2015 RS5 Cyinders Misfiring

A5/S5/RS5
#1

I’ve been lurking around for the past year or so and haven’t had a chance to post (mainly due to crazy work hours). I bought a Misano Red 2015 RS5 in August of 2019 that just rolled 30k miles, and have had nothing short of an awesome experience, up until now.

I’m located in western PA so I was only able to drive it last year until late October, and brought it out of storage in early May. I haven’t had any problems until about a month ago when my coolant thermostat went and I had painfully replace that.

While I was under there with everything removed I decided to change out the rear diff and transmission fluids as the service was upcoming and it’d just make life easier in the long term. Everything felt and ran strong until last week when the CEL came on and put her in limp mode.

I ran the VCDS and came up with a misfire on cylinders 3 and 7. I assumed the best choice was to replace the spark plugs and ordered NGK Ruthenium HX plugs. Replaced them and still came up with a misfire, this time only on 7. I thought that the coil may possibly be shot, but before ordering them I swapped coil 7 with coil 1 and ran the scan again only to come up with cylinder 7 still misfiring. I went ahead an ordered all new coils from HS Tuning.

https://www.hstuning.com/ignition-coil-kit-06E905115G-8-pack-r8-coils.html

I just received the coils about an hour ago and installed them, hence the reason for posting because I have no clue which direction to proceed from here. I ran the scan hoping to resolve the issue, this time with cylinder 7 and 3 misfiring again. Note - I did run the scan with the intake setup still removed.

VCDS readout:

Address 01: Engine (------CFSA) Labels:. 079-907-560-CFS.clb
Part No SW: 8T2 907 560 F HW: 8T1 907 560
Component: 4.2l V8HDZ / H04 0003
Revision: NAH04—
Coding: 1A25003225A6080D3000
Shop #: WSC 06325 000 00000
ASAM Dataset: EV_ECM42FSI0118T2907560F 001002
ROD: EV_ECM42FSI011_AU48.rod
VCID: 3FDB451C37F1B0C36B9-806A

10 Faults Found:
2638 - Low Pressure Fuel regulation
P310B 00 [096] - Fuel Pressure Outside Specification
Intermittent - Not Confirmed - Tested Since Memory Clear

10541 - Camshaft Adj. Bank 2 Intake
P052C 00 [096] - Cold-Start Timing not Reached
Intermittent - Not Confirmed - Tested Since Memory Clear

10203 - Random/Multiple Cylinder Misfire Detected
P0300 00 [237] - -
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 60130 km
Date: 2020.10.04
Time: 16:32:10

                Engine speed: 3985.00 /min
                Normed load value: 78.8 %
                Vehicle speed: 50 km/h
                Coolant temperature: 98 °C
                Intake air temperature: 40 °C
                Ambient air pressure: 980 mbar
                Voltage terminal 30: 14.253 V
                Unlearning counter according OBD: 40
                AFS dm: 435.8 kg/h
                Median injection timing: 1.960 ms
                Engine operating condition: Part. load
                Engine operating condition-Test_Program_Channel 87: 6

10593 - Cylinder 3
P0303 00 [101] - Misfire Detected
Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 60132 km
Date: 2020.10.04
Time: 16:33:59

                Engine speed: 3148.50 /min
                Normed load value: 26.7 %
                Vehicle speed: 57 km/h
                Coolant temperature: 102 °C
                Intake air temperature: 40 °C
                Ambient air pressure: 970 mbar
                Voltage terminal 30: 14.701 V
                Unlearning counter according OBD: 77
                AFS dm: 105.0 kg/h
                Median injection timing: 0.980 ms
                Engine operating condition: Part. load
                Engine operating condition-Test_Program_Channel 87: 6

10597 - Cylinder 7
P0307 00 [237] - Misfire Detected
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 60130 km
Date: 2020.10.04
Time: 16:32:10

