Re: [ST] Check Engine Light on

[Frederic NIZERY <frederic.nizery@xxxxxxxxxxxxxxxxx>]

Marc,

Yes it is. ISO 9141.
You can as part of the standard software OBDII port (PID).
I think I noted at  home the bit map of the supported PID on
my 02 ST.

I use windows at home (linux at work) and I only tried windows
software for that matter.
http://scantool.net/?mode=displaySoftware&software_id=39&category=ScanTool.net
I use also my PDA w/
http://www.qcontinuum.org/obdgauge/

Note that I don't have the bit map for the pre 02 engine. Probably the same
except the O2 sensor which is not present on this model.
I can read most of the sensor data and the fault codes. I can reset the 
MIL too.

The problem that you could face is adjusting the CO rate as it's 
proprietary PID's.
The throttle position sensor could also be a problem as the it's the 
absolute throttle pos
that can be read and not the relative pos. The absolute pos is related 
to the potentiometer
voltage reading, and the relative one is related to the corrected 
position as used by the ECU.
To make it short, the relative position should be 0 or very close to 
when the throttle body
butterflies are closed.

But their is a trick to bypass that problem that works most of the case 
(worked for me).
SOmething I learned reading carrefully the tuneboy online help. Fasten 
your seat belt:
When starting, the ECU reads the relative throttle position RelPos.  
RelPos is calculated
by:
AbsPos - CorrectionFactor = RelPos

If the reading is negative i.e. RelPos < 0, then the ECU recalculates 
the CorrectionFactor
and keeps it in flash.

The dealer procedure and the tuneboy procedure is to modify the 
CorrectionFactor (they can do it w/
proprietary PID) turn on the key and then the ECU will compute a new 
CorrectionFactor to have RelPos = 0.

TuneBoy event mention that they post-adjust the CorrectionFactor in a 
tiny extend. I think to avoid the
stalling problem when the throttle close up rapidely w/o any charge (in 
neutral or clutched out).

But you can reach the same point by setting AbsPos. Setting AbsPos means 
moving the throttle position sensor
(it is on the left of the throttle body on the 02 engine) in such a way 
that AbsPos becomes lower than CorrectionFactor.
But it's a blind manipulation as you can't read CorrectionFactor nor 
RelPos w/ the stadard PID's.
Then the next time you switch the key on the ECU will adjust itself.

Honestly I don't remind for sure if it's clockwise or counterclockwise. 
I could probably have a look at mine as I put
 the sensor at the max possible position. But I have to remove the tank 
probably which is not so easy.
Normally, giving the direction in which the butterflies rotate you can 
determine that yourself.

Then how I know it worked? Because w/ an O2 sensor, when the ECU reads 
RelPos = 0, it will use the O2 sensor voltage
to regulate the mixture. Then you can see it going up and down arround 
0.5 volts (0.450V actually). And w/ scantool, the last
indication of the first page (I don't know which PID it's related to) 
it's showing if it's driving, idling closed loop or idling
open loop.

The reason why I had to do that is because my dealer mechanic  wasn't 
able to fix a stalling problem properly and modified
the pos sensor to enrich the mixture artificially (he didn't say it 
though). I just saw the scratches on the sensor screws.
Result: no more O2 sensor regulation and a consumption going hight and 
higher when commuting.

Hey, Hey. Are you asleep?

Fred ST 02 BRG






 

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