Misfire/Hard Start issues S3

[Thewheelm4n]

Hey guys, looking for some ideas:

2015 S3, 169k. Had been getting bank 1 sensor 1 o2 code for a good while, fuel economy/general running condition unaffected until maybe 15k miles ago. Dropped a good 4-5mpg average, kept getting hard starts, same code every time CEL came on. Got misfire codes once, replaced coils, those went away, still got hard start every once and a while. Finally changed out that o2, code is gone but still getting hard starts, misfire codes came back and fuel economy is only marginally improved. No other codes related to engine at all. Also have slightly rough idle, have had since purchase at 132k. Assuming injectors are original. CEL came on today, bank 1 system too rich at idle (have gotten this code before in conjunction with the o2 code that's no longer present after replacement). Was told a backpressure cat test could reveal if they may be clogging exhaust at idle throwing the rich code. Thoughts?
Screenshot_20230104-175033.jpg

[Thejacobhood]

Have you had valves and injectors cleaned?

[Thewheelm4n]

Have you had valves and injectors cleaned?

I had a carbon cleaning done a few thousand miles ago by a reputable German shop, I've run probably at least 6 Liquomoly Jectron cans through over the past 8 months or so.

[Thewheelm4n]

Had Carbon cleaning done recently like I told the other member here, I don't drive aggressively very often at all, just want to make sure it needs injectors 100% before I do it cuz it's not going to be cheap.

[BKozS3]

Def suggest the injectors. If you could watch logs of the fueling; LTFT, STFT, AFR actual and SP you would probably see swings. I recently dealt with this and replaced the injectors. Going to be replacing the HPFP soon too since it is probably also going out.

[Thewheelm4n]

Previous post here just saying it probably needs them?

[Thewheelm4n]

Had the same shop that did the carbon cleaning do a lengthy test drive with a scanner, they didn't see any HPFP issues at all thankfully, recommended I do the o2 first and see what happened after, if I was still getting rough idle/hard start issues then their next recommendation was for new injectors. Thanks guys.

[Thewheelm4n]

I had a 2010 A4 that had that piston ring oil consumption issue. Drank a quart every 3-400 miles, absolutely insane. At 170k with a new PCV/breather hose and having switched to Liquomoly oil changes as soon as I bought the car, I've got exactly zero oil consumption whatsoever since my first oil change, so I must have gotten the updated rings.

[Thewheelm4n]

Fueling...precise fueling is critical on engines under boost. If the engine continue to see boost and has fueling issues...it can damage the motor severly. Audi has updated the injectors on the S3 engines allot. My original 2015 injectors had the letter L on the end of their part number. The newest ones I got after 7 years had the letters AK.

Local indy VAG shop I've had most of the work on the car done at suggested my issues could be being caused by a bad coolant sensor. I've been getting two codes:

Coolant shut off valve short circuit to ground/open circut
Coolant shut off valve short circuit to B +

Didn't think anything of it but they said it could absolutely cause misfire codes/rough idle and especially hard start. Going to replace the sensor on the water pump next week and I'll report back.

[vy8v_s3]

Might be worth a try to replace the camshaft sensors

[Thewheelm4n]

Might be worth a try to replace the camshaft sensors

I think I had someone else mention something similar on another thread, do you happen to have part #s and locations on the engine for these? Thanks.

[vy8v_s3]

I think I had someone else mention something similar on another thread, do you happen to have part #s and locations on the engine for these? Thanks.

I think it's actually the camshaft adjuster magnet. This video may help. Its the first thing he does in the video for the same symptoms. There's two that appear to be on the passenger side (US) of the engine pretty much next to each other by the coolant reservoir.

https://www.youtube.com/watch?v=T2ER...vuEuxA&index=6

[Thewheelm4n]

I think it's actually the camshaft adjuster magnet. This video may help. Its the first thing he does in the video for the same symptoms. There's two that appear to be on the passenger side (US) of the engine pretty much next to each other by the coolant reservoir.

https://www.youtube.com/watch?v=T2ER...vuEuxA&index=6

Great, thank you!

[vy8v_s3]

Great, thank you!

NP, good luck! let us know how it goes.

[Thewheelm4n]

NP, good luck! let us know how it goes.

Will do!

