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Q5 FSI Carbon Build-up
12-04-2011, 09:18 AM
#21
AudiWorld Super User
True, especially on a grocery-getter like the Q5. It's a whole other story though with an enthusiast's car like the RS4. Most everybody either cleans the carbon or has it done by a pro just to restore the power that they paid (a lot of) money for.
12-05-2011, 07:53 PM
#22
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Got my Q5 back today. I went in and had a chat with the tech who was working on it. He told me there wasn't too much carbon buildup on the valves but they cleaned what was there. He also showed me the injectors that were replaced....they had a bit of carbon but not scary looking like some pics. One interesting thing he did tell me was that the new injectors he put in and what Audi is using in newer builds have a cone shaped head instead of being flat. This reduces the buildup of carbon on the injectors....certainly the car was more responsive after....
12-06-2011, 01:45 AM
#23
AudiWorld Member
I'm not necessarily suggesting it's a hi-temp thing. I'm suggesting it's a velocity thing.
I try to drive my wife's A6 once a week. Once it's at operating temp, I'll run it up to the red line once or twice. When I do this, huge amounts of particulate matter are discharged. I contend that this stuff is building up during the course of the week as she putters around at 1500 - 2000 rpm. If I were to do subsequent dashes to the red line, there is no more discharge; the exhaust coming out is clean. There is stuff accumulating in the system, I'm not sure where .
I see the same thing on my A4. The cloud of dust is much smaller than the A6, but it is accumulating somewhere in the system.
I try to drive my wife's A6 once a week. Once it's at operating temp, I'll run it up to the red line once or twice. When I do this, huge amounts of particulate matter are discharged. I contend that this stuff is building up during the course of the week as she putters around at 1500 - 2000 rpm. If I were to do subsequent dashes to the red line, there is no more discharge; the exhaust coming out is clean. There is stuff accumulating in the system, I'm not sure where .
I see the same thing on my A4. The cloud of dust is much smaller than the A6, but it is accumulating somewhere in the system.
However, I've dismantled more than my fair share of cylinder heads and the amount of carbon that ends up on exhaust valves is often alarming. So when you consider that the gas velocity out the exhaust is many times what it is in the inlet, it's hard to imagine that gas velocity over the inlet valves would do much at all.
12-06-2011, 09:12 AM
#24
AudiWorld Super User
Very good point but as you say, it's not really possible to tell where the "stuff" is coming from - could be just built up in the exhaust.
I agree, I have no way of knowing where the source is located.
However, I've dismantled more than my fair share of cylinder heads and the amount of carbon that ends up on exhaust valves is often alarming. So when you consider that the gas velocity out the exhaust is many times what it is in the inlet, it's hard to imagine that gas velocity over the inlet valves would do much at all.
I agree, I have no way of knowing where the source is located.
However, I've dismantled more than my fair share of cylinder heads and the amount of carbon that ends up on exhaust valves is often alarming. So when you consider that the gas velocity out the exhaust is many times what it is in the inlet, it's hard to imagine that gas velocity over the inlet valves would do much at all.
Ultimately the VNT mechanisms freeze up due to accumulations and lack of "excercise". VAG likes to blame it on the fuels in the USA.
12-07-2011, 01:57 AM
#25
AudiWorld Member
That's a seriously impressive picture - is it an inlet manifold?
Unfortunately carbon build up on inlet valves has plagued modern DI technology since it was introduced on a commercial scale by Mitsubishi back in the mid 90's with their Galant GDI (what a dog that was - almost broke Mitsubishi). All the manufacturers have struggled with it - VAG is far from alone on this one.
Unfortunately carbon build up on inlet valves has plagued modern DI technology since it was introduced on a commercial scale by Mitsubishi back in the mid 90's with their Galant GDI (what a dog that was - almost broke Mitsubishi). All the manufacturers have struggled with it - VAG is far from alone on this one.
