VW Mags... why is my 2.5 Jetta Sportwagen trying to stall out when it starts up?

[radam]

Ok. The car in question is a 2012 Jetta Sportwagen 2.5 SE. In warm weather it starts fine. In colder weather, below about 32, it seems like it is always trying to stall out when starting up after sitting for more than a few hours. The engine sort of flutters a bit and even the headlights will flicker. Giving it some gas and bringing up the engine revs helps and is sometimes necessary to keep it from stalling out altogether. The battery has been tested, spark plugs have been replaced and the car has also been left with a VW dealer for diagnostics. They found nothing.

Here's a video (accidentally had the radio on at first but you can still hear the engine struggle and also see the tach needle bounce):



Edit to add: The problem happens until the revs stabilize at idle (20-30 seconds maybe) and then does not re-occur until the car has been sitting unused for many hours in the cold.

So.. any thoughts?

[SB]

Sounds like a sensor, had my crank revolution sensor go bad last year. Replaced and fixed it.

I have a 2004 1.8T Jetta wagon.

[radam]

Did yours throw a code when it went bad? Mine isn't throwing any codes.

[SB]

I don't think it did, dropped my car to a local WV guy and it took him a day or so to figure it out. If it had been a code he would have found it right away me thinks.

[El Chupacabra]

Not a VW guy (more of an anti-VW guy), but - fuel pressure regulator? Injector leak down? Fuel pump or filter?

Still under warranty?

[radam]

Yes, still under warranty. Just a difficult thing to deal with because it needs to both be cold and the car has to have been sitting for a while to reproduce the issue. The dealership had it overnight during a good single-digit temperature stretch but couldn't figure out what was wrong. They suggested just changing spark plugs at the next service interval. Spark plugs are cheap and easy so I went ahead and did that on my own... didn't help. Without a code to guide them in any sort of direction, they were reluctant to just start swapping parts all willy nilly, but they may be the only solution if the problem persists but never throws a code.

[MarcusBrody]

My Honda Fit has started doing this too. I think that we should check what they're putting in the anti-skid at Magic's parking lot. I bet it's the mercury!

Obviously they're likely very different engines, but the most common causes for the Fit seem to be bad O2 sensors and valves being out of adjustment, the latter being harder to catch.

[char]

Yes, still under warranty. Just a difficult thing to deal with because it needs to both be cold and the car has to have been sitting for a while to reproduce the issue. The dealership had it overnight during a good single-digit temperature stretch but couldn't figure out what was wrong. They suggested just changing spark plugs at the next service interval. Spark plugs are cheap and easy so I went ahead and did that on my own... didn't help. Without a code to guide them in any sort of direction, they were reluctant to just start swapping parts all willy nilly, but they may be the only solution if the problem persists but never throws a code.

If it was spark plugs/wires it would be a constant issue. I had a bad wire in a toyota and it was un-drivable. If the air system is good, IE clean MAF, O2, air filter, etc it must be fuel right?

[radam]

If it was fuel related, would the issue go away after the engine is not crazy cold? If it's been less than say... 3 or 4 hours since the car has been driven, it starts up just fine, even in very cold temps.

[HankScorpio]

I had similar problem with my '11 2.5l Jetta Wagon. It would hesitate to start in cold temps and then the RPMs wouldn't go above 3k. It was the a sensor, maybe the camshaft? I don't remember exactly. I brought to the dealer and it was fixed in a just a few minutes under warranty. Haven't had a problem since.

[radam]

I had similar problem with my '11 2.5l Jetta Wagon. It would hesitate to start in cold temps and then the RPMs wouldn't go above 3k. It was the a sensor, maybe the camshaft? I don't remember exactly. I brought to the dealer and it was fixed in a just a few minutes under warranty. Haven't had a problem since.

Yeah, I started reading about the crankshaft sensor that scottyb mentioned and then came across info on camshaft sensors and the symptoms of a bad camshaft sensor seemed to fit a bit better. At this point I'm debating if the $60 to fix it myself is less hassle than convincing a dealership to replace one specific thing that they have not yet determined to be faulty.

[El Chupacabra]

If it was fuel related, would the issue go away after the engine is not crazy cold? If it's been less than say... 3 or 4 hours since the car has been driven, it starts up just fine, even in very cold temps.

Possibly. That's why I mentioned things relative to the fuel pressure bleeding down over time. I'm focusing here on the length of time between starts, and not anything to do with ambient temperature.

