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· in dire need of an organic chemistry lesson
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Discussion Starter · #1 ·
Continuing with the saga, I started the car (1.8T AWM) this morning and less than a .5 mile it started stalling. A mile later it went off and the red battery light was on. I restarted it and the problem of stalling continues.

Is this a dying battery/alternator problem or the fuel pump? Any advice as where I should start? Thanks.

P.S. No CEL and no fault code at all.
 

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Seems to me that you would have trouble starting with a bad battery, or at least notice that the battery is very sluggish at best.

The symptom of starting and stalling very shortly afterwards, plus no codes, is very similar to what I faced when my fuel pump died. Others will chime in, but I'd be tempted to start investigating the fuel pump. How many miles are on that fuel pump?
 

· in dire need of an organic chemistry lesson
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Discussion Starter · #3 ·
Seems to me that you would have trouble starting with a bad battery, or at least notice that the battery is very sluggish at best.
The symptom of starting and stalling very shortly afterwards, plus no codes, is very similar to what I faced when my fuel pump died. Others will chime in, but I'd be tempted to start investigating the fuel pump. How many miles are on that fuel pump?
This is the original pump at 130K miles now. Like you I also incline towards a dying fuel pump. My question is whether the pump dies suddenly or shows signs of dying out?

The car right now starts fine so I doubt if the battery has any problem. Nevertheless, if I manage to take it home today I will test the battery and alternator. But how do I test the fuel pump?
 

· in dire need of an organic chemistry lesson
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Discussion Starter · #4 ·
I was reading the forums and some people mentioning fuel pump control module or crank case position sensor may also cause the car stall.

A few days ago I had the codes related to MAF sensor. It seemed that the wires were a bit displaced. After fixing the wires the MAF doesn't give any error and it's g/s is about 3.0 when I tested it with VCDS.

Given the car hiccups while driving and that is a known symptom of a bad MAF, I also suspecting cleaning the MAF last weekend may have somehow damaged it.

Any opinion on this ones?
 

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FWIW, my fuel died an instant death, and right around the mileage of yours coincidentally. The wife was driving the car and it stranded her. I went to look at the car the next day, it started and went a few hundred yards before stalling out. Had to get it towed home.

The fuel pump on the Passat is extremely easy to get at....one thing goes in our favor for once on these cars. I took mine out and hooked it directly to a battery, where it refused to operate, confirming my dead pump theory.
 

· in dire need of an organic chemistry lesson
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Discussion Starter · #6 ·
The fuel pump on the Passat is extremely easy to get at....one thing goes in our favor for once on these cars. I took mine out and hooked it directly to a battery, where it refused to operate, confirming my dead pump theory.
Understand that but I just cranked the car in my work's parking lot and it started normal. My point is that the fuel pump is surely working or otherwise the car won't even start. But whether is dying, I have no idea. I am ready to replace the pump only if I know it's the culprit. I hate spending the money and the problem is still there.
 

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Understand that but I just cranked the car in my work's parking lot and it started normal. My point is that the fuel pump is surely working or otherwise the car won't even start. But whether is dying, I have no idea. I am ready to replace the pump only if I know it's the culprit. I hate spending the money and the problem is still there.
Mine started too, and ran for a few hundred yards before dying. Not sure how or why it got enough fuel to do that, but it did. Bottom line, I think this is a good place to start, and if the fuel pump tests OK then it's time to look at other culprits. My thread on the topic, TomVW had a wealth of excellent info.

http://www.passatworld.com/forums/v...so-wifes-goes-out-my-vw-comes-home-honda.html
 

· in dire need of an organic chemistry lesson
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Discussion Starter · #8 ·

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I'm more late, but this is all pointing to the MAF sensor. It's failing on you. With your baby on, remove the MAF senor; If nothing happenings then there's your problem. Cleaning it probably damaged the tiny wire that monitors the air flow.
An inexpensive part. Should cost around 20$
 

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I'm more late, but this is all pointing to the MAF sensor. It's failing on you. With your baby on, remove the MAF senor; If nothing happenings then there's your problem. Cleaning it probably damaged the tiny wire that monitors the air flow.
An inexpensive part. Should cost around 20$
I think that you mean remove the MAF sensor's connector, not the whole sensor! And smac4th is correct about the type of flow sensor, I think. My old '96 A4 did indeed have the tiny thermistors instead of thin film version.
 

· in dire need of an organic chemistry lesson
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Discussion Starter · #13 ·
When I was trying to take out the MAF for cleaning, I broke it's harness lock. It is now more than a week that the car runs great with no problems. So I'm thinking either pushing the harness have made better contact or it was something I read in another forum.

someone wrote that when you clean K&N air filter and you spray a bit too much oil on it, that extra oil could cover the surface of the MAF sensor and causing low/high signals. After a while when the oil evaporates from the engine heat, the sensor functions again.
This situation overlaps with what I did. I cleaned the K&N filter and actually sprayed too much oil on its sides. Exactly after that I got the MAF issues.

Anyway, the car works fine as of now until we see what happens to her again.
 

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someone wrote that when you clean K&N air filter and you spray a bit too much oil on it, that extra oil could cover the surface of the MAF sensor and causing low/high signals. After a while when the oil evaporates from the engine heat, the sensor functions again.
This situation overlaps with what I did. I cleaned the K&N filter and actually sprayed too much oil on its sides. Exactly after that I got the MAF issues.
OK, now we're getting somewhere. If you still have the original air box and intake duct, put it back on with a new, clean pleated paper filter. The intake air will be cooler/denser, cleaner, the MAF won't get contaminated, so the car will run properly and have more power. And except for the oil problem, same goes for the pod filter.
 
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