Vac leak is what is usually fixed on these cars when they pick up a giant amount of power from a carbon clean pre/post dyno. 50-80 hp is what a vac leak costs an rs4.
never thought of that, that would make sense why some ppl say its like night and day. that was not my experience after cleaning.
Exactly, that was your experience, my experience, bangoman’s experience, mistro’s experience, and countless others.
yeah, if you have a healthy car, carbon might take away your top 10-20 hp…which comes from 7500-8200 RPM (your power curve will flatten there if you’re badly carboned up, as opposed to maintaining a positive slope. If you have modest carbon, you will just have a gentle positive slope) . If you have a vac leak, and it’s fixed during the process, the car will feel like a raped ape when you get it back compared to before.
There are some people who have an insane amount of carbon (think 100,000 miles and never cleaned) and for them, the amount of obstruction can be enough to legitimately create a big performance difference. They’re super rare though. Most of the people who crow about how it transformed the car just don’t realise they had a vacuum leak fixed…or they’re just wanting to feel it and are doing so subconsciously to justify the $1100 they just paid.
While the huge gain I had may seem like it was related to a vacuum leak, it was not - I had it checked after the disappointing dyno result. The carbon was very bad on my car - the trailing end of the port separators were extended by almost 5mm and they were about 6mm thick in places. I was surprised that I didn’t get any codes. My car stopped making power at 6k - it was flat from that point, even though the flap in the airbox opened.
My car had 58k miles when I got it, was never carbon cleaned and was babied by the PO. I like that is was babied - it is immaculate inside and out.
mine was not that bad when opened up. it was def caked up but nowhere near as bad as some other ones ive seen. mistros looked absolutely horrific in comparison. I cleaned mine at 140km so it must have been done before.
heres a pic of the worst ones.
As far as carbon goes that looks very tame.
I made a silly mistake when installing my intake spacers. I actually left the port separators in initially. It killed the top end performance and completely choked off the car. Once the separators were removed (as JHM instructs you to) the car performed as it should.
So are we maybe thinking that removing the port separators might at least somewhat alleviate some of the issues?
Good for decking
Yeah, me too. I saw that but I can’t find a way to edit the Subject 
lmao, especially tune teak.
Actually teak trim would be quite something in the Audi interior. Someone get on it.
Yes, teak trim wood.
Cocunut palm wood looks nice too. We have a carpenter here and the lines in the wood are awesome.
So here is a technical question since it looks like the flap system is required for a part of the JHM tune…
What is the voltage going to the flap solenoid to open them?
What is the voltage on the flap position sensor when they are open and when they are closed?
In general:
Solenoids that open and close see 12 volts.
Position sensors run off 0-5 volts.
Oldish thread…but…
Just did a CC on my car. The buildup was BAD. Everything had been functioning properly (random ecp from flap sensor) and the 5500 kick was there so vac was ok. After the cleaning, that 5500 kick was a REAL kick and it pulls a LOT harder all the way to the limiter.
As an old-school car guy who has ported his share of heads, I don’t know how people can say that carbon buildup doesn’t effect performance. The way the port transitions into the valve pocket and especially on the short-side radius is so important to the efficiency at which the air enters the cylinder. I can see where low-rpm torque might not be changed very much - as a narrow, low-volume runner creates higher velocity which is important to part-throttle, low-rpm torque. When the IM flaps are open at high RPMs and the engine demands increased flow - no carbon should always make more power.
So I’m far from a boy-racer and I’m usually very critical of power claims of any product (because you can almost never “truly” feel most bolt-on mods with the butt dyno). That said, I’d bet money that I recovered 30-40hp with the carbon cleaning. 62k miles, never done before.
Unfortunately you didn’t test it. Would have been cool to have some acceleration data before and after
I too carbon cleaned my car. After about 40,000 miles I think (can’t remember). Barely a difference in acceleration testing and I didn’t really notice much.
Mistro also carbon cleaned. We did a bunch of before and after testing for him too. Same thing. Almost no change in performance testing.
I wrote a thread about this.
Feel does not equal performance. If you can feel the change that can be a few things. Vac leak fixed. Temp change. Psyching yourself out. Etc. It recovery of lost top end.
However if you measure actual performance you will find that the Delta is pretty minor and not really enough to impact most acceleration tests.
To give you an idea, my car set (and still holds) the fastest ever stock 1/4 mile for an rs4. 12.75@108.36. It did so with 35,000 miles of carbon on it.
Maybe 15-20 hp lost from carbon. Here’s a good thread on CC: http://audirevolution.net/forum/index.php?topic=1875.0