Cylinder 5 Issues (The Dreaded Cylinder 5 Misfire)

[13s4grey]

THE DREADED CYLINDER 5 MISFIRE!!!

Been meaning to start this thread for quite some time. I think we should put together as much information as we can about the cylinder 5 misfire. It only makes senes to look at the underlying issues, potential service history, engine failures, any results from engine tear downs after the fact, any patterns at all.

Let's get the info needed in this thread to potentially find a real solution to what may be the real cause behind this cylinder 5 misfire. I will look at all the comments people post and start making a list at the top of this thread.


Courtesy of Mahhdd:

1) Year, Transmission −
2) Mileage the failure happened −
3) What time of year did #5 go? What was the temperature out? DA (Density Altitude)? −
4) Were you running Ethanol Blends? E40? −
5) Octane gas you mostly use? −
6) Did you have an ECA (Ethanol Content Analyzer) that posted to your phone (FuelIt!) or to a P3 Gauge? −
7) List of Engine/Power Increasing Mods you had (which tuner and stage, intake, throttle bodies, ported blower) −
8) Pulley Ratio? (size of crank pulley / exact supercharger pulley size) −
9) Any fuel upgrades? (HPFP, LPFP, fuel rails) −
10) Any cooling upgrades? (Upgraded HX, Coolant Pump) −
11) Maintenance: Did you have your PCV replaced? Did you ever have your IC bricks serviced? Losing any coolant? How often were you changing your spark plugs? −
Note: If the answer is that you weren't doing any of this, that's OK... Nobody is going to roast you. Just let us know!

12) Were the cats in the stock location? Test Pipes? Relocated cats? See any issues with them upon inspection? −
13) Did you have any other symptoms/issues/problems you were experiencing? Plagued with? Things you noticed but couldn't solve before it happened? −
14) Did you ever pay attention to your injectors? Ever refresh/rebuild/clean/replace them? −
15) Did you ever log the car? Did you ever have the logs sent to a tuner for review/problem-check? Have any gauges to help you keep an eye on temps/IATs? −

[Smogmonster]

Looking forward to seeing what people's thoughts are on this, mine is currently in the garage awaiting a strip down to find what I'm assuming are damaged rings on cyl 5!

[430hps4]

I had a #5 ring failure back in July 2021. I went through several shady sellers, before finally finding a good used 50k mileengine to replace my old 135k mile one with.

[mahhdd]

Anyone posting needs to provide more information than "my #5 went..."

For this thread to go anywhere, we're going to need to start getting extremely specific to drill into the cause of why this is happening. Data will allow us to formulate ideas to get out in front of this:

1) Year, Transmission −
2) Mileage the failure happened −
3) What time of year did #5 go? What was the temperature out? DA (Density Altitude)? −
4) Were you running Ethanol Blends? E40? −
5) Octane gas you mostly use? −
6) Did you have an ECA (Ethanol Content Analyzer) that posted to your phone (FuelIt!) or to a P3 Gauge? −
7) List of Engine/Power Increasing Mods you had (which tuner and stage, intake, throttle bodies, ported blower) −
8) Pulley Ratio? (size of crank pulley / exact supercharger pulley size) −
9) Any fuel upgrades? (HPFP, LPFP, fuel rails) −
10) Any cooling upgrades? (Upgraded HX, Coolant Pump) −
11) Maintenance: Did you have your PCV replaced? Did you ever have your IC bricks serviced? Losing any coolant? How often were you changing your spark plugs? −

Note: If the answer is that you weren't doing any of this, that's OK... Nobody is going to roast you. Just let us know!

12) Were the cats in the stock location? Test Pipes? Relocated cats? See any issues with them upon inspection? −
13) Did you have any other symptoms/issues/problems you were experiencing? Plagued with? Things you noticed but couldn't solve before it happened? −
14) Did you ever pay attention to your injectors? Ever refresh/rebuild/clean/replace them? −
15) Did you ever log the car? Did you ever have the logs sent to a tuner for review/problem-check? Have any gauges to help you keep an eye on temps/IATs? −

Quote my post and add your answers out to the side.

We think this is something related to heat and running lean (running Ethanol in the cold, aging injectors).

This was posted on Facebook, so hopefully this thread gets traction.

If you have technical data to add to the thread, feel free. This is more than just a data cultivation thread.

