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Mass Airflow Sensor (MAF)


Guest Kingsley

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Guest Kingsley

About 18 months or so ago, there was considerable discussion centering on this sensor. I do not ever recall seeing a picture of the inside of one so here is one now.

Some of the detail is obsured by the gel overlay smudge but there is enough that you can get an idea of it - it is rather complicated.

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MAF sensors on any car are very very picky. You suck up one drop of water and it's done and it causes a mess of drivabillity conscerns that could have you going in one direction one minute and another direction the next. And that picture shows why. Very very compliated microchips.

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Hopefully this thread will save me some time. I was just about to come check for posts about MAF and water. I went to start my 89' today, and it was running right. Got the CRT warning that the was an electrical issue. Checked for codes. Code 34 MAF - current. Code 23 - MAT Low - in history. Have never had any similar issues before. Only variable I could think of was that the last time I drove her (Thursday), I was driving in a torrential downpour. Went through the diag procedure from FSM. Points toward faulty MAF or MAF connection. Seems fair to look into new MAF first.

You know a forum is good when you have a question, and it's answered in the top thread before you even ask the question.

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If this is indeed what's wrong with mine, Is it possible to get just the electrical portion of the sensor (shown above) without replacing the whole sensor to the tune of $200+, or would water have affected the rest of the unit adversely too?

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Guest Kingsley

Just as additional info, you might try jfinn@cpinternet.com and he coukld just have a good used one. Also, there is an aerosol clearner advertised as being especially for MAF sensors and they can be successfully cleaned when done very carefully. Available at your FLAPS.

Edited by Kingsley
Change vebiage (see edit history)
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I would try cleaning the MAF first. This is a tutorial I have been planning on putting on my website but haven't done it yet.

  1. Remove the electrical connector (photo 1)
  2. Remove the three screws holding the MAF in place (photo 1). (careful not to lose the o-ring (photo 2)
  3. Lightly spray the tiny coiled wires with MAF cleaner (photo 3)
  4. Do not touch, brush or otherwise damage the wires
  5. Reinstall making sure the o-ring is in place.

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I already used MAF cleaner to no avail. Good call though. I was thinking that I'd hit the local junkyards on Monday and try to grab a couple, and hope to get a good one one. I know it's far from ideal, but I'm starting a new job next week and I'm super thin on cash until I get a few paychecks and can spring for one from Jim or a newie.

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Guest Richard D

I used the puddle method with non-flamable contact cleaner a couple of years ago for my neighbor's Mazda. Actually I sprayed it into a small plastic cap and dipped the sensor a few times, the cleaner boiled for about two seconds around the coil. Still working.

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Guest Kingsley

As mentioned earlier, I have successfully sprayed but, should I find myself in the same situation again, I would definitely use the dip approach.

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Guest Mc_Reatta

CRC MAF Cleaner is mostly Hexane based as are their electronic contact cleaners.

Carb cleaners are acetone based.

Brake parts cleaners are based on chlorinated solvents like PERC.

I'd stay with a contact cleaner or a quality alcohol if not a MAF sensor designed product.

Carb and brake cleaners not recommended.

MAF and contact cleaners are designed to be applied by spraying. Dipping is not necessary. Just don't touch the wires directly as you don't want to subject them to mechanical damage from the nozzle while cleaning.

Edited by Mc_Reatta (see edit history)
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Guest Mc_Reatta

I'd follow the directions on the can as to how close you should be to the wire while spraying.

No need to be so close that you risk hitting the wires with the nozzle. The thinness of the those wire limits the forces applied too.

I'm sure the forces involved were factored in to the cleaning action of the product. Friction of the flow past the wire will help strip off deposits, and the continuous flow of fresh clean solvent will prevent dissolved dirt from remaining on the wire as the product evaporates more than dipping would do.

Padgett, you reputation for cautiousness is well documented, but I bet you couldn't break an undamaged MAF wire just by spraying if you tried.

Anyone got a bad sensor on hand that they can experiment with to see if they can break a wire just by spraying?

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Geeeeze - Thanks Kingsley for starting this thread .... I had no idea this repair / maintenance procedure even existed ! And added HP at the wheels to top it off ! ! I'll do it as maintenance regardless if the HP is even a tiny bit significant ...... THANKS ALL :)

Nic

Being sent to the printer....

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Anyone have any experience using a MAF from an Olds Ciera? (Just the sensor portion) If I recall correctly, I believe it's a VIN N engine. The part number appears to be the same (AFH50M-02A), and when I seared for the part on car-part.com, a couple of cieras came up. I found one at the local junk and it seems to work. It turned of my CEL and code 034 is gone. Just wanted to make sure it's not calculated differently, and could cause me to run lean or anything. Thoughts?

Edited by jwin (see edit history)
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FYI.. Just bought some CRC MAF Sensor Cleaner at my local NAPA store on sale...normally $9.97 for 11oz can...purchased for $5.79 plus tax...if you are interested recommend you check your local store now... Bar Code 0 78254 05110 9

Edited by 88atta (see edit history)
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Anyone have any experience using a MAF from an Olds Ciera? (Just the sensor portion) If I recall correctly, I believe it's a VIN N engine. The part number appears to be the same (AFH50M-02A), and when I seared for the part on car-part.com, a couple of cieras came up. I found one at the local junk and it seems to work. It turned of my CEL and code 034 is gone. Just wanted to make sure it's not calculated differently, and could cause me to run lean or anything. Thoughts?

Just for the record, the Ciera MAF did clear code 034 & the engine idled fine, but ran terribly when i drove it, so I found a VIN C MAF at the junk and all is good.

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Since parts houses don't sell the sensor by itself, I've wondered if the sensor is calibrated to a specfic honeycomb housing for optimum performance. I bought one once at NAPA the had theft deterent screw heads to hold the sensor to the housing

Either that, or they just want to sell a more expensive part.

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No, there is no calibration to the screen ahead of the sensor. It only cares about reasonably smooth, laminar flow, across the sensor. Some have had success with no screen at all, which reduces restriction, but that requires a fair amount of smooth straight pipe ahead of the sensor. Many of us have swapped sensors without incident, however, there is a different calibration from one engine series to another. Best to stick with vin code "C" sensors unless you have the ability to check the calibration. In a pinch, it looks like the sensor from a 3300 engine will work although the calibration is slightly different. Given time, the ECM may be able to adjust the fuel flow to the MAF reading even if slightly out of expected range. From the testing I have done, no two sensors read EXACTLY the same.

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