1.9 TDI 105 BHP - Engine stuttering during start up, but only when warm!

**Drazen** · 10-03-2016,05:42 PM

Hello people!

I had received great help on a previous thread so I decided to post again to see what you guys have to say about this.

So my Golf has been having this problem since I bought it. When the engine is cold the car starts up perfectly, but as soon as it's run warm it starts to rattle/stutter when trying to turn it on. The car turns on every time, it's just that the stuttering is annoying and this is not normal behavior.

A local mechanic told me it's a "Software issue", he told he'd fix it for about 75€. What do you guys think about this offer?

**DannyBoyGolf** · 11-03-2016,04:31 PM

Could be the coolant temperature sensor.
Depending on your engine code this could be a 4 pin or a 2 pin sensor/sender.

You can get the VW part for around £15 I think. Do not buy a 3rd party brand, use VW part for best results.
I can't guarentee this is the fix, but you are not the first with this problem.

To test if this sensor is the root cause, disconnect the wiring / electrical connection and try starting up. If it starts up first time, when you know your engine is warm, you can be sure this is the problem.

Be careful not to pull the sensor out though, otherwise you will loose all your coolant

Hope this makes sense?

**Drazen** · 11-03-2016,06:22 PM

Originally Posted by DannyBoyGolf

Could be the coolant temperature sensor.
Depending on your engine code this could be a 4 pin or a 2 pin sensor/sender.

You can get the VW part for around £15 I think. Do not buy a 3rd party brand, use VW part for best results.
I can't guarentee this is the fix, but you are not the first with this problem.

To test if this sensor is the root cause, disconnect the wiring / electrical connection and try starting up. If it starts up first time, when you know your engine is warm, you can be sure this is the problem.

Be careful not to pull the sensor out though, otherwise you will loose all your coolant

Hope this makes sense?

Yes, it does make sense! But when you say "Disconnect the wiring / electrical connection" what exactly do you mean? The wiring of the coolant temperature sensor?

**DannyBoyGolf** · 11-03-2016,06:54 PM

The sensor is half plastic half metal. The metal end keeps coolant in the car with a rubber seal. The other end is an electrical connection for the wiring. This connection is made by way of a plastic clip which covers the plastic end of the sensor. U might need a tiny flat screw driver to prise it off

**Drazen** · 11-03-2016,06:57 PM

So unplug (by leaving the metal end inside, so the coolant doesn't leak out), then try a warm start, if it starts up fine then the sensor needs to be replaced.

Did I get that right?

**DannyBoyGolf** · 11-03-2016,07:01 PM

Exactly that pal!

**Drazen** · 14-03-2016,02:19 PM

Originally Posted by DannyBoyGolf

Exactly that pal!

I tried it just now and it isn't the coolant temp sensor. It still stutters when turning on.

Although the only thing I did different is that I unplugged the sensor when the engine was cold, then ran the car warm, turned it off and tried it. Does this matter?

**niall campbell** · 14-03-2016,02:49 PM

no as long as the car is warm when you try it

Is there a fuel temp sender on your car ?

When starting car, do you turn ignition on, wait for glow plugs to go out. wait another 2 seconds & then turn engine over ? Even when car is warm ?

**DannyBoyGolf** · 14-03-2016,02:51 PM

Ok, a VCDS scan might highlight a known fault. Also, a stuttering start could just be your alternator. Halfords do free vehicle safety checks and this includes alternators.

**Drazen** · 14-03-2016,05:07 PM

Originally Posted by niall campbell

no as long as the car is warm when you try it

Is there a fuel temp sender on your car ?

When starting car, do you turn ignition on, wait for glow plugs to go out. wait another 2 seconds & then turn engine over ? Even when car is warm ?

Yes, that's how I do it. Correct me if I'm wrong but from what I know when I turn the key halfway (ignition) the glowplugs start to warm up, so I give them a few seconds and turn the key all the way so they could ignite the fuel. I do this even when the car is warm.

Originally Posted by DannyBoyGolf

Ok, a VCDS scan might highlight a known fault. Also, a stuttering start could just be your alternator. Halfords do free vehicle safety checks and this includes alternators.

Thing is, I'm not from the UK, I'm from Bosnia. But I think an alternator check up would be next on the to-do list. What do you suspect could be wrong with it?