[Thewheelm4n]

Alright, so finally had a chance to replace the cam magnet sensors. Got Pierburg ones. Super easy swap. Upon start, idle seemed smooth as it should be. Fuel economy seemed marginally improved, almost to the average of 27-28 I'd expect. However, later in the night last night, after getting out of the car and going in to eat for maybe 20min or so, had a hard start condition again coming back to the car. Took 3 starts to get it to stay running. No CEL though, and I'm still not getting all my monitors to run, an evap related "EGR/VVT" monitor has consistently not ran for weeks now, and a "Fuel system" monitor sometimes will run but is usually also in a failed state. I have to get it NYS inspected by the 28th. To recap, I've replaced:

Plugs (ngk iridium)
Coils (APR)
Cam magnet sensors
Carbon cleaning
Have tried several run throughs in the past 9 months of Liquomoly Jectron
PCV valve and breather hose
Bank 1 sensor 1 o2

Still getting "system too rich at idle bank 1" code I've had for months, and newer code "evap very small leak". Neither have been present for a couple weeks though.

Really trying to avoid injectors but I'm not sure what else could cause these issues at this point, thoughts?

[CXSnail]

Purge valve failures crosses my mind, now with the addition of the evap code.

If the purge is stuck open, the engine vacuum will constantly pull raw gas vapors from the tank. Can cause stalling, extended cranks, backfires on decel, etc.

The number one giveaway is it won't start after fill-up at the gar station (filling with gas displaces vapors into the intake when the purge has failed open, it won't start till it's cranked enough that the intake has filled with fresh oxygen). Are you especially seeing this issue pop up at the gas station?

[Thewheelm4n]

Purge valve failures crosses my mind, now with the addition of the evap code.

If the purge is stuck open, the engine vacuum will constantly pull raw gas vapors from the tank. Can cause stalling, extended cranks, backfires on decel, etc.

The number one giveaway is it won't start after fill-up at the gar station (filling with gas displaces vapors into the intake when the purge has failed open, it won't start till it's cranked enough that the intake has filled with fresh oxygen). Are you especially seeing this issue pop up at the gas station?

Purge valve is what the breather hose from the PCV connects to I believe, correct?

And unfortunately no, I've never had a hard start right after fill up, it just seems to happen randomly. Never happens when the car is cold though, always after I've been driving for a while.

[CXSnail]

It would be hooked to a manifold vacuum source then directly to a line back to the evap canister.

[Thewheelm4n]

It would be hooked to a manifold vacuum source then directly to a line back to the evap canister.

Do you think I should try replacing it? Or have a smoke test done? Since the hard start issue doesn't happen specifically when I fill up fuel?

I'd been getting the system too rich at idle bank 1 code for months before I replaced the o2 sensor, thought it'd go away after but it hasn't. Have also had misfire codes pop up a few times in the past after several hard starts, but not recently. Getting tired of throwing parts at it.

[CXSnail]

I also hate throwing parts, but because this one is so intermittent, it may be closed and working fine when you have the smoke test done (assuming this is even faulty). Paying a shop for a smoke test will probably be more expensive than just replacing the purge, but again, it's just a guess at this point and I would definitely expect a hard start after filling up the tank, which hasn't happened.

If it were possible to do at your house- I would love to see you pull the spark plugs minutes after it cranked but doesn't fire up. I'm curious if one or more of them would be soaked, indicating a stuck or leaking injector. If an injector pintle is sticking or not sealing properly, no amount of cleaner is going to fix it. It would have failed due to wear, not necessarily crud.

Just some ideas for you. I don't have any other solid recommendations since every other option would just cost you more money without a guaranteed fix

[MikTip]

Purge valve failures crosses my mind, now with the addition of the evap code.

If the purge is stuck open, the engine vacuum will constantly pull raw gas vapors from the tank. Can cause stalling, extended cranks, backfires on decel, etc.

The number one giveaway is it won't start after fill-up at the gar station (filling with gas displaces vapors into the intake when the purge has failed open, it won't start till it's cranked enough that the intake has filled with fresh oxygen). Are you especially seeing this issue pop up at the gas station?

The purge valve can be tested with VCDS and will tell you in 2 seconds if its bad...

Here is an actual picture of an actual S3 valve...



Its not what goes bad on the S3 Evap system...its often the fuel cap.

[CXSnail]

The purge valve can be tested with VCDS and will tell you in 2 seconds if its bad...

Here is an actual picture of an actual S3 valve...



Its not what goes bad on the S3 Evap system...its often the fuel cap.

Does the VCDS test use fuel tank pressure as the monitor?

[Thewheelm4n]

I also hate throwing parts, but because this one is so intermittent, it may be closed and working fine when you have the smoke test done (assuming this is even faulty). Paying a shop for a smoke test will probably be more expensive than just replacing the purge, but again, it's just a guess at this point and I would definitely expect a hard start after filling up the tank, which hasn't happened.

If it were possible to do at your house- I would love to see you pull the spark plugs minutes after it cranked but doesn't fire up. I'm curious if one or more of them would be soaked, indicating a stuck or leaking injector. If an injector pintle is sticking or not sealing properly, no amount of cleaner is going to fix it. It would have failed due to wear, not necessarily crud.

