I have a few problems on my 1.4 tdi polo, first is when doing a cold start it has a really rough start, when starting when it’s warm it is less rough but still quite rough. I have read it could be sensors, not enough fuel supplied, glow plug. I have checked for error codes and I had a camshaft sensor error but cleared it and it has not popped up since. Also when breaking gently it grips then let’s go and then grips and then let’s go, the break pedal bounces when that happens as well, also how do I fix the rear window heating. Only 3 heating lines work.

Drain while water system refill with relevant diluted antifreeze fresh 

Breaks clean the thoroughly pipes pads and refresh break fluid get air bubs out

On 07/02/2020 at 09:41, adrian111 said:

...... I had a camshaft sensor error but cleared it

Did you check the wiring to the camshaft sensor or replaced it ?

The braking problem sounds to me as if the ABS (Anti-lock Braking System) is activating each time that you apply the brakes, this, of course, should only happen if one (or more) wheels start to lock up whilst braking - on ice say.

It is possible that one of the wheel sensors is faulty, the sensor wiring is damaged, or the reluctor (the toothed part that the sensor picks its signal up from) is damaged. It is also possible that the ABS unit itself is faulty, but this is less likely.

 

To be honest, the rough start problem could be one of a host of problems, but as there are no fault codes showing now, it could be something as simple as water in the fuel filter(which, of cause, needs IMMEDIATE attention to avoid damage to the pump.)

Servicing of the injectors may also help.

Providing that there is 'normal' power available one the engine is hot and there isn't an excessive amount of exhaust smoke, the problem is unlikely to be due to low compression pressures - but it might be worthwhile checking them if no other cause for the problem can be found.

 

Just to clarify, I take it that this roughness does continue after the starter is disengaged?

 

Regards