Are you smarter than a certified vw mechanic? MAF and EGR problems, nobody can fix?

Wow! I left my car at Ganley Volkswagen for 2 days, and after spending $430.00, they couldn't fix it, and the car is still throwing the same codes!
Can you solve this difficult puzzle?
Here are the codes :
000257 Mass Air Flow Sensor (G70)
Impausible Signal
001026 EGR System
Excessive Flow
005686 Power Train Data Bus
Missing Message from Airbag Controller, Value of resistance too great
Do the MAF, the EGR share the same ground?
This has become a whack-a-mole project, and I seem to be the mole getting the whacking!
The VW is a Jetta Wolfsburg Diesel 1.9 2006-2007 model, with 180,000 miles on it.
Previously I have ultrasonically cleaned the Altitude Sensor (boost sensor) and cleaned the N75 valve, and ultrasonically cleaned the EGR valve (it was pretty dirty and sticky with black gunk, but it is now nice and clean.) I replaced the MAF with a new Chinesium made MAF.
I replaced the Anti-Shutter valve after it threw a code.
Previously the MAF problem was different. Previously as soon as I turned on the car the MAF immediately threw a code, reporting signal too low.
Now the MAF does not throw a code immediately upon starting the car. Now the MAF throws a code after the car has been running for about 15-30 minutes, after the engine has got to operating temperature. It seems to throw the code at freeway speeds, as I remove my foot from the gas pedal slightly to deaccelerate, throwing the code as I do so. And I guess it also throws the EGR code at the same time. At least both codes show up at the same time when I scan the system.
About the airbag problem, it's likely not related. I am going to try some Stabilant 22 on the airbag controller ground bolts, to see if that fixes the problem.
Thanks for any ideas you have. I need to drive from Cleveland to Newark in a couple of weeks and I want my check engine problem fixed by then.

Anything Chinesium is suspect. If it were me , I would replace the MAF with something else. Either brand new or from a wrecking yard.

If the EGR is really clean and still throws codes , I would suspect a diaghram failure. Once again , if providing vacuum for testing purposes is inconclusive , replace the entire EGR / ASV assembly.

The chinesim MAF is probably under-reporting and the computer thinks its either a wrong signal or the EGR is flowing too much.

Replace the MAF with a proper Bosch unit and see what happens. Even if you can get a known good used one it would probably be miles ahead the crap china one.

The missing message from SRS is probably unrelated but interesting.

Thank you Mining Man. Happy Golfing. My momma was born in Edmonton, as was my brother. Me, I am stuck in Cleveland! Thanks!

Going with Chinese parts almost always costs more in the long run than buying quality parts. My Chinese ball joint the tire shop installed lasted less than 30K miles. That one was replaced with a proper Lemforder and should last 200K miles.

Many dealer techs don't know how to troubleshoot. what they do is pull the DTC's and then just start replacing parts that are called out in the text of the code(s) instead of actually finding out why the code was set.

A guy posted that his steering warning lights were on and his steering assist wasn't working. The dealer pulled the codes and recommended that the steering rack should be replaced for something like $2500.00. It turns out that the ground located under the airbox was loose. He fixed it himself on a Saturday. Total cost? An hour or two of owner labor and say 89 cents for a new locknut.

You got off easy if you only got bent over for $430.00..............

Some proper investigation with the correct scan tool is in order. I would be curious to see the MAF values when running basic setting 003.

Also, for the record, the manifold absolute pressure sensor is NOT the same as the F96 barometric pressure sensor. That one is built into the engine computer and is used as a check for the MAP sensor's plausibility the moment you key the car on, before the engine is started. The reading of both sensors can be viewed in measured value block 10.

Well these cars are getting older so many of the newbie techs coming on the scene have little or no experience with them.

Here is what Ross-tech says about the data bus code.

http://wiki.ross-tech.com/wiki/index.php/18044/P1636/005686

Egr may just need to be cleaned but probably needs replacing. Check your local junkyard or pick n pull.

Replace MAF with a real one not a cheap fake copy. If you find an egr at the junkyard grab the MAF also.

If you can't get it working properly, I believe an ECU tune can eliminate the need for a MAF and disable EGR, along with giving you more power. (For "off road use only" of course)

For the money you've spent, you could have done that already.

Anyway, it's just an idea. It would be better to fix it correctly, if you can.

Have you checked your main electrical harness under the air box and battery? It makes a pretty sharp turn at the frame/unibody rail and has been know to chafe and short a couple wires. Pretty good bundle of some light gauge wires to many sensors. Try searching "harness" in the MkV forum.

Good luck, John

I have been told by people with WAY more experience than me this is why you don't clean the electronic EGR valves. And I add my vote on the Chinese MAF being suspect.

Jason

ROFL @ ChinaMAF

He could always send it to Prothe. That way it could be resold to someone that doesn't mind putting garbage parts on their car............

Does it work? I don't care, it was cheap and I still have money left over to buy 3 or 4 more.

The EGR flow is checked by the ECU by watching the MAF value. MAFs rarely fail on the BRMs. By the time the BRM came to be, Bosch got the durability of the hot-film type MAF pretty well sorted. They can still be damaged by crappy air filters, by "cleaning" them, etc. But outright failure like many of us remember from the late '90s-early-'00s seems to be ancient history.

But, if the MAF is not working correctly or sending the ECU the wrong information, the EGR also cannot work correctly. Aftermarket hot-film MAFs, if they are not just a reboxed Bosch, are always very suspect.

If I got a BRM car in here with any sort of MAF DTC, and an EGR flow DTC, and there was no obvious problem like something not plugged in or some tube hanging off, and it had some non-Bosch MAF, I would put a new MAF on the car. I would not even waste my time watching the EGR flow via the actual/requested data in the scan tool, because I would not trust that MAF.

Thank you everyone for your great advice!

I have been driving the car for a few weeks now, and no codes!

I was wrong about Ganley. They were correct.

Your forum posts were spot on. It was the purchased on Ebay Made in China Broken As Manufactured MAF.

As soon as I installed a Bosch MAF all of my problems got solved.

Thank you for your enthusiasm! Allen

Actually the replacement Bosch MAF did not work after all. The MAF CEL was quiet for a few weeks, and then it came back on again, everytime I started the car.

However, I took my car into Cool Air in Belton MO for some axle work. While there the nice folks at Cool Air also fixed my MAF problem. I have not had a problem with the MAF CEL now in 2 weeks.

So I guess my takeaway is that if I get a MAF CEL, I should just take it to Cool Air and let them fix it

And the "fix" was?

aheng said:

I replaced the Anti-Shutter valve after it threw a code.

Click to expand...

Wait, what? The ASV, when it fails, doesn't give any indication it has done so. You have to remove the hose and look in there yourself while someone else turns the engine over.

Tell us what Cool Air did to fix it, please.

My guess: Needed a cam/lifters?

Magic hands baby! Magic hands!

We did the work from the following link. No relation to the maf.

http://forums.tdiclub.com/showthread.php?t=482206