All cylinders misfire

[drambo136]

Hey everyone,
So I've been having all my cylinders randomly misfiring. No a lot but about 10 misfires for a 20 minute drive. To me it sounds like my pcv is going but wanted to check if it could be something else. I have a 16 A3 2.0 with 95k miles on it. I do have the eurodyne engine and dsg tune.
Thanks
David

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[Spinnetti]

sounds like time for a carbon buildup check

[railroader]

Hey everyone,
So I've been having all my cylinders randomly misfiring. No a lot but about 10 misfires for a 20 minute drive. To me it sounds like my pcv is going but wanted to check if it could be something else. I have a 16 A3 2.0 with 95k miles on it. I do have the eurodyne engine and dsg tune.
Thanks
David

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Have you ever done a carbon cleaning

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[drambo136]

Have you ever done a carbon cleaning

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Nope, never even heard of that.

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[railroader]

Nope, never even heard of that.

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Direct injected cars build up carbon over time on the valves, when it gets to a point it will create misfires, something to look into being your mileage is high, also start simple and check your plugs and the gap

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[evo v]

Direct injected cars build up carbon over time on the valves, when it gets to a point it will create misfires, something to look into being your mileage is high, also start simple and check your plugs and the gap

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Second that. I did carbon buildup cleaning on my '15 A3 last year when the thermostat went bad (105k miles). The buildup was not as bad as the previous generation A3 with similar mileage. It was throwing CEL from time to time. Audi of Burlington quoted me $1200 for the labor few years ago. Indy shops can do it for half. I was scared the first time I did my old A3 but since then I've done it probably 6-7 times on all my VW and As.

[drambo136]

Direct injected cars build up carbon over time on the valves, when it gets to a point it will create misfires, something to look into being your mileage is high, also start simple and check your plugs and the gap

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Yaaaa just read a few articles about it. I come from the jdm and old school muscle car world so this wasn't a problem. Seems pretty easy to do. Just a pain

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[mroberte]

Could also be your injectors are clogged/clogging. Many variables, but 10 in 20 isn't that much, when it gets into 50-100 that's when something is really wrong.

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[drambo136]

Could also be your injectors are clogged/clogging. Many variables, but 10 in 20 isn't that much, when it gets into 50-100 that's when something is really wrong.

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Yaaa thats why I wanted to do something about it now. I'm not even throwing a CEL. I just noticed it when the car was idling so I started to monitor it with OBD11

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[MikTip]

https://www.audizine.com/forum/showt...res-but-no-CEL

[aaronc7]

'^^^^^^^^^^this

[S3NICK]

Yaaaa just read a few articles about it. I come from the jdm and old school muscle car world so this wasn't a problem. Seems pretty easy to do. Just a pain

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Unfortunately, it doesn't seem to really matter for DI engines unless they are paired with port injection. The new LT1/2 V8s in the Camaros, Vettes, trucks, etc. all have direct injection only and I can confirm from a firsthand account that there is carbon buildup on the back of the valves. Hyundais get it, Chevy Impalas get it, Hondas get it. It comes with the territory. Some are worse than others.

If the problem persists after the carbon clean, replace your injectors. I had to do that to alleviate my issues. Really annoying and unnecessarily pricey. Definitely left a bad taste in mouth.

[Muggus]

I just changed my injectors and did a carbon clean because my car was stalling and running rough. The tech at audi said he was able to diagnose the injectors by using a boroscope to watch the injector fire. I'm guessing through the plug hole. I'm not sure the best way to fire the injectors. I'm sure he just used a computer to fire them individually.

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[Sv2k]

Hey everyone,
So I've been having all my cylinders randomly misfiring. No a lot but about 10 misfires for a 20 minute drive. To me it sounds like my pcv is going but wanted to check if it could be something else. I have a 16 A3 2.0 with 95k miles on it. I do have the eurodyne engine and dsg tune.
Thanks
David

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When was the last time you changed the plugs? Depending on the plug type and mileage, I’d start there. It’s a hell of a lot easier and cheaper that doing carbon cleaning.


