Engine Jerks

[simon.wiltshire]

Hi All

2014 POlo 1.2 TSI.

When doing a steady 30mph either in 3rd or 4th the engine just jerks ever now and again. I did take it to MEchaic and he suggested first thing to try was new spark plugs which have been swapped but its still happening. Anyone any ideas where to look now?

Thanks in advace

[joe6]

You really need a diagnostic scan. Without any details it could be ignition coil, occasional low fuel pressure, fuel injector problem, ......

[simon.wiltshire]

Morning its in the garage now, lets see what hopefully is found. I have never noticed the engine light come on though to indicate a problem.

regards

[simon.wiltshire]

So diagnostic showed "engine miss fire" AS part of the troubleshooting the Spark Plugs were replaced, they had kind of melted (the rubber protector) and took a long time to get removed. ISsue was same low mileage jumps. Next Coil PAck? was replaced, same no change. My mechanic who I have trusted for 30 years isnt to sure what to do next without just replacing parts which off course is costing me each time in parts and labour

Diagnostic tool was not showing any further errors after the changes.

Im wondering if its worth just getting it into a VW Dealer see if they have any better ideas?

[RUM4MO]

I'm assuming that along with the plugs and coil pack, the HT leads were replaced as they, I believe, needed to be modified by adding some protection - now if that sorts out or would have sorted out your issue, I can't say.

What sort of mileage does that car have, also, is the oil separator in good condition, or to put it another way, does that engine "use" oil?

[simon.wiltshire]

Hi

Im afraid I am not a car person.. But the Oil light never comes on and doesnt seem to use it, the car has done 41k.

Dumb question what are HT cables, and I Dont think they have been changed..

Thank you

[joe6]

This is what ignition (HT) leads look like. https://www.amazon.co.uk/s?k=ignition+l ... dp41lwh3_e

They are model and engine specific and go between the coils and spark plugs. The problem could also be caused by an intermittent low voltage wiring fault for the injectors or the coil.

[simon.wiltshire]

SO the car has been to 2 Garages and no fix, 2nd Garage said it looks to be a ECU Issue but they cant fix that but if it is that its could be expensive. Rang the dealer up and asked them to take alook and repair it as others cant and it probably falls under Consumer Act 2015 covering major issues in a car of this age and only 40k miles.

They took it and they can not find the issue either and offered us a full refund which is good, apart from with swapping insurance and some repairs I will still be out of pocket around £800, but I guess its better than potentially what it could be!...

[joe6]

If they think it is an ECU issue they could re-flash the ECU. Had to have this done to a previous VW car.

[Brian422]

Which cylinder did diagnostics identify as having caused the misfire?

Has anyone performed a compression test?

[simon.wiltshire]

Hi I have no idea what tests have been done to be honest, I was told by all garages nothing was coming up when they put it on the computer to get error codes.

I guess its interesting and suprising though that the dealer has admitted a fault and offered to give me the full £6500 back!. I think were going to take the money back rather than chase a "cure" for the car though...