[byront8]

1. 2009, DSG
2. 78,000km (48,000miles)
3. Summer, 27deg C
4. No, engine wasn’t even tuned
5. 98/100ron (93/94oct) - non E blended
6. Not at that stage
7. HX was the only installed item
8. OEM SC and OEM crank
9. Stock
10. Merc Racing
11. Maintenance was up to date, pcv changed, intercooler bricks were original
12. Stock cats
13. None
14. No, they have been cleaned since
15. Car was untuned, looks like a brick failure, engine failed at 40km/h@2240rpm, just pulling out of a driveway



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[mahhdd]

byront8, that's the most gentle case I've ever heard before... OFC you post first

Were the cats reused? Verified as good? New engine reinstalled and no issues since?

[430hps4]

Anyone posting needs to provide more information than "my #5 went..."

For this thread to go anywhere, we're going to need to start getting extremely specific to drill into the cause of why this is happening. Data will allow us to formulate ideas to get out in front of this:

1. 2014 A6 Auto
2. 135k
3. 120* Summer in Arizona
4. 91 Octane
5. 91
6. N/A
7. Intake/Test Pipes/Exhaust
8. 187/57.5 DP JHM ECU/TCU
9. N/A
10. Merc Racing
11. PCV-yes Bricks-no Leaks-no Plugs-less than a year old
    
12. See Above
13. Negative
14. No
15. No and No

See above

[Smogmonster]

1: 2014, DSG
2: 54 000 miles
3: January 10 deg C
4: less than 5% Ethanol content
5: 99
6: No I haven't got one.
7: IE intake, MRC tuned to 470 Bhp, done at about 50 000 miles
8:179mm crank pulley, standard SC
9: No
10: No
11: Just usual service items, plugs changed when I bought the car at about 45 000, not using any coolant, used about 1 litre of oil in 4000 miles
12: Stock cats
13: No issues at all
14: No
15: Health check when crank pulley changed and tuned, didn't show any issues.

Plugs show no sign of running lean, and I live in the UK so IAT's rarely get that high.

Currently waiting for my mechanic to strip the engine.

Supercharger is off and no issue with the intercooler cores.

I'll post some pictures when I can and follow up with more info.

[byront8]

byront8, that's the most gentle case I've ever heard before... OFC you post first

Were the cats reused? Verified as good? New engine reinstalled and no issues since?

Cats were the factory original - the car was not used very much or or long journeys prior to my ownership - so can only assume the few times it got driven close to hard when I owned it stressed the bricks into failure. I had owned the car 89 days at that stage.

Dealer paid half a long block cost, I footed the rest, fitted it myself and installed headers (plus all the other dual pulley goodies).

Cars been a champ since - but I also run a P3, log religiously, run E100 in my fuel, don’t run E40 files yet, and have only taken it on a 1/4 run maybe 20 times (6 on a track). She does 11.3@119mph on 93 pump gas files - so I’m happy.


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[13s4grey]

Anyone posting needs to provide more information than "my #5 went..."

For this thread to go anywhere, we're going to need to start getting extremely specific to drill into the cause of why this is happening. Data will allow us to formulate ideas to get out in front of this:

1) Year, Transmission −
2) Mileage the failure happened −
3) What time of year did #5 go? What was the temperature out? DA (Density Altitude)? −
4) Were you running Ethanol Blends? E40? −
5) Octane gas you mostly use? −
6) Did you have an ECA (Ethanol Content Analyzer) that posted to your phone (FuelIt!) or to a P3 Gauge? −
7) List of Engine/Power Increasing Mods you had (which tuner and stage, intake, throttle bodies, ported blower) −
8) Pulley Ratio? (size of crank pulley / exact supercharger pulley size) −
9) Any fuel upgrades? (HPFP, LPFP, fuel rails) −
10) Any cooling upgrades? (Upgraded HX, Coolant Pump) −
11) Maintenance: Did you have your PCV replaced? Did you ever have your IC bricks serviced? Losing any coolant? How often were you changing your spark plugs? −

Note: If the answer is that you weren't doing any of this, that's OK... Nobody is going to roast you. Just let us know!

12) Were the cats in the stock location? Test Pipes? Relocated cats? −
13) Did you have any other symptoms/issues/problems you were experiencing? Plagued with? Things you noticed but couldn't solve before it happened? −
14) Did you ever pay attention to your injectors? Ever refresh/rebuild/clean them? −
15) Did you ever log the car? Did you ever have the logs sent to a tuner for review/problem-check? Have any gauges to help you keep an eye on temps/IATs? − [/LIST]

Quote my post and add your answers out to the side.

