Hey guys,

 

Hoping you can help.

 

I have a 2014 VRS (Petrol) that has an extremely rough idle (But no engine light) this has been going on a couple of weeks and seems to be intermittent and not temperature dependant. Some days when I start the car it starts fine, but as the engine warms and RPM's drop to 750RPM it feels like the car is running on 3 cylinders, this is accompanied by what can only be described as a "Squeak" noise from the engine. If it shut the car off and start up again the problem goes away.

When the problem is happening if I touch the throttle, even just raising the RPM by 100 the problem goes away and the engine is smooth. If I let me foot off and the RPM's drop, the problem starts again. (Unless I turn the car off and start it back up, in which case it's fine)

 

At my wits end I plugged in my old ODB2 reader which is registering a "Pending" code of 'P0302' which when I check online indicates " Cylinder number 2 misfire"

 

Ok, so that makes sense, but what I can't wrap my head around is why the problem is intermittent? and why shutting the engine down fix it? Surely if the coil pack or plug are dead stopping/starting shouldn't fix it?

 

Can anyone advise before I make a trip to the garage and get fleased in "Investigation" fees?

 

Thanks guys.

For the cost involved I'd change the plug (or all 4 if its anywhere near due) and clean down the plug leads. A misfire could be the fuel / air mix or the spark, the plug is the easy fix. 

Thanks Bud.

 

Can a plug be intermittent like that though? the car only has 27000 miles. 

In my experience the plugs either work, or they don't. 

I've known rough running sorted by changing plugs, and yes, plugs that work better at high rpm or when hot. But relatively so cheap to change that its got to be worth doing that before you spend any money investigating. I'd also put a shot of Redex in the tank to clean the injectors. On a service I usually wipe down the HT leads (or LT leads) with a cloth with some white spirit on to remove any oily residue. 

 

Out of interest what is the plug change mileage from the service schedule?

I believe from the factory they recommend the plugs and coils are replaced at 40k.

 

I've heard that getting the coils out of these engines at home isn't an easy task, it's very easy to damage the boots on the coils and temporarily brick your car. So i'm very reluctant to go fiddling.

I had this issue, and it was the plugs. Eventually the misfire became a permanent feature.

 

And yes, the coils were stuck in and ended up breaking as they came up, so make sure you have replacements before you start the job if you can't be without your car. Although I, annoyingly, got all but one out fine, so theres a chance you could get all four out without damage.

Hi Saint,

 

I've oredered 4 new NGK plugs and 1 new coil. I've heared that if you get the car up to operating temp the coils are much easier to remove? Not sure if anyone else has found this?

 

The parts should arrive Tuesday so I'll give it a go at my grandfathers house as he has more tools than I do

The only tip I've read on coil removal is to pull vertically as much as possible. Personally I think I'd spray a dash of silicone lube if possible to try and minimise any snagging, but not sure you'd get any access - I haven't had to do this yet. 

 

On the plugs situation I've found in the past fuel economy slightly better with new plugs, they will hopefully repay some of the cost in fuel savings. Have a look at the plugs when they come out and report back, also on how you got on with the coil packs removal and refitting. Good luck!

Edited 8 September, 20196 yr by VRS_White_Hatch
spelling!

Will do

 

I just find it so odd that a spark plug could be so inconsistent like that though? If it was consistently crap at idle then fair enough!

 

I guess we'll find out on Tuesday 😁

Update!

 

All 4 plugs changed and for belts and braces the coil pack on cylinder 2 was changed at the same time (Warm the engine up first and they just pop right out 😁)

 

The plug in cylinder 2 really didn't look faulty as you can see here:

 

 

I couldn't see any cracks in the ceramic, and the electrode looked worn, but not overly so.

 

The coil also looked fine with no obvious problems:

 

 

However after replacement I can confirm the issue does appear to have been solved. We now have a nice smooth and quiet idle. Although it was intermittent before so it's possible it might resurface!

 

I gave her a good blast on a quiet dual carriageway and the engine definatley sounds happier past 4000RPM, it's far smoother.

I'll keep you both updated on how the car does over the next couple of days, but thanks for your help so far

 

Great job. New plugs always make a car run better when I change 'em … even if its just in my mind!!

Another update!

 

Not good news though 😣

 

Misfire is back on Cylinder #2. I even managed to capture it in progress this time -

 

 

The moment I touched the throttle (I literally raised the RPM by about 50) the problem went away and the misfire counter stopped climbing. The car was then fine.

I phoned my local Skoda Dealer (Skoda North Wales) and explained what was happening and the mechanic had never come across the problem as described. (fills you with loads of confidence)

 

This really feels like an error in the software/Engine map, and not a mechanical fault at this stage. Me touching the throttle should not fix the problem until the next time the car is started up.

 

Any suggestions? 😕

 

[edit] Yeah, I'm pretty convinced this is software, take a look at these threads and let me know what you guys think -

 

https://www.golfmk7.com/forums/showthread.php?t=17553
https://www.golfmk7.com/forums/showthread.php?t=22341

 

Edited 20 September, 20196 yr by the_slug