sswari

TLDR: The biggest point here is, DO NOT JUST THROW PARTS AT YOUR MOTOR. This took a while, but cost less than $300.00 in parts and I got to spend all the money I could have tossed at coils, injectors, plugs(over a hundred $$ alone), and lord knows what else on tools and fuel. May post photos later.

After several months of multi cylinder random misfires and to lean off idle codes, I am fairly sure I have that all taken care of.
Step 1 was going back through several months of VCDS scans and clearing codes, I charted which cylinders were misfiring the most. There were a few that always misfired, 2 or 3 that were there most of the time, and 1 or 2 that never seemed to misfire. I swapped around the coils and plugs so as to be able to monitor the cylinders again for a few weeks. The same cylinders that were there all the time, were still there all the time, and most of the others just cleared up, so not the coils or plugs. May have been excessive oil in the wells, loose coil connections or just crudded up plugs and or a combination of all of that. So on to step 2

Step 2 was a carbon cleaning, which reduced the misfires to cylinder 10 almost exclusively. During this, I pulled the manifold apart, and cleaned it out completely it was pretty damn oily. The flaps were almost all in good working order, except for the connection between flaps 6 and 7 (the last ones in the chain) I got out the JB Weld and glued those back together and crossed my fingers, toes and eyes that it would hold.

Step 3 Since after about 6 months, I still had the misfires on cylinder 10 almost all the time and sometimes to the point where it felt like something was broken in the motor, once in a while, other cylinders would join in, but none of them were in any way consistent. I Decided to take a shot at cleaning and testing the injectors. The intent was to again, keep them with their current cylinders, but that failed as sharpies just can't hold up to injector cleaner, all in all, not really a big deal.
Anyway, on to the work.

3a) Pulled the manifold off again, ran a scope into it to see if I was going to have to take it apart again, but the JB Weld seems to be holding just fine.

3b) Pulled the injectors, removed the O rings, seals and micro filters, or at least the metal top ring that would normally be attached to the filters. This is a fairly common issue and I would/will probably do this on any C6, those little plastic parts could very well be causing issues in your injectors. There was only 1 injector that still had any signs of ever really even having a filter basket.

3c) For the cleaning, I used a few cans of Berryman 3 small glass jam jars, in a Mophorn 6L Ultrasonic Cleaner 28/40khz Dual Frequency Ultrasonic Cleaner, and Autool CT 60 and a few brushes. 2 injectors in the first jar for 10 to 15 minutes, then into the next jar, another 10ish minutes then into the 3 jar attached to the Autool CT60 for 10is more minutes, as each set moved through the jars, a new pair was added to the prior jar and so it went for a few hours. As the first jar would get super dirty, it would get fresh cleaner after the second set of injectors, as would the other jars as needed. After the 3rd bath, I ran some cleaner through them with the cheapie plastic tool and other fittings I ended up making, to check for at least a decent misting pattern, rather than dripping. Most were Okay, but none were really great, so they so they all got a reverse flush of cleaner, which not surprisingly, produced at least few very fine chunks of what I believe to be the micro filter baskets. This is not even close to having them serviced, but did seem to produce fairly decent results. In went the New Baskets, O rings and seals on each of the injectors. Read up on installing the seals, there is plenty of content out there.

3d) On to the second carbon cleaning. Most of the cylinders were pretty much ok, but since I was in there, what the hell. Cylinder 10 looked like I missed it completely, quite gummed up and nasty. A few were worse than I expected after only 6 months but again most were pretty clean, they all got blasted anyway. As a side note, during the install of the Manifold, I discovered that with a bit of care and finesse, you really do not need to remove the High-Pressure fuel lines. the Low side do need to come off, but they are easy to tighten with the Manifold in place. The high-pressure side, not so much. There is one line on the V10 at least that is very difficult to get to with the manifold on. Get the HP side line in place and tight before you install the Manifold. Also ran compression and leak down testing on all cylinders and was relieved to find them within spec.

Start up and warm up was a bit disappointing. I knew from the first CC that it needed to burn the gunk and walnut shells before it would settle down, but this seemed a bit extreme. After a few minutes, the motor was still running pretty rough and again several cylinders misfiring. Cleared all the codes from the compression test, Double check O2 Sensor plugs and other sensors that were unplugged for the compression test, made sure all spark plugs were tight and the coils were connected correctly, as well as the oil wells HA were as clean as possible. Calibrated the throttle bodies and she fired up pretty smooth. The next few day there were a few CELs with misfires and now lean off idle (much better then misfires) started rearing it’s ugly heard. A few high RPM runs and the misfires have gone away.

