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Discussion Starter #1
So we all know beetle 1.8 turbo doesn't make any blow off valve noise.

My car does that. it's fun to hear but it has a lot less power now.


One day, the car just kept dying at the stop light. I changed the air filter. still the same.

I unplugged the MAF sensor and it didn't die at the stop light so I figured I had bad MAF.

I cleaned it and put it back but still the same when I replugged it.

So far, I tried 2 used MAF sensors from salvaged cars.

Maybe my original MAF went bad and 2 used MAF I got were also bad ones?

If I just get new MAF, will it fix all the problems? (car won't die, no bad idling, no throwing air in the air)
 

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I've never had any luck with cleaning a MAF, can't imagine a salvaged one would be worth messing with either. Last time I bought a cheapo on Ebay and that did the trick, and if it doesn't then you are only out a few bucks. Do you have any lights on the dash? Popping could be your diverter valve. To test it you can pull it off, compress the spring with a socket, hold your finger over the vacuum nipple, if it's good then the spring should stay compressed until you remove your finger.
 

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Likely a hose, solenoid or valve problem of some sort.

Be careful about changing/replacing MAF with a cheap unit.

There are a lot of cheap/counterfeit MAF's floating around and can be a real headache to identify and flag. If you do decide to replace the MAF, keep the original MAF as you will likely be putting it back on the engine.

I have never replaced a MAF on any car I have ever owned yet, most are 10 years old and have close to or over 100k miles.
 

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Discussion Starter #5
So it wasn't MAFs problem at all? If I plug in right now, I can't even drive.

I am not sure what hose or valve I have to look for. Does that mean I have vacuum leak somewhere?

check engine light is on and I guess I should get the code first before keep asking questions.....
 

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If the engine will not run with the MAF connected, then likely you have a vacuum leak, unplugging the MAF puts the engine is a fixed richer fuel map.

Even if you get the codes read and it indicates a lean codes, it does not tell you where they will be. Maybe you will have a diverter valve or some other code as well.

Codes are helpful and a good start.

Suggest you read the first link below in my signature as anyone that has a car or truck outside of the new car warranty should have an OBDII scan tool.

Start by checking near the back of the engine for loose or broken hoses.
 

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check valves

I bet it's your vacuum check valves they are notorious for failures with temperature and time. Mine went out two years ago. luckily their only 6-8 bucks online. here is a picture of what to look for. Just don't buy it at the Dealer or you'll end up paying $50 for a plastic part that's only worth $10
 

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Discussion Starter #8
Thanks I checked that vacuum valve (passenger side near the washer tank) I could blow it only one way so it's not bad. Are there more of those?

I think I need to look at those little vacuum lines under the engine cover. Some of it has messed up fabric cover and I can't tell if they are leaking or not. (how to find leak, spray the carb cleaner? spray the soap water?)
 

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Smoke testing is the typical way of finding vacuum leaks. Put a rubber glove over the throttle bottle opening, then inject smoke either from a machine or cigar or cigarette into a vacuum hose and look for the leak.

As for the small check valves, at least on my 2003 1.8, I think I have 2 on top of the engine near the center and the white plastic breaks down on the bottom. If you have the black and white check valves likely they are bad.
 
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