                Engine speed: 3985.00 /min
                Normed load value: 78.8 %
                Vehicle speed: 50 km/h
                Coolant temperature: 98 °C
                Intake air temperature: 40 °C
                Ambient air pressure: 980 mbar
                Voltage terminal 30: 14.253 V
                Unlearning counter according OBD: 40
                AFS dm: 435.8 kg/h
                Median injection timing: 1.960 ms
                Engine operating condition: Part. load
                Engine operating condition-Test_Program_Channel 87: 6

10205 - Cylinder Disabling
P130A 00 [032] - -
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 60130 km
Date: 2020.10.04
Time: 16:32:18

                Engine speed: 3714.50 /min
                Normed load value: 33.3 %
                Vehicle speed: 66 km/h
                Coolant temperature: 98 °C
                Intake air temperature: 38 °C
                Ambient air pressure: 980 mbar
                Voltage terminal 30: 14.465 V
                Unlearning counter according OBD: 40
                AFS dm: 166.1 kg/h
                Median injection timing: 1.278 ms
                Engine operating condition: Part. load
                Engine operating condition-Test_Program_Channel 87: 6

7656 - Secondary Air Injection System: Bank 2
P0492 00 [096] - Insufficient Flow
Intermittent - Not Confirmed - Tested Since Memory Clear

7654 - Secondary Air Injection System: Bank 1
P0491 00 [096] - Insufficient Flow
Intermittent - Not Confirmed - Tested Since Memory Clear

7781 - Engine Off Timer Performance
P150A 00 [032] - -
Intermittent - Not Confirmed - Tested Since Memory Clear

4201 - Fuel Level too Low
P1250 00 [032] - -
Intermittent - Not Confirmed - Tested Since Memory Clear

Readiness: 0000 0000

The only other thoughts I have are high pressure fuel pump, low pressure fuel pump, injectors, or a carbon clean.

You guys on this forum are incredible and have lead me to such a wealth of knowledge trying to understand this beast.

Ape, you’re my hero because without you I wouldn’t have been able to do all of the maintenance and problem solving up to this point without your vast amount of postings.

I’m at a loss with how to proceed as of now and any insight is greatly appreciated.

  • Luke
1 Like
#2

Just from seeing the fueling issue and subsequent misfires, I’d chalk it up to either failing injectors, carbon buildup OR both. Depending on your mileage, injectors tend to fail at around 70-85K miles and carbon buildup needs to be kept at bay usually every 25-30K from a preventative maintenance standpoint.

Take one of the plugs out (perhaps cyl 3,7) and look in there for excessive carbon. Carbon buildup is usually the #1 killer to our injectors. If you do end up needing new injectors, let me know as I found them over 50% new recently.

Ape and I will be replacing all 8 and a carbon clean later this month.

#3

I would listen for vacuum leaks and make sure all hoses are attached–if not it will misfire randomly.

Clean/change the air filters as well (due every 20.000 miles).

Is the car tuned? I have twice the mileage (75.000) no issues or needing injectors.

What points to carbon buildup is the cylinders affected: they are two out of the four getting most of PCV induced buildup. However, I know S5s with terrible buildup that still ran fine.

Spark plugs are due soon so you might as well change them.

Why not run fuel injector/system cleaner and maybe CRC valve cleaner and try a different fuel or just do a proper Italian tuneup?

#4

Mileage is 37,363. When I changed the spark plugs, cylinder 7 definitely was fouled. The remaining plugs looked perfectly fine.

Air filters were replaced with K&N filters at the last oil change approximately 1,500 miles ago. Car is completely stock except for the air filters and a resonator delete from the previous owner.

From what I gathered, the previous owner didn’t run the car hard at all and it was in great condition. I, on the other hand, do push it more frequently than not. Regardless, injector failure this early does seem odd, but certainly not impossible.

I don’t have time today to tear back into it unfortunately. Another possibility that dawned on me last night is some sort of electrical issue.

#5

Perhaps check your connectors and your battery voltage using VCDS (will show 0.2 or so lower than your actual at the battery): I have seen the fuel pressure too low fault with loose connectors (when I have myself forgotten to put them back on :slight_smile: ). Look around the engine and where it has been worked on recently. Low voltage can indicate either of the two. It would, however, more likely throw faults on the electronic park brakes, TPMS, ESP if it was voltage/a connector.

