Q5 FSI Carbon Build-up - AudiWorld Forums



Q5/SQ5 MKI (8R) Discussion Discussion forum for the First Generation Audi Q5 SUV produced from 2008 to 2017

     
Old 07-25-2016, 03:16 PM
How-Tos on this Topic
 
Last edit by: IB Advertising
See related guides and technical advice from our community experts:Browse all: Audi Q5 or Q7 Specifications & General Maintenance
Print Wikipost

Q5 FSI Carbon Build-up

Reply
 
 
 
Thread Tools Search this Thread
Old 12-02-2011, 07:35 PM   #1
Audiworld Junior Member
Thread Starter
 
mpurewal's Avatar
 
Join Date: Apr 2009
Location: Toronto
Posts: 49
Default Q5 FSI Carbon Build-up

My Q5:
- 2010 Q5 3.2 FSI, 34k, picked up in June 2009
- Maintained by Audi (Audi care)
- Fuel - 99% of the time Shell 91 octane
- Typically drive around the city plus some highway - in S mode at times

Issues:
- Rough idling/shudder about 2 months ago
- 2-3 tries before the car would start (usually twice a week). Over the last 3 weeks.
- Check engine light on for about a day (2 days ago)

So of course I came to the AudiWorld and other Audi forums (the Audi community is awesome ) which led me to believe this might be a carbon buildup problem based on the symptoms. I took it to my Audi dealer yesterday (Toronto area) and they confirmed that this is a carbon buildup problem. They'll be keeping my car for a few days and replacing the injectors under warranty - very decent dealer btw, always look into and fix any issues I bring to them - of course it helps that I'm always right

For those interested here's a summary of the information I've collected....

Issue - Direct injection engines such as FSI get carbon buildup on the valves and injectors because there is no fuel passing over them as it does for other engine designs - so no cleaning. This leads to misfires, loss of HP (substantial) and potentially other issues for the engine.

Turbo engines - 3.0 T (supercharged) and 2.0T seem to suffer a lot less from the carbon buildup issue, possibly due to higher engine temps in the manifold which burns off the carbon deposits.

What doesn't seem to work to prevent this:
- Catch cans don't have much effect (don't know the technical details are but something to do with the "gunk" coming out of the engine which isn't prevented by the catch can)
- Frequent oil changes
- Fuel additives (the additives never make it out to the valves so they have no effect)

What may work:
- Always using approved gas (top tier with detergents - not really convinced on what impact this would have...maybe burning cleaner so less deposits making it out to the valves)
- DIY cleaning agents for valves (probably shouldn't try this unless you know a lot about cars - I don't)
- Driving for a long distance (highway) once or twice a week - perhaps also combined with higher revs for a limited time 3000 - 40000rpms or so (to burn off deposits)
- Spirited driving (to burn off deposits)

Warranty and other stuff:
- Most decent dealers will clean/replace under warranty once there is a check engine light and error code confirms (there might not always be a check engine light). Might want to make sure the error code wasn't simply turned off.
- Audi doesn't seem to be doing anything in terms of adding this to maintenance probably due to the amount of time it takes; dealer told me half day's worth of effort. This is quite sad and unreasonable as we as customers who purchase these luxury products should be entitled to having these products work...seems basic to me.
- Out of warranty you're looking at about $500+ every 3 years or so. Audi should step up and extend the warranty for this issue, likely though they're probably waiting for a class action.
- For dealers who try to ignore you I suggest you tap into the great wealth of knowledge available in this forum and others so you can challenge your dealer. Persistence is also a great technique....

So that's it...if you have an FSI engine you will eventually get carbon buildup and possibly have to dish out some $$$. As for me I've ordered an S5 with a 4.2 V8 FSI (new S5 with 3.0T is just too ugly) which should be arriving this Christmas....maybe I can get a discount on the valve cleaning with two FSI engines I'm an optimist....seriously though I will be writing a letter to Audi NA....this is so not cool Audi, clean up your act.
mpurewal is offline   Reply With Quote
Old 12-03-2011, 04:30 AM   #2
AudiWorld Super User
 
ELEVENS's Avatar
 
Join Date: Jun 2006
Location: great lakes, yoo ess of eh
Posts: 4,582
Default

Excellent and accurate summary, nice job. My discussions with Audi was fruitless on this matter -my car was still under warranty coverage too with 30K miles - so I had to do it myself. It took over 13 hours of dirty, tedious, backbreaking labor. 30 horsepower was restored post-cleaning

You are absolutely correct, Audi needs to clean up it's act. Here's some carbon **** from my car (before/after):
Attached Images
  
ELEVENS is offline   Reply With Quote
Old 12-03-2011, 04:47 AM   #3
AudiWorld Member
 
Join Date: Sep 2010
Location: Gladwyne, PA
Posts: 520
Default

It's unlikely Audi will do anything to fix the previous engine designs, but I know the new engine, the 1.8T, that they just designed with VW has port injection as well as direct injection. It seems they do learn, albeit slowly.
UrbanExtant is offline   Reply With Quote
Old 12-03-2011, 04:53 AM   #4
AudiWorld Super User
 
uberwgn's Avatar
 
Join Date: Sep 2009
Location: MA
Posts: 5,112
Default

They have updated and improved the vapor separators over time:


Quote:

High-performance technology - precision engineering in a confined space

For Audi A6 engines

Compact modular technology reduces operating costs. Connecting lines, couplings, gaskets and fasteners can be eliminated. High performance in a small space: A machine-made crankcase cover made of plastic (basic module), free-form channels for coolant distribution, a smaller pressure control valve, crankcase ventilation oil mist separation with multicyclone and pressure regulating valve and increased efficiency cal all be achieved by material substitution and intelligent process technology.

