Hi Guys/Girls,

 

I'm hoping someone can assist.

 

I have a 2014 VRS TSI which has had an idle misfire problem for 2 1/2 years now.

The car has been taken to two independent garages, and the Skoda main dealer for North Wales, all of which were unable to find the fault.

 

The symptoms are a misfire that occurs when the engine is cold, but does not occur under load. The car is very smooth to drive. The misfires affect Cylinders #2/3.

 

The following has been tried:

 

Coil packs have been swapped - Fault stays.

New Plugs - Fault stays

Compression Test - Within spec.

Manifold fuel injectors swapped - Fault stays (DI injectors not touched as of yet)

 

The cars ECU just logs misfires and that's it. All other modules pass tests and report no errors.

 

So at this point I'm getting pretty desperate. So I rang a local VW specialist who went through what had been done so far and even he was stumped, then he suggested checking the fuel trim on the car.

I've attached two images, one before resetting the ECU (To clear LTFT behaviour) and one after a reset. As you can see, my trim is running rich. I believe VW's limit before it will throw a fault is 10% and my car is constantly bouncing from 8-13% negative trim.

 

The specialist thinks this could be carbon build up preventing proper seating of the valves. Although I'm not sure that would the engine to run rich?

 

Does anyone have any suggestions before I spend even more money just to be told "I've never seen this issue before" 😕

 

Thanks all.

What type of fuels do you use? If Supermarket fuels, please don't use them. It causes performance issues.

 

If the fault is at cold, consider an electrical earthing issue (is the earth's on the coil packs corroded - they are a pain to keep clean....). Issue is cause by bi-metallic corrosion.

 

Can you check to see if there have been no changes to the ECU (either via mapping or mod boxes).

 

You could be suffering from sticking valves or gunk in the injectors caused by poor fuel. 

 

Do you run on E10 or E5 fuels? If E10 has this problem only just started?

 

A few things to consider.

13 hours ago, varaderoguy said:

What type of fuels do you use? If Supermarket fuels, please don't use them. It causes performance issues.

Shell V-power Nitro.

 

13 hours ago, varaderoguy said:

If the fault is at cold, consider an electrical earthing issue (is the earth's on the coil packs corroded - they are a pain to keep clean....). Issue is cause by bi-metallic corrosion.

Coil packs have been swapped, and spark plugs replaced. Issue stays.

 

13 hours ago, varaderoguy said:

 

Can you check to see if there have been no changes to the ECU (either via mapping or mod boxes).

Skoda checked the ECU when it was with them a couple of months ago and confirmed the stock MAP is present.

 

13 hours ago, varaderoguy said:

 

You could be suffering from sticking valves or gunk in the injectors caused by poor fuel. 

Possibly, but I have ran a couple of treatments of STP fuel system cleaner through the car over the past two years.

The car is actually booked in at another independent VW specialist in November to inspect the intake valves.

 

13 hours ago, varaderoguy said:

 

Do you run on E10 or E5 fuels? If E10 has this problem only just started?

E5 only.

 

Thanks for replying

 

Edited 17 October, 20214 yr by the_slug

5 minutes ago, the_slug said:

Coil packs have been swapped, and spark plugs replaced. Issue stays.

Arh - good call for the rest of these - wanted to check out whether the Earthing tabs which bolt onto the engine block are clean of corrosion.  The story behind this was that on a 2018 VRS TSI engine that I had, the car had an intermittent rough running on cold.  I thought it was spark plugs, but when I took off the coil packs, the earth connections onto the block itself were heavily corroded.  I cleaned up the earthing points on the block and the tabs - and the problem went away.  The engine ran even smoother!!!

19 minutes ago, varaderoguy said:

Arh - good call for the rest of these - wanted to check out whether the Earthing tabs which bolt onto the engine block are clean of corrosion.  The story behind this was that on a 2018 VRS TSI engine that I had, the car had an intermittent rough running on cold.  I thought it was spark plugs, but when I took off the coil packs, the earth connections onto the block itself were heavily corroded.  I cleaned up the earthing points on the block and the tabs - and the problem went away.  The engine ran even smoother!!!

