Audi S7 15' Idle issues

[Gutek21]

Hello from Germany!

My Car:
Audi S7 15' Facelift
34k miles on it.
New turbos + latest filter and strainer in Dec 2019
New spark plugs and oil 5w40 Oct 2020

I have a problem with my car.
I can feel the idleing in my Car (like missfire?) or stumbling is the better word for it.
New plugs (2 months old) (Audi spark plugs) -> bevor the change, the engine was stumbling slightly.
When hot or cold no hard start issues. The engine starts pretty quick.
No VCDS Codes and no CEL.

On 2k RPM you can hear a slight missfire on hot engine from the exhaust (not importent if the car is on P or N)
Car is running pretty well when the engine is cold.
In lower rpm when you hit the gas, the accelerate is not so clean (Highway).
Driving in the city is ok.

Could this be a possible coil pack failure ?

I hope someone can help me out!

Sorry for bad language!

Thanks!

Adrian

[csaba.meszaros]

I have an RS7 '16 and I can feel it too when I stop at the lights right after for like 30 seconds and after that, it smooths out. I have the start/stop coded out, I think most folks didn't experience this because the engine stops normally.

I've driven some other direct injection cars as well and they all had this issue with a not perfectly clean idle.

Make sure you change the oil regularly and not with the flexible OCI.

I do not experience the other issues you've mentioned.

[digdah]

Before throwing too much money at this try the Audi G17 fuel additive. I went through replacing motor mount (which really helped but didn't completely fix) to changing spark plugs. I was about to start changing my coils then decided to try the G17 additive. It completely fixed my issue and can be found on the usual sites using a Google search.

[gk1]

Before throwing too much money at this try the Audi G17 fuel additive. I went through replacing motor mount (which really helped but didn't completely fix) to changing spark plugs. I was about to start changing my coils then decided to try the G17 additive. It completely fixed my issue and can be found on the usual sites using a Google search.

Good suggestion.
As an alternative might I also suggest Redline SI-1
https://www.redlineoil.com/si-1-comp...system-cleaner

[135Hoser]

Do either of those products do anything considering the motor is DI, and top tier gasoline brands already carry a fair number of detergents in them?

[gk1]

Do either of those products do anything considering the motor is DI, and top tier gasoline brands already carry a fair number of detergents in them?

For fuel injectors, yes, for valve deposits...probably no.

"A vehicle may have low mileage, but short drive cycles and increased heat soaks can clog the injector.
In the case of a direct fuel injector where the tip is exposed to the combustion event, carbon can stick to the nozzle and cause a bad spray pattern, because carbon searches for other carbon."
"Since the formation of these deposits is a normal consequence of engine operation, detergents are added to gasoline to help keep the injectors clean. But if a vehicle is used primarily for short-trip driving, the deposits may build up faster than the detergents can wash them away. "
So a huge boost in detergents from a FI cleaner can indeed help.
Gasoline may carry a fair number of detergents, even top-tier gasoline, but guaranteed the gasoline peddlers will do the bare minimum to meet that top-tier standard (if they want that rating) and maximize profits and no idea if OP is using even top-tier gas or driving habits.
Or put another way...it can't hurt to try it and if it resolves the issue like in digdah's case then it for sure works.

[Alabama]

Gasoline may carry a fair number of detergents, even top-tier gasoline, but guaranteed the gasoline peddlers will do the bare minimum to meet that top-tier standard.

My understanding is that most additives are mixed in at the terminal, so even stations don't know for sure if they're getting what they paid for out of the tank truck (assuming they're paying for it). I try to use Costco gasoline because Costco buys their additive package directly and mixes it at the station. At the "National Tanks Conference" in 2013 a Costco employee noted "Costco has added tanks and piping at most of our gas stations, to increase the amount of detergent additive in our gasoline." I suspect their employees are also more reliable at maintaining the equipment, especially the filters. When traveling, I purchase from the busiest Top Tier station in town and knock on the wood grain interior trim Audi conveniently provides for that purpose!

[gk1]

My understanding is that most additives are mixed in at the terminal, so even stations don't know for sure if they're getting what they paid for out of the tank truck (assuming they're paying for it). I try to use Costco gasoline because Costco buys their additive package directly and mixes it at the station. At the "National Tanks Conference" in 2013 a Costco employee noted "Costco has added tanks and piping at most of our gas stations, to increase the amount of detergent additive in our gasoline." I suspect their employees are also more reliable at maintaining the equipment, especially the filters. When traveling, I purchase from the busiest Top Tier station in town and knock on the wood grain interior trim Audi conveniently provides for that purpose!

Really? That is very interesting to know. I had no idea any brand mixed "at the station". Very interesting indeed.

