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MAF symptoms?


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20 replies to this topic

#1 bluegrasssboy

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Posted 18 February 2006 - 05:04 PM

My 97 Impreza 2.2 with 143k has developed a bad bucking, not running right problem. This weekend I installed a new coil pack( with the integrated ignitor), new NGK plugs, wires and fuel filter. It had no effect. What are the symptoms of the mass air flow sensor going out?

Thanks.

#2 Legacy777

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Posted 18 February 2006 - 09:01 PM

Some of the symptoms can be what you have described.

#3 3Pin

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Posted 18 February 2006 - 09:49 PM

Is your check engine light on?

#4 bluegrasssboy

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Posted 18 February 2006 - 10:45 PM

Is your check engine light on?



Yep, it's on. I have to drive about 10 miles to the nearest Autozone. I'm not sure if it would make it there.

I was hoping it was the ignitor/coil pack, but that wasn't it.

#5 doktorbill

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Posted 19 February 2006 - 12:32 AM

Greetings from Doktorbill. You have exactly described the symptoms when the MAF started getting sick on my wife's 87 Buick Park Avenue with 3.8 V6 and crank-triggered ignition. After replacing everything else (all sensors, car computer, coil pack, etc.), tried a rebuilt MAF. Problem solved. See if you can get a MAF for your car out of a junkyard for fairly cheap-- otherwise try one or more of the parts houses for a rebuilt unit with warranty. If you are good at whining, see if one of your friends/neighbors has a Subaru with a compatible MAF-- you just remove the air cleaner lid and MAF, swapping to your car for a test, then put the good one back, and buy that person a nice dinner. At least you have pinpointed the problem.

#6 3Pin

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Posted 19 February 2006 - 12:41 AM

I have a Maf in the classified section for sale.

#7 bluegrasssboy

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Posted 19 February 2006 - 05:20 PM

I know on a ford forum I used to be on guys talked about cleaning the MAF, using a Q-tip and isopropyl alcohol. Reasoning I think was the element becomes dirty basically and no longer functions like it should. At least that was the thinking. Anyone else do this?

#8 dxrflyboy

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Posted 20 February 2006 - 06:50 AM

I know on a ford forum I used to be on guys talked about cleaning the MAF, using a Q-tip and isopropyl alcohol. Reasoning I think was the element becomes dirty basically and no longer functions like it should. At least that was the thinking. Anyone else do this?

This is easy to do on older Ford MAFs, since they can be removed from the housing, exposing the elements. The Ford MAF problem usually manifests itself as a lean mixture code (P0171 & P0174) on higher mileage vehicles. With a Subaru, the code may be P0170, which is a general fuel trim code. If removing the MAF from the housing exposes the elements and they are a dull grey, cleaning them with brake cleaner or alcohol on a swab may solve the problem.

#9 bluegrasssboy

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Posted 20 February 2006 - 10:16 AM

If removing the MAF from the housing exposes the elements and they are a dull grey, cleaning them with brake cleaner or alcohol on a swab may solve the problem.



I'll try to get this done today and report back on what I find.

#10 bluegrasssboy

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Posted 20 February 2006 - 07:29 PM

I'll try to get this done today and report back on what I find.



Well, I was cleaning it -and broke it. Bubba move on my part. Was even trying to be careful.

Got a used one on the way, so we'll see how it acts once I get them changed out.

#11 brus brother

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Posted 20 February 2006 - 08:07 PM

Keep us posted Bubba. Fingers crossed.

Well, I was cleaning it -and broke it. Bubba move on my part. Was even trying to be careful.

Got a used one on the way, so we'll see how it acts once I get them changed out.



#12 JT95

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Posted 21 February 2006 - 08:23 PM

Where in KY you from?


Well, I was cleaning it -and broke it. Bubba move on my part. Was even trying to be careful.

Got a used one on the way, so we'll see how it acts once I get them changed out.



#13 bluegrasssboy

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Posted 21 February 2006 - 10:12 PM

Where in KY you from?



I'm from near Ashland. But I live about an hour south of Lexington these days.

#14 beezer

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Posted 21 February 2006 - 10:31 PM

Sorry to hear that, that really sucks!

As far as MAF sensors go, I'm pretty sure the fords used a "film" type MAF sensor. While Subes use a wire type MAF. This may explain why cleaning the Ford ones may help, but, it is pretty much useless on the Subes. I also think the MAF cleans itself by heating the element up to around 1000 deg. when you shut the car off. Please correct me if I'm wrong.



Beezer

#15 bluegrasssboy

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Posted 21 February 2006 - 11:03 PM

Sorry to hear that, that really sucks!

As far as MAF sensors go, I'm pretty sure the fords used a "film" type MAF sensor. While Subes use a wire type MAF. This may explain why cleaning the Ford ones may help, but, it is pretty much useless on the Subes. I also think the MAF cleans itself by heating the element up to around 1000 deg. when you shut the car off. Please correct me if I'm wrong.