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[drambo136]

When was the last time you changed the plugs? Depending on the plug type and mileage, I’d start there. It’s a hell of a lot easier and cheaper that doing carbon cleaning.


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About 10k miles and they r oem rs7 plugs

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[Sv2k]

About 10k miles and they r oem rs7 plugs

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If you read my thread on low rpm misfires, the general feedback I got is that it’s nothing to be too concerned about. So, if I were you and considering mileage on the car, I wouldn’t worry too much about it right now. 10 misfires does not sound bad for a car with almost 100k especially if there is not CEL.

My car is exactly the same as yours and my first Audi. So not knowing much about the platform, I did a bunch of reading researching which plugs to switch before I tune it. I considered rs7 and other options, and ended up with the conclusion that OE plug is going to be the best option. Even for tuning the car to stage 1. I think my misfires went down one or two total since I swapped them for newer plugs. So, you can try that plug, if you are concerned. ECS sells a set of 4 for $37, so not going to cost you much to try. They come pregapped to factory spec also. I think rs7 plugs are a tad smaller gap.

Lastly, no matter what happens with the plugs, I’d look to do a carbon clean since you have so many miles on the car. Here is a vid of a golf r with 10k miles and you can see how noticeable it is. I have no idea what it looks like after 95k, but I imagine it’s quite a bit.

https://youtu.be/CB5ThYfX7ag


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[Makersmark]

If it was enough to be concerned about there would be a CEL.

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[bakedcorn]

A couple of years ago my car one day decided to misfire like crazy almost felt like a machine gun under WOT. It was just horrible and never got a CEL. Took it to the dealership and they diagnosed it as a bad coil and was replaced under warranty. As mentioned above there must be some serious amount of misfires in order to trigger an alert on the dash as I assumed in my case it would be there.



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[Muggus]

same, when my car kept stalling and misfiring I never got a cel

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[40hands]

i had some startup misfires on my s3 that was covered under warranty. They had to update the ECU (good thing i wasnt tuned at the time). They also recommended a carbon cleaning even though im at 25k miles and just had it done at 19k. Since you are at such high mileage, id opt for an independent shop to do the carbon cleaning.

[MikTip]

My 2015 S3 has 110,000 miles. Runs fine. Maybe the gas where people live?

[Sv2k]

My 2015 S3 has 110,000 miles. Runs fine. Maybe the gas where people live?

Have you ever done a carbon clean? Do you do anything to maintain?


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[S3NICK]

My 2015 S3 has 110,000 miles. Runs fine. Maybe the gas where people live?

Have you ever done a carbon clean? Do you do anything to maintain?

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I really wish carbon build up wasn't a reality on this chassis. I hoped that was relegated to the older TSI motors in the MK6 GTIs, etc., but I gaurantee @ 110k without a carbon clean those valves and head ports will be gummed up. If it's running fine, and you're ok with some power loss vs. a clean head, keep rolling. If the car starts to act up, then it may be time for action.

I would route a cam through the intake manifold to see what the valves look like. I would also observe misfire counts through OBDeleven and keep an eye on things. If you have a dragy, do a 1/4mi run and see how it performs. When you change your spark plugs, stick a cam in the cylinders and take a look at the walls and the injector tips, if possible.

[Spinnetti]

I just re-read your original post. 10-20 missfires in a 20 min drive? Doing the math and assuming the top end of your number, lets say 2500 rpm average, 2 sparks per rev for 20 min / 20 missfires = .02% if I did the math right. I'd say its running superbly, and missfiring much less than the norm.

[drambo136]

I just re-read your original post. 10-20 missfires in a 20 min drive? Doing the math and assuming the top end of your number, lets say 2500 rpm average, 2 sparks per rev for 20 min / 20 missfires = .02% if I did the math right. I'd say its running superbly, and missfiring much less than the norm.

Yaa I'm not very concerned. I just noticed it and wanna get ahead of any further issues. But thank you

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[MikTip]

Have you ever done a carbon clean? Do you do anything to maintain?


