Mass Air Flow sensor issue

I am a newbie, just got a 2005 Beetle TDI 2 weeks ago with 125K miles. Only gets 39-40 mpg and I perused the postings on what to do for poor mileage. I noticed a lot of you said get a can of MAF sensor cleaner and clean the MAF, which I did. I let it air dry and also changed the air filter at the same time. About 2 days later, the check engine idiot light came on, I pulled into a VW dealer (the closest one from where I live is ~100 miles) and had them run a scan. It came back bad MAF sensor! A replacement is about $375! Help, what did I do wrong, is there any way to correct this without dropping a bundle of cash?

For what they charged you to diagnose it, you could have bought a MAF.

http://www.metalmanparts.com/product.sc?productId=307&categoryId=-1 <--- $120 shipped.

Instead of the dealer, either purchase a VCDS tool @ Http://www.ross-tech.com or go to advance auto/autozone/napa for a generic scan next time!

Thanks for the website link, I will favorite it and use them in the future. I was reading in some of the TDI advice threads that reading the codes with an improper scanner could kill some of the electronics internally, that is why I didn't go to Autozone. Is that correct or should I not have any worries? I live in a small town but there is a NAPA nearby that will read codes for several $'s. If improper code readers are an issue, what type of scanner should they be using?

The generic OBD readers you find at those stores will read a limited number of codes - mainly those dealing with emissions. The only real problems to have cropped up were with early airbag controllers that had a defect, but those generic readers can't go there...

Just save your pennies and buy yourself a real Ross-Tech VCDS (new name for Vag-Com) cable...

Yuri

Thanks for all the advice.

Use Vag-com and check for cam sensor out of range codes. That will tell your if the timing is out or not. If your timing is out, it will throw a cam sensor code(non-OBD) and effects how much air goes into the engine and throw a MAF code(OBD).

I would never clean a hot-film MAF, that'll kill them more than likely.

Depending on a great many factors, your mileage can vary a great deal.

You did not say if your NB is a stick or not, although the automatics used that year are the DSGs in that model, so either way the fuel economy should be close, but I'd still suspect the autobox to get a wee bit less.

Thermostat, timing, tires, brake cables, etc. can all have a 2-3 MPG change as well. Even if that car is a stick, and it perfect tune with proper tires and all, I'd not expect it to get much past 45 at constant highway speeds anyways.

At any rate, the generic scan tools are pretty much useless, and I doubt the dealer even knows how/where to check the timing, most don't.

My 2005 NB TDI is a 5 speed manual. I guess I need to invest in a Vag-com and become my own mechanic. Are there any good TDI PD mechanics manuals out there?

Driving style (speed, braking, etc) can have a large impact on fuel economy, up to a 10 MPG change. As Oilhammer said, your car is probably getting lower fuel economy due to a combination of factors.

As for that funky security torx screw that holds the MAF sensor on, you can buy the special bit from MetalMan, or just hacksaw a slot in the head so a screwdriver will remove it. I found out that Craftsman brand security torx bits do not fit! The number of lobes are different, 5 vs. 6 I forget which number the MAF fastner has.

--Nate

The Bosch MAFs are held together with Tamper-Resistant Torx Plus. The Snap-On bit I use is TTXR25TPE.

http://www.google.com/imgres?imgurl=http://buy1.snapon.com/catalog/OBJECTS/57600/57528.JPG&imgrefurl=http://buy1.snapon.com/catalog/item.asp%3Fitem_ID%3D73633%26group_ID%3D19384&usg=__T41CWuLdt8L4fYH_uQzLJbYLTjs=&h=300&w=216&sz=48&hl=en&start=1&zoom=1&tbnid=AN6yycQA5j-RKM:&tbnh=116&tbnw=84&prev=/images%3Fq%3DSnap%2BOn%2BTTXR25TPE%26um%3D1%26hl%3Den%26safe%3Doff%26sa%3DN%26rls%3Dig%26tbs%3Disch:1&um=1&itbs=1

Torx: 6-point.

Tamper-Resistant Torx: 6-point with a center lug.

Torx Plus: rounded 6-spoint.

Tamper-Resistant Torx Plus: rounded 5-point with a center lug.

I have sets of all of them. There are more things all the time using the Tamper-Resistant Torx Plus fasteners, especially in transmissions and diesel injection systems. My dad's 4320 JD tractor is loaded with them.

Yes... you certainly can justify the expense of a Snap-On set of bits for this!!

For "the rest of us"... there's a set of bits for about $20 on eBay, and for those of us who don't wish to spend even that, there's also a bunch of real cheapos on eBay... for instance item number 130418890943 - from Spain... "5 & 6 punto torx destornillador para Bosch caudalimetro"... about 2 Euros...

A bit less elegant is Wingnut's use of something resembling a fondue fork with 2 smallish tines, and of course, even less elegant is to saw or Dremel a slot in those security screws...

Yuri

You can buy just that one socket from Snap-On for about $25, you do not have to buy them in a set. The set has 11 pieces, you probably don't want to know what that costs.

I just replaced mine. Used a small pair of pliers on the side of the screws to remove and replaced the factory tamper proof screws with phillips that are the same thread pitch and length. 5 minute job.

25IPR, if that fits the security bolts on my MAF, I can now transfer them to my rear license plate in the hope that it won't get stolen again. A more useful function IMO. Brian thanx for the Snap-On link.