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Matt, Engineer
Category: VW
Satisfied Customers: 20377
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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I have a 2009 wolfsburg jetta. This morning it was

Customer Question

I have a 2009 wolfsburg jetta. This morning it was hesitation when starting it up. This evening I was getting ready to go to the store, it starts up (hesitate) and then quickly shuts down. the engine light is on as well
JA: Will the headlights turn on? Is the battery fully charged?
Customer: I believe the headlights turn on. At first I thought it was the battery but I just got a new battery about 4-5 months ago
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I plan on taking it to a mechanic, just wanted to get an idea what it might be
JA: Anything else you think the mechanic should know?
Customer: The engine light has occasionally come on but then it goes away
Submitted: 3 months ago.
Category: VW
Expert:  Matt replied 3 months ago.


I'm assuming that this as a petrol engine version?

can you tell me what one?

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattenedpiece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements

Expert:  Matt replied 3 months ago.


do you still need help?

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