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No carbon clean... Maintain???

I DIY everything on my S3.

Its never given me any issues related to needing a carbon cleaning...

[MikTip]

I really wish carbon build up wasn't a reality on this chassis. I hoped that was relegated to the older TSI motors in the MK6 GTIs, etc., but I gaurantee @ 110k without a carbon clean those valves and head ports will be gummed up. If it's running fine, and you're ok with some power loss vs. a clean head, keep rolling. If the car starts to act up, then it may be time for action.

I would route a cam through the intake manifold to see what the valves look like. I would also observe misfire counts through OBDeleven and keep an eye on things. If you have a dragy, do a 1/4mi run and see how it performs. When you change your spark plugs, stick a cam in the cylinders and take a look at the walls and the injector tips, if possible.

I can see inspecting the valves and head ports for...

OBD 11 I dont have. Got VCDS...

This post says misfires are normal:

https://www.audizine.com/forum/showt...1#post14119601

Anyone ever consider...maybe the gasoline might be an issue? Or the PVC oil fumes sucked back into the intake?

APR says: The APR Oil Catch Can System traps excessive crankcase oil vapors and gunk from entering the engine.
The system reduces carbon buildup on intake valves,

https://www.goapr.com/products/catch_can_mqb_ea888.html

Anyone check their oil separators(PVC) hasn't failed....

Allowing excessive oil fumes into the intake...which probably excells carbon build-up on the valves...

[aaronc7]

Catch cans can help prevent the buildup on valves...but there's a few gotchas.

The factory PCV on top of the engine is usually quite good at separating the air and oil and getting the oil back to the pan. But a catch can like like APR only 'filters' the air when under load. The factory PCV is a 2 way system, under 99 percent of driving conditions the fumes get routed straight back into the intake manifold.

A full replacement system that replaces the PCV on top of the engine blocks off that port and routes all flow back in through the air intake tract. With a catch can--all air is filtered, but these aftermarket PCV plates tend to not have as good of baffling in place, so the can will fill up every so often and you'll need to get a feel for how often that is and empty it regularly.

Even if you do all of these things, you are still going to get buildup on the valves from exhaust reversion (burnt air/gas mix flowing back into intake manifold). If you guys remember EGR valves/systems from back in the day...they were needed to reduce NOx emissions by re-burning some of the exhaust gasses essentially. Cars still need to do this for emissions reasons, but they are able to accomplish it by phasing the intake and exhaust cams to control valve overlap.

The type of oil you use also affects buildup. One of the oil properties/tests they do is sulfated ash...how much ash the oil leaves behind when burned. An oil with high SA will leave behind more deposits over time. Even with a catch can you're going to be burning some oil from the cylinder walls etc...but yes a catch can here can help some too. If you're big into oil specs, a 502 oil is a high SA oil and 504 is a "mid" level SA oil.

From what I can see, these cars don't have nearly the kind of intake buildup issues that the earlier, first gen DI engines had, but still a thing. Even cars that don't run catch cans, high SA oil seem to do just fine. But at 100k miles a valve cleaning is probably a good idea either way!

[MikTip]

Catch cans can help prevent the buildup on valves...but there's a few gotchas.

The factory PCV on top of the engine is usually quite good at separating the air and oil and getting the oil back to the pan. But a catch can like like APR only 'filters' the air when under load. The factory PCV is a 2 way system, under 99 percent of driving conditions the fumes get routed straight back into the intake manifold.

A full replacement system that replaces the PCV on top of the engine blocks off that port and routes all flow back in through the air intake tract. With a catch can--all air is filtered, but these aftermarket PCV plates tend to not have as good of baffling in place, so the can will fill up every so often and you'll need to get a feel for how often that is and empty it regularly.