Beezer


Well, I've got a used one on it's way. So we'll see how it acts once I get it on there. I'm afraid the little Sube's days are numbered with me. I've had it for over 2 years and put over 30k on it. Never a problem until now. My job has me on the road 4 days a week. This impreza is really just a work car. But I have to drive FOR work and I need a little better car. It's also got the oil leak/smoking problem. If I only had to putter back and forth to work it'd be different. But I drive about 700 miles M-T and I need something a tad better. I'm shopping for a little newer/nicer car.

#16 dxrflyboy

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Posted 22 February 2006 - 07:49 PM

Sorry to hear that, that really sucks!

As far as MAF sensors go, I'm pretty sure the fords used a "film" type MAF sensor. While Subes use a wire type MAF. This may explain why cleaning the Ford ones may help, but, it is pretty much useless on the Subes. I also think the MAF cleans itself by heating the element up to around 1000 deg. when you shut the car off. Please correct me if I'm wrong.

Beezer

Ford also uses a hot wire type MAF sensor. GM uses a film type. Cleaning doesn't always help, but contaminants can and do bake onto the wire.

#17 bluegrasssboy

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Posted 23 February 2006 - 12:58 AM

Ford also uses a hot wire type MAF sensor. GM uses a film type. Cleaning doesn't always help, but contaminants can and do bake onto the wire.


the screen on the end of the MAF tube was black. Rubbed my hand across it and it was bright and silver again. It's had 143k miles worth of air going across it, it just stands to reason it will get dirty. The element was a dull gray before I cleaned it. It was a little brighter looking when I got done and the head of the Qtip was a little dirty. When I get the used one in, I'm going to clean it, but not break it this time. I wonder too about the oil leak and smoking that this car does. With a new oil change, it's not bad at all. You might smell it, but it's not visible. But it'll let you know when it's time for a change, cause it'll get much worse. and come wafting out from the front of the car. So, I'm wondering about oil smoke going through there as well. Was the black film on the screen just years of accumulated dust or a few years of inhaling oil smoke?? Of course the whole deal about them getting dirty I guess is the fact that enough of these contaminants can "cover up" the element and cause it not to be able to provide an accurate measurement of the air passing through there as it was designed to. Similar perhaps to putting a coat of paint on a fire suppresion system water sprinkler head. It changes the amount of heat it takes to do it's job. So I could see how properly cleaning one could help. We'll see.

I'm about to buy a 2000 Chevy Prizm. Cool car I know, but hey, the price is right. And besides, I just need a work car, something clean, good on gas and reliable. Not living in Northern Indiana anymore, the AWD that came in so handy is really not an issue to me anymore. The Prizm, being a Corolla underneath the bowties, fits the bill nicely.

#18 dxrflyboy

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Posted 23 February 2006 - 06:22 AM

The part of the MAF that affects air flow readings is behind that screen. There should be two screws on top of the sensor body. Remove the screws and pull the element out. CAREFULLY clean the wires with a swab moistened with alcohol or brake cleaner.

#19 bluegrasssboy

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Posted 24 February 2006 - 11:17 PM

The part of the MAF that affects air flow readings is behind that screen. There should be two screws on top of the sensor body. Remove the screws and pull the element out. CAREFULLY clean the wires with a swab moistened with alcohol or brake cleaner.


Mine isn't built that way. There's a flat plastic "cover" on top of the housing. I took that cover off. There's a circuit board with soldered connections to the electical plug on the side of the housing. The element can't be removed without breaking those joints.

#20 dxrflyboy

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Posted 25 February 2006 - 07:26 AM

Mine isn't built that way. There's a flat plastic "cover" on top of the housing. I took that cover off. There's a circuit board with soldered connections to the electical plug on the side of the housing. The element can't be removed without breaking those joints.

Usually that cover stays in place and the entire sensor slides out of the housing with it. There may be several different sensor designs, some of which cannot be cleaned. I took an older Subaru MAF apart the other day and it appears to be made like the newer Ford ones. The wires are in the plastic housing and are hard to reach. I checked one from a WRX as well. The wires in that one were even harder to reach. It may not be practical to clean the wires in either case, but if you know it isn't working right, it can't hurt to try.

#21 bluegrasssboy

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Posted 25 February 2006 - 06:11 PM

Usually that cover stays in place and the entire sensor slides out of the housing with it. .



The plug for the wiring harness is screwed onto the side of the housing. Once I got the cover off I could see the connectors for that plug were soldered to the part of the circuit board inside. So it appears the element and related parts were put in from the top, the plug from the side and then they were soldered together. There was no way I could see it coming out without breaking those joints. I was hoping the used MAF I've got coming would have shown up by now. But I'm still waiting.




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