My carbon is back :-(

[DazN]

Hi,

Around 5,000 miles ago we spent 2 days removing the manifold and cleaning the carbon from the tops of the valves and ports, since then the car has only had v power and has recently had a full service and oil change. I've driven it normally most of the time but then also done the 'Italian service' as much as possible.

I thought now might be a good time to have a look and see if the build up is coming back.

(forgive my terms here, not exactly sure what each bit is, I usually just hold screw drivers and make coffee)

Just had the air intake off and then the metal part at the end of that which has the flappy bit in it. Got a flexible camera and tried to look at the first couple of valves, couldn't get in so we removed the passenger side coil pack connectors and want in through one of those by removing a spark plug.

The top of 2 of the valves have a very slight amount of carbon on them, it looked wet and certainly not the polished ones we left in there several months ago

I'm going to get some intake cleaner and give that a good blast, but I doubt it will shift it all.

My mechanic mate said you can fit an oil catch can but he doesn't think it would do much on this engine, he's more than willing to help me install one on the end of the breather pipes but then you don't know what else you're effecting.

Car certainly doesn't feel any slower!!

So is this just something we live with?

Cheers

Daz

[pad125]

...you might want to step back from your computer Daz before the blast does you some damage.

[P_G]

Just something you live with Daz, you would have to elminate valve overlap and reprofie the cams to potentially reduce it or better still, supercharge it with the increased airflow which may be even more preventative.

The design of the engine means it will always accumulate build up. I'm going to do the same as you and crack mine open again in a few thousand miles to see if the Royal Purple Oil I ma using has stemmed the accumulattion any but I suspect not as mine still belos black crud every now and aagain when use the full extent of its capabilities.

[DazN]

...you might want to step back from your computer Daz before the blast does you some damage.

Have I just lit the touch paper...?

[adsgreen]

Catch can has been proven to not work on these engines - it's not exhaust blow by.

The finger of blame is looking like valve stem seals and/or the valve overlap used when the internal exhaust gas recirculation kicks in.

If you do clean them again then you might want to see about replacing the valve stem seals as thats about the only thing you can do aside from manual cleaning or dumping in some intake cleaner.
I did think about replacing the core plugs with some kind of sealable port so you could inject the intake cleaner right on the problem area but never got round to it.

[PetrolDave]

Have I just lit the touch paper...?

Yes, we've been round this topic many times and it's caused strongly held views to be expressed, sometimes in "Anglo Saxon".

The bottom line? - you clean it, it comes back; you add a catch can, it comes back; you live with it.

[DazN]

Bought 2 cans of intake cleaner, job done

[sonny]

Have I just lit the touch paper...?

caused strongly held views to be expressed, sometimes in "Anglo Saxon".
.

Legend.

[lengster1]

Its normal to have 'some' and the wer look is a byproduct of the valve timing overlap the engine runs,i had carbon clean on my first visit to mrc and 6 months later and a few k miles when i took it back for full hog stage 2 manifold and CAI etc i had another mini clean done as what you describe had re appeared,that level is normal if its never driven at high rpm on a regular basis and effectively blow it through you will get too much and start to lose performance.

[edge]

Just something you live with Daz, you would have to elminate valve overlap and reprofie the cams to potentially reduce it or better still, supercharge it with the increased airflow which may be even more preventative.

Well then its settled, this is the best reason to supercharger her

[adsgreen]

I doubt supercharger would get rid of it completely - the higher airflow (looks like about 50% more ish) would certainly blow off the larger formations but alot of the time the engine will be off boost and still be operating in a vacuum... it'll always be there.

The problem with the valve overlap is that you remove the EGR part and thats actually very useful. You'd have a pretty steep drop in MPG through pumping losses and temps in the engine would be higher. Oh, and the emissions might be a problem too.

[alex020869]

and then the metal part at the end of that which has the flappy bit in it.

I know I have no input into your problem Daz but this made me laugh!!!!

Alex

[DazN]

I don't think mine has actually "built up" again, there's just residue and driving with a few bounces off the rev limiter should keep it at the same level

[sakimano]

I don't think I would lose sleep over carbon buildup. It's certainly going to eventually get bad enough to rob you of some top end, but a clean every 15,000 miles ought to stop it from getting ridiculous. Probably $750 (475 pounds) at a time...which is about 3 months of petrol money so no biggie.

My car runs reasonably strongly for a bone stock 2008 that has never been carbon cleaned. Nominal timing retardation (never more than 5 degrees when its cool out). It went 12.9 @ 107.8 at the dragstrip, good enough for the third fastest stock time on the forums. I'm sure I'm losing maybe 10-20 whp but it's likely all top top end, rather than loss of area under the curve across the entire rev range. My car might have a 12.8 @ 108.5 in it or something...but not like that's enough to cry about. I don't seem to lose any races that I shouldn't.

here's a couple of 3rd gear logs and an hp/torque chart I made for fun off the 'engine torque' data in the first log (converted nm to lb-ft)

p.s. I hate the stock torque/throttle limiter. Looking at logs with throttle valve angle logged is annoying.





here's another

[RIV]

When I got my car back from a good old carbon clean, it pulls much stronger and more responsive in the lower rev range so I don't think its all top end performance were the gains are from