We think it's something related to heat and running lean (running Ethanol in the cold, aging injectors).

This was posted on Facebook, so hopefully this thread gets traction.

I will be putting together a google sheet in the near future with all the entries/ variables and keep it updated. Thank you for your detailed comment with a break down of potential variables.

[mahhdd]

The trimmed down version of 034's response to the ring related question.
https://www.youtube.com/watch?v=aCFxK3_Ugnk

[430hps4]

The trimmed down version of 034's response to the ring related question.
https://www.youtube.com/watch?v=aCFxK3_Ugnk

So in short... to prevent another failure, we all get with our tuners and add more fuel?

[mahhdd]

So in short... to prevent another failure, we all get with our tuners and add more fuel?

I just had a private conversation with a well known somebody in your part of town who agrees that the logs from a lot of the big tuners look a little lean to him... Especially since he deals with 100 degree temps.

I know nothing about tuning; but, I wonder if it's possible to throw a little extra fuel at #5 for the "Fuel to cool" approach.

[killer_s4]

And also don’t throw on the biggest pulley ratio you can find

[RoofRails]

So I came across an older post of a cylinder 5 failure on the B8 S4 page that illustrates a ring land failure due to detonation. On the live stream outake that is posted above 034 points out that the rings aren't failing on their own but they are failing as a result of the ring land failing. We usually only see pictures of scored cylinder walls and rarely see the top of the piston it's even more rare to see the piston outside of the block since most people trash the blown engine and source a used replacement. The clues left behind by this individual was that the S4 was purchased used (only 36K miles ) and had a engine failure a relatively short time after it was purchased. There was someone from the shop that chimed in and mentioned there was no ECA gauge and the OP said the shop blamed the HPFP so you can draw your own conclusion as to what caused this. The OP never said what tune was on the vehicle or what fuel they were running. It sounded like the vehicle had a tune on it when it was purchased ( just my gues).

First picture shows the ring land failure , second and third picture show what looks very much like detonation (white specs on the right) right above the ring land damage and the last picture shows the cylinder wall damage.


We don't know what caused the detonation but like I said HPFP was tossed out as a suspect and there was mention of there being no ECA. I still think that there is enough examples out there to point to cylinder 5 being first to go when there is a fueling issue. We just don't know why that happens yet, and honestly, it's less important than just figuring out how to keep all 6 cylinders in happy Lamda land (MPI ?) .

FB_IMG_1644277664702.jpgScreenshot_20220207-185326.jpgFB_IMG_1644278467973.jpgFB_IMG_1644278440342.jpgundefined_w1400.jpg

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[430hps4]

I just had a private conversation with a well known somebody in your part of town who agrees that the logs from a lot of the big tuners look a little lean to him... Especially since he deals with 100 degree temps.

I know nothing about tuning; but, I wonder if it's possible to throw a little extra fuel at #5 for the "Fuel to cool" approach.

Wanna PM me with who you are referring to?

[RoofRails]

There was no story behind this #5 failure, but I thought it was a good picture to add to the thread. There is definitely some unusual looking marks around the outer edge of this piston that look like detonation and maybe even some melting ? FB_IMG_1644837142896.jpg

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[Smogmonster]

Does anyone know which way the coolant flows around the block? Does bank 1 get the coolant first then it passes through bank 2 or vice versa? Haven't got my car here to check!

[MSq5]

There was no story behind this #5 failure, but I thought it was a good picture to add to the thread. There is definitely some unusual looking marks around the outer edge of this piston that look like detonation and maybe even some melting ? FB_IMG_1644837142896.jpg

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Hard to tell from that photo, but I think you are right about signs of detonation. More obvious on the piston top in your earlier posted group photos.

One observation: we all know that running lean, especially under boost can produce detonation. Timing pull in the tune can help save your ass, if in time. So does cylinder cooling from intentionally running rich under heavy load. Where tuners can get into trouble is trying to win the hp race by pushing timing out too far, not being aggressive enough to pull it back early enough, and setting target AFR too lean under high boost/heavy load.

I'd rather give up 5 hp or so and keep AFRs under load richer and seeing a little timing pull on my logs and know my engine is staying safe. I theorize that competitive pressure on tuners to have the quickest quarter mile times for a particular stage of tune and fuel may be contributing to some of the failures along with owners failing to properly mix high ethanol tunes.