The coolant distribution channels are designed with large cross sections, smooth interior walls and fast design-to-production times using new 3D technology. The plastic used withstands even the demanding temperature conditions during ventilation with peaks up to 160C. Because of its advanced projection capabilities, the smaller pressure control valve can be protected against freezing by placing it directly on the coolant line. The effective oil mist separation is accomplished with a patented latest-generation multicyclone with pressure regulating valve.

uberwgn is offline   Reply With Quote
Old 12-03-2011, 04:57 AM   #5
AudiWorld Super User
 
uberwgn's Avatar
 
Join Date: Sep 2009
Location: MA
Posts: 5,112
Default

I believe this is at the heart of the matter. During normal driving, these cars turn ultra-low revs rarely exceeding 2,000 rpm with around town driving.

Quote:
Originally Posted by mpurewal View Post

What may work:
- Driving for a long distance (highway) once or twice a week - perhaps also combined with higher revs for a limited time 3000 - 40000rpms or so (to burn off deposits)
- Spirited driving (to burn off deposits)
Someone else appropriately said: A redline a day keeps the (Audi) doctor away
uberwgn is offline   Reply With Quote
Old 12-03-2011, 05:08 AM   #6
AudiWorld Member
 
Join Date: Aug 2011
Location: Westchester, New York
Posts: 495
Default

Quote:
Originally Posted by uberwgn View Post
Someone else appropriately said: A redline a day keeps the (Audi) doctor away
Thats my theory for all engines. They need to be worked hard on a regular basis.
johncaravello is offline   Reply With Quote
Old 12-03-2011, 07:58 AM   #7
AudiWorld Super User
 
ELEVENS's Avatar
 
Join Date: Jun 2006
Location: great lakes, yoo ess of eh
Posts: 4,582
Default

Port injection, combined with DFI, is effective at keeping the carbon monster away, Neither of the last two "solutions" are an effective fix. The RS4 has an uber-efficient triple-stage cyclonic vapor separator but crankcase vapor is only part of the problem. A study of the VW FSI patent reveals the carbon comes from 3 sources: Valve overlap ("internal EGR"), seeping valve oil seals, and crankcase ventilation vapors. Several reports of elaborate vapor catch cans in addition to the RS4's cyclonic system have shown to be useless. The patent lists a half dozen or so systems to deal with the known carbon buildup problem.

Here's a link to the patent. It's LOADED with useful information and a thorough study of it will get you a gold star!

http://www.google.com/patents?id=fLI...page&q&f=false

Last edited by ELEVENS; 12-03-2011 at 08:01 AM.
ELEVENS is offline   Reply With Quote
Old 12-03-2011, 02:55 PM   #8
AudiWorld Member
 
Join Date: Nov 2001
Location: Maine
Posts: 537
Default

I've got a 3.2 q5 with 33k miles and a 4.2 s5 with 19k. I plan on opening then both up in the near future to check on the buildup status. It will be interesting to see if given their different normal usage which one is worse.
rs4-380 is offline   Reply With Quote
Old 12-03-2011, 02:58 PM   #9
AudiWorld Member
 
Join Date: Nov 2001
Location: Maine
Posts: 537
Default

by the way, I hope they do a mechanical cleaning along with injector replacement or you aren't going to see much difference.
rs4-380 is offline   Reply With Quote
Old 12-03-2011, 03:05 PM   #10
DrV
AudiWorld Senior Member
 
Join Date: May 2009
Location: Nova Scotia
Posts: 861
Default

mpurewal,
You may want to read my thread about my experience with carbon buildup in the exhaust air ports.
http://forums.audiworld.com/showthread.php?t=2816385
DrV is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
PARTING OUT 2002 A4 B6 1.8T Cmmartin23 Parts For Sale 26 08-23-2016 04:44 PM
Help with 2005 Audi A6-3.2L quattro BKH bballfreak A6 / S6 (C6 Platform) Discussion 4 10-12-2015 05:14 PM
05 3.2 tranny issues fixmya6 A6 / S6 (C6 Platform) Discussion 4 10-01-2015 02:00 PM
CARBON FIBER HOOD? DanfZX14 A6 (C7 Platform) Discussion 6 09-29-2015 10:18 AM
Just got a 06, a few questions 2005audia6 A6 / S6 (C6 Platform) Discussion 4 09-08-2015 11:54 AM


Tags
20t, a4, audi, avoid, build, buildup, bulit, carbon, cleaning, engine, fsi, intake, manifold, q5, tfsi, valves, vw

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -8. The time now is 06:08 PM.


 
  • Ask a Question
    Get answers from community experts
What's your question?
Send