Misfire at idle 1.2 TSI (CJZC)

[steevs]

Hi All,

Ever since I bought this car I have noticed for a while after starting that there is a somewhat lumpy idle.

Some days it continues to be lumpy even after a long drive when you return to idle, and even worse sometimes when pulling away the car is a bit jerky.

 

I have tried running VPower for a couple of refills and tried resetting fuel trim adaption with no avail.

 

Only today did I decide to monitor the car on startup and noticed via OBDEleven that all cylinders are logging misfires (you can feel it happen when it does!)

It doesn't seem to misfire enough to trigger any codes which has me stumped.

 

 

Does anyone know of common problems with these engines, I am about to start throwing parts at the engine but would prefer not to waste money.

 

Finally, it just reached 30,000 miles and was serviced regularly by a Skoda dealership - the car is a mid 2016 model.

(Screenshot attached from OBDEleven that was taken just after I disconnected)

[Ootohere]

@stevob21

What has Skoda Servicing actually involved?   Probably not much in 4 years.

Have you looked in the Air Box at the Air Filters condition?

The Spark Plugs might well require replacing as i imagine that any Dealership Staff will say they are special long life plugs and good for 60,000 miles but might get replaced at 40,000 miles.

 

It used to be at the 2nd Major Service / 4 years, so that is about now.

[steevs]

@e-Roottoot

Amazingly, the online service history (that's all I ever had access to) doesn't specify what was done - just the mileage and that it was a service, I assume just oil + filter + excessive labour costs

 

I have looked at the Air filter, this doesn't look the worst I have seen though I'm unsure how sensitive petrol engines are to this (Have always had diesel prior)

I removed the spark plugs and there is a small amount of build up, I wouldn't say anything particularly noticeable.

 

Air filter and plugs are my first plan, Is there anything else that commonly happens?

 

 

Thanks!

[Ootohere]

They are quite sensitive to needing a clean air filter in that the fuel consumption can increase.

As to the spark plugs it is the gap and plug type i check in what comes out and to what the gap should be.

(Incase someone cleaned and gaped them, or not.)

 

Someone will be along that knows about your engine as i do not, just generally 1,390 cc TSI Twinchargers.

 

 

[TerFar]

Although it may be plugs are reaching eol, but all four together seems wrong. Ditto the ignition coils. However, the simplest diagnostic is to replace the plugs. 

Have the oil and coolant levels been ok? I'm slightly suspicious that something other than fuel/air is getting into the combustion chambers even though you say the plugs look good. 

[krigl]

The engine is constantly checking the fuel quality by intentionally advancing ignition timing and producing either mild knock or misfires on all cylinders, to be as efficient as possible. Once it reaches this point it backs off a bit and then tries again after some time. This is why you get counters increased, but no codes.  Do not worry about it. Your numbers seem good to me, I have similar ratio between cylinders, but my is DSG, so the ride is smooth.

[steevs]

@TerFar Oil level is perfect for being serviced 2k miles ago, no noticeable drop. colour seems good though didn't check the viscosity to see if it was watered down by fuel.

On that subject, coolant level has been solid since I got the car just over a year ago.

 

 

[steevs]

@krigl at first I thought it could be that, it noticeably adds to these counts when idle which is the worrying part. it is also getting progressively worse/lasting longer when cold starting. 

[SirRahikkala]

On 11/08/2020 at 20:17, steevs said:

Hi All,

Ever since I bought this car I have noticed for a while after starting that there is a somewhat lumpy idle.

Some days it continues to be lumpy even after a long drive when you return to idle, and even worse sometimes when pulling away the car is a bit jerky.

 

I have tried running VPower for a couple of refills and tried resetting fuel trim adaption with no avail.

 

Only today did I decide to monitor the car on startup and noticed via OBDEleven that all cylinders are logging misfires (you can feel it happen when it does!)

It doesn't seem to misfire enough to trigger any codes which has me stumped.

 

 

Does anyone know of common problems with these engines, I am about to start throwing parts at the engine but would prefer not to waste money.

 

Finally, it just reached 30,000 miles and was serviced regularly by a Skoda dealership - the car is a mid 2016 model.

(Screenshot attached from OBDEleven that was taken just after I disconnected)

 

Hey, did you get the lumpy cold idle sorted? I have the same...

[nta16]

12 hours ago, SirRahikkala said:

Hey, did you get the lumpy cold idle sorted? I have the same...

 

If you have followed all of the good advice above, timely engine oil & filter changes with good quality oil, use good quality petrol, have changed air filter and plugs, then you could look at cleaning the throttle body (and MAF).

 

Let us know what you do and how you got on otherwise the subject will remain unanswered here.

[J.R.]

What possible relevance can " timely engine oil & filter changes with good quality oil" be to a percieved misfire at idle speed?

[steevs]

I got new coils recently and spark plugs, this completely solved the hesitation. Rough idle is only there with a hot restart after 2-3 hours but this is a documented (normal) issue to do with the catalytic converter. 

 

Cold starts are completely fine now.

 

Note: I changed spark plugs at the start of this thread, that alone didn't fix the issue.

Edited 20 May, 2022 by steevs

[Ootohere]

@steevsWho has documented this and said it was normal?    Is that on Social Media / Forums?

 Only normal if something is not quite right.   If it is someone at at Dealership saying 'They all do that' then they are telling lies.

Edited 20 May, 2022 by roottoot

[steevs]

10 minutes ago, roottoot said:

@steevsWho has documented this and said it was normal?    Is that on Social Media / Forums?

 Only normal if something is not quite right.   If it is someone at at Dealership saying 'They all do that' then they are telling lies.

