How to Test if MAF is working correctly - 986 Forum - The Community for Porsche Boxster & Cayman Owners

ajgray925 · 01-08-2007, 12:39 PM

Has anyone ever tried to test to see if their MAF Sensor is working correctly by the below method?

http://en.wikipedia.org/wiki/Mass_flow_sensor

"Manufacturers claim that a simple but extremely reliable test to ensure correct functionality is to tap the unit with the back of a screwdriver while the car is running, if this causes any changes in the output frequency then the unit should be discarded and an OEM replacement installed."

I think I might try this at home tonight and see since I've been getting the ever so common P1128/P1130 CEL code.

denverpete · 01-08-2007, 03:04 PM

I haven't tried this. While I'm certainly no expert, I think it's fairly safe to assume that you'll know if your MAF isn't working correctly. When mine began to fail it was extremely noticeable.....

ohioboxster · 01-08-2007, 03:57 PM

Link didnt work for me, I tested mine by unpluging it if it runs better its bad. If its unplugged it will go to a set parameter of a/f this is not a WOT test by the way.

MNBoxster · 01-08-2007, 04:29 PM

Hi,

There are two types of MAF sensors. One uses a thin wire while the other uses a hot conductive film (foil or metalicized Mylar). I'd be leery about tapping either one of them. Unplug it while running, it's just as good a test and virtually non-destructive...

Happy Motoring!... Jim'99

wvicary · 01-08-2007, 07:41 PM

In the mid to late 80's GM used to tell us techs to test the MAF by tapping on it. The problem was that some techs had rather heavy hands and I used to see sensors with holes or even worse damage...... that test method was soon discontinued. I wouldn't use on the newer sensors

socratic · 01-08-2007, 11:50 PM

How does a car with a bad MAF run? Idles poorly? Less power?

Does it come on gradually or will it suddenly go bad one day?

ajgray925 · 01-09-2007, 06:37 AM

Quote:

Originally Posted by ohioboxster

Link didnt work for me, I tested mine by unpluging it if it runs better its bad. If its unplugged it will go to a set parameter of a/f this is not a WOT test by the way.

Thanks for the response OhioBoxster...

I unplugged my MAF (with engine off), started-up, and drove around town. My engine still did not perform well, having 1st gear acceleration problems, as well as small backfire popping sounds. Did you unplug your MAF while your engine was running and only let it idle or did you drive around with it unplugged? Either way, I have ordered a new air filter and new MAF sensor and will be installing both once received by next week. I have a feeling that my problems will still exist, but that will be ruled out. Any comments are appreciated.

MNBoxster · 01-09-2007, 09:08 AM

Quote:

Originally Posted by ajgray925

Thanks for the response OhioBoxster...

I unplugged my MAF (with engine off), started-up, and drove around town. My engine still did not perform well, having 1st gear acceleration problems, as well as small backfire popping sounds. Did you unplug your MAF while your engine was running and only let it idle or did you drive around with it unplugged? Either way, I have ordered a new air filter and new MAF sensor and will be installing both once received by next week. I have a feeling that my problems will still exist, but that will be ruled out. Any comments are appreciated.

Hi,

Without a MAF (or a malfunctioning one), unplugging it should have the exact effect you experienced. Replace the MAF and I bet you're good to go...

Happy Motoring!... Jim'99

ohioboxster · 01-09-2007, 11:24 AM

Interesting, you described a popping sound. Have you done anything else to the car lately? When I had a popping sound it was due to a vacuum leak. Its a big long boring story but it ended up being a broken oil tube. I tought my maf was bad too and as it turns out it probably wasnt. Does your car have a rough idle? When the car is cold it takes readings from the maf until the 02's heat up. The car switches back and forth between 02's and maf. Another question, do you get a check engine light? If so another board member turned me on to running the car to Autozone and getting them to tell me the code for free. I bought a code reader on e-bay since then so I can read my own codes now.

denverpete · 01-09-2007, 11:37 AM

Quote:

Originally Posted by ajgray925

Thanks for the response OhioBoxster...

I unplugged my MAF (with engine off), started-up, and drove around town. My engine still did not perform well, having 1st gear acceleration problems, as well as small backfire popping sounds. Did you unplug your MAF while your engine was running and only let it idle or did you drive around with it unplugged? Either way, I have ordered a new air filter and new MAF sensor and will be installing both once received by next week. I have a feeling that my problems will still exist, but that will be ruled out. Any comments are appreciated.

One thing to keep in mind is that if the MAF does go bad and is not replaced in a timely enough matter you can foul your plugs. When my MAF went out I had it replaced and they cleaned the plugs. But just a few days later the problems resurfaced and they determined they had to replace a couple plugs.

Just an idea....

mn box s · 02-10-2007, 06:00 PM

mentioned flickering of dome light etc. Same problem for me dont think its alt. or batt.
Have cel on with wandering idle my s has alittle over 60k Im going to replace all 4 02 sensors and my maf. If the problem persists Ill go from there.

xclusivecar · 02-10-2007, 09:02 PM

Quote:

Originally Posted by mn box s

mentioned flickering of dome light etc. Same problem for me dont think its alt. or batt.
Have cel on with wandering idle my s has alittle over 60k Im going to replace all 4 02 sensors and my maf. If the problem persists Ill go from there.

Your posts are a ******************** to read...run on, incoherent, lack of punctuation, etc. This isn't IM. If people can understand what you are trying to say without needing a decoder you will receive some great info. Just a suggestion.

MNBoxster · 02-10-2007, 09:07 PM

Quote:

Originally Posted by xclusivecar

Your posts are a ******************** to read...run on, incoherent, lack of punctuation, etc. This isn't IM. If people can understand what you are trying to say without needing a decoder you will receive some great info. Just a suggestion.

Hi,

Excellent point...

Happy Motoring!... Jim'99

ajgray925 · 02-25-2007, 04:10 PM

Okay, I took it over to a porsche dealer and they ran a diagnostic and couldn't find anything creating the idle problem due a computer/cel issue. They were fairly sure that the idle problem was due to the throttle body. They wanted to replace the throttle body for $328 in addition to the $100 I had already spent for the 1 hour diagnostic. I opted to take it home and clean it myself. A quick trip to autozone, I purchased STP throttle body and air intake cleaner for about $3. After cleaning, the idle problem is NONEXISTENT!

The throttle body was extremely dirty, and to all of you with MAF problems due to not replacing the air filter regularly or due to an aftermarket oil type filter that was maybe over-oiled, you may also have the same exact problem as me if you have idle fluctuations.

Thanks for everyone's help in helping me diagnos my problem here. All is good now, but I'll be in touch when the next issue arrises.