INPA Help Part 2

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Lancsbob
Joined: Fri 15 Aug, 2014 16:35
Posts: 256

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Location: Ormskirk

INPA Help Part 2

Post by Lancsbob »

Hi
After all of 2 weeks my DSC lights have reappeared this time its the acceleration sensor
which was looking iffy all along as the meter showed it off zero so i replaced it.
It wasn't showing any faults but changed it anyway.

Image

Now its gone off the scale & i can't delete fault as it comes straight back on again.
Have tried a number of times to zero the sensor using INPA but it wont work.
Iv'e put old sensor back on but to no avail. :(

Does anyone know if anything else can affect the sensor, am thinking the main unit on the master cylinder for example.

Looking like i will have to bight the bullet & put it into the experts & take the hit. :evil: :bawl:

Cheers Bob
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pingu
Joined: Fri 30 Apr, 2004 16:01
Posts: 3412

  M roadster S50

Re: INPA Help Part 2

Post by pingu »

Have you tried tilting it?

If it's difficult to remove, jack the car up on one side to see what happens.
Pingu
Lancsbob
Joined: Fri 15 Aug, 2014 16:35
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Re: INPA Help Part 2

Post by Lancsbob »

pingu wrote:Have you tried tilting it?

If it's difficult to remove, jack the car up on one side to see what happens.
Its pretty easy to remove (I cut the carpet :wink: ) If i tilt it for & aft as its the acceleration sensor
& bolted to the side should that move the pointer?
If it does do you suggest elongating a bolt hole to reset it?
If it just gets rid of the lights for the MOT will do.

Cheers Bob
therealdb1
Joined: Tue 25 Jun, 2013 21:47
Posts: 263

  Z3 roadster 2.0

Re: INPA Help Part 2

Post by therealdb1 »

From the INPA screen it looks like the lateral acceleration sensor has an offset outside BMW's limits.
This is to measure cornering acceleration (g) and is nothing to do with going faster or slower so tilting fore and aft will not make any difference to it.
I suspect that it is some kind of capacitive or piezo accelerometer and will therefore only respond to rapid movements to the left or right.
Since you say it is easily accessable now, unbolt it but leave it connected, quickly move it from side to side whilst watching the INPA screen.
The indicator should move and if it does then the sensor is working it probably just needs its zero point to be set to be within the green area.
INPA should be able to calibrate this for you but I have not done it so without having a go myself I'm not sure where to point you.
Have you found somewhere in INPA to set the sensor zero and it does not respond or have you not found the correct setting screen?
Lancsbob
Joined: Fri 15 Aug, 2014 16:35
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Re: INPA Help Part 2

Post by Lancsbob »

therealdb1 wrote:From the INPA screen it looks like the lateral acceleration sensor has an offset outside BMW's limits.
This is to measure cornering acceleration (g) and is nothing to do with going faster or slower so tilting fore and aft will not make any difference to it.
I suspect that it is some kind of capacitive or piezo accelerometer and will therefore only respond to rapid movements to the left or right.
Since you say it is easily accessable now, unbolt it but leave it connected, quickly move it from side to side whilst watching the INPA screen.
The indicator should move and if it does then the sensor is working it probably just needs its zero point to be set to be within the green area.
INPA should be able to calibrate this for you but I have not done it so without having a go myself I'm not sure where to point you.
Have you found somewhere in INPA to set the sensor zero and it does not respond or have you not found the correct setting screen?
Thanks for your input.
Tried what you said & removed sensor & moved it about. The pointer on the meter on the left (all green) moved either side of central which
as you say proves the sensor is registering. The meter on the right (red & green) stayed stationery which is the problem one. I think this one
may be just for calibrating the sensor to the car. Somehow its got itself out of calibration. As it turns out i went through the calibration procedure
again seeing i was all connected up & lo and behold it just came into the green portion & the lights went out. :D I'm not holding my breath though
as i'm not confident it will remain in cal.

Next question is, What could be altering the calibration of the sensor, what controls it? What part of the electronics gets reset when you carry out a recal, its not the sensor itself.
Electronics is all Smoke & Mirrors to me.

Thanks all for your help. Me thinks i will be back. :roll:

Bob
therealdb1
Joined: Tue 25 Jun, 2013 21:47
Posts: 263

  Z3 roadster 2.0

Re: INPA Help Part 2

Post by therealdb1 »

Yes I believe the all green section on the left is live sensor input which is why it responded to you shaking the sensor around. The right hand side is showing where the sensor is centred in the control unit memory so this would only change when the sensor is successfully calibrated.
The sensor provides a voltage to the control unit, probably between 0.5V and 4.5V, that the control unit interprets as cornering force.
With the car not moving the voltage should be somewhere near the middle of the range, 2V or thereabouts. Obviously there is a tolerance built in to the system represented by the green section on the right hand display and provided the centring of the sensor is within this section the system will function and everyone is happy.
Since your sensor was way over to one side the fault light was lit.
All that sensor calibration does is informs the control unit what voltage to expect from that sensor in a stationary position whether that is 1.8V, 2V or 2.2V or whatever. The control unit then knows by a change in that voltage that the car is cornering left or right and how intense for want of a better word the cornering is. Combined with other inputs from the wheel sensors, yaw sensor, throttle position, etc. the control unit can decide if it should help you out or leave you to fend for yourself! :)
I'm not sure which sensor you have installed now with the swapping that has gone on but since you have tried to calibrate on several occasions it may have confused the control unit but the latest calibration appears to have been successful and should last for a good while.
Lancsbob
Joined: Fri 15 Aug, 2014 16:35
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Re: INPA Help Part 2

Post by Lancsbob »

therealdb1 wrote:Yes I believe the all green section on the left is live sensor input which is why it responded to you shaking the sensor around. The right hand side is showing where the sensor is centred in the control unit memory so this would only change when the sensor is successfully calibrated.
The sensor provides a voltage to the control unit, probably between 0.5V and 4.5V, that the control unit interprets as cornering force.
With the car not moving the voltage should be somewhere near the middle of the range, 2V or thereabouts. Obviously there is a tolerance built in to the system represented by the green section on the right hand display and provided the centring of the sensor is within this section the system will function and everyone is happy.
Since your sensor was way over to one side the fault light was lit.
All that sensor calibration does is informs the control unit what voltage to expect from that sensor in a stationary position whether that is 1.8V, 2V or 2.2V or whatever. The control unit then knows by a change in that voltage that the car is cornering left or right and how intense for want of a better word the cornering is. Combined with other inputs from the wheel sensors, yaw sensor, throttle position, etc. the control unit can decide if it should help you out or leave you to fend for yourself! :)
I'm not sure which sensor you have installed now with the swapping that has gone on but since you have tried to calibrate on several occasions it may have confused the control unit but the latest calibration appears to have been successful and should last for a good while.
Thanks for the in depth explanation, i sort of understand it.
I have put back the original sensor.
So if it doesn't hold its calibration it could be the control unit at fault or the voltage its recieving from the sensor is not stable which sounds serious.
We will see.

Cheers Bob
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