(Please advise if there is a better section for this; I believe this is the most appropriate)
** Thereís a lot of text here. If you donít want to read it all, watch the BEFORE video posted below. It shows the carbon buildup very clearly **
After countless hours of research on this topic of carbon buildup in (specifically) the 4.2 BAR FSI engines, I was unable to come up with any concrete answers (this post HERE
is about the best reference Iíve come up with). There's plenty of information on 2.0t engines, as well as some of the V6 FSI engines, but other than the RS4 application of the 4.2 FSI, very little. I'm not going to get into speculating why or how this issue is what it is.
My opinion? It's something that needs to be addressed at regular (albeit probably pretty spaced out) intervals. I did mine at 100k miles (~160k KM). Since itís hard to pin down exactly what causes the buildup, itís also hard to specify an exact recommended service interval. I would say every 100 000 miles at most.
There are a few products that have claimed to fix this issue without removing the intake manifold and manually cleaning the intake ports & valves, but they've pretty much been 100% debunked as not really doing anything.
WHAT THIS POST IS:
WHAT THIS POST IS NOT:
- Some reference footage and pictures of the buildup I found in my engine, with around 100 000 miles. As stated in the video, I am the third owner and thus donít know much about how this vehicle was driven before me.
- Some suggestions on how to clean the ports (see video)
- Feedback on the process and results
To hopefully make things easier, I have named the pictures 1.jpg through 7.jpg and will reference them as such.
- A theory on why the buildup occurs (I do have a couple but nothing I can substantiate)
- A solution to prevent the buildup (most of my reading has turned up that catch cans do NOT make any noticeable reduction in deposits)
- A step-by-step tutorial on how to remove the intake manifold and clean the ports (I can post a writeup for intake manifold removal if there isnít anything out there already, although I didnít take any pictures along the way)
I decided to pull my intake manifold on Saturday morning to inspect and clean my intake ports if necessary. The actual removal of the manifold took me around 3 hours, as I did it without any sort of guide. Itís fairly straightforward, although itís certainly tight in some areas.
Pictures 1-3 show the buildup I found. Distribution was fairly even; no cylinder seemed to be plugged up more than another. I would say that the buildup ranged from around 1mm thick on most of the port walls, to 3mm, maybe 4mm around the valve stems. Pretty bad.
Cleaning was pretty straightforward, although time consuming. I discussed most of what I did in the AFTER video below, so Iím not going to reiterate that here.
The BEFORE video is probably the one of most interest to most people here since it demonstrates the buildup you might expect for an engine with around 100k miles. As I mentioned above, and in the video, I am the third owner. I do not know if the ports were cleaned before, however I highly doubt it (the previous owner who has had it since ~50k miles ish didnít indicate that any major service of any kind was performed on the Touareg.
Pictures 4 & 5 show what the ports and dividers should look like when cleaned (of course this depends on how fussy you want to be with cleaning).
For those curious, pictures 6 & 7 are what the inside of the intake manifold looks like. As you can probably imagine, itís a bit tricky to separate the two halves. I donít know that I would split the manifold if I did this job again, since there really wasnít any buildup anywhere other than the flaps that are directly above the intake ports. If youíre careful, you should be able to clean them without dropping anything into the depths of the manifold where it could potentially cause harm. I would, at the very least, clean the backside of the flaps a bit, just so they donít start sticking down the road.
The 4.2 FSI V8 engines in the Touaregs/Q7 ARE affected by carbon buildup in the intake ports. Maybe not as bad as some RS4s you may have seen, but still pretty bad. So for those who have been asking the question, these are some pictures for you to look at.
The engine never exhibited any stuttering, rough idle, misfiring, or any codes prior to this cleaning. It ran pretty well. However, after the cleaning, I noticed the engine pulls much harder after ~4000 RPM. Prior to cleaning, the engine pulled well but felt somewhat ďflatĒ through the whole power band. Overall I wouldnít say itís a super night and day difference, but I did notice an improvement.
Fuel economy? Throttle response?
Iíll have to drive around for some time before I can comment on fuel economy. Throttle response is improved somewhat, but I think that has more to do with the throttle/transmission adaptation reset since I had the battery disconnected during the cleaning.
- I would certainly recommend anyone who has a Touareg with over 100 000 miles to definitely consider an intake port cleaning. I canít guarantee what youíll find, but Iím thinking that most engines are pretty gummed up by that point, as mine was.
- As I discussed in the video, I reused my intake manifold gaskets. So far, so good. Take that as you will; Iím certainly not recommending that anyone reuse theirs, but depending on the shape theyíre in it might be an option.
- Rather than try and prescribe a fixed interval, I would suggest you pull your intake manifold and assess the buildup. Some engines may be worse than others. In my case, I think Iíll wait another 100k miles to clean it again. However, you may find that a 50k mile interval is warranted. Itís impossible to predict this sort of thing without seeing whatís in there.
- I do not know if VR6s are affected by this, or to what extent, as I do not own one. I am only familiar with the 4.2 and 2.0t (my motherís car, which I have not cleaned yet).
- Extending on point 3, every engine is different. Speaking of 2.0t engines, some seem to be prone to issues every 40-50k miles, while others go well over 100k without so much as a misfire. Donít assume that what one person finds in their ports will be whatís in yours. There are far too many variables involved in this issue.
So there you have it. I hope at least a few people will benefit from my findings. Again, my intent with this post & videos is to shed some light on how this issue affects these Touaregs. Theyíre getting to the age where people like myself are picking them up second or third hand, with higher miles, where these types of issues need to be addressed.