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Carbon cleaning & cylinder 4 random misfire code - advice?

Neopork

Passed Driver's Ed
Hi guys,

If you have the tools, a garage, and a weekend, I would recommend doing the carbon cleaning yourself. I was quoted like $850 or something for the cleaning from my local dealer. I had read enough DIYs and bought the one day ElsaWin subscription, so I felt really confident that I could get the manifold off, do the cleaning, and put the manifold back on. It was a huge PITA but for reasons that might not affect everyone. If you have the right tools, all you need is to follow directions well and be super diligent about disconnecting and reconnecting everything properly.
I made a DIY tips on this that I posted recently on the MKV forums since I technically have a 2009 (MKV). All tips and steps should apply to the MK6 TSI as well.
Link:
http://www.golfmkv.com/forums/showthread.php?t=199802

Oh, I forgot to mention - I had to buy a torque wrench and a bunch of bits & extensions for this job. All in I was at less than $150 plus all my time which is free because i wanted to do this, so in a way I saved $750.

-Neo
 

aj_law

Go Kart Champion
IMO, carbon cleaning done properly should run you between upper $500s to $700 depending on the area of the country you live.
 

Tony48

Go Kart Champion
Hi guys,

If you have the tools, a garage, and a weekend, I would recommend doing the carbon cleaning yourself. I was quoted like $850 or something for the cleaning from my local dealer. I had read enough DIYs and bought the one day ElsaWin subscription, so I felt really confident that I could get the manifold off, do the cleaning, and put the manifold back on. It was a huge PITA but for reasons that might not affect everyone. If you have the right tools, all you need is to follow directions well and be super diligent about disconnecting and reconnecting everything properly.
I made a DIY tips on this that I posted recently on the MKV forums since I technically have a 2009 (MKV). All tips and steps should apply to the MK6 TSI as well.
Link:
http://www.golfmkv.com/forums/showthread.php?t=199802

Oh, I forgot to mention - I had to buy a torque wrench and a bunch of bits & extensions for this job. All in I was at less than $150 plus all my time which is free because i wanted to do this, so in a way I saved $750.

-Neo

Just read through your guide and it's fantastic. Many thanks for putting it together :clap:
 

NYCSuits

Go Kart Champion
I had the same cylinder 4 misfire around 100k miles, where one morning (below freezing), it threw a CEL. Started using LiquiMoly Valve Cleaner with every fill up and by the third fill up, no CEL and no stored soft codes via vagcom.

Fast forward to about a week ago, it was -7F in the morning and still had no misfires at 131k miles. Idled high but smooth on start up.
 

Neopork

Passed Driver's Ed
I had the same cylinder 4 misfire around 100k miles, where one morning (below freezing), it threw a CEL. Started using LiquiMoly Valve Cleaner with every fill up and by the third fill up, no CEL and no stored soft codes via vagcom.

Fast forward to about a week ago, it was -7F in the morning and still had no misfires at 131k miles. Idled high but smooth on start up.

I'm glad that's working for you in the short term, but carbon buildup is inevitable on this engine unless you drive it like a bat out of hell all the time. I included a couple pictures of 135k, first carbon cleaning, in my .pdf that I referenced above. I would estimate the intake ports and valves were restricted to about 60-70% of their normal flow capacity just eyeballing it.

No amount of fuel additive valve cleaner is going to remove the buildup on the valves because the fuel is injected directly into the cylinder on these cars, below the intake valves where the carbon accumulates. Cleaner injected through the intake has a minimal effect after the carbon has already built up. Only way to restore full performance and airflow is to take the manifold off and scrape all that carbon gunk out (and there was a shiiiit-ton at 135k).
 

Neopork

Passed Driver's Ed
About how often should a carbon cleaning be done, do you all think?