Now what about those pesky LOI codes? fortunately they were always on Bank2, so probably not the HPFPs, as they are not really bank specific on the V10 (look it up) Could be a few different things. Vacuum leak Probably not again as this really seemed to be bank specific, MAF sensor issues, O2 sensors, TB issues, who knows what else.

Step 1) Decided to go after the low hanging fruit first. clean and swap MAF sensors. The filters were/are pretty dirty (new ones coming Monday), and well honestly expensive, so I just dusted them off really well for now, as this was more about the MAFs then the filters at the moment. There was what looked like a bee or fly caught up in the screen of Bank 2, so there was that. Sprayed the MAFs off really well with MAF cleaner, and reinstalled Filters stayed on the original bank, MAFs were swapped. Quick Check for codes on all 3 Engine modules, remember this is a V10. Nothing there, so off for a few errands.

3 Days later, and NO codes (Probably just jinxed that). Will report back again in the near future. The biggest point here is, DO NOT JUST THROW PARTS AT YOUR MOTOR. Spend that money on more and better tools, tool boxes or gas, as these beasts are not really fuel efficient.

AudiAllTheWay

What is the mileage of the existing plugs? For example 2nd owner, I found original plugs at 115,000KM so automatic replace as tips were obviously worn.

Would be curious to learn more about 3b) and the missing screens?

3d) was the crankshaft rotated by hand to clean all intake valves closed?

G-Can

New injectors would be a great option on older and high mileage engines, but they are so freaking expensive

sswari

So all of this started right about 85K. I am the second owner, the first owner bought the car had ALL but the last few services done here at the dealership, the last few were done at a dealer ship in CO. I have a very extensive CarFax and Audi Log of services, including an engine out repair for a leaky trans pan gasket. Sad part is, they do not fully list all of the work done, but I am fairly sure that the plugs are not original. They still had to proper gap, and cleaned up pretty well in the US cleaner.

As for the micro filter baskets, this seems to be a fairly unknown issue. In fact, very few of the "Rebuild" kits even have them included,to a point that I was not sure that these injectors even had them. It wasn't even until I found the Injector Rehab site that I was sure that they did actually exist. After talking with the folks there, I Ordered this kit https://injector-rehab.com/product/0...r-rebuild-kit/
Again, I am 100% back to stop tossing part at it, do a bit/lot of research.

sswari

I would never buy new, just for the sake of buying new injectors. It all goes back to troubleshoot first.

In all honesty, Injectors very rarely go bad. They get gummed up and in the case of most of our cars, the filter baskets break and clog them up. Talk to the guys at injector Rehab for more info.
While I was work on my F150 5.8 rebuild, I had been out to the junk yard a few times and grabbed a few different sets of what I thought were identical injectors. Come to find out, there are very slight differences between them for these motors.

I had some how mixed up the 2 sets when I did the install, and the truck was running ok, but not really right. after tons of logging and the such, I decided I might try one more set from the JY, as they were super cheap. Got them home cleaned them up really well, replaced the pintal caps, filters and O rings, and guess what. Yep, it ran like a champ. It wasn't until I pulled the mix matched set that I figured out what I had done.

Clean and Rebuild them first, and if the problem is still existing, send them out to a pro, you can save a boat load of $$$

AudiAllTheWay

One item to seriously consider is the V10 intake replacement or alternative non-OE decisions such as remove the flap assemblies to permanently seal the flap openings etc. When the stock flap assemblies age out and start to disintegrate then worst case, in the blink of an eye, it could destroy the engine. I will post more info soon but will say some serious good luck was on my side and this home made specialty tool saved an engine pull in order to tear a cylinder head apart.

sswari

Would never pay the price of a new Intake manifold or change the way they were designed to work. The loss of power is not worth it to me.
There is a new, and untested 3D Printed part out there from Russia, that looks to be promising.

3D printed flap assembly

Only time will tell on this.

jonzie77

This seemed like a pretty good thread for me to mention this. I have a 2K8, 3.2 and needed to do a second timing chain tensioner (did the first one about a year earlier) but also decided to do a carbon cleaning as well as reseal the cam girdles. To make a long story short the cam girdle thing makes the CC "easier" in that you don't have to worry about which valves are closed because they will all be closed with the cam girdles off which is done with the camshaft locks still in place and the crank locked as well.

sswari

Good info for the V6 cars, but V8 and V10 anything to do with the timing system is a engine out deal, so at that point, you are doing way more than just a carbon cleaning