All I can add is I know the SI-1 is one of the few cleaners still with PEA which in my readings is still the strongest, best detergent available.
https://www.redlineoil.com/content/f...ner%20MSDS.pdf
https://www.redlineoil.com/content/f...DS%2012-12.pdf

I personally use a maintenance dose of 3oz per tank and a full bottle one tank before oil changes on both of my car's combined 120k miles since new. People can say what they will about it being a waste of money, if nothing else I can say it has caused no harm and gives me peace of mind.

[Alabama]

All I can add is I know the SI-1 is one of the few cleaners still with PEA which in my readings is still the strongest, best detergent available.

Not even so simple as apparently there are different flavors of polyether amines (PEA), and the best gasoline additive products are a combination of additives with different properties (post #7 above) including PEA. I suspect the key confusion is that a brand of gas additive may have multiple products under the main brand name so may be missed by a casual consumer. For example, "Gumout Fuel System Treatment" apparently does not contain PEA, while "Gumout Complete Fuel System Cleaner" does. Techron Complete Fuel System Cleaner apparently does have PEA and for the month of January is on sale at AutoZone for $5 per 12 oz. bottle. As gk1 notes, the proper use is to achieve the correct dilution/concentration of additive in the tank (typically one bottle to 10-12 gallons of fuel; should say on the bottle) and to add some gasoline after pouring in the additive to make sure all the additive is in the tank and some not still in the fuel filler neck.

[Alabama]

Really? That is very interesting to know. I had no idea any brand mixed "at the station". Very interesting indeed.

Indeed. No mention of why Costco went this route but I suspect it gives them better negotiating power for the wholesale pricing on their fuel. Supposedly several years ago fuel sales accounted for about 10% of total Costco sales nationwide.

[Alabama]

Do either of those products do anything considering the motor is DI, and top tier gasoline brands already carry a fair number of detergents in them?

First, "Top Tier" is primarily a North American marketing group apparently not used in Germany (where OP is). Germany may have an equivalent marketing program. AAA did a study that showed while top tier gasoline greatly reduced carbon build-up on valves, there was only about a 27% reduction in "total carbon deposits". A European marketing study projecting increased need for gasoline additives noted the following: "Port injection fuel delivery systems used to be the norm. However, new gasoline direct injection or GDI technology is becoming standard equipment on many new cars, especially in high-performance vehicles. In this innovative fuel delivery system, the injector is placed inside the combustion chamber yielding improved combustion to produce better performance, improved gas mileage, and fewer emissions. Deposits in GDI systems are extremely hard to remove and require more fuel additives". A report from the Technical Committee of Petroleum Additive Manufacturers in Europe notes that additive packages may have many components and functions including Deposit Control, Fluidizers, Friction Modifiers, Corrosion Inhibitors, Antioxidants, Conductivity Improvers, Metal Deactivators (to trap soluble metal salts), Demulsifiers, Corrosion Inhibitors, Octane Boosters, and Anti-Valve Seat Recession additives (Whew!). I've asked but have been unable to find good data to compare various commercial additive packages (such as Audi G17 versus Redline versus Motul GDI Clean for example). Bottom line, certainly use Top Tier gasoline or equivalent, but probably also need to continue preventive periodic use of a good brand additive, and as digdah and gk1 suggest, specific use of a good brand additive as a first try to fix those minor engine running issues like OP describes.

[Gutek21]

Hello from Germany!

Happy new year!
Thanks for the advice!
Motor mounts schould be fine. No Vibrations.
But i will test the mounts using VCDS.
I will test the additiv!
I use 102 oct (95 Ron) gasoline.
In Germany is this the best gasoline.
The car is driven much on short Trips..
And very defensiv. No hard acceleration.

I will report..

Thanks to all of you!

Adrian

[Gutek21]

Should i use one full bottle of redline for one full Tank of gasoline?
I have ordered one bottle now..
Thanks!

[gk1]

Should i use one full bottle of redline for one full Tank of gasoline?
I have ordered one bottle now..
Thanks!

In your case, yes, since you are trying to resolve a potential clogged injector issue.
Best is to have a near empty tank, then pour in the bottle then fill with gas.

[Gutek21]

Hello from Germany!

Redline was delivered today. Tank was near empty. Filled the redline in the Tank and then i Filled up with gasoline.

I hope this will help...

When the engine is getting hotter, the stumbling is worser.

At the end of the exhaust you can hear the misfire when you rev and hold the engine up to 2k RPM..

No CEL..

Greetings

[digdah]

I started seeing improvements after burning through about half a tank. All the best to you. Misfiring / rough idling drives me nuts!

