DIY Traction Control

[Bruce]

I'd first tackle things a bit differently.  You way seems to really beat on
the engine.
I'd start with a timing and fuel map, that is referenced to TPS, and VSS (of
a none slipping wheel).  It would be just enough timing and fuel to possibly
haz the tires, and then use the Traction Control to fine tune that set of
maps with some feed back.
   With a displacement of 1.8L that would seem to be a 4 banger, dropping
one cylinder is going to be like a 30+% drop in power, which is alot
Bruce





----- Original Message -----
From: "Jorgen Karlsson" <jorgen.m.karlsson at home.se>
To: <diy_efi at diy-efi.org>
Sent: Thursday, March 14, 2002 6:53 PM
Subject: RE: DIY Traction Control


> Hi,
>
> Lets assume that you have a turbo car with no catalytic converter.
>
> I think that we want to keep the boost as high as possible even when TC is
> doing its job, this would require us to alternate between cutting sparc
and
> fuel.
>
> Cutting spark will limit power and send raw fuel out into the exhaust
> manifold where it will ignite, this will cause very high exhaust
> temperatures and lots of exhaust energy that drives ther turbine.
>
> Cutting fuel will limit power and will not provide any energy that drives
> the turbine.
>
> Changing spark timing would be nice as it can act like something between a
> cut spark and a normal combustion. It will provide some power and a bit
more
> exhaust energy to drive the turbine. But lets stay away from that for now.
>
>
> If we want to do this right we need to know: if the clutch is released,
real
> vehicle speed, driven wheel speed, Boost, throttle and exhaust
temperature.
>
> The exhast temperature tell us if we can cut spark without melting the
> manifold or the turbine.
>
> The throttle position can be used to tell the system what boost level we
> want to keep when the TC is working.
>
> The boost tell us if we need can cut fuel without letting the boost drop
to
> much or if we need to dump some fuel to keep the turbo spinning.
>
>
> Example.
> Car:
> Honda civic FWD, manual, 1.8l, turbo, no cat, lots of power.
> Maximum boost 1.2bar gauge, maximum exhast temperature 1800oF.
> We want to optimize this car for streetracing on low profile tires, this
> mean that we can let the exhaust gas temperature get as high as 1800oF and
> that we will have our share of traction problems.
>
> We want to keep the boost above 1.0bar if the EGT permits.
>
> A two step rev limiter will simplify the starting procedure a lot on a FWD
> dragrace car and that function is best built into the TC box too but we'll
> ignore that for now.
>
> The TC is not activated until the clutch is released and this occurs when
> the speed is high enough to keep the engine above 5k. Because of the TC
the
> throttle is floored until we reach the finish line.
>
> The front wheels lose traction at once and are spinning 70% faster then we
> want them too, EGT=1300, BOOST=0.5. This tell us that we want to cut lots
of
> power, we want more boost and the EGT is very safe. We try cutting 40%
power
> by running this sequence:
> no spark, fire, no spark, fire, fire.
>
> After a few cycls of this we find:
>
> 30% wheel spin, Boost 0.8bar, EGT 1350(probably sensor lag.)
> Need to decrease power a bit, Boost still to low, EGT still safe.
>
> We don't want to cut one spark after an other because we pay our own
turbos
> and are forced to run this sequence (40% of total power):
> no spark, fire, no spark, fire, no fuel.
>
> After a few cycls of this we find:
>
> 5% wheel spin, Boost 0.9bar, EGT 1400.
> Need to increase power a bit, Boost still to low, EGT still safe.
> We jump back to the 60% power sequence:
> no spark, fire, no spark, fire, fire.
>
> After a few cycls of this we find:
>
> 15% wheel spin, Boost 1.1bar, EGT 1450
> Power is ok, Boost higher then needed, EGT still safe.
> We modify the 60% power sequence:
> no spark, fire, no fuel, fire, fire.
>
> After a few cycls of this we find:
>
> 15% wheel spin, Boost 1.2bar, EGT 1500
> Power is ok, Boost high enough to open the wastegate, EGT still safe.
> We modify the 60% power sequence again to limit exhaust energy:
> no fuel, fire, no fuel, fire, fire.
>
>
> Depending on the amount of wheel spin compared with the current engine
> output we decide the amount of power we want to try next time. The way we
> decrease the power is decided by the boost level unless the exhaust
> temperature is to high.
>
> Power to high>cut more cylinders.
>
> Power to low> cut less cylinders.
>
> Low boost> cut more spark and less fuel.
>
> High boost> cut less spark and more fuel.
>
> High EGT> cut less spark and more fuel.
>
>
> The software pick the right power level depending on wheel spin and the
> right sequence depending on boost and EGT.
> Sequences suitable for a four cylinder engine:
>
> 80% Power
> spark, fire, fire, fire, fire
> fuel, fire, fire, fire, fire
>
> 60% Power
> spark, fire, spark, fire, fire
> spark, fire, fuel, fire, fire
> fuel, fire, fuel, fire, fire
>
> 40% Power
> spark, fire, spark, fire, fuel
> spark, fire, fuel , fire, fuel
> fuel, fire, fuel, fire, fuel
>
> 20% Power
> spark, fire, spark, fuel, fuel
> spark, fire, fuel, fuel, fuel
> fuel, fire, fuel, fuel, fuel
>
>
> This system would only need an rpm input to allow it to double as 2 step
> revlimiter, launch control, flatshift, ALS and ALS cooldown idle control.
> All of them very cool functions.
>
> Comments are welcome!
>
>
> Jorgen Karlsson
> Gothenburg, Sweden.
>
>
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