Does anyone have a valid answer?

[perrya]

Many 2002 VW Jetta 1,8T, automatic, owners have had similar issues about to be described: When engine is cold, say overnight, and started then driven without warm up of 10 min, upon acceleration the car jerks or bucks some and\or seems to go into neutral (meaning, the engine does not stall, but there is no power to keep moving) for 1-2 seconds before accelerating again. This is a dangerous thing in traffic.

The mystery to this remains: if you let the car warmup for 10 min or more even after sitting for a long time, the car runs smooth and normal. Some have suggested it is grounds, but then, it should do this all the time not just when cold. Some think the turbo has to warm up first, but is it active in just idle? Some think its a tranny thing, but why just when its cold? Is this a calibration issue to sync the turbo to the tranny in the ECM? Is it a sign the turbo is failing?

Like others, there are no codes. Car has 100K on it.

 

[benshaw]

im no expert.
I don't know how long u had it but have u changed the coolant temperature sensor? if its original I would for a genuine part only.

 

[BobnOH]

Gas Engine.
Valid Answer, maybe.
These cars have several temperature sensors, check them all cold, then hot, look for wack readings. Other than that you got fuel mixture, timing, etc.

 

[steve6]

I would say the car is misfiring, weren't these cars very prone to coil failures?

 

[perrya]

The coolant temp sensor was changed, as to coils, if the coil was bad or intermittant, it would throw a code. As I said, there are none. It would also misfire all the time, not just when cold. It seems to be temp related-maybe there is no answer!

 

[BobnOH]

Oh there is answer, and it will seem obvious when you find it.
Could the timing be way advanced? Air/fuel mix not adjusting to cold?
Embarrassed to say I don't really know exactly what the mechanism is for "choke" on these. Mix needs to a tad rich when cold.

 

[runonbeer]

5 speed or 4 speed auto?

 

[perrya]

5 spd.

 

[runonbeer]

Needs shift solenoids.

 

[turbovan+tdi]

Needs shift solenoids.

This!