There is a lot pointing to air flow issues in the faults:
3 and 7 are opposite/mirrors of each other more or less and there is one high pressure pump for each bank; also, I think it will fail more likely for a car that has been driven hard/is tuned.

For the low pressure pump/carbon buildup: If it idles smoothly at 600 RPM, then less likely it is severe carbon build-up.

You should be getting pretty good gas mileage, but not much performance. I would check/clean the filters and remove the tube/casing; then rev it up to 4000 (where there fault was triggered) and check.

#6

Welcome to the forum.

You have a lot of issues on bank 2. And bank 2 is where cylinder number 7 is. So I would keep that in mind.
You have VCDS so that will be helpful. Pull the LTFT or long term fuel data and post that. If all of the plugs looked good but number 7 and cylinder 7 is getting the codes than that tells you most of what you need to know.

If you let the car sit in storage over the winter it’s not uncommon to have low mileage injector failure and there is a chance that if cylinder 7 was wet for fouled that you could have a leaky injector. Now that you replaced the plugs and packs. I would check the fuel trims on bank 2 and then over the next few weeks watch cylinder 7. If you have a leaky injector that can damage a motor. And these injectors need to be serviced or replaced. They are not life of vehicle parts

#7

10541 - Camshaft Adj. Bank 2 Intake – I wouldn’t make much if anything out of that; the one thing that stands out is the word “intake”.

Google above code and it comes up possibly causes misfires but what does not?

This points to the air intake filters and oil level.

As for cars sitting for a long time, I would like to find out what causes the pump failure. I can only think of rust, but I don’t believe it is likely.

#8

Couple of things…if you’re getting cylinder deactivation, this is usually the result of a bad injector. The ECU does this to prevent cylinder damage. But…it happened once. Assuming it stopped on its own or did you clear the codes with the VCDS?

Do pull up the fuel trims (long term) but also look at the number of misfires per cylinder and that’ll be a good indicator of where the problems lie. Could be more than cylinder 7.

I’ve discovered these cars do not like to sit. Most cars don’t. And I know of at least one RS5 which needed new injectors at a mileage similar to yours, just after having his engine carbon cleaned.

The low pressure fuel regulation and camshaft cold start timing…neither is confirmed but they may be confirmed and produce a CEL if you drive the car more. I don’t actually advocate driving the car further however. I’d make damn sure the #3 and #7 injectors are still good. If you pull the plugs again, as others have suggested, and they’re black, you’re looking two failed injectors. Plus, with the low pressure fuel system, you’re feeding both banks so you’d see more than one cylinder having issues.

The secondary air injection…another conundrum unless it was caused by running the engine with the intake off for a good period of time. The air injection hose doesn’t actually interface with the intake but routes into the throttle body.

IF the intake cam sensor is bad, the good news is it is relatively cheap and very easy to replace. It sits right in front of the high pressure fuel pump on that bank. It could be that a fuel-related issue is causing the ECU to try and adjust to the point where you’re getting an implausible camshaft reading.

Your battery voltage looks ok. Everything is in the 14V range.

So to summarize…
-Pull plugs and check for black, fouled plug
-Check oil level
-With the VCDS, check long-term fuel trim. If it’s above or below 8%, you likely have a fuel-related issue. If you’ve cleared codes already, you’ve erased the long term fuel trim.
-If you’ve removed the intake system, double check the PCV hose on the bottom of the intake elbow (both sides) is connected and not leaking.

#9

I was finally able to mess with it again yesterday after work. I had to take my truck to the dealership for an issue so I had downtime while I waited to pick it back up.