Ring land failure risk is increased as boost and engine load increase. Cylinder cooling from richer AFR really helps. Another common failure point for detonation is transient drop in hpfp pressure. It only takes a fraction of a second, noticeable on good logs, for this to produce a lean out. The ECU tries to compensate by increasing injector pulse width. It substitutes increased duration for higher pressure so that the same AFR is maintained. But, the lower pressure does not atomize the fuel as well. It does not burn cleanly, can pool up in places on tbe top of tbe piston, burn longer and produce hot spots. By longer, this is in microseconds, perhaps nanoseconds.

Executive summary: when tuners push timing and get a bit too lean on AFRs just to outdo each other for a tenth in the quarter or 5 hp or a bit more torque on the dyno under heavy load, especially with the higher boost of dual pulley tunes, don't be surprised to see ring land failure and signs of detonation. And log high pressure pump rail pressure and injector pulse width from time to time to make sure your pump is staying good, especially you guys running higher ethanol, even with upgraded pump pistons.

[RoofRails]

Does anyone know which way the coolant flows around the block? Does bank 1 get the coolant first then it passes through bank 2 or vice versa? Haven't got my car here to check!

According to this diagram, cooling should be equal across both banks. Audizine%20Forum-524289991.jpg

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[RoofRails]

Ring land failure risk is increased as boost and engine load increase. Cylinder cooling from richer AFR really helps. Another common failure point for detonation is transient drop in hpfp pressure. It only takes a fraction of a second, noticeable on good logs, for this to produce a lean out. The ECU tries to compensate by increasing injector pulse width. It substitutes increased duration for higher pressure so that the same AFR is maintained. But, the lower pressure does not atomize the fuel as well. It does not burn cleanly, can pool up in places on tbe top of tbe piston, burn longer and produce hot spots. By longer, this is in microseconds, perhaps nanoseconds.

Great write up MSq5. I was reading an article about the effects of long injector pulse timing and they touched on the unburnt fuel causing issues but didn't mention the cause being the lowered rail pressure and poor atomization. That makes sense.





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[wes8398]

What are your thoughts on tunes (tuners) that stick with the oem enrichment program to take care of things? I've noticed my EPL tune(s) lambda requests are a bit lean compared to others, but I've heard many mentions that this is because they keep oem enrichment in tact for their tunes. I wonder if this might also be why they seem to have such a good record with catalytic converters and engines staying together...

[Smogmonster]

So someone mentioned you don't often see pictures of the pistons as people usually just scrap the engine. Got these lovely pics from my tech today.

This is piston number 5 or most of it anyway.

I've not seen the cylinder since this was removed but before it was removed with the piston at the bottom of its travel there was no visible damage to it.

Will be going over for a look on Saturday so will take some more pics.IMG-20220224-WA0003.jpgIMG-20220224-WA0002.jpg

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[RoofRails]

So someone mentioned you don't often see pictures of the pistons as people usually just scrap the engine. Got these lovely pics from my tech today.

This is piston number 5 or most of it anyway.

I've not seen the cylinder since this was removed but before it was removed with the piston at the bottom of its travel there was no visible damage to it.

Will be going over for a look on Saturday so will take some more pics.IMG-20220224-WA0003.jpgIMG-20220224-WA0002.jpg

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Is that the damaged area being shown in the picture ?

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[Smogmonster]

Yeah, will get some clearer pics tomorrow.Screenshot_20220225-101213_Gallery.jpg

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[RoofRails]

Yeah, will get some clearer pics tomorrow.Screenshot_20220225-101213_Gallery.jpg

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I thought that's where I saw it. But this one is a better shot. Thanks.

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[Smogmonster]

My number 5 piston had a bit more damage than I originally thought, tech was having another look at it and a rather large chunk fell off!20220321_115950.jpg20220321_115903.jpg20220321_115909.jpg

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[mahhdd]

"Since the #5 Cylinder runs the hottest on the B8/B8.5 S4, can we have that cylinder richened up a bit so the additional fuel is used to cool"

https://youtu.be/u9WiqSxL6PU?t=3261

54:21

[celticsevad]

"Since the #5 Cylinder runs the hottest on the B8/B8.5 S4, can we have that cylinder richened up a bit so the additional fuel is used to cool"

https://youtu.be/u9WiqSxL6PU?t=3261

54:21

thats a nice idea, but im not sure since all of our stage2 cars max out the fuel pump tho..

