Stability Control

WKB · #1 (**permalink**) 10-31-2011, 03:33 AM

Can any electonic guru explain in detail how the the stability control works, ideally in a BF Falcon, but if not any late model system eg how the steering sensor works in conjunction with direction of the car and the influence on the abs controller.
I had all the fault codes cleared and/or reset in the 540 today and as well the steering position senor calibrated. Now the stability control starts to activate at speed going around some corners. I know of another 540 with stability control doing something similar.
I have got to try to work out why it does and can it be fixed. I am thinking the shorter wheelbase compared to the falcon could be the cause, but I need to understand how the system works.

Warren

Gaz64 · #2 (**permalink**) 10-31-2011, 03:48 AM

I think you'll find with a system fitted from another vehicle is where the problem lies.

The programming would be for "x" track and "y" wheelbase, "z" wheelspeed difference on lockup etc etc.

Extreme cornering in a car with better grip and suspension that can generate higher lateral g forces may log codes for yaw rate sensor range/performance and/or SAS range/performance.

With codes logged, ESP and ABS would be disabled.

WKB · #3 (**permalink**) 10-31-2011, 06:55 AM

Thanks for the information.
Although the system is from a BF Falcon, The whole vehicle(SC540)basically is a rebodied Falcon. The only difference is the wheelbase. All sensors, electonic components and mechanical components are from the Falcon
I was thinking along with what you said, the cornering (it activates well before xtreme)dynamics increases proportionally the lateral g force due to the shorter wheelbase.
I have just have work out how or who can fix it.
If all else fails I will just leave the the traction control/ stability control turned off.

Warren

Gaz64 · #4 (**permalink**) 10-31-2011, 02:31 PM

Ok Warren, I understand.

A thought I have is the wheel speed difference from front to rear, albiet from wheel rolling diameter and/or while cornering, together with SAS input and yaw rate sensor input could put the ABS/ESP beyond it's programmed parameters.

I'm in no way a programmer, but hope this helps.

sideshow · #5 (**permalink**) 11-01-2011, 08:45 PM

u need to find a scanner and read live data of the stability control
thats if its possible on a ford as their data can be crap sometimes
as they used to give limited live data afew years ago
u might get lucky and find someone who is actually willing to look at it first
then they might know how to cure it
but basically look at all the live data and guess which might be having slightly wrong values due to the fact its in another car
then rent a ford and read its live data and comnpare results
might be easy fix
might be massive fix
u r the first to try this
so spend a million dollars fixing it then tell me how to fix it for the next customer hehehe
thats what our cusotmers and forums people want heheheeh

anyway the first thing i would check is make sure the speed the abs ecu thinks its doing
is the exact accurate speed
then also see how accurate the steering sensor is
maybe on the bf 2 turns of the wheel is 50%
but your 540 2 turns might be 30 or 70%

the other thing is the yaw sensor
im pretty sure that measures g forces and body roll
maybe thats giving a bigger or smaller figure due to stiffer suspension
maybe try undoing it and sitting it on something soft or a very small beanbag type of thing where it wont react as quick so it matches body roll of the bf

but if u can road test it with live data this might point u in right direction

maybe even by the genuine ford diagnosing tool this might help u read all the live data possible

WKB · #6 (**permalink**) 11-03-2011, 01:21 AM

Well after some investigation it appears it not the stability control causing the issues I have. There apears no easy fix yet.

The tyres I have on the car, although the rolling distance is close (about 12mm), it is enough to bring difference in the speed of the tyres to a point where the traction control operates going around corners.
The setup in the the ford workshop computer won't let you customise the size for tyres

, it only allows tyres that are available on the car standard and the front and rear are the same size.

Warren

Gaz64 · #7 (**permalink**) 11-03-2011, 01:39 AM

Warren,

I don't know current Fords, but I do know that with HSV you can get 245/35/20 on the Front, 275/30/20 on the rear.
Wider tyres on the rear, but near enough SAME rolling diameter.

I think with an ESP car, the tyres NEED to be the same rolling diameter.