The cylinder deactivation has happened the last 3 times I’ve started and ran a scan. I’m still learning all of the capabilities of the VCDS, and in my ignorance I cleared all of the codes after I replaced the plugs and coils so unfortunately I can’t pull up the fuel trims. Yesterday I did, however, discover how to monitor the misfires per cylinder as you mentioned. At startup, right away 7 and 3 were misfiring. I think I may have had one misfire on 5. I only had it running for 30 seconds before I was uncomfortable letting it go any further. Cylinder 7 Had 170 + misfires and cylinder 3 was around 80 in that time frame.

As for the low pressure fuel regulation, I chalked that up as caused by the misfiring and cylinder deactivation. If I do manage to solve this issue with new injectors and that still occurs, I’ll tackle that next. There is no chance I’m moving it from where it’s parked unless it’s on a tow truck.

I assumed the secondary air injection was caused by running it with the intake off as you said. I’m not overly concerned with the remaining codes that were thrown until after I clear up the misfires. They don’t seem that severe in terms of repair, time, or money.

I bought a CTEK battery charger last year as I knew the car would be in storage for a few months. One of the best investments I’ve ever made. It basically repairs your old battery to brand new status and works on just about anything from quads, bikes, and tractors to heavy duty batteries used in large machinery.

When I have time next I’ll check the plugs as suggested. I know the oil level is good as I check it weekly. I didn’t realize at first how much oil this engine actually consumes (especially when driving spirited) so I’ve made a point to monitor it. As stated earlier, I cleared the codes so the long term fuel trim is gone. I did check the PCV hoses yesterday and they were both secure.

I’m convinced the injectors need replaced and a carbon clean needs done. My only conundrum is do I take this on myself with the help of a close friend or do I take it to a reputable shop? If I decide to do this I’m certain I can accomplish the feat, but the issue is time. I most likely won’t be able to get started on it for a few weeks and then we start to approach winter. I do hate the fact that I have to store it, but if you saw what the chemicals they put on the roads in the Pittsburgh area do to your vehicle you wouldn’t want to leave your house. The municipalities switched to a new chemical compound 3 years ago and its eaten my truck to pieces. If I decide to take it to a shop I have a few concerns. First, there aren’t many shops around the area capable of completing this task and the dealership is flat out not an option. I haven’t heard anything but bad regarding the local Audi dealerships. Second, once I’ve found a shop that has the know-how, I’m not convinced they’re going to do it as well/thoroughly as I would. The third is price, but I can’t necessarily make that call until I have a quote.

Thoughts?

1 Like
#10

Sorry I missed, critically, you ran the car with the airboxes off meaning the Insufficient Flow faults are now gone? That definitely points to buildup then assuming everything was put back together properly.

The intake pressure sensor, if malfunctioning, will definitely cause misfires, although only trip a random misfire fault, I believe. Any other connector loose around the engine will as well.

Did you really only get one misfire on all the other cylinders combined? If not, as bad as it sound with 170 misfires in 30 seconds, it does not mean that there is anything more serious at fault than a loose vacuum hose or similar. Probably the injector as the others have pointed out and not the wrong oil. What kind of oil consumption are you getting? I am not getting extreme oil consumption at all. It could be the valve seals on 3 and 7 but I have never heard of them failing. Two bad injectors though, surely must point to bad fuel.

If the issue is carbon buildup on the valves it normally distributes more evenly across all cylinders. To clean them anyway, check out the carbon clean thread by apefactory. You can also go to his CRC thread. The CRC treatment in itself will, however, cause misfires for a temporary nature but not concentrated to any one cylinders.

Regarding the car sitting, I leave my car for long periods and it has not caused any issues yet.

Regarding rust. The car body is completely sealed underneath. The rear axle piece however, is not. That part is off the a4, a5 and can be replaced by a rust free part used for 100 USD or so. You can replace the whole rear axle years down the line getting new control arms and so on. Meaning in the worst case it is only a handful of rusted on bolts that will need to be heated up and removed to separate the whole rear axle. There is one suspension part, rubber or similar, in the wheel almost that gets worn on mine. Maybe that does not like the chemicals and deteriorates faster. Otherwise, I have not had any rubber parts crack/look nasty.

