imp

Symptoms: '94 GT 5.0 5-speed. Lately, sluggish acceleration at mid-range ~ 2000 rpm, 2nd, 3rd gears, with half-throttle, given more, sudden surge of power. Idles fine. Starts fine.

So far: Replaced fuel filter first, after checking fuel pressure, which was OK at idle. This helped some, but sluggishness remained.

Thinking: Possible Throttle Position Sensor problem, but it's near brand-new off a brand-new Motorsport eng. Unlikely. Mass Air: Dirty? I've never opened one up that looked dirty to the naked eye, before. This time:











So, likely this critter is giving bad data. Everybody suggests "clean the Mass Air". Carb cleaner? Reluctant to blow hard-force compressed air on these tiny elements. Or should I replace the damned thing?

Looking into duct, there is evidence of dirt built up inside the sensor opening. HTH can dust be getting in? I have a K&N filter like this:






Everything duct-wise is good and tight, blue silicone rubber ducts. Could a K&N be improperly-made or something? Lot of dough tied up in the damned thing, not to mention, how much dust is eating away pistons & rings?

Any ideas, appreciated. Will clean, look for improvement in performance. imp

08'MustangDude

The oil that is on the K&N filters gets sucked into the intake, and that
builds up on the MAF and IAT sensors, which can then hinder their
readings. That's why some cars can't use them. Also, they do
not filter smaller particles like paper filters do. This is why paper
filters have a short service life due to their tendency to "surface load."

K&N and other oiled filters have "depth loading". The multiple layers
of cotton fibers provide many levels of dust retention. It will reach a
point where it will pass microns of dust particles through when the
filter loads. These particles stick to the oil residue on the senor(s), and
intake tube (if any), AND, if the filter gets wet, then you get some dirty
water passes through.

K&N says that automotive air filters are not rated by micron size, they are
rated by efficiency, but that's not really true. K&N filters can only get
particles as low as 10-20 microns. Dry and paper filters down to 5 microns.

Even with OE paper filters, they get dirty, but don't get that crud on them, and
the sensors are more easy to clean when they don't have the oil from the filter
on them.

No single air filter is 100%, so no matter what, the sensor will get dusty, but
not oily with those type filters. I can use K&N on my VW, it does not have
a MAF sensor, or any other sensor in the intake all the way to the turbo
inlet. So, there is an application for them, just not in front of a MAF sensor
for the most part. You can use it, you just have another item to clean when
you re-oil the filter...

Urambo Tauro

Definitely try cleaning it first. Rumor has it that you shouldn't use carb or brake cleaner, though. There are "specially formulated" MAF sensor cleaners out there that you're supposed to use instead. The stuff that I use is made by CRC and comes in a spray can with a grey/white label. It typically retails for about $6-$10/can at local parts stores.

imp

Thank you for your lengthy and comprehensive reply! Turns out, I sprayed the MAF elements with Carb Cleaner (Toluene Acetone & Methanol), took the car out, and it went like a raped ape! So, the crux of the question is answered. Why did dust surround the MAF elements? Determined today. The damned filter has a huge hole designed to accomodate a bunch of duct sizes. They provide big rubber bushings which fit within each other coaxially. The "fit" after clamping on the duct tube allowed loose engagement in the filter end, and it could wiggle around (my BAD I didn't catch that!). Dust entered around that multiple rubber bushing, a P.O.S. design in my estimation, but I will try to effectively seal off that bushing and continue using the element as space requirements are very tight. imp