 

 

It's a TSB that can be seen in Erwin, unfortunately you need to pay to access Erwin.

[Ootohere]

So is there a Software Update or a hardware update for the fundamental fault, or what does the TSB tell you?

 

Has someone from VW Group told people if their car runs rough after a hot start after 2-3 hours then tough titty this is normal?

 

How is a 1.2 engine doing a hot start after 2-3 hours, is this in tropical conditions or something? 

?

Have those with cars that start and run smoothly just ended up lucky?

Edited 20 May, 2022 by roottoot

[steevs]

10 hours ago, roottoot said:

So is there a Software Update or a hardware update for the fundamental fault, or what does the TSB tell you?

 

Has someone from VW Group told people if their car runs rough after a hot start after 2-3 hours then tough titty this is normal?

 

How is a 1.2 engine doing a hot start after 2-3 hours, is this in tropical conditions or something? 

?

Have those with cars that start and run smoothly just ended up lucky?

 

Edited 21 May, 2022 by steevs

[Ootohere]

Thanks.

That should be clearly published in the Owners Manuals.   

Now it can be maybe Pinned on here so that people need not pay to find out when Dealership Employees do not demonstrate to the customer that running rough can be 'Normal'. 

 

Also that when you open the drivers door after the car has sat a while the fuel will be primed before the car is started, or even before a key goes in the ignition if the car has a key. 

 

Coolant temperatures of 18*oC- 33*oC are going to be uncommon when the car is used in much of the UK through winters where the Ambient temp is not even in the teens so the coolant will not be when the car is sitting.

 

So no issues or rough idling with Catalytic warming when the coolant is below 18*oC?

Just the increased RPM that might drop off after 40 seconds. 

Edited 21 May, 2022 by roottoot

[SirRahikkala]

What is the TSB number of that?

[AGFalco]

6 hours ago, roottoot said:

fuel will be primed before the car is started

 

With mine the fuel pump:-

does not start when you unlock the car.

does not start when you open the car door.

 

does start when you turn the ignition on.

I always turn the ignition on, then put my seat belt on, then start the car.

A habit I developed from older Diesel engines. 

 

I have noticed this on my Fabia.

As they say, not so noticeable when it IS cold.

 

The first time you start driving the car there is a slight hesitancy.

Never bothered me.

 

Thanks, AG Falco

[steevs]

4 minutes ago, AGFalco said:

 

With mine the fuel pump:-

does not start when you unlock the car.

does not start when you open the car door.

 

does start when you turn the ignition on.

I always turn the ignition on, then put my seat belt on, then start the car.

A habit I developed from older Diesel engines. 

 

I have noticed this on my Fabia.

As they say, not so noticeable when it IS cold.

 

The first time you start driving the car there is a slight hesitancy.

Never bothered me.

 

Thanks, AG Falco

 

This is my first petrol car which could be why I noticed these things, I've only had modern diesels previously and they started and ran the same each time without any sort of hesitation or jittery idle.

[Ootohere]

@AGFalco I am surprised that your TSI does not prime the fuel rail after the car has sat long enough. (Before the ignition is on and then the fuel pump runs.)

I am not surprised that TSI's do it and drivers are not aware when it does.

 

Maybe listen closely.

   If you have the car left with the doors unlocked and get in the passengers door then listen as you open the drivers door.

 

Maybe this never passed on from Mk2 Fabia.

http://briskoda.net/forums/topic/217514-motor-noise-upon-opening-drivers-door-but-no-other-doors

http://mk5golfgti.co.uk/forum/index.php?topic=41524.15

 

Edited 21 May, 2022 by roottoot

[rum4mo]

4 hours ago, roottoot said:

@AGFalco I am surprised that your TSI does not prime the fuel rail after the car has sat long enough. (Before the ignition is on and then the fuel pump runs.)

I am not surprised that TSI's do it and drivers are not aware when it does.

 

Maybe listen closely.

   If you have the car left with the doors unlocked and get in the passengers door then listen as you open the drivers door.

 

Maybe this never passed on from Mk2 Fabia.

http://briskoda.net/forums/topic/217514-motor-noise-upon-opening-drivers-door-but-no-other-doors

http://mk5golfgti.co.uk/forum/index.php?topic=41524.15

 

My wife's late June 2015 build VW Polo 1.2TSI 110PS does not prime at "unlock" or "driver's door opening" - though her August 2002 VW Polo 1.4 16V did, I've forgotten if my older daughter's late 2009 Ibiza 1.4 16V did or didn't do that. 

[AGFalco]

17 hours ago, roottoot said:

Maybe this never passed on from Mk2 Fabia.

I can only here the pump start when I turn the ignition on.

 

Car is always locked and in a garage so there is no distracting noises.

I normally open the passenger door first on a work day.

Again no pump noise on either door opening.

 

Thanks, AG Falco

 

[rum4mo]

Yes, same on my wife's 2015 VW Polo 1.2TSI 16V, I'm guessing that this current system just runs the pump for say 4 secs then stops as its run time period has ended, as this Polo has not been used for 17 days, I tried switching the ignition off, then and again the pump ran for say 4 secs then stopped, so I repeated that once again and it again ran for say 4 secs and stopped - what I was initially wondering was, is there a lift pump circuit fuel pressure sensor/switch that allows that low pressure system to only run the pump initially until the design line pressure has been reached - but it seems that nothing like that exists or happens and the lift pump is only run for a short period, maybe a throw back to the original safety feature built into the electric fuel pump circuit of indirect injection engines, which was put in place to avoid the electric pump running continuously unless the ignition system was running - in other words, to avoid the high pressure electric injection pump running after an accident etc.