Just some ideas for you. I don't have any other solid recommendations since every other option would just cost you more money without a guaranteed fix

I can definitely try and pull a plug if it does it again, the issue is the hard starts happens so infrequently and so randomly I'd have to carry tools with me and make sure I had some sort of flashlight just in case, and I'd obviously have to pull all 4 to see if any of them are wet with fuel. Not a huge deal I guess, is there an easier way to test injectors for failure?

[Thewheelm4n]

The purge valve can be tested with VCDS and will tell you in 2 seconds if its bad...

Here is an actual picture of an actual S3 valve...



Its not what goes bad on the S3 Evap system...its often the fuel cap.

That's the part I mentioned above, I thought that was the purge valve, thanks for confirming. I was going to replace that along with the PCV and breather hose that connects to it but was advised here that it probably isn't faulty and to not waste the money. Unfortunately I don't have VCDS, just Carly. I have only had the evap "very small leak" code pop up once or twice, no engine codes are currently present at all since I swapped out the cam magnet sensors, but still getting below average fuel economy, slightly rough idle and can't get evap/egrvvt/fuel system monitors to all run properly. Guess I could try replacing the fuel cap?

[Thewheelm4n]

I can't for the life of me find the correct fuel cap. The two listed on Audi's own parts site are not correct either, one is for a diesel vehicle and the other I believe is for the previous generation A3. The cap on my car has a conicle protrusion from the under side allowing it to be stuck in a retaining hole during fueling, neither of these have that either.

https://parts.audiusa.com/t/Audi_201...-Tank-Cap.html

[Thewheelm4n]

I pulled the fuel cap and tried running both things that looked like part numbers in an online search, when I do the "500 201 553" it does come up with fuel caps but none of them are the right one either. Super confused here.

[vy8v_s3]

Alright, so finally had a chance to replace the cam magnet sensors. Got Pierburg ones. Super easy swap. Upon start, idle seemed smooth as it should be. Fuel economy seemed marginally improved, almost to the average of 27-28 I'd expect. However, later in the night last night, after getting out of the car and going in to eat for maybe 20min or so, had a hard start condition again coming back to the car. Took 3 starts to get it to stay running. No CEL though, and I'm still not getting all my monitors to run, an evap related "EGR/VVT" monitor has consistently not ran for weeks now, and a "Fuel system" monitor sometimes will run but is usually also in a failed state. I have to get it NYS inspected by the 28th. To recap, I've replaced:

Plugs (ngk iridium)
Coils (APR)
Cam magnet sensors
Carbon cleaning
Have tried several run throughs in the past 9 months of Liquomoly Jectron
PCV valve and breather hose
Bank 1 sensor 1 o2

Still getting "system too rich at idle bank 1" code I've had for months, and newer code "evap very small leak". Neither have been present for a couple weeks though.

Really trying to avoid injectors but I'm not sure what else could cause these issues at this point, thoughts?

damn dude this sounds like quite the headache for you. Just some fuel for thought, you could bring it to your shop and have them scan it with a better scanner, find out what's exactly wrong, then fix it yourself if its doable. Hope you find a solution.

[MikTip]

I pulled the fuel cap and tried running both things that looked like part numbers in an online search, when I do the "500 201 553" it does come up with fuel caps but none of them are the right one either. Super confused here.

Yes Audi part numbers change cause parts get superseded...order one from an Audi dealership online...they will run it against your VIN and ensure you get the correct one...and dont be surprised if the part numbers different

[Thewheelm4n]

Its easy bro...order one from an Audi dealership online...they will run it against your VIN and ensure you get the correct one...and dont be suprised if the part numbers different

I included a link above when I did a search on their official parts website and neither result that came up was the correct cap. I'll give it a shot though and see what ends up showing up in the mail.

[MikTip]

I included a link above when I did a search on their official parts website and neither result that came up was the correct cap. I'll give it a shot though and see what ends up showing up in the mail.

I did same...what showed up in the mail was a different part number cap...but it fit and functioned fine.

[Thewheelm4n]

damn dude this sounds like quite the headache for you. Just some fuel for thought, you could bring it to your shop and have them scan it with a better scanner, find out what's exactly wrong, then fix it yourself if its doable. Hope you find a solution.

One piece of good news, I was able to get it NYSI today, one monitor can be failed and still allow it to pass. That monitor appears to fluctuate between EGR/VVT and Evap. So something is still causing this. Local shop scanned with VCDS and said evap monitors won't run as it was showing coolant temp too low, said probably needs a coolant sensor, although I have no codes related to the cooling system.