[430hps4]

I like the 034 videos... but to have them "laugh" at the idea that there is even a problem... c'mon.

They may not wanna invest the R&D money, which I get. But that doesn't mean there isn't a problem. Just admit you don't wanna help solve it.

[Fresh.S4]

I'm sure they laugh because it's nothing wrong with the tune. It's all user error and folks adding extras to try and reach for the moon. Can't blame them for it

[430hps4]

I hear ya, that the tune (no matter who's you are running) is 100% the issue.

But there is a problem... and it would be nice if one of these companies would take the time to dig in and provide a possible solution.

Meanwhile, we as the end users, have to resort to threads like this to try and collect data and find a common thread that could potentially solve the problem. And when someone makes a suggestion to a tuner, to possibly try something... they "scoff" at the notion.

[MSq5]

thats a nice idea, but im not sure since all of our stage2 cars max out the fuel pump tho..

Maxxed out fuel pump on 93 octane E10 pump gas? "All Stage 2 cars"?

[Smogmonster]

I don't believe that my tune caused my issue, its not a common problem over here in the UK and the company who's tune I have have done a lot of these. I had only done about 3000 miles with the tune when this happened.

Also found out today that my vacuum actuated waterpump was no longer functioning correctly, when I noticed the small pipe on the pump I asked my tech what it was for, when he tried to show me the way it operates he discovered that the shroud was stuck, I always thought the car took a while to heat up from cold!

Another issue that will not have helped my problem!

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[killer_s4]

I hear ya, that the tune (no matter who's you are running) is 100% the issue.

But there is a problem... and it would be nice if one of these companies would take the time to dig in and provide a possible solution.

Meanwhile, we as the end users, have to resort to threads like this to try and collect data and find a common thread that could potentially solve the problem. And when someone makes a suggestion to a tuner, to possibly try something... they "scoff" at the notion.

Is there really a problem though?

Thread has been up since beginning of feb and there’s not even 1 page of failures. One of the issues is on stock tune too. Sounds like if you keep up with your aging car you’ll be fine. There might be a slim amount of failures but nothing to scare off people from modifying their cars.

[Shane Horning]

Yes it is a problem. I have 5 3.0s engines in the garage with no compression on cylinder 5. Unfortunately I haven't had time to disassemble them but from bore scope it appears same issue as the fellows above. Yes I've heard of other cylinders going but most are #5

[mahhdd]

Yes it is a problem. I have 5 3.0s engines in the garage with no compression on cylinder 5. Unfortunately I haven't had time to disassemble them but from bore scope it appears same issue as the fellows above. Yes I've heard of other cylinders going but most are #5

I ask those who have more experience with this speak up to the tuner(s). More data and info for them can't hurt. I think we'll just be seeing more and more of it until it becomes undeniable.

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[Shane Horning]

I ask those who have more experience with this speak up to the tuner(s). More data and info for them can't hurt. I think we'll just be seeing more and more of it until it becomes undeniable.

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What's weird is most cylinder 5 failure are 034 tunes. A few are other companies but the majority of my customers that had #5 go are 034. B8.5 a4 with apr have same issue with pistons breaking especially with e85. Here is a pic of a4 piston. Have done approximately 10 of these in last 2 years all b8.5 apr tuned20220314_224902.jpg20220314_224910.jpg20220318_215832.jpg

[Smogmonster]

Yes it is a problem. I have 5 3.0s engines in the garage with no compression on cylinder 5. Unfortunately I haven't had time to disassemble them but from bore scope it appears same issue as the fellows above. Yes I've heard of other cylinders going but most are #5

It'll be interesting to see what the pistons in those look like, I had no damage whatsoever to the bore, I think probably more due to luck than anything else tbh. Mine is also the later revision with cast liners so obviously tougher bores than the ali ones.

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[RoofRails]

Is there really a problem though?

Thread has been up since beginning of feb and there’s not even 1 page of failures. One of the issues is on stock tune too. Sounds like if you keep up with your aging car you’ll be fine. There might be a slim amount of failures but nothing to scare off people from modifying their cars.

Yeah , there is a problem. There is too much evidence out there on the FB pages to deny that cylinder 5 doesn't fail at a higher rate then the others. I just think less people are posting on Audizine these days and more people are using Facebook. I actually disagree with the statement about this not scaring people off. I see more and more people recommending to the new guys to stay STG1 on. People are also commenting to stay off of E40 and of all things people recommending APR software to the new guys is making a come back.