I use the car in bad weather and winter. Especially in autumn on mud and leaves but also in snow are great times to use it.

#11

Update:

After 3 months I was finally able to get the car towed to a garage where I can work on it. I started tearing into it about a week and a half ago with what spare time I have, along with my buddy. By Friday of last week we had the injectors pulled and I sent them out to get cleaned and flow tested. This past Tuesday we began the carbon clean and I couldn’t believe the amount of build up there was. I mean I expected there to be a lot, but I was truly shocked when I started to pick away. I started with cylinder 1 and worked my way through 3 the first night. The second night I didn’t have as much time so I only got to 4, 8, and the initial blast on 7 before I had to wrap up, which leads me to last night. I started to pick at 7 (the original cylinder that was misfiring terribly) and noticed the exhaust valve wasn’t 100% seated. With all of the carbon I didn’t initially see this, resulting in a small amount of media making it past the valve. While that’s concerning in itself, the fact that the valve wasn’t fully closed is a much larger problem. When I was using the pick to scrape near the seal the entire valve began to spin. Upon further inspection we could slightly push the valve down with a finger, leading us to believe the actual issue is a mechanical failure of the valve and not a clogged injector. The injectors just arrived at the shop yesterday so I’ll have a definitive answer on that soon.

Once we realized the valve wasn’t working properly we took the cylinder head cover off to borescope the valve and confirm there wasn’t anything else causing it to fail. The high pressure fuel pump is located between cylinders 7 & 8. The part that the fuel pump bolts into is actually forged into the cylinder head preventing us from being able to borescope. Right around this time I had to wrap everything up as I was about to run late for a prior obligation so we didn’t look very hard. Once I have a chance to actually analyze what’s in front of me I’ll report back, in the meantime here are a few photos that I took as I was working.

IMG_4779
IMG_47791512×2016 897 KB

Initial removal of lower intake manifold

IMG_4782
IMG_47823024×4032 1.23 MB

First look into one of the ports.

IMG_4794
IMG_47943024×4032 2.68 MB

Cylinder 3 pre-blast

IMG_4795
IMG_47951512×2016 1.03 MB

Cylinder 3 half way through blasting

IMG_4798
IMG_47983024×4032 2.44 MB

No clue why I didn’t take a picture of cylinder 3 finished, but here’s a picture of cylinder 4 finished.

IMG_4802
IMG_48024032×3024 2.67 MB

And last but not least, the left bank with the cylinder head cover removed.

I’m going away for the weekend to snowboard so I may not be able to reply until Sunday. Let me know what you guys think.

#12

Could be valvetrain wear, a damaged valve stem guide, etc…I’d definitely be removing the cams on that head and fully inspecting the valve and related hardware. If I remember correctly, we do have roller rockers with hydraulic lifters. Not unheard of for those to go bad or become clogged in modern engines and not fully pump up. If the lash is too great, you’d be able to move the valve like you describe.

If you let it go, it’ll beat itself to death and cause further damage.

#13

I reread my last post and realized I said exhaust valve instead of intake valve. My apologies. We’re about to start the process of removing the cams and currently going through the repair manual hundreds of times over so we don’t miss anything. I’ve ordered, and am currently awaiting, all of the required tools to arrive so we can begin. The tools were surprisingly hard to source and I could only find them through Snap-on where they were actually priced affordably. Of course, as mentioned previously, the one valve that’s bad is the one we can’t get to and prevents us from seeing the actual issue. While going through the repair manual (Ape I can’t thank you enough for your post on Audizine on how to go about downloading them) it states to pull the motor. To me this is a rather large undertaking and may not be within our capabilities to do. I know we’re already this far and I’d hate to give up now, but is there any chance you think we can take the cams off without pulling the engine? As I was looking over the engine bay last night it seemed feasible, but as I went through the manual again today I started to get concerned. Mainly considering how the cams are involved with the timing chain. I won’t truly know until I tear into it, and we do plan to go as far we’re capable, but it’s concerning nonetheless. Ape, I doubt you’ve looked at the valvetrain repair manual in awhile, but if you have a moment could you give your thoughts on the matter? It’d be greatly appreciated. If not no worries as like I said we’re going to keep going until we can’t.