 

Thanks anyway mate.

 

I'm still puzzled as to why the car is running rich though? I don't get why carbon build up would cause that?

Apologies I think you misunderstood me. This is issues that are electrical. The negative earth from the coil pack to the engine....

On 17/10/2021 at 11:02, the_slug said:

 

Thanks anyway mate.

 

I'm still puzzled as to why the car is running rich though? I don't get why carbon build up would cause that?

If your car is running rich I would check lambda (oxygen) sensor values. If they are reading low then the car will over fuel. My guess is one of the sensor are on the way out.

Maybe I have solution fort this one. I remember you already had a topic with same problem as mine, but I see you have very big SFT and LFT after, so maybe it is not the same problem.

I had rough idle when car warms up. That is a point when camshaft adjustment magnets start to work.
I thought the problem is with injectors, Fuel trim was going up to 7 on idle, rough idle, misfire on 2. and 3. cylinder (probably most affected cylinders, which can be seen on one of the pictures from Super 280 topic). But did not had misfire while driving.

I tried to swap coils, without success. Replaced two MPI injectors (the one working on idle), without success.

Then I saw on YouTube a guy remapping Superb 280 and he was checking Camshaft Adjustment Intake Bank 1 Actual and Specified. Specified was 15 or 16, while Actual was going from 0 to 30. They replaced both magnets and after that did remap.
This was case with my values too. 

I have cleaned intake magnet, it was sticky but it was working just half an hour. I already ordered new one and decided to give it a try.
Now with new magnet is it totally different. Smooth idle, not to mention smooth gear changes (DSG) which I forgot how they can be smooth. Enjoyment.
I am replacing in a few days Exhaust camshaft magnet too, I saw it is not consistent with actual value, not following specified. But not so bad.

 

So, check these values first with VCDS or any other tool. Camshaft adjustment intake actual and specified.
Magnet change camshaft position, so it can have more or less air and due to that you get misfire, strange lambda reading and so on...

 

Also, check both O2 sensors.
If first sensor is wideband you can see lambda staying around 1 (or I think around 1900mv for tsi)

Second sensor should be between 0.2 and 0.7v (probably around 0.390v)

 

Depress the gas pedal and see if both change in opposite direction. As you see on pictures how values go for rich and lean, opposite way.
If they are properly working they should move.
Also second sensor should be steady on idle, meaning cat is working.

 

If first sensor is narrow band, then both values should go in same direction when you depress gas pedal while standing.

If first sensor is narrow band, it should fluctuate at the idle, meaning it is changing from rich to lean, but second one should be steady meaning cat is working.
If first one is lazy, then it is not working.

Hey @Bingodalton

 

I've just hooked up my monitoring to the car and I don't have "Camshaft Adjustment Intake Bank 1" but I do have "VVT Monitor Bank 1"

Here are the results:

 

 

Do these look out of spec to you?

 

Give me half an hour, will reply

Give me half an hour, will reply.

 

This is when engine is warm? 

 

Guessing by vcds, first value is echaus specified, then exhaust actual, then intake specified, then intake actual.

 

After engine settles from cold start, first one is 0, as well assecond one, third one probably depends on engine. On mine it is 15 or 16 and fourth one shoukd be +/- with third one, fluctuating. For example 14.2, 14.3, 14.2, 14.4,...

 

Check which ones are steady, defined and which ones go up and down.

Just at the Gym but will reply when I'm home. Thanks for your help so far @Bingodalton

I checked on torque pro. These are not those values. They do not show the same value as on vcds.

@BingodaltonMy misfire occurs when the engine is slightly warm or hot. Usually when it's bone cold there are no misfires.

Here is the data from the engine being luke-warm:

 

 

4 minutes ago, Bingodalton said:

I checked on torque pro. These are not those values. They do not show the same value as on vcds.

 

Hmm, I guess I'm going to need VCDS to check the requested/actual readings from the cam adjusters then?

Try to check it out.

Might be that problem. There are maybe more problems, but I guess magnets are one of issues.

 

Maybe there is somebody with vcds near you.

