# need clarification about 2001 GLS 2.0 MAF and intake issues



## stimper (Jun 8, 2011)

hi all, I've been struggling with my 190k Jetta for a bit now and I've won the day (it currently runs) but fear I'm losing the war. The car rather suddenly started throwing p300, 301, and 303. the symptoms were very rough idle going to stall but no troubles above 1200rpm. I was worried about all sorts of complicated and expensive things, but a little MAF cleaner and the problem cleared right up. 

..during the figuring out process I saw a decent amount of oil in the intake tube btw.

A week later the car started doing the same thing and throwing the same codes. MAF cleaner didn't work but soaking the MAF in alcohol for a while did the trick. 

Currently we're running fine except for the typical mkIV door module issues, but I'm concerned that I have a bad valve on the intake tube coming from the crank case and its just going to pour oil into my intake until the MAF quits working again. 

Does anyone have experience with this? I don't know if the valve on the intake tube between the MAF and the intake should be normally closed or normally open. I also don't know if its a big issue even if it is bad. I really can't afford a $170 part, but REALLY can't afford TWO $170 parts (the MAF and the intake tube)

here's the valve in question. it doesn't seem to be removable from the tube. (thanks VW)










during my searching I found this quote from Tdogg74 talking about it:
"Actually, it's NOT a PCV heater. 2.0's DON'T have PCV heaters.

All that is is a solenoid-actuated diaphragm designed to keep the oil vapor from the PCV puck from entering the intake tube and soaking the MAF & filter with residual oil. VW started installing these in 1998 on the ABA's and the new AEG engines in the New Beetle. 

I took one apart when I did the MKIV intake conversion last year. There's no heater element in it....just a diaphragm membrane. Seeing how my car didn't have the wiring for it, I just knocked out the diaphragm."


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## cameronmfjay (Apr 19, 2011)

Ok so Im currently having somewhat the same problem having to do with that valve/solenoid or w.e the hell it is. Ive searched everywhere and cant find anything about it!! Its the reason behind my ****ty idle. And Im also almost positive its causing my evap code. 

Can someone PLEASEE shed some light on this part?!


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## h20 (Apr 28, 2011)

Bump because I'm having a similar issue. When you press on the gas lightly, do the rpm's start to go up, then (for my car) at about 1300 rpm it goes dead and almost stalls? At that point I just give it more gas and it revvs up like normal.


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## stimper (Jun 8, 2011)

this might help you two. this is the part number for the intake tube with that solenoid: 

Intake tube part #
1J0-129-684-BK

What I did to get mine running again for a week is soak the MAF in alcohol for a half hour.. its back to the same issue again so I'm assuming that valve does need to be replaced


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## stimper (Jun 8, 2011)

just ordered one from VW, the part number for an AZG engine is 1J0-129-684-AS

Its special order $180 so I hope its the problem! I'll make sure to reply next week when I have the part in.


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## tdogg74 (Mar 1, 2002)

Im not sure if its normally opened or closed (voltage-wise). You would have to put a volt meter on the connector to see that. (shoulda done that before dumping $180 into a part you probably didnt need. Used MKIV intake tubes are a dime a dozen and can be picked up for 1/4 the price) But I do know it has to be open with the engine running, otherwise, the PCV puck is rendered inoperable. If, for whatever reason, it's not closing when it should, the worst that will occur is any residual vapors coming out of the PCV will travel into the intake tube.....just like the >1998 ABA 2.0.s 

But OP, you shouldn't have to keep cleaning your MAF like that....cleaning it once should last you a long time before it dirties up again. One of two things is occurring: 

1) your MAF just needs to be replaced.
2) you are having massive blow-by with your valve stem seals and excessive vapors are leeching out. Pull the connection from the PCV puck to that device and take a look at what comes out of the puck when you race up the engine.


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## stimper (Jun 8, 2011)

first off thanks much for the reply. 

I checked voltage at idle, it is getting juice but staying open. 