[Gutek21]

Thanks @digdah!

Yea..the problem is, that there is no Code.. Without a Code or a CEL i dont know where to start..

I think that dying coil packs should be possible..

[Gutek21]

Hello from Germany

Today i drove on the Highway 63 miles on full throtle.
The car is running a bit better.

Ive checked the motor mounts.
These are fine.

Then i started a missfire detection using VCDS:

bevor the hard drive:
Number of missfires detected on Cyl 1: 635
Number of missfires detected on Cyl 2: 2797
Number of missfires detected on Cyl 3: 250
Number of missfires detected on Cyl 4: 659
Number of missfires detected on Cyl 5: 1486
Number of missfires detected on Cyl 6: 524
Number of missfires detected on Cyl 7: 568
Number of missfires detected on Cyl 8: 1130

after the drive:
Number of missfires detected on Cyl 1: 636
Number of missfires detected on Cyl 2: 2800
Number of missfires detected on Cyl 3: 250
Number of missfires detected on Cyl 4: 659
Number of missfires detected on Cyl 5: 1487
Number of missfires detected on Cyl 6: 525
Number of missfires detected on Cyl 7: 568
Number of missfires detected on Cyl 8: 1131

So we have an increase on these Cylinders:
Cylinder 1: by 1
Cylinder 2: by 3
Cylinder 5: by 1
Cylinder 6: by 1
Cylinder 8: by 1

I think this is ok..

No fault codes. Just one exhaust Valve which is deactivated.

Greetings

[Andreasmkr]

Hello from Germany!

My Car:
Audi S7 15' Facelift
34k miles on it.
New turbos + latest filter and strainer in Dec 2019
New spark plugs and oil 5w40 Oct 2020

I have a problem with my car.
I can feel the idleing in my Car (like missfire?) or stumbling is the better word for it.
New plugs (2 months old) (Audi spark plugs) -> bevor the change, the engine was stumbling slightly.
When hot or cold no hard start issues. The engine starts pretty quick.
No VCDS Codes and no CEL.

On 2k RPM you can hear a slight missfire on hot engine from the exhaust (not importent if the car is on P or N)
Car is running pretty well when the engine is cold.
In lower rpm when you hit the gas, the accelerate is not so clean (Highway).
Driving in the city is ok.

Could this be a possible coil pack failure ?

I hope someone can help me out!

Sorry for bad language!

Thanks!

Adrian

I hade exactly the same issue after new engine and turbos where fitted. Ended up beeing a foul sparkplug from factory..

[Gutek21]

@andreasmkr:
Pretty interesting Information..
With the old plugs the car was running pretty fine. Minimal stumbling at idle but no hearable misfire..
On 18 November the local audi service changed my plugs and made an oil change.
Since then the car is running worse..
I will check that..i call my dealer..
Thanks for that info!

[digdah]

Did you ever get this resolved?

[Gutek21]

Hello @ All

sorry for this really late replay.
The issue is not resolved.
The dealer had checked spark plugs and coils (They were OK)
Then we used 3 Times gasoline additives over 6 months. (Redline, Audi additive and liqui moly).
Using the additives did not help.
Today the dealer is updating the engine ECU to the newest software + deleting the engine adaptations.

I hope this will help.

[ichi d]

Hello @ All

sorry for this really late replay.
The issue is not resolved.
The dealer had checked spark plugs and coils (They were OK)
Then we used 3 Times gasoline additives over 6 months. (Redline, Audi additive and liqui moly).
Using the additives did not help.
Today the dealer is updating the engine ECU to the newest software + deleting the engine adaptations.

I hope this will help.

keep us posted!

[mrkubanftw]

Hello from Germany!

My Car:
Audi S7 15' Facelift
34k miles on it.
New turbos + latest filter and strainer in Dec 2019
New spark plugs and oil 5w40 Oct 2020

I have a problem with my car.
I can feel the idleing in my Car (like missfire?) or stumbling is the better word for it.
New plugs (2 months old) (Audi spark plugs) -> bevor the change, the engine was stumbling slightly.
When hot or cold no hard start issues. The engine starts pretty quick.
No VCDS Codes and no CEL.

On 2k RPM you can hear a slight missfire on hot engine from the exhaust (not importent if the car is on P or N)
Car is running pretty well when the engine is cold.
In lower rpm when you hit the gas, the accelerate is not so clean (Highway).
Driving in the city is ok.

Could this be a possible coil pack failure ?

I hope someone can help me out!

Sorry for bad language!

Thanks!

