S40 V40: OBD2 Live Data mystery

[emtor]

Here's something for you to wrap your heads around:

Engine: B4184, inline 4 cylinder.
Scantool: Vgate Maxiscan VS 890.

Live data streaming is nice for diagnosing. That is, until you get data that is confusing.
I have no problem understanding what the different PIDs mean, but this one makes me wonder what the hell is going on.

The other night I started my car and hooked up my scanner tool and looked at some live data streaming.
The short term and long term fuel trims are confusing beyond belief.
A four cyl. engine should show only Bank1 . . . right?
Well, my scan tool shows fuel trims for both Bank1 and Bank3.
The short term fuel trim for Bank1 is around 2% and 17% for Bank3.
Problem is,-Bank3 shouldn't exist at all, unless two of the cylinders are designated Bank1 and the other two Bank3.
The problem with this is that for this to happen there would be two separate exhaust systems on this engine, which there isn't.

Does anyone have anything smart to comment on this one?

[ww1dm1]

It's probably just the scan tool misinterpreting the data if it shows anything for bank3, blame that. Is all data present for both banks? Maybe 17% is actually the bank1 long term fuel trim?

[emtor]

Originally Posted by ww1dm1

It's probably just the scan tool misinterpreting the data if it shows anything for bank3, blame that. Is all data present for both banks? Maybe 17% is actually the bank1 long term fuel trim?

No, not all data is present for both banks (1 and 3).
O2-sensors 1 and 2 are only present for bank1,
The same with short term fuel trim sensors 1 and 2, only present for bank 1.
One would expect that short term fuel trim sensors 1 and 2 would be present for bank 3 also if the scanner interprets data correctly, but this is not the case.

The only PIDs that shows bank 1 and 3 are short and long term fuel trims.

SHRTFT 1 and SHRTFT 3 are both varying slightly around 0.8% and 10,2% respectivily.
LONGFT 1 and LONGFT 3 are both steady at 6.2 and 17.2% respectivily.
It seems like short term 3 and long term 3 behaves in the same manner as the respective values for bank 1.
Although the values for bank 3 are about 10 times higher than bank 1, bank 3 values behaves much in the same manner as those for bank 1.
In other words, they behave like legitimate fuel trim values.
When I increase RPM all values change slightly in the same manner also.

I have no idea were the scanner gets the bank 3 values from.

I'll could buy another scanner to check wether or not the new scanner presents data in the same way.
If not, then my Maxiscan messes up data in some weird way.
I could also test it on other cars to see if it has the same behaviour.

[ww1dm1]

Odd, I'd guess the bank3 trim values are actually some other (possibly Volvo specific) values that are being misinterpreted by the scan tool as trims. But they do behave as trims, which is strange. I guess you could try another scan tool and see which values match.

[emtor]

Originally Posted by ww1dm1

Odd, I'd guess the bank3 trim values are actually some other (possibly Volvo specific) values that are being misinterpreted by the scan tool as trims. But they do behave as trims, which is strange. I guess you could try another scan tool and see which values match.

I'm set at getting to the bottom of this. The values are so different between bank1 and bank3 that choosing one of them to aid in diagnosing is not a good idea.

I'll buy another scanner that works with these models of volvos.