Thank you for checking anyway @Bingodalton

 

I'm going to buy a VCDS cable as I live in a fairly rural part of the UK so I don't think anyone will have VCDS near me.

Plus I can use it in the future.

 

I'm just hoping that the cam magnets are the issue as I'm running out of ideas at this point 😞

 

Did your car only misfire when warm/hot? Mine is always ok when cold. It's only when there is heat in the engine I get misfires.

From start when cold it works good. 

But when it goes in closed loop and warm a little bit it starts to behave rough. And not absolutely always.

No rule that you can pinpoint to problem. 

 

3 minutes ago, Bingodalton said:

From start when cold it works good. 

But when it goes in closed loop and warm a little bit it starts to behave rough. And not absolutely always.

No rule that you can pinpoint to problem. 

 

 

Yep, exactly like my car then.

 

Did your car have any codes stored for the adjuster failure? If not then it sounds like this might be the problem I have!

No codes at all. Running good. Economy so so, nothing unrealistic or dramatic, maybe coukd be better.

I feel diffence with new magnet, I am waiting for exhaust one to see if this one is getting stuck too. 

Its still not perfect.

But values which were fluctuating before are now according to actual, so this part was broken and even cleaning did not helped.

In a few days I will replace other one and be able to say if graph for that one is better.

 

First picture, while driving.

You can see, upper two lines are intake magnet actual/specified.

Lower two lines are exhaust magnet actual/specified.

Difference between first two is less than 1, while for other two is more in some cases.

In data left upper corner, firs is exhaust, then intake.

 

Second picture is with old intake magnet on idle. Then exhaust is on 0.

You can see how intake tries to catch 15, going up and down.

 

You realize how good should work new magnet, following specified value.

 

Thank you for the screenshots! Very helpful.

 

I think this person had the same issue as yourself:

I'm going to pull the adjuster on the weekend and see if mine is stuck/sticky.

It may look like it is not stuck/sticky.

I have cleaned mine, it was almost perfectly moving, but when I replaced it 2 days later I realized how it was not like the new one, even cleaned.

I will try to upload a video of new and old one for comparison.

Unfortunatelly I have video of old new, 2 days after cleaning, second new one is on the way.

For sure you can remove it, it is easy.

There will be oil, do not worry.

Underneath the magnet you will see a valve. It has two excentric holes and "button" in the middle.

Cllick it with a finger, should move freely. And defaulf position should be flattened with its surrounding.

As a matter of magnet, you can get it cheap, for even 20 or more.

Do not know if the ones from Febi, Pierburg, Swag have incorporated change of revisioned part. Original is around 50-55.

@BingodaltonI pulled mine off today and it was very "Sticky" it wasn't loose and free moving like it should be. It was like the unit was full of syrup. I cleaned it and got it moving a bit better which seems to have helped but obviously the unit needs to be replaced.

I've ordered a replacement unit so once that arrives I will update the thread.

Is it any better after you cleaned it?
I think something stops to work properly even if you clean it. It is not responding strong enough or fast enough. Hot oil is there and it affects its functioning.

I am waiting to hear news when you get new part?

What have you ordered, which one, which price?

It seems to be slightly better yes. But like you, my problem is intermittent so until some time passes it's hard to say.

But it's definitely not working correctly as the pin is very sluggish and sticky. I recorded a video of the unit here: https://drive.google.com/file/d/1kZ_dZ1kPEcRTDISp4Aq9bDa-lsPgrSEw/view?usp=sharing

 

This is the part I ordered: https://www.ebay.co.uk/itm/264317656665

 

You can see the difference between a new one and a stuck one here: https://www.youtube.com/watch?v=-eSOaYRzNAU&t=4s

 

I know the video. He was lucky with just cleaning. Mine was not stuck like that, after cleaning it was same as his, but still not working properly. Hope you will get it soon.

My exhaust one is on the way. Not sure if I will have time tomorrow to replace it. it is getting dark very early, I do not want to lose screws.

But I want to do this as soon as possible.  Saturday morning I am going on short trip, so I want to try it and check it with VCDS on the road, but for sure I will check it in the evening too and post my results if exhaust one has improved something and how graph readings look like.