Do you have a traditional keyed ignition, or a pushbutton start? If keyed, try this: when you turn the key to "on" (but just before the position that triggers the starter), do you hear the fuel pump pressurize? (a humming noise, will not be very loud, might want someone outside the car to listen closely)

If so - then, when the car has sat overnight and you expect to have a difficult startup - - key the ignition on to that position, key it off again, and repeat. The point of this is to ensure pressure buildup in the fuel system. Then try starting the motor, and see if it starts normally, or still struggles.

If it starts normally, I think you've just diagnosed a fuel system pressure bleed down problem. Something is losing pressure when it sits for awhile.

[Timberridge]

For a sensor related issue, or anything related to spark, fuel, O2 sensors, etc. the shop should be getting a stored misfire or sensor code. That no codes are being stored means its likely something else; something that doesn't trigger a code.

Vacuum leak on the intake side comes to mind. Check the filter housing to MAF to manifold for leaks. It could also be something as simple as a dipstick (not sure if this vehicle has one) not being inserted fully or loose oil fill cap.

If that checks ok, I would suggest inspecting and cleaning the MAF, you can probably google instructions for this for your car, or just replace it. You don't mention the mileage, but if the MAF looks dirty, consider replacing the PCV valve if you have 60K-70K+ as well.

[kpace2]

This may sound funny but I would check your O2 sensor and temperature sensor gauge. I had the same issue with my Subaru a few years back.


A faulty O2 sensor can actually cause powers surges. The computer that regulates your cars idle, fuel mixture,etc runs mainly from the info collected by your O2 sensor.

The temperature sensor on my car was also out of wack. It was telling my computer that my car was -50, so it would over compensate by flooding the engine with fuel and Air.

Trust me I know it sounds far fetched but I spent hundreds of dollars trying to figure out why my car was running so poorly. A friend recommended taking it to a local shop and they told me the O2 sensor and temperature sensor gauge is commonly over looked.
They changed both and my car ran fantastic !

[kpace2]

Timberridge is right on the money.

I would still have the O2 and temp gauged check.
They can both cause major voltage issues.

And sometimes if those gauges are really bad the computer in gauge a codex

[Aldo]

How many miles?

[radam]

37,000 miles.

Thanks guys, lots of good things for me or the dealer to check.

[AK47bp]

Have you checked the specs on the rotary girder?

[Todd Zander]

You didnt say how long this problem persists for, my first guess is its given extra fuel for startup thinking its cold but doesnt require it.

Not sure the 02 sensors are even involved within the first couple minutes.

[XXX-er]

Did you try a VW specific user site? Why would you ask a bunch of dentists/bankers/lawyers about a VW on a skiing site where most of them don't ski much ?

If you wanted to know who is the best porsche mechanic or where to get italian loafers resoled with the original materials ...sure

[radam]

Did you try a VW specific user site? Why would you ask a bunch of dentists/bankers/lawyers about a VW on a skiing site where most of them don't ski much ?

If you wanted to know who is the best porsche mechanic or where to get italian loafers resoled with the original materials ...sure

Because... I like this forum?

Also, in trying to search the VW forums for info on this, it would appear that the 2.5 Sportwagen is decidedly uncool and if I wanted a wealth of internet info at my fingertips I should've bought a TDI or an older VW which has been heavily modified.

[fatnslow]

Try turning your key to the"on" position for about 20 seconds before cranking. If your fuel system is having trouble creating fuel pressure when it's cold it can cause some issues like this. If you have a warranty take the thing back and "BITCH". Problem with this type of issue is when a tech fires it up once and it starts they don't want to touch it since they only get paid book rate and this will most likely have a return visit that they don't get paid for, especially warranty work. Take the car back and show them the clip AND ask for a loaner car. Crank position sensors can cause this type of issues, make sure you a OEM/Bosch not some shitty Chinese one if you decide to replace. Do you buy gas at the same place ? Try a name brand station next fill up WITH a bottle of techron. Assuming this is not diesel. You might also try cleaning/reseating connector on the MAF sensor. --Also make sure you are wearing light colored pants with Italian loafers when you work on the car, preferably Bruno Magli's-OJ collection. If you want to infinitely increase possibility of repair it's mandatory to cut your hand on a sharp edge in the engine bay during diagnosis and sacrifice some blood to the repair god.

[Aldo]

Take a look at the secondary air system

[fatnslow]

Take a look at the secondary air system

For the cure !

[radam]

Take a look at the secondary air system

Where/what is that and how do I check it?