[DJH1211]

I recently had a misbehavin' engine where it would sometimes stumble, sometimes idle wierd, most of the time run great, then stumble again, you know what I mean.

I bought the special screwdriver (tamper-proof torx) to remove the sensor from the air intake pipe, cleaned it by spraying it with CRC MAF Sensor Cleaner, a pressurized solvent. I reinstalled the MAF and upon starting the car, noticed it fired up better and ran better.

But, after a few miles, same story. So I removed the MAF again and looked at the elements with a magnifying lens and thought I could see something on the coils. Wanting a better look, I got a 30X illuminated microscope (bought at Radio Shack) and looked at the coils. They both had what looked like a coating of amber colored granules on them, but only on the side of the element that would be wind-ward, the leading side of the element.

So I sprayed the cleaner again, inspected, the amber stuff still there, but maybe slightly less. Repeated, still with not much luck removing it. Well, getting frustrated, I used a very fine artist's paintbrush to brush sensor cleaner on the MAF elements. The amber stuff started coming off. I kept spraying and brushing the elements until they were finally clean. I was surprised at how stubborn that amber stuff was to finally loosen and get off the two sensors.

I concluded that the contaminent I had cleaned was oil from the K&N air filter. What else could it be? Anyways, I now had a clean-as-brand-new MAF sensor, as seen thru the microscope.

So just because you've sprayed and sprayed your sensor, you won't really know it's clean until you really inspect it, with a microscope like I did. The paint brush was delicate enough that it did no damage to the wire coils of the two elements.

One last thing, it's a good idea to disconnect your battery and reboot your car's computers to force them to relearn the clean MAF sensor.

I hope this helps all the people who can't understand why cleaning the sensor didn't help fix their stumbling/idling problem, and then go chasing IAC and TPS and EGR symptoms, still with no success at solving their original problem.

Please add your experience to this thread, because I think this is a common problem.

 

[05RedHorse]

Interesting post. Was casually discussing possible modifications to my '05 V6 with the mechanic I use. Told me if I went the K&N/CAI route my car would wind up with exactly what you described. For a daily driver, and not going to realize huge performance gains, he told me it was up to me if I wanted to do it but it was more trouble than what it was worth....the oil would foul the sensor.
He also suggested I dry the MAF sensor with a hair dryer before re-installing it, even if I just wanted to clean my present stock-setup sensor.......

 

[frankp]

The cleaners used today do not clean oil off as effectively as Trichloroethylene, which was banned due to VOCs (volatile organic compounds) destroying our ozone. If you have access to an ultrasonic cleaner and acetone, you can do a very effective job of removing the oily residue from your MAF.

The main thing to consider is how much oil you spray down your air filter with, and how long do you wait after cleaning and oiling your air filter. Too much is worse than too little, your air filter should look light gray with a hint of red, once it has been thoroughly cleaned. I wait at least 4 hours with the air filter in the sun, before I re-install it. Also make sure there isn't any oil residue at the bottom of the air filter after you oil it. I use a kim wipe to remove any oil I find. This will keep your MAF cleaner.

 

[DJH1211]

Thanks, that explains why the Sensor Cleaner wasn't very effective. But let's clarify something here for everybody. I'd use Acetone, but I remember posts a year ago: "don't use brake cleaner because it will damage the plastic parts of the MAF". If brake cleaner is too strong for the MAF, wouldn't acetone wreck it as well?

Personally, I think those brake cleaner posts weren't accurate, and I'd try the acetone if my MAF is ever that contaminated again. I don't know what the previous owner of my car did to the K&N air cleaner, but I can guess.

Anyways, I may go back to a stock filter, as I'm not racing my car, and the paper filters filter better (of course, at the cost of slightly less air flow). But that's another topic. :laugh: