Maf 101

My hat is off to you sir!

I just visited, and registered, your forum over there, and came across a plethora of DIYs and other valuable information. It is obvious you have put forth a great deal of effort ....... and I want to thank you for that.

I am a new owner of 06 Jettas, and while not overly mechanically inclined, find this forum, and now yours, extremely valuable and useful. So much so that now for the past 2-3 hours, I have been 'grabbing' as many of the DIY articles over at your site in order to put them into my reference notebook ... one for me, and one for the grandaughter whom we recently also got an 06 for.

Please keep your forum going, and am looking forward to further additions over there.
doon

chittychittybangbang said:

Well I did give "bam bam dip" credit on the picture with a watermark! If you have any suggestions I am always available to edit/correct it or remove pictures that can be credited to you that you wish.

http://www.myturbodiesel.com/1000q_how_to/multi/MAFfaq.htm
A more general FAQ on the mk3, mk4, mk5 MAF w/clickable part numbers to worldimpex for the MAF and metalnerd for the MAF removal tool.

Every writeup on the site also follows a standard format (introduction, parts, procedure).

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Thanks, anyone is free to copy my articles for personal, non commericial use. However, I do not use .pdfs or encourage people to save the writeups because they are always edited and updated. Static writeups get old.

I can understand if you want to save some of it because I also mirrored a few writeups from various other sites - websites or hosts go down and that info is lost forever, just make sure to check for updates.

My turn, my turn!

Anyone care to guess about what this means?

If this is your 2003 Jetta, I'd guess it's your car hitting limp mode because the ecu couldn't control the VNT actuator, probably the N75 valve.

I checked my MAF on a 98 tdi beetle and it showed the actual dropped under 800 as the rpms rised doing a 3rd gear pull up hill. I ordered a new maf and installed last week. Did the same 3rd gear pull on the same hill and the actual reading did not change at all. It pours out the black smoke when this happens and seems to lose a little power as well. What else could be causing this reading. There is no way that 2 maf's can perform the exact same way. The logs from Vag-com look identicle.

Did you also map the MAP? If the MAF is dropping, while MAP isn't, then it's your MAF. If you're just dropping boost, it's probably intake clogging. Do you go into limp mode?

What if my specified MAF is stuck at 850? My Maf actually bounces all over the place and doesn't hold at 800 going uphill in 3rd with WOT, In fact its lucky to go above 600 most of the time and even then it goes right back down. I unplugged the MAF and the power did seem to increase slightly, however my specified MAF was still stuck at 850mg/H. Why would it not be moving? I thought the two were supposed to move tandum with eachother, aka as one moved up the other one moved to match? a little help would be very grateful as Im not sure what the heck is wrong with my car haha.

More MAF ?????????s

Ok. Here I go: '02 Golf, ~70K miles, 5spd, no mods. other than a TDI heater. The CEL came on and the code is "P0102-MAF circuit low input". The car has a loss of power most noticeable when trying to accelerate up hill. With both the MAF plugged and unplugged I can rev in neutral to 5100rpm. After I did this I cleared the code, drove to work (20 miles) without the CEL coming back on. It did come back on shortly after start up when I left work. Same code. Is this a "dieing MAF"? Sorry, no VAGCOM info. Thanks for any insight.
paul

my 00 has smokey cold start-up's and BIG loss of power after it warms up and sometimes a rough idle...i am guessing the MAF is shot ?

Gman, A log of your specified and Actual will help with diagnosing your problem, just because you have a 'all of a sudden problem' you cant peg it on the MAF. take a log of you MAF then we can definately say is it is or not.

MAF / lack of turbo perfomance ?

2000 Jetta TDI,......I'm having what I think is a turbo boost problem. I checked the n75 with an ohm meter and it appears to be good. I checked the waste gate actuator valve with a light and mirror as suggested in one of the threads I read, and I don't see it moving when the ignition is turned on. It's not stuck,..I can move it by hand. I haven't got a vacuum pressure gauge (yet !) but may move on to that, and..replacing all the vacuum lines,..however,...I tried to check the MAF sensor with an ohmmeter as suggested in the Bentley manual page 24c-13 for the MAF G70,..... and I don't get a reading at all !! I actually tried this on two MAF sensors,...I had a good spare from previously thinking I had a MAF problem, when it was actually an intake carbon problem. Neither MAF sensor shows any ohms ( no reading) when I check them,...

Any one ever try the ohm meter trick to verify a faulty MAF.

I live in the boonies, so just dropping by the local VW guy is not an option...

Bucque

I have an odd feeling that my MAF is dead. I haven't gone through the diagnosing steps yet but I always have this irrestible desire to share with the tdiclub forum people, so hence this post.