I've heard that it depends a lot on how you usually drive the car. Worst case scenario is small grocery trips as the norm where the car never warms up and revs stay below 3k the majority of the time. Best case scenario is that you do have a highway commute, the car stays warm for a while, and you keep the car at or above 3k for quite a while.

Some people have said they noticed the misfires and cold start issues at as low as 50k. For me, personally, I didn't even know this was an issue until I started getting cold misfires and surging acceleration at about 130k. For the first 8 years of life, my car was doing power commutes to work most of the time, and only in the last year has it become a grocery getter, which I assume is the reason the carbon accumulated and started causing problems now and not before.

It would be interesting to hear when other started noticing the symptoms and how they typically drive.
 

gti2015

Passed Driver's Ed
I've driven my car 75k and generally only drive short trips. I first noticed my misfire a few hundred miles ago but I didn't realize that is what it was until my mechanic read the code. I didn't and don't have a check engine light on for it.
 

NYCSuits

Go Kart Champion
I'm glad that's working for you in the short term, but carbon buildup is inevitable on this engine unless you drive it like a bat out of hell all the time. I included a couple pictures of 135k, first carbon cleaning, in my .pdf that I referenced above. I would estimate the intake ports and valves were restricted to about 60-70% of their normal flow capacity just eyeballing it.

No amount of fuel additive valve cleaner is going to remove the buildup on the valves because the fuel is injected directly into the cylinder on these cars, below the intake valves where the carbon accumulates. Cleaner injected through the intake has a minimal effect after the carbon has already built up. Only way to restore full performance and airflow is to take the manifold off and scrape all that carbon gunk out (and there was a shiiiit-ton at 135k).

Totally agree. It'll catch up to me eventually and I'll have to do a proper intake cleaning once it becomes a drivability issue. My one way commute is 77 miles, where I sit at 3k rpms/74 mph for about 70 of those miles which definitely helps in slowing the buildup process.

The funny thing is I do maintenance items waaaay before they are due. Oil change every 4k miles, DSG service every 30k, R8 coil packs + spark plugs every 30k, tires around 4/32nds but I can't get myself to do a proper valve cleaning. Because if I decide to do a proper valve cleaning, I'll want/need to get the newest intake manifold revision and all new injectors...otherwise it'll bother me.

One question I have...if an engine runs rich (stage 1 by Revo runs very rich at full throttle), would fuel remain in the combustion chamber after the exhaust valves close? or is the vacuum created, strong enough that it pulls out all of the fuel particles out of the chamber? Because if fuel remains in the combustion chamber and the intake valve opens, wouldn't the intake air push some of those particles out of the chamber onto the intake valves. Even if it's small amount, wouldn't the fuel + valve cleaner start to breakdown the carbon on the valves over miles and miles of driving?
 

Neopork

Passed Driver's Ed
One question I have...if an engine runs rich (stage 1 by Revo runs very rich at full throttle), would fuel remain in the combustion chamber after the exhaust valves close? or is the vacuum created, strong enough that it pulls out all of the fuel particles out of the chamber? Because if fuel remains in the combustion chamber and the intake valve opens, wouldn't the intake air push some of those particles out of the chamber onto the intake valves. Even if it's small amount, wouldn't the fuel + valve cleaner start to breakdown the carbon on the valves over miles and miles of driving?

I am not an expert on internal combustion, but I highly doubt it simply because the air going into the intake has been turbocharged so it has a high pressure. The intake valves being closed prevents that charged air from entering the cylinder until it is ready, and then when it does open all the pressure in the intake would enter the cylinder, so I doubt there would be a chance for the fuel to escape the cylinder (AKA positive pressure leading into the open cylinder always). Even if that does happen a little bit, its obviously not enough to clean the intake valves since they get so bad on these cars. Maybe someone with more mechanical knowledge can answer this better. Plus if you can tell/smell that it is rich, doesn't that mean the unlit gas is going through your exhaust system, and thus being pulled out of the cylinders? IDK, i am just making this up :)
-Neo
 
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