Round #2,2008 Replacement 08 S6 has more issues????

A6 All/ S6 All
#1

Hello again,
So after my 2008 S6 was totaled in accident [I was only passenger in car]. I fought with ins co, and didnt really make out besides my replacement 08 S6 has 76k mi on her. Last 08 had 125+k. Either way new car has nasty missfires off idle to redline… scanner shows a code for [HIDE CYL] which in theory i understand to kill affected missfiring cyl’s injectors.

I am positive IM needs replacement as well as PCV system, and all 4 corner pad and rotor swap.

My issue is the miss, I am replacing fuel and air filters this upcoming week. I am unfortunately unable to work due to a industrial accident this year that left me with medical issues. as well as lack of funds… so my progress will be slow but steady.

Thank you for your interest and any help in advance into my issues… You Guys have been Great to me in the past, So Thanks Again.

#2

Missifres all the way from idle to red line.

You deffinitly don’t want to drive the car if you can help it. I would smoke or pressure test the entire intake system to see if there are any obvious leaks. Thats gonig to be the first line of defense.

The intake manifold is not going to help the car run better if its broken obviously but you want to make sure its not broken parts from the intake manifold that are getting stuck or are already stuck in the cylinder head ports.

#3

Justin, I noticed the misses seem to go away after 4-4500 RPM? I am pulling IM as we speak. As I pulled the plenum I felt the linkage bar at rear of manifold from right to left was off, so right away the right side (pass side) was obviously not operating correctly. I should have the intake off in the next hr or so…
Anyone who has serious insight into these issues could always call me on my Cel 774-279-8672, I am in MA so thats Eastern time zone, but im always available even late night 1-2am here… have a feeling i will be up even later tonight… lol
I could explain a lot better over the phone if ypu have time to talk for an hr or less…

#4

This is my take on sorting out the issues in order of mostly likely culprits:

  1. Intake manifold - With 75K miles, if it is the original manifold, 99% likely you will need to change it out. (I had to replace mine.)

  2. Dirty valves - Valves will most likely need to have the carbon cleaned off of them. (I did this when I changed the manifold.)

  3. Spark Plugs and or Coils - Car may need new plugs and new coils. Also, check the coil connectors. If there are any broken connectors, then they probably are not making good contact and can cause misfires. (I replace all my plugs just in case. Coils seemed good so left those alone. I had to replace 4 of the connectors.)

  4. Vacuum leaks - Look for any damaged hoses and vacuum lines. Can definitely make the car run rough. Its a good idea to replace the valve cover gaskets too. While bad gaskets can leak oil, a bigger problem is that they are a potential source of vacuum leaks.

  5. Injectors - Failing injectors on these cars a known common cause of misfires. (I did not replace mine but will do this next year as preventative maintenance).

  6. High Pressure Fuel Pump - Seems to be pretty rare to fail but they can (I had one fail about 2 weeks after I purchased my 2008 with 71K miles. I changed out both.)

I purchased my 2008 almost three months ago and I did #'s 1-4 and 6. I did not replace my injectors as I was at the limit of my budget for repairs but I will do them next year. I also replaced a the PCV hose that connects the valve covers at the back of the engine to the oil separator. Also, replaced the oil separator.

I want to emphasize how important it is to make sure the engine does not have vacuum is. This can cause rough running and misfires. Also, any vacuum leak will cause the car to run lean. This causes the ECM’s to compensate by adding extra fuel. If this condition goes on for a while, it can kill your catalytic converters and your O2 sensors.

Luckily, the V10 seems to only have these things as common issues. Once you are through them, the car is reliable.

Mine has been trouble free for almost 2 months now.

#5

I’m up late as well. Pull the plugs and packs check the built on date. That will help give you more info. Post pics if you find anything suspect. You have know the usual suspects at this point check all of those and let us know.

#6

Check battery condition.

I had misses from low battery voltage. The battery would start the car, but was still at a 12.2 or lower charge when sitting.

I figured this out after charging the battery over night and they went a way with a 12.8V starting charge. Just a thought.

#7

Murph,
I actually replaced the battery the other day due to the car sitting for some time as the previous owner told me he had to charge it over night. The only thing about that is the original battery was a 110AH, and my new one is a 85AH, both AGM and actually the new aftermarket batt, has more CA and CCA… I have the IM off as we speak and i have 3 broken connector’s for flaps, so 7 cyl’s are operating properly 3 not so much. I am in the Process of a carbon clean and replacing the O-rings for the oil filter housing to block as well as the rest of applicable o rings, oil is running down the block valley and down the front of the the engine.

I am forming a plan to either repair the flap connectors or just epoxy all 10 in place? Not sure which way I’m going at this point… I will be buying a new IM from JHM as soon as possible as weel as a set of flowed injectors and spacers.

#8

Hello again,
So the coil packs r from 07 per build date. Plugs are factory (VW AG NGK). Car was one owner, strange part is I have all service records from 40mi up to 72+k. So I am assuming previous owner was having issues after 72k and did not include missing RO’s for a reason. He stated car was always maintained at the local Audi dealer. From the records I received I believe him. Would like to know what is missing in the last 4k mi b4 I purchased her. I will try n upload the records so maybe someone else could possibly pick up on something I missed while going over them. I was aware the ABS was an issue b4 I decided to purchase.

#9

Bump, this is a really great list. Plus one on the injectors, and plugs and nice tip on the connectors. Broken IM isn’t going to help things but this is a damn good list to help troubleshoot!

#10

Hello all,
Thank you for all the help/suggestions, You are all the best possible people I have ever had the pleasure of speaking to.

Thank You All Again,
I will keep you all updated on the progress of this current saga.

I honestly can’t thank you all enough!!