How MAF sensor operates


Well-known member

I am going to trust you guys because this engine is touchy and has its own issues. No need to poke the bear.

You might be interested because K&N would love to hear from you.

They requested evidence to support this from dealerships and no dealership provided it.

Here is a clip... For article...
To understand the problem you have to understand the operation of the hot wire MAF sensor .
Briefly a thin wire inside the unit is conducting a fixed current, hence it becomes hot.
The rate of air flowing under the influence of the engine flowing through the unit cools the exposed wire and that in turn demands more current to instantly get it back to the same value.
That varying air flow & wire cooling rate is translated into a signal which the PCM can evaluate into a fueling map.
When you switch off the engine, the PCM sends a jolt of current through the sensor wire and it glows momentarily . This is the auto cleaning feature built into the unit to ensure accurate fueling upon the next start up.

Obviously then oil or any contamination on the sensing wire will affect how the engine performs when its running..
Since by itself its self cleaning, then post evidence of wire contamination may not be present under examination , unless its excessive.

In today's world of very precise engine controls, the MAF plays a vital role affecting EGR and turbo operations, any deviation can affect how the engine performs, in fact on the Sprinter it is sometimes necessary to "adapt" the air filter to the engine in question.

In the world of auto manufacturing if the K&N was superior in design & filtering capacity then all the manufacturers would be using it; but as we know fibreglass reinforced paper element has yet to be beaten in performance and durability. Which can be instantly changed out with minimal fuss & cost penalty when required at a specified point or earlier if operating in dusty conditions ,which might be a daily task in extreme conditions.
I wager the K&N demands you keep enhanced vigilance on air filtration over the standard paper factory fit ,and as we know changing or cleaning filters is the last thing an owner wants do do.

To emphasis the point. when living in dusty Baghdad it was an early sabbath day chore to clean the blasted Landrover oil bath air cleaner, before getting your cozzie for a Brit Club poolside boozy breakfast with a bucks fizz.
Then along came my new Series 3 WITH paper element air filter.
Just a few minutes to dust it off, and it was ready to go, enjoying in turn the best parking spot and poolside umbrella table at the club.
All the more reason to get with the program by using the latest and greatest, not to mention enough punctual time to pick up a busty Russian girlfriend for a day at the club .
Experience:- Russian ladies like to be cosseted with attention.
"Dennis, Not everything is so cold in Russia !" :devilish:


Erratic Member
To add to that, here's what MB has to say about the MAF (from this resource)




2015 3500 X long limo RV
What was it about Russian ladies?
I heard you can get Ukrainian date easy those days?
Coming to K&N filters

No MB filter included in the test, but even comparing to AC-DELCO, the K&N allows 19.75 times more dirt.
Any future comments?
Ford Truck have filter minders factory mounted for decades, while MB never installs them even on hard working vans.
Still there is no excuse why not add $10 gauge to you lovely drive.
I had air filter lasting 100,000 miles in California, or 1000 miles in Baja. No rules and without the gauge you are driving blindfolded.

Aqua Puttana

Poly - Thread Finder
As the MAF thread title has continued with engine air filters...

The T1N optional ASSYST maintenance minder includes a engine air filter monitor that is mounted on the air filter box. The proper filter used with the ASSYST air filter minder has a coarse layer flat media included in the design. Obviously the flat coarse filter media will catch mostly larger particles. I suspect that one of the purposes of the flat media is to prevent possible "pagoda" effect of the finer pleated media as the pleated media loads up with contaminants.

The typical T1N engine pleated air filter doesn't have the flat filter media.

This link is for illustration purposes only. I have no idea about the filter quality offered on Amazon. Including the flat filter media could be a good sign though.

PG Air Filter PA5539



Some Air Filter information.
Thanks goes to Cdman1674. :thumbup:

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Engineer In Residence
The T1N has an air filter box mounted pressure sensor on the clean side of the filter, which the ECM compares to its internal pressure sensor. In theory it should report a clogged air filter via trouble code. This setup is more sensitive/specific than the physical indicator, and also much more visible. Though in practice I have never seen this happen. I am pretty good about cleaning/replacing the air filter though.


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