I have a 2002 3.0 as well. I just changed this about 3 months ago. I was getting a missfire on 4,5, and 6. Becareful, there is a plastic insert in the rear of the (change over valve?) that will fall out during the change. I lost mine in the manifold and took hrs to fish it back out.
I remember being disapointed, because the missfire on all 3 did not go away immediatly, however it seems to have gone away. I did not do a hard reset on the computer...i just kept clearing codes. Not sure if this caused me grief or not? The part was $460 piece of plastic. I hear you on the vent tubing breaking. Mine has been plugged, Identical to your photos...however i didnt go for the new hoses...to expensive. I will build my own.
The real reason I went down this road was a tapping noise under acceleration from 1800 - 2100 rpm. I still have the problem and still cant find it. Im concerned it might be oil flow. Recently had an oil sensor (yellow indication) come on and off (3 or 4 times) over the last 100 miles. Not quite sure what this means? Keep posting.

 

mlwaterbug: Thanks for the info! I looked inside the manifold and there was indeed a little plastic hat still stuck to the back. I'm hoping the change-over unit comes with it. I'm also concerned that because the change-over unit became disconnected with the vacuum drive mechanism that the intake might be damaged...I checked but don't see anything obvious.

What did you do to clean it? Mine is seriously gunky inside.

Also, I'm VERY concerned that because there are so many chards of plastic missing that some may have fallen into the valves and perhaps into the cylinder! I found little fragments of the spring all throughout the gunky mess inside the changeover unit also.

Any ideas how to inspect the cylinders without removing the heads? Peaking through the spark plug hole is really not very revealing.

Thanks,
Rob

 

Those are the intake manifold change over valves, the basically change the intake runner lengths to increase torque or horsepower over the entire powerband. If you change it you will definately notice a change in how it performes, however they usually DON'T cause misfires. If it breaks, you're usually just stuck with either a short intake runner, or a long one. (depending on when it breaks) There have been people that have made custom metal arms, or used JB weld to fix the old ones, but as far as an aftermarket one you can buy? I don't know.

As far as looking at the cylinders, without a borescope you have to remove the cylinder heads. Removing the heads will pour coolant in the cylinders though, which makes it hard to see if there is actually coolant leaking into the cylinders in the first place.

 

Well... Bad news for me. I opened up my intake and found plactic pieces in my intake valves....gets worse. manually turned the engine over and noticed a lot of back pressure comming back up through the exhaust? So I did a pressure test...not good. 100, 58, 68, 81, 70, 61 PSI. 1/2 of what its suppose to be. This isnt good. I have tore down the entire engine, and now can get the heads off due to T10070.

So Rob. It might be a good idea to do a pressure test. I thought i read above that you did? My gut feeling is that these plastic pieces got into the intake and melted around the intake valves...they were not small either. So my thought is these pieces got stuck, melted...and dammaged my valves....thus .not getting the pressure i need. make sure you are very thorough (picky) about going thru your intake manifold looking for these pieces.

Any ideas where to get new heads for a AVK 3.0...or rework?

Stephen

 

Sorry. I meant back pressure comming back through my intake.

 

Well, so after putting it all back together with the new parts (change over drive unit, driver side fan, crank shaft ventilation assembly)...It still misfires...and still on cylinder 4. For a little bit it seemed to behave differently immediately after running the engine after reassembly, it misfired on 4 5 and 6 and then after driving it a bit, it stopped misfiring all together. But then i did my normal highway driving and as always between 60-65mph in 6th gear it always is misfiring ... usually under load (up hills, down hills it seems to stop misfiring).

I then drove it around a little more and now have about 120mi since the repair and the last drive home it didn't misfire even between the trouble band of 60-65mph. I'm not optimistic enough to believe it's done for good. I think the warmer temps (40F) made a difference, it hates cold air temps it seems. Misfires are far more prevalent.

The fan runs great though

mlwaterbug: I did do a compression test as well as a mechanic. 150psi accross the board. Text book according to him. So it seems to say my valves and rings are OK? Also, if you take a peak at some of the pictures you'll see 3 of the 5 valves per cylinder and they seem ok also (according to 2 different techs). If you have low compression I would think at least you have a smoking gun there. Whether it's from the heads or ring seals around the piston I just don't know enough. I guess that's why they do a leak down test? And unfortunately, I have no experience getting new heads or rework. however if you do, PLEASE let me know some prices. I may be heading down that road at some point...would be nice to know if I need to take out a second mortgage!

auditech79: I did see an improvement in performance during the duration it wasn't misfiring. In some cases it ran just so downright smooth I thought it might have worked. However, it seems to still be there, the misfiring on 4. My next step is to take the valve cover off for the driver side bank. I'm hoping something might pop out like a worn cam on 4. If that doesn't reveal anything...I have to think it's gotta be something electrical. Now, they may not have a new flash for my ECM but what about just a hard software reset? Or I can't imagine how, but wire harnesses to the injectors or coils (can't see how that would relate to driving but..)? The mechanic also said he wanted to do a smoke test on it, but I'm not sure why as the compression test seemed to show no leaks.

