drive the car and play with it. I don't think it would be possible to scope the signal!

Unless, I lift the car....

Which, would be super dangerous because it would be up on jack stands with the motor hovering around 800rpm in first gear....

I'll see what I can come up with!

 

my wheels have never slipped during launch with the vdc on. what's wrong with launching with the vdc on?

 

If you get it working, I think you're guaranteed enough sales to make it worth your effort. Can't you have someone else drive your car while you work the scope? (assuming you allow someone else to drive your car)

 

Yeah, that would be an option, but like I said, the scope isn't small, and the car isn't big. I think the best thing would be just to jack the rear up a bit and let it idle in first. I'll just have to have someone there kinda watching over the car to make sure it doesn't start to fall or whatever.

Unfortunately, since I don't have my car right now, I can't even start this project. I will have to wait until the engine build is done, then I can do something.

 

Nothing if your driving around town, or trying to get in front of the mini-van next to you @ the light. But @ the track, you couldnt pull lower than a 2.2 60ft prolly with VDC on, and that sucks....

 

What about a 2-step rev limit to control launch rpm's? This might not be as good as a new launch traction control system, but it would def help.

 

You just need a buddy to ride along and man the scope. I've used the little portable Teks before, should be adequate for this.

 

either your in an AT and not TQ brakeing or you got a serious slug.
With OEM Rubber and bone stock G35C-MT I could just fry the tires.
With FI of any sort ,getting a consistent lunch is extremely hit or miss. No human can launch consistantly on all surfaces all the time. Launch control is really what's missing, other than converting to AWD

 

The annoying aspect of the OEM VDC traction control algorithm is it was designed to conservatively "save your butt" under most all situations. So it uses a combo of TB back off and fuel cut. Were the big "dump " occurs is at fuel cut IMO (like the rev limit) and it is far from graceful. Fuel cut is not a good "effector" for launch control (way to abrupt) ,but TB modulation and/or Boost retard is.

 

Thanx, Alberto....................................

 

subscribing.....

 

I think I figured our the wheel sensor problem. From the manual I can tell that one wire is at least 8vdc and the other one is most likely the feedback in which the manual hints that its a square wave. I just got done developing the KPtechnologies programmable shift light, which, in its most basic form, is a pulse timer. So, If I hook a shift light to the wheel sensor and program it to 2,000 RPM in 5th gear I can extract the EXACT timing value. I can then compare it to a measurement taken at 2,500 RPM and calcuate the difference. The beauty of this method is that if it works (and it should) I basically already have all the capture software written, I'll just have to modify it to montor five sources instead of one.

I wish I had a handheld scope... maybe if I finish this project I'll be able to afford one! Hell, I would even settle for a bench mount DSO.

 

Kevin,

What about going on a dyno? If you hop on a load-based dyno, it should provide you with the appropriate feedback without you having to be in the car.

I know what you mean about the scope- my dad's old scope probably weighs 60-70 lbs!

 

The closest load based dyno is over an hour away. If my shift light module idea doesn't give me the desired results then I'll look in to other options. Hopefully all will be well though with just timing the pulses and crunching some numbers.