Passat Cold Start Problem

Tropheus · 21-09-2009 3:17pm #1

Hi,

My Father in Law has a 2001 2.0l petrol Passat. It's well maintained, but recently has problems cold starting. It has never failed, but is slow to start and takes about 10 seconds after starting before it's turning over normally. It only happens first thing when the engine is cold. It's fine for the rest of the day.

Any ideas?

Muckie · 21-09-2009 5:46pm

Whats the battery like, does the starter motor turn over alrite.

Tropheus · 21-09-2009 6:02pm

It's the original batter, but it's turning over the car fine.

crosstownk · 21-09-2009 6:43pm

ksimpson wrote: »

is slow to start and takes about 10 seconds after starting before it's turning over normally.

ksimpson wrote: »

It's the original battery, but it's turning over the car fine.

Slightly confusing.

It might be worth having the engine temperature checked as it may be reading incorrectly. This can cause hard starting issues. There are plenty of other culprits for hard starting but the temp sensor is a good place to start.

Tropheus · 21-09-2009 6:54pm

Thanks, I'll take a look at it.

Just to clear it up. The engine turns over (via the starter motor) fine when it's cold, it just doesn't start first time. If it was the battery, I would expect the turnover to be sluggish before it starts.

crosstownk · 21-09-2009 8:40pm

It's either a fuel or ignition problem both of which can be caused by a variety of sensors reporting incorrect data to the ECU. The problem is determining which one. It might be no harm to get a diagnostic tool hooked up so values can be measured in real time.

Slidey · 22-09-2009 8:54am

Although the heater plugs are not definitely needed on these engines they do make a difference.

It could be either the heater plugs or the heater plug relay/controller.

darragh o meara · 22-09-2009 10:57am

I would lay my money on the temperature sensor. They give lots of bother accross the VW range. The car has two seperate maps for starting depending on the temp of the engine, Cold Map which richens up the mixture and retards the timing slightly to help start in the cold, whereas the hot map is not so rich as the car is usually up to ideal temp when its needed and its easier to start. In theory its like a automatic choke for want of a better description.

Get somebody to plug into the car with a diagnostics unit and check the values the sensor is reading...

Passat Cold Start Problem

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