I'm in serious need of good ideas to look into.

1895: You can see all the plastic that got lost and chewed up/burnt up from the change over drive. Ridiculous they don't have a screen to make sure they don't get chewed up by the valves. I blew compressed air through my intake and snaked every runner in the intake and nothing came out. Not sure how else I could have cleaned it (apart from also using carb cleaner as I did).

1897: The little plastic piece mlwaterbug warned me about put on backwards to show. thanks!

1911: All back together and! still misfiring. new coolant, fan and oil though.

 

Also, I'm looking for a USB scope for putting it down my spark plug holes to inspect the cylinders. I figure I've got the price of taking the heads off to invest into this. So ... about 13,000 dollars? Hah kididng, somewhere under 150$ if possible. Problem is I don't know the diameter of the hole for my plug so I don't want to get something that doesn't fit.

Thanks,
Rob

 

Im telling you its too common a problem to misfire on cylinder 4 with these engines to be coincidence. It HAS to be either the ECM's fault or that coolant leakage into the cylinder problem. Im more inclined to think its the ECM because the reflash fixes those A6 3.0L's lickidy split.

P.S. You MAY want to check where the main harness meets the forward firewall for any breaks in the harness, on B7 2.0T engines the harness rubs on on the bottom of that firewall and rubs a hole into the harness causing all sorts of issues. Its just something else to check if anything.

 

FYI
I will be removing my heads this afternoon. I ordered the T01007 tool. I found a shop out of town that will do a re-valve job for about $600 (estimated both sides), so that is much better than purchasing new heads.

Rob have you tried swapping out injectors and seeing if the problem follows? Injectors can be a tricky and can cause an intermittent misfire? I had one going bad in my truck and it was sticking...I put Lucas fuel suppliment and it solved the problem. I must had run 10 other fuel injector cleaners, but for some reason this is what solved the prob...go figure. However yours does sounds to be more temperature related?

just another thought... If you do have coolant leak by on #4 it may look you might try making sure your head bolt torque is where it should be. You can easily to this with the valve cover off. You'll need the tool

 

So ok, I took off the valve cover and just don't see anything horrible. I mean, without having a machine shop inspect the lobes to see if they are fractions of an inch off cylinder 4 lobes look the same as cylinder 6. I think I saw one or two pits on the corner of the lobe but I also saw that on 5. Things seem normal!

I then bought a scope to look inside cylinder 4 through the plug and then I looked at 5. Cylinder 4 looks much shinier, but i don't know what that means. It's like it's getting washed in someway. Or the combustion isn't happening or leaving any residue. Also, there was no evidence of liquid inside cylinder 4 that I could detect. If any of what you're seeing looks odd please let me know.

Cylinder 5 looks normal as far as a burnt look, like it's getting the right mixture.

What would a shiny piston head indicate? Rich fuel or or too much air?

The stupid wiring harness for the coils and injectors is part of one harness that seems to have every electrical harness in the engine compartment. It's cost? 1350 dollars. However, the harness adapters for each coil is only 20 bucks. What a deal. But I'm not convinced there is any relation to a wiring issue because it seems (while still intermittent) that it is heavily dependent upon driving. I can understand how it could be the ECM but not a connector or wire issue.

auditech79: Ok, I'm certainly interested in giving the ECM a shot, but how? They've already told me there is no new software to flash it with. Can I request for them to just erase it and reflash it? Should I send it to someone like Revo and have them chip it? would that change behavior cheaper? Any ideas as to how about going about exploring the ECM as a possible suspect would be appreciated. Can I just swap it with one from a junk yard?

mlwaterbug: I think 600$ is actually reasonable for both heads. I was told a couple hundred a piece so we're on the right order of magnitude. How much was the tool and where did you get it? I really don't think it's my heads but if the ECM proves to show no success...I am at a loss as to what to do.

DIGI0965: Cylinder 4
DIGI0970: Cylinder 5
IMG_1932: Intake Cam Lobes Cylinder 4
IMG_1934: Exhaust Cam Lobes Cylinder 4
IMG_1935: Intake Cam Lobes Cylinder 6

Anything else I should do while the valve cover is off?