Even if you do all of these things, you are still going to get buildup on the valves from exhaust reversion (burnt air/gas mix flowing back into intake manifold). If you guys remember EGR valves/systems from back in the day...they were needed to reduce NOx emissions by re-burning some of the exhaust gasses essentially. Cars still need to do this for emissions reasons, but they are able to accomplish it by phasing the intake and exhaust cams to control valve overlap.

The type of oil you use also affects buildup. One of the oil properties/tests they do is sulfated ash...how much ash the oil leaves behind when burned. An oil with high SA will leave behind more deposits over time. Even with a catch can you're going to be burning some oil from the cylinder walls etc...but yes a catch can here can help some too. If you're big into oil specs, a 502 oil is a high SA oil and 504 is a "mid" level SA oil.

From what I can see, these cars don't have nearly the kind of intake buildup issues that the earlier, first gen DI engines had, but still a thing. Even cars that don't run catch cans, high SA oil seem to do just fine. But at 100k miles a valve cleaning is probably a good idea either way!

Good info

Wouldnt an inspection of the ports first be advisable?

To see just how much carbon build up?

Vise just getting a carbon clean....

Especially since it seems shops cannot perform the carbon cleaning without issue...

Anyone try the Rotella T6 here?

[aaronc7]

I ran it like 10 years ago. T6 is no longer diesel and gas dual rated....it is now diesel only.

Will your car blow up if you run it...nah. But I think there are many better choices when it comes to small displacement turbo gas DI engines.

504 is probably the best option for us... as 502 is kinda old now and 504/508 are the current specs.

If you wanted to look at the rest of the field and what they run for similar type of engines, the most common is dexos1 gen2 which is 0w-20 to 5w30. They tend to be 'thinner' 30wt oils while 504 are usually 'thicker' 30wt oils. And many say the 504 add pack is better, higher quality oil and I sure would hope so as most 504 oils are $10/qt. 504 is also dual rated for gas and diesel

Another option I've kinda been casually looking into is dexos2 oils-- they are usually 40 weight oils and are dual rated gas and diesel. This seems the most synonymous with 504 spec but I don't think I've found an oil that meets both.

It gets a little confusing and complicated to me... look at the pennzoil line. Euro-502 spec , Euro L-Dexos2, Euro LX-504 spec, but also has some overlapping building approvals with "L".

I'm still running mobil 1 0w40 which is 502 spec because it's available locally for a good price and I run a conservative 5k OCI. I have been keeping my eyes peeled for a good deal on 504 oil though, online and locally. Really nothing yet. I guess the pennzoil "LX" is available locally in some areas, but not here.

[MikTip]

I liked the T6 cause it cleaned the internals extremely well on my B6 1.8t.

[MikTip]

https://m.youtube.com/watch?v=-kpiRESTS4k

[MikTip]

https://m.youtube.com/watch?v=lT07rHjFsus

[Sv2k]

Unfortunately most of these “spray into the intake/manifold solutions to go over the valves do not seem to do much.

Bluechem Carbon X looks promising but I have no idea where to buy it. It does not appear to be sold in US.

Watch “Bluechem CarbonX” on Vimeo: https://vimeo.com/248172536?ref=em-share

Otherwise, it appears the best way is to take off manifold and walnut blast or clean the ports, valves with some sort of carbon removal solution. Basically major PITA.


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[aaronc7]

The CRC stuff is supposed to be a lot better than what many guys used in the past...seafoam etc. Like 150x more PEA which I guess is the main ingredient you want to break the stuff up. Plus it's already aerosol form which is best. IIRC I watched a few youtube videos with guys that had borescopes and you could see the difference after. But I wouldn't expect it to really clean off a setup that's really caked up already etc. Plus if it did work, that might be some big chunks of carbon coming off, going into the engine etc.

Used as a "do it every 10k miles" kinda thing seems like a reasonable preventative maintenance measure. I would do it leading up to an oil change.

Another consideration is finding a good spot to spray it. You can use the MAP sensor hole on these cars....but from the looks of it might not result in great / even cylinder distribution. If you could pull the charge piping off the throttle body and spray it right into the TB that would be best....but sounds like too much work for me.