Some SW versions have bad MAF calibration (same sensor in two same cars, same ECU and different linearisation).
That was corrected in newer SW numbers. Look for MAF sensor linearisation copy axis and values from newer SW...

be careful in some sw numbers linearisation maps are reversed backwards...

I've seen a wide range of MAF calibration values across the many available in all the PSA cars.

They are all roughly in the same ball park though, even through to 04/05 206's which are the latest HDi90 cars that I know of... I guess 2.0 HDi110s stopped around 2005 too. I'm not sure of the reason for the difference in calibrations, but they are so close it's kinda irrelevant, which do you trust I guess is the question :D


I think some engines use a bigger sensor body. Ie, the C5 HDi110 has a very different MAF calibration look up table to the earlier 110's and 90's, and I think it's different hardware too, bigger basically. Need to double check on that on parts box.

Never seen a backwards one yet but I guess it'd stand out nicely if you did :D

Dave

Hi,
I was writing about exactly same car, all hardware and ECU,
but different SW versions, so all hardware match 100%.

For sample if you take 2002 and 2004 2.2 hdi, same engine,
same parts but different sw, you will find different maf calibration at high airflows also map "turned" backwards...
Maf part number for sure the same... :)

This is the case for p406,
they have changed calibration after few years...

Perhaps this was the manufacturer attempting a "quick fix" for a known issue? (We all know about the bad methods of tuning which involve tweaking calibration maps such as the injection time, perhaps this is the manufacturer doing the same thing!) :lol:

Also it would be intersting to know what effects the 2 different calibrations had on any running or performance - I bet the change was emissions related rather than for a running fault ;)

I'm still confused, upgraded software is rare to find isn't it?

I know only a few Peugeot 306's for example where there are multiple sw for the same hw number.

Maybe I need to go look at more P406 hehe.


Still, we DO see a lot of variance in MAF calibration across the models from 98 or so to 2005, despite it being the same MAF sensor.

Maybe things like airbox design impact the way the sensor sees a given flow?!

Dave

You raise a valid point there Dave, is the MAF calibration given for just the MAF in isolation, or is it tested\calculated using the whole air inlet\air filter, filter box and inlet pipe design.... Hmmm!

In theory, taking the MAF calibration in isolation should be fine in my view, but you never know..!

I was doing google image search for luftmassmesser last night, not sure why.

There was a picture of a MAF sensor being calibrated. A long (several metres) laminar flow pipe with a pump at one end, a man with a white lab coat on, a power supply and some other stuff, and a big K&N alike cone filter on the end just up-stream of the sensor.

Makes you wonder indeed.

I guess this is why they have a gauss and fins at the back... probably to try make the flow as turbulent and neutral as possible before resuming it's path through the maf, thus making any config pre-sensor irrelevant to calibrations!?

Dave

The Honda HDS system has a MAF sensor relearn function.
Does the dealer peugeot software have the same capability ?
Just wondering if that would explain the differences.

I was chatting to a uni lecturer in motor-sport and engine tuning last night (specifically fluid dynamics) and he said the gauss on the sensors is generally to diffuse flow so the sensor should hopefully read the same signal irrespective of up-stream conditions.

BUT, he said airbox > cone type filters can alter the calibration a little bit as the air flow over the sensor interior changes.

It'd be interesting to take calibration plots for same HW sensors and see if any physical hardware changes on the air-boxes etc explain the calibration changes made.


No idea if there are, just it might be interesting to see if there is a correlation of different physical hardware where the MAF calibration is changed :)

Dave

Those two cars I mentioned, have exactly the same hardware for intake...same part numbers.
I have tested new calibration, and there is little difference at maximum airflow peak +100mg/stroke of air.

At very low lambda that would be 8mm3/stroke of fuel less limited by MAF...

cheers