I went to lunch and noticed my boost gauge was reading unusually high. So I floored it and watched the boost swing past 20 psi and almost up to 30 psi before I let off the throttle. My usual high is 22 psi spike settling back to 16psi. Checking my scangauge I noticed the FIA temperature was also reading high. Maintaining 65 mph on the highway the temp was reading 145 degrees F. At that speed my boost gauge was on a solid 14 psi on flat ground.... Should be a fun ride home tonight, I'll be disconnecting the MAF before I start out.

terrydtdi said:

I've seen 4 different part numbers for the ALH . The one that TDIparts sells is a different part number from the one World Impex sells ,then I've seen one on ebay that matches the part number of the MAF thats on the car . Which one is the recomended MAF ?

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I'm looking for one for my new to me Golf with intermitent power and there seems to be a huge price spread on them too. There's a ~$70 to $120+/- Bosch unit and then I found a Cardone unit via Advance Auto for $135 w/ lifetime warranty. So, which one is the better one? Lifetime warranties are great as long as you live long enough

Hey guys, my car is slow. Can't go over 85 and 0-60 in over 20 seconds. Anyway, logged it yesterday and got this... thoughts? Throttle position is plotted on a secondary axis for scaling purposes.

MyBlack94GST said:

Hey guys, my car is slow. Can't go over 85 and 0-60 in over 20 seconds. Anyway, logged it yesterday and got this... thoughts?

<img>

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Does it get better when the MAF is unplugged?

velociT said:

Does it get better when the MAF is unplugged?

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Going to try that tomorrow morning... just wondering if you guys could tell anything from this.

MyBlack94GST said:

Going to try that tomorrow morning... just wondering if you guys could tell anything from this.

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Ah the pic wasn't up when I first replied.

It's definitely showing less than requested.

yeah, that definately looks like a MAF issue. unplug it, drive it. it should drive better.

What does the MAP requested/actual say?

Looks kinda like a bad MAF to me, but also could have intake issues.

Unplugged it, definite increase in power, and now it will rev past 5000 in neutral where it didn't before.

I don't have a MAP requested, but the log says that it reaches 19xx mbar each time I floor it.

If MAP actual goes to close to 2K, and MAF actual stays in the 500 range, you've got a MAF that's not properly reporting airflow, and the ecu uses that in the fueling decisions. Unplugging confirms the problem. If it were my car, I'd get a new MAF.

MyBlack94GST said:

Unplugged it, definite increase in power, and now it will rev past 5000 in neutral where it didn't before.

I don't have a MAP requested, but the log says that it reaches 19xx mbar each time I floor it.

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You mentioned that there is no map/boost request in your log?

Check the map plug/wires for shorts.

Jeff

check it out!
http://forums.tdiclub.com/showpost.php?p=910070&postcount=16

jsrmonster said:

You mentioned that there is no map/boost request in your log?

Check the map plug/wires for shorts.

Jeff

check it out!
http://forums.tdiclub.com/showpost.php?p=910070&postcount=16

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Hey, I'll definitely do that. What I meant though, was that in the log, I see actual boost, but not calculated boost. Maybe it just didn't log.

Group C has MAF Sensor, Atmos. Pressure, Manifold Pressure, Throttle.

jheen said:

What is the size of the safety torx screws to get the MAF off. Been looking for a while and can not find for the life of me... thanks

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Has anyone answered that question yet? Does anyone know the answer to that question?

Joe_Meehan said:

Has anyone answered that question yet? Does anyone know the answer to that question?

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Early 2ks were 6 point Torx security. All later were 5 point security Torx. Metalnerd has them.

Joe_Meehan said:

Has anyone answered that question yet? Does anyone know the answer to that question?

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T20 tamper proof/safety bit

Same problem

Keebler145 said:

What if my specified MAF is stuck at 850? My Maf actually bounces all over the place and doesn't hold at 800 going uphill in 3rd with WOT, In fact its lucky to go above 600 most of the time and even then it goes right back down. I unplugged the MAF and the power did seem to increase slightly, however my specified MAF was still stuck at 850mg/H. Why would it not be moving? I thought the two were supposed to move tandum with eachother, aka as one moved up the other one moved to match? a little help would be very grateful as Im not sure what the heck is wrong with my car haha.

Click to expand...

Same basic issue on my '04 PD Jetta. I have been searching for an answer but have not come up with anything yet.

http://forums.tdiclub.com/showthread.php?t=250053

Sorry, I'm dumb and didn't realize RC tunes had that effect on the MAF reading. All is normal.

Yup, that's part of the EGR delete, IIRC.

I searched this thread for k&n filters to no avail. Can someone tell me if it's ok to use one without doing damage to the MAF?