The two hoses going into it are the big one coming from the top of the engine next to the oil fill cap and the small one splits, one end going to the intake and one end going to the passenger side, through the purge valve, and then down out of site in the body of the car. I've seen pictures of other engines with pcv pucks, but I was told this car doesn't even have a pcv valve. I've also read that the valve I'm monkeying with IS the PCV valve.

there's vacuum at the small hose and nothing much at the large hose. The engine idles terribly unless I plug in (or just plug) the small hose, and nothing evil comes out anywhere, though the oil in the intake tube must be coming from one or the other. (maybe the large tube after the car heats up?)

Hopefully I won't have to replace the MAF. It seems strange that it works perfectly for a while then needs to be cleaned to work again. that doesn't sound like a faulty part to me but what the hell do I know anyway... :screwy:


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## cameronmfjay (Apr 19, 2011)

Ok so Ive been driving with it unplugged. And theres no difference. Wtf is it for 

Sent from my Dell Streak using Tapatalk


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## stimper (Jun 8, 2011)

talked to the VW people.. Its not a solenoid. Its just a partial barrier to collect and drip sludge that might get spit up from the big tube so that it gets sucked up by the small tube. Southern cars don't have the electrical going to it, which is just there to power a heater for cold climates.

too much sludge getting passed that partial barrier would be either your engine spitting out more or the vacuum system not sucking it back out.

hope this helps!


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## stimper (Jun 8, 2011)

all right... I swapped my MAF for a new one and no change. My neighbor, the Wilson to my Tim Allen, peeks through the fence and asks if I had tried disconnecting the battery. I did that and everything worked again. I then put the old cleaned MAF in and it worked with the old one too. This whole thing makes no sense to me but I hope it stays fixed this time!

would a normal MAF cleaning DIY involve pulling a battery cable by chance?

btw, anyone want to buy a MAF? 

:wave: If my idiocy helped you in any way please send beer to the following address...


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## cameronmfjay (Apr 19, 2011)

it will probably start acting wierd again.
my jetta ('01 4cyl 2.0L no mods) has like 5 different personalities.

this can all happen in one day between starting and shutting off:
runs like a brand new car!!! WOOOOOT 
...next start, epc is on and rpms going up and down.
turn off, wait 5 seconds, start again, new car yay!!!! 
20 mins of driving later. CLUNK! ugh. starts downshifting rough, upshifts are long, and sometimes if im lucky NO 4TH GEAR! come to a stop light, turn off and on (


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## stimper (Jun 8, 2011)

yep. back to F*d up again today. 

Anyone have any ideas on this one? I really don't think its a mechanical issue. I think the computer gets confused by something. I drove all over town yesterday for a couple hours without a hickup, then today it's consistently misfiring.


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## dkfackler (Feb 8, 2010)

Aren't those codes in the original post misfire codes? Posting the three-letter engine code would be helpful. Some of these had coil or coil ground issues which could be solved by cleaning/replacing the coilpack ground.

See this thread:

http://www.ross-tech.com/vag-com/cars/fuel-trim.html

You need to run the described WOT MAF test to verify or eliminate the MAF as suspect. If you don't own VAG-COM, see whether there is a Vortex member in your area. We're a helpful bunch.


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## stimper (Jun 8, 2011)

so I'll never be sure that the problem is gone, but figured I'd post an update since its been a few weeks with no trouble.

I took a break from the problem and went back a week later. the problem didn't surface but I don't have any reason to think it wasn't still broken. I took a fresh look at everything, hooked up a vacuum gauge, and cleaned a secondary wire going from the pos. terminal to the fuse box sitting right on top of the battery. I also sprayed silicone on the wires and coil pack. No further hint of trouble in the last 15 startups or so. I should have cleaned grounds and such before but the wires felt fine and I've never had that sort of trouble before. 

DK: The engine is an AZG 2 liter. I thought the coil pack troubles were in the 1.8 but there's been a ton of bad info so far on the internet about this car  

Now if I could only trick the computer into not caring about the secondary air injector that seems to have stopped working again. I HATE CELs 

peace out all!


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## stimper (Jun 8, 2011)

yep.. trouble came back in two weeks so I resprayed the coil pack and it cleared up immediately. Hopefully its just a crack and I can fix it with $4 worth of epoxy

Somewhat surprisingly my secondary air pump worked when I short it to the battery so I'll have to figure out why it wasn't working before. It (OF COURSE) seems to be working fine right now but the mil status on it is still 'incorrect'

Im paddling upstream here!


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