kafklatsch

QUESTION with supporting information below:
Can I use Xentry as the indicator of when to change the air filter?

Background
So, I recall seeing downstream air filter pressure in Xentry. It was time for my annual air filter change... about 20,000 miles.
I decided to actually look at what Xentry showed for pressure with my old filter before removing it.

The atmospheric pressure showed as 957.0hpa (13.880 psi)
Xentry shows the acceptable range as 927-987hpa ( 13.445 - 14.315 psi) NOTE: the sensors and computer account for my higher elevation of about 1600ft abv sea level
Mercedes thusly allows about 0.44 psi of differential pressure before the filter would be out of range (clogged)
My Dirty OEM filter showed as 962.1hpa (13.96psi)... just 0.08 psi differential pressure. I really expected a higher number as the filter is slightly visibly dirty.

The new OEM filter now shows almost equal to atmospheric pressure (957.6hpa) on the filter.
so, with the old dirty filter only showing a 0.08 psi differential, is there any reason to really change it?.. are there other factors to consider
Is the OEM "paper" superior?

Xentry is a great tool.. thank you, Ninja, for setting this up for me 4 years ago...

VII

0.44 lb diffential at idle or WOT at 7k rpm?
You'd need to dip a filter in mud to get a 0.44 differential at idle.

kafklatsch

Do you have any suggestions for how far above 500rpm (that MB asks for in Xentry) I should try?
Ill give it another shot...

It is interesting that Xentry doesn't give note on load, or vehicle speed... it only says >500rpm for the reading... sounded like idle to me
but, while I was on the accelerator (2000rpm), the boost pressure changed significantly, but the sensor pressure stayed nearly the same at around 959.XX (with the new filters)
I don't know what it would have read with the old filters ....

If im moving my pressure reading gets help from the inrush of air...and I im also not sure how the turbos affect the reading under WOT... MB gives the pressure range parameters at >500rpm engine speed - no other info.

dlafever

After I bought my W222 last year I was working through the 100k mile service sheet and got to the air filters. Opening the filter boxes I found so much dirt and debris that it actually shocked me (I'm older, not much shocks me.) BUT, the magic was driving the car after the filter change! The turbo engine is hungry for air, so at idle (as mentioned) no real difference, but holy kick in the pants down the highway the car turned into a rocket.

I think on the turbo engines, somewhat dirty filters make a difference.

VII

The greater the airflow the greater the pressure drop.
I think mercedes decided not to go through the ordeal of trying to calibrate a curve to indicate when a change is needed it simply left the programing to trigger in case of severe abuse.

kafklatsch

Yeah..... good points....taking this all in means that Xentry does NOT appear to be a way of determining the replacement time for air filters.
Maybe a "break glass" indicator only.....

no difference in the engine performance between my old and new filters... and this normal in my experience, and likely a good thing.

thanks all

Nice Ride

Purchase your Filters from FCP, replace every 2 years for Free.