Help! Extremely Rough Idle

[Stewie2k7]

Any Advice or Help is really appreciated as I love this car

So my 2006 Polo 9N3 has been idling rough for the last 2 months, and in the last 2 weeks, it's gotten much worse.
If idling for more than 30/40 Seconds the car starts to shake harshly and there is a loss of power if driven, then the check engine light flashes.
but when driving normally the car is absolutely fine.

I brought it to a mechanic and he suggested it might be a burnt-out exhaust valve, so we did a compression test and there were no abnormalities. we replaced the ignition coils and spark plugs with brand new NGK's. but the problem still occurs.

I have temporarily got around the issue by avoiding traffic lights and turning off the car if sitting for more than 10 seconds.

I don't have any sort of diagnostic tool and cannot scan it myself.

Once again Any Advice or Help is really appreciated as I love this car.

[CarbonChaos]

What engine is fitted ? 1.2 3 cylinder ?

[Stewie2k7]

Apologizes Yes, Its a 1.2 3 Cylinder 55/54BHP

What engine is fitted ? 1.2 3 cylinder ?

[CarbonChaos]

Do you have the compression readings still ?

Take a good look through this thread and compare your results to these

viewtopic.php?t=77259

Get the codes read and recorded

[Stewie2k7]

Thanks for the reply

I’ll get onto the mechanic to get the results over to me, I didn’t see any results he just said that it was all good. Im a reoccurring customer to him so I don’t see why he would say otherwise.

I’ll have a look through the tread and post an update when I have a look

Thanks Pal

[Stewie2k7]

Do you have the compression readings still ?

Take a good look through this thread and compare your results to these

viewtopic.php?t=77259

Get the codes read and recorded

Also just to let you know I received your PM, I’m not being rude or ungrateful I just can’t seem to reply yet as my account is newly registered.

But spot on mate I’ll do as you say and let you know how I get on

Enjoy your weekend

Kind Regards

[johntheo2]

I still wouldn't rule out a valve problem as these can stick partly open occasionally which leads to valve/seat burning and eventual permanent low compression, however there are a few things to check out before going down that road as it idles OK for 30secs or so. A vacuum gauge connected to the brake servo pipe would tell alot and should be ~ 16ins. I would also check all vacuum lines (like brake servo) for cracks, some of these pipes are plasticky and difficult to see any cracks, generally a permanent crack results in a high idling speed. Another (unlikely) possibility is that the TB (throttle butterfly) is jamming on a carbon build up in the throttle body/plate, a squirt of even wd40 onto the throttle plate with engine stopped will sometimes clear this. Also a suspect would be the PCV valve which may be operating erratically, very easy to change this. I will edit and try to attach a photo/link later.

Can't post photo but here is a link to symptoms of a failed one. https://www.autoguru.com.au/repairs/pcv ... wagen/polo

[Brian422]

Suggest checking valve timing.

I understand that it's not uncommon for timing chain to jump even after an oil change.

It's a bit tricky but i used my phones camera.

https://www.youtube.com/watch?v=_dYEDZNNwws