12-07-2011, 03:18 AM
#26
AudiWorld Super User
That's the main portion of the inlet path just before the intake manifold, just after the EGR inlet point. Do you think all that soft material plugs up the passage ways in the head badly? 
We've seen instances where that entire cross-section (probably 60mm) is restricted down to an opening maybe 10mm across and the car still runs !! That's quite a mess to clean up and dealing with the intake passages in the head is a roulette game.
Petrol direct injection is much newer to us Americans. They always struggled to get the cars to pass EPA regs. It's great they can sell this design here now, but the side-effect is clearly a long-term problem.
We've seen instances where that entire cross-section (probably 60mm) is restricted down to an opening maybe 10mm across and the car still runs !! That's quite a mess to clean up and dealing with the intake passages in the head is a roulette game.
Petrol direct injection is much newer to us Americans. They always struggled to get the cars to pass EPA regs. It's great they can sell this design here now, but the side-effect is clearly a long-term problem.
12-23-2011, 06:19 PM
#27
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Well I just got back from my Audi dealer after seeing why the check engine light stayed on... Guess what they have to drop the engine to clean the outakes or something because of the carbon. 25 hour job it's all covered by the warrenty. My q5 has only 34,000 Km . It's a 2010 and I'm not happy about this.
Now I can buy a brand new Q5 2012 for like 16K with exchanging my 2010 Q5 with the 2.0 TFSI engine instead of the 3.2 ... But will this problem happen again? I'm not sure what I'm going to do here.... So I make the trade ?
Now I can buy a brand new Q5 2012 for like 16K with exchanging my 2010 Q5 with the 2.0 TFSI engine instead of the 3.2 ... But will this problem happen again? I'm not sure what I'm going to do here.... So I make the trade ?
12-23-2011, 07:35 PM
#28
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Our other car is a 2011 Range Rover Sport, which also has the same direct injection design (Jaguar 5.0). The problem is handled via a TSB with treatments of BG 44K Power Enhancer Cleaner.
Also, the "Top Tier" detergent gasolines are supposed to reduce this issue. I've decided to use only Chevron Premium in both vehicles when possible.
Also, the "Top Tier" detergent gasolines are supposed to reduce this issue. I've decided to use only Chevron Premium in both vehicles when possible.
12-24-2011, 02:23 AM
#29
AudiWorld Super User
I don't mean to be a wise guy or disrespectful, but chemicals won't help the carbon. Even with the heads off and soaking overnight in the best of the best chemicals, the carbon (coke, actually) won't budge. It must be removed manually with scraping. Since Audi has it's entire engine line based on direct injection, of course they have to have an official "solution" when confronted with the very real burden of a 12-25 hour engine tear down on a regular basis as routine maintenance. The "top tier fuel" thing is another easy way for Audi to point the finger away from THEIR problem.. I'm not making this stuff up, just head over to any RS4 forum (the RS4 is one of the first Audi direct injection engines to come out (in 2006). We all have/had to do the manual carbon at least once so far, many multiple times.
Audis are great driving cars but you HAVE to realize that carbon cleaning is a requirement. This is why I leased my Q5 instead of buying. The carbon will be Audi's problem, not mine. Don't be a sucker like me, make sure Audi is responsible for their inadequate engine design, not you the owner.
Audis are great driving cars but you HAVE to realize that carbon cleaning is a requirement. This is why I leased my Q5 instead of buying. The carbon will be Audi's problem, not mine. Don't be a sucker like me, make sure Audi is responsible for their inadequate engine design, not you the owner.
12-24-2011, 07:29 AM
#30
Seems like this problem is related to the 3.2FSI and 4.2FSI engines. 2.0T and 3.0T seem to be free of this issue. I've been following this issue for some time now and yet to see a single 2.0T TFSI engine with this problem.
3.2 seems to be the one having the most issues with the carbon built-up. I have seen some getting it regularly every 10k miles.
3.2 seems to be the one having the most issues with the carbon built-up. I have seen some getting it regularly every 10k miles.