I had one car years ago that would log wheel speed sensor codes for the rear wheels.
After many repairs guided by the manufacturer, it ended up being a software issue they were unaware of.
The wheel speed differences while cornering ( ie: roundabout) were too large, going outside programmed parameters.

On your car I would try same size tyres all round first to prove the exercise, but if the data shows differences at the moment, I don't know how you will get around it.

Aussie Mike · #8 (**permalink**) 11-03-2011, 01:44 AM

It's going to come back to pulses per revolution of the wheels. It may be possible to make new tone wheels (The toothed wheel on the drive shaft) for either the front or rear to make up for the difference in wheel diameters. It'd take some careful measuring and math to work out.

Cheers

Gaz64 · #9 (**permalink**) 11-03-2011, 01:48 AM

Quote:

Originally Posted by Aussie Mike

It's going to come back to pulses per revolution of the wheels. It may be possible to make new tone wheels (The toothed wheel on the drive shaft) for either the front or rear to make up for the difference in wheel diameters. It'd take some careful measuring and math to work out.

Cheers

That's a good idea Mike.

So more pulses required from the rear wheels.

sideshow · #10 (**permalink**) 11-03-2011, 04:53 AM

I've got pulse adjusting boxes which I use to calibrate speedos
But u would need at least two for rear wheels to make speed read
Same as fronts or vise versa
Bit they are not cheap
On the other hand u can try using the cheap and nasty jaycar kits

Treeve · #11 (**permalink**) 11-12-2011, 04:24 PM

My guess here would be there are at least two factors combining to modify the operation of TCS.

% difference of wheel speed will be a lot lower at higher speeds than lower speeds when you lose traction. Traction control is of more value at higher speeds (it's not there to give you a good launch, it's a safety system). With the same wheelbase, going around a corner at the same speed as the donor vehicle will give a greater % diff across your wheels. TCS will be designed to cut in before you lose significant amounts of traction, i.e. it will be programmed conservatively. This is probably what is tripping you up.

You'll need to do some data logging in an original donor and your car though to know what the differences are, and you'll have to trigger TCS at lots of different speeds to get a good idea for how Ford programmed it in the first place (per Sideshow's suggestion).

Can you live with it?

Treeve

WKB · #12 (**permalink**) 11-13-2011, 05:19 AM

Quote:

Originally Posted by Treeve

My guess here would be there are at least two factors combining to modify the operation of TCS.

% difference of wheel speed will be a lot lower at higher speeds than lower speeds when you lose traction. Traction control is of more value at higher speeds (it's not there to give you a good launch, it's a safety system). With the same wheelbase, going around a corner at the same speed as the donor vehicle will give a greater % diff across your wheels. TCS will be designed to cut in before you lose significant amounts of traction, i.e. it will be programmed conservatively. This is probably what is tripping you up.

You'll need to do some data logging in an original donor and your car though to know what the differences are, and you'll have to trigger TCS at lots of different speeds to get a good idea for how Ford programmed it in the first place (per Sideshow's suggestion).

Can you live with it?

Treeve

Treeve,
"Can I live with it" I am turning off the traction control every time I start car, occasionally I forget to turn it off, remember when it comes on when I am going around a corner or bend in the road.
I think I will unplug a wheel speed senor. This will leave the TC locked out, but I don't know what the loss of signal from the unplugged sensor will cause.

I was told today that the software the tuners use to flash tune your car is capable of altering the wheel in size information and save it to the ecu. Another avenue to chase up.

If this is a dead end, I might have to look at Sideshows or Aussie Mike's suggetions.

Warren

sideshow · #13 (**permalink**) 11-14-2011, 04:02 AM

U need to program the abs ecu which is say good fking luck hehehe
The engine ecu reads road speed from the abs ecu
It might be easy fix it might be hard
But finding if it's going to be hard or easy well this is the hard bit
So unless u put a scanner on it and read abs trac etc live data
While your driving then u got nothing to go by
On the Holden's my scanner will show me the wheel speed for each
Wheel and then I compare that to the actual wheel speed
But for now forget about engine ecu until u get abs ecu reading correct
Figures then maybe u can look at reprogramming engine ecu