Of course (thankfully, though) almost right after I got the inspection done, had a hard start, CEL did come on this time. Threw the following codes:

Random cylinder misfire
Cyl 1 misfire
Cyl 4 misfire
System too rich at idle bank 1

Fuel trim; system too rich bank 1 (this code is new, other 4 have occurred before)

Thoughts?

[Thewheelm4n]

Update:

Had several hard starts today, always only after shutting the car off for a few min after it's fully warned up having driven for a while, shop scanned car with VCDS, found cyl 2 to be constantly misfiring. Was about 10k from my planned plug replacement, but threw a set of NGK Laser Platinums in anyway. Seemed to solve the misfire issue initially. Old plugs 2 and 4 had oil on them, 1 and 3 were dry. Also found to my aggravation that the coil pack bolt holes for cyl 1 and 2 are stripped so I can't properly tighten those coils down, although I don't think that's really affecting anything as they're not popping out or anything (anything I can do about this?). Cleared codes and drove a while, CEL came back on 100mi or so later, only engine code is again that same "system too rich at idle bank 1". Car always has a rough idle, purge valve didn't show any issues through VCDS, have never gotten any other codes other than the ones listed above. Something has got to be going on with the fuel delivery for bank 1 here. Really at a loss here.

[rowlands57]

It may have been mentioned in the thread already, but did you run a compression test? Oil on the plugs is never a good sign. For what it's worth on my regular 2.0 I lost cylinder 4 literally out of nowhere, almost no compression at all; and it all manifested itself with a sudden misfire. My mechanic thought it was an on-going injector issue causing the cylinder to run very hot melting the rings. I take very good care of my vehicles and to say I was surprised is putting it mildly but apparently I am not alone in having this issue.

[BKozS3]

Where was the oil on the plugs. Could be the cam cradle leaking. Also, I would think if the hard start occurs after you have been driving and shut it off then it may be a stuck open injector, its expensive but having a leaking injector is not going to be good in the long run.

[Thewheelm4n]

It may have been mentioned in the thread already, but did you run a compression test? Oil on the plugs is never a good sign. For what it's worth on my regular 2.0 I lost cylinder 4 literally out of nowhere, almost no compression at all; and it all manifested itself with a sudden misfire. My mechanic thought it was an on-going injector issue causing the cylinder to run very hot melting the rings. I take very good care of my vehicles and to say I was surprised is putting it mildly but apparently I am not alone in having this issue.

I have not although the shop did look at timing #s yesterday through VCDS and everything looked good there, I have literally zero oil consumption between oil changes, I mean zero ever since I did my first oil change with Liquomoly after purchase last April at 132k (at 174k now), and I showed them the two plugs that had oil on them and they said it didn't look bad, looked pretty minor. I think the TFSI 2.0s in the S3's are a lot better built than the regular ones in other Audi models. I had a 2010 A4 with the ring blow-by problem, needed a quart with every fuel fill up. Insane.

That being said, they did ask if I'd replaced the PCV, when you pull the dipstick/oil cap there is a lot of pressure, they said that shouldn't be the case. I'm wondering if the new PCV I replaced last year has failed (or the diaphragm), or was somehow not a current revision (I know MikTip has mentioned sometimes places will send you an old part marked as a current part, I got it from FCP I believe). Think it'd be worth it to warranty out the PCV and start there?

[Thewheelm4n]

Where was the oil on the plugs. Could be the cam cradle leaking. Also, I would think if the hard start occurs after you have been driving and shut it off then it may be a stuck open injector, its expensive but having a leaking injector is not going to be good in the long run.

Pics of plugs attached.

Shop said a bad injector would cause a ton of white smoke (overly rich condition) to blow out the exhaust, I had this happen on my last BMW 335D when it ended up needing 3 injectors. But I have been thinking for a while now that it may have at least one injector sticking open, at least on start/at idle, because the only codes coming back have been misfires after a hard start and two bank one rich fuel codes. I've replaced basicslly everything else at this point. I'm assuming cyl 2 is in bank 1? That was the one misfiring constantly yesterday before I swapped the plugs out.

[BKozS3]

Look down the spark plug bore, you should be able to make out where the cradle mates to the head, and there may be oil on it, that is what mine looked like when I swap plugs right after buying it.

[Thewheelm4n]

Look down the spark plug bore, you should be able to make out where the cradle mates to the head, and there may be oil on it, that is what mine looked like when I swap plugs right after buying it.

If that's the case, what's the next move?

[BKozS3]

You'd need to reseal the cam cradle, it's a silicone sealant I believe. I thankfully had it done under the warranty that came with the car, it was not a cheap procedure. I am sure you can do it yourself if you have the tools and know how.