#14

I honestly think it’ll be tough if not impossible to get to the timing chain and get everything “timed” correctly upon reinstallation. These are pretty precise engines and probably an interference design (valves hit pistons if not timed correctly). I wouldn’t take any chances. Sorry to say.

This is the first valve issue I’ve come across honestly. I read about one car, when they were first released, that dropped a valve (valve stem snap) but other than that, I’ve not heard of any valve failures. I “think” I remember hearing something with the R8, where a car or two had some issues but they actually rev higher than the RS5.

#15

Pulling the Cams themselves isn’t a problem, the problem lies in the getting the Chains off which is the problem. If you lowered the engine a little you just need remove the rear Cam cover and remove the large bolt holding on the Variable Cam timing pulley with the chain. If you mark the link and teeth it would be easy to get it back in place as long as you’re careful and the rest of the timing chains and guides are good.
With all of that said you will need to pull the head to install a new valve and/or check the valve seat (inspection camera through the plug hole with a reflecting mirror would help). In order to pull the head the exhaust manifold will have to come off and that means lowering the engine at least 8~12" minimum. Hate to say it but if I remember right the Left manifold is the more difficult one (sorry).
Yea, just goes from the cam to a roller rocker to a lifter over the valve. Standard keeper and retainers hold the valve springs in place.

Head
Head1644×1757 141 KB

#16

I went to the dealership to see if I could talk to a tech and get their opinion on how to proceed. He diagnosed it as a broken valve spring, and that I’m very fortunate that the valve didn’t drop. Apparently it’s pretty rare for the spring to break, but not impossible as they have seen it before. He went on to explain how to fix it from the top without dropping the engine, but unfortunately that still seemed outside of my skillset so the out comes the engine.

I was fortunate, however, to find a local shop close to me with a very good reputation. The owner was a tech at an Audi dealership for 10 years and just opened up his own shop in November. I went and spoke with him last week to take a look at his shop and determine how he’d like me to prep the car for him to work on it. To my relief, he said that if I brought the engine to him in a box of parts he’d have no problem getting it back together and to just take it out of service position and leave the top end off. He gave me an estimate of roughly 13-14 hours to complete everything @ $120 per hour. So it looks like I’m getting out of this mess for under $3k without the added stress of doing it myself and probably causing more issues to arise. He’s pretty booked so I’m scheduled to go under the knife on the 25th.

On a completely separate topic - I came across this thread while researching PCV valves. Apparently Audi doesn’t offer a rebuild kit for the valve, but this guy realized that they look identical to the Mercedes 6.2l V8. He swapped the internals from the Merc PCV valve into his and had zero issues. With the price of the Mercedes PCV valve at $130 its a good way to save a few hundred dollars.

Link:

#17

I think Ape has a writeup on the PCV valve and the alternate part, if not on here then on Audizine.
As far as the cylinder, you can pressurize the cylinder through the sparkplug hole to keep the valve closed while you remove the spring and replace it. I’d only be worried that the valve seating surface was burnt a little and may not seal quite as good. As I mentioned before, a quality video borescope through the plug hole to inspect the cylinder and the valve seat is a must.

#18

Yes ape does have a write up about this somewhere ? He did say a company he knew maybe selling the pcv valves we need but have not heard anything since ?

#19

I copied the page from lquattro04’s link and saved it for future use :slight_smile:

#20

There were a few valve spring issues early on in the RS5’s life. But yes, it’s rare these days. Glad they figured it out.

And great idea to make sure the valve seat hasn’t been damaged. That’s basically a pressed-in insert into the head. It’s hardened material and very resistant to wear. But if it is chipped or burned badly, head would need to come off.

I did write something on replacing the PCV valve with the MB part a while back and then promptly forgot all about it until someone reminded me that I’D written about it. Good times.