Adrian

Did you do the oil separator at the same time as the turbo's and screens? Those are known for cracking and causing a boost leak. I imagine misfires would come along with that - though I doubt they would be consistent misfires or on consistent cylinders. I get some vibration in 4cyl mode, but this is due to a bad motor mount, and they are active dampening - which are really mostly needed for 4cyl mode. Motor mount doesn't throw a warning or anything, I only found the fault in VCDS.

[gk1]

It is very strange to have a mis or stumble without any codes be generated at all.
Almost everything causes a code if the engine is running poorly.
bad plugs
bad injectors
fuel delivery
knock sensors
motor mounts

From my recent fuel pump failure your description sound similar.
"In lower rpm when you hit the gas, the accelerate is not so clean (Highway)."
So perhaps your LPFP is going south. I did get many codes though, but perhaps yours is just starting to fail, but has not completely given up yet.

Just a suggestion but maybe post the full VCDS scan after it runs poorly, perhaps you have overlooked something?

[digdah]

Were there any codes being thrown on your LPFP?

It is very strange to have a mis or stumble without any codes be generated at all.
Almost everything causes a code if the engine is running poorly.
bad plugs
bad injectors
fuel delivery
knock sensors
motor mounts

From my recent fuel pump failure your description sound similar.
"In lower rpm when you hit the gas, the accelerate is not so clean (Highway)."
So perhaps your LPFP is going south. I did get many codes though, but perhaps yours is just starting to fail, but has not completely given up yet.

Just a suggestion but maybe post the full VCDS scan after it runs poorly, perhaps you have overlooked something?

[gk1]

Were there any codes being thrown on your LPFP?

When it failed, yes, but I believe it was failING for quite a while without codes. Bogging off the line and initial throttle hesitation were the only things I noticed. Sometimes I'd be in a situation where I needed more throttle and I would have to floor it because it was not reacting to my throttle input appropriately and it felt like there was no power, then a sudden rush. There were no codes at that time. When I finally got faults if I cleared them it would drive ok for a while (few days) then I'd have issues again, but after the replacement the car drives better than it did even before it failed with codes, the partial throttle is better and smoother, and it doesn't bog like it did.

I had taken some LTFT reading before it failed and now after.
Honestly I don't know if these are good or bad, but I just notice they are very different now.

Last ones are after the pump was replaced.
IDE00597 Long Term adaptation of mixture formation bank 1 -2.3% -6.3% -3.9% -7.8%
IDE00598 Long Term adaptation of mixture formation bank 2 -4.7% -7.8% -5.5% -10.2%

IDE01869 Long Term Fuel Trim @idle Bank 1 -0.98% -0.98% -0.98% -1.22%
IDE03794 Long Term Fuel Trim @idle Bank 2 -0.98% -0.98% -0.98% -1.45%

These are the fault code for when it failed.

10060 - Fuel Pump
P308D 00 [038] - RPM too Low

10061 - Fuel Pump
P3043 00 [167] - Mechanical Malfunction

10064 - Fuel Pump
P308D 00 [038] - RPM too Low

2636 - Low Pressure Fuel regulation
P310B 00 [039] - Fuel Pressure Outside Specification
(Low Pressure fuel regulator is part of th epump assembly.)

5644 - Low Pressure Fuel Regulation
P310A 00 [101] - Fuel Pressure Fluctuates

...and side effects of the faulty pump

10203 - Random/Multiple Cylinder Misfire Detected
P0300 00 [039] - -
10595 - Cylinder 5
P0305 00 [039] - Misfire Detected
10596 - Cylinder 6
P0306 00 [039] - Misfire Detected
10597 - Cylinder 7
P0307 00 [039] - Misfire Detected
10598 - Cylinder 8
P0308 00 [101] - Misfire Detected
17902 - Fuel Rail/System Pressure Bank 2
P01C9 00 [100] - Too High

Saddest part of all is even when I brought it to the dearer with all those fault codes they still diagnosed it as "issue with the tune" which I had for 5 years. I had to tell them to replace the fuel pump anyway. Luckily they did a really good job with the replacement, just the diagnosis to quickly point fingers at the tune even though I was paying for repairs is a bit annoying.

[Gutek21]

Hi there!

sooo.. there is no new info from my side..
The dealer said that my car has the latest engine ECU software (done in 2019 when the turbos died)
I said that they should reset the engine adaptation values for testing, but they dont want.
Ive tried to reset it with VCDS, but no luck.
They have just done normal service ( Engine air filter and DSG oil change. Car has 32,397 Miles)


I will buy 8 used coils for testing.

I report back!


@gk1 Thanks for your help! I check every weekend for fault codes..VCDS is clean. When the pumps are starting dying, then i should have a code or not? The car is stumbling for months now..it doesn't get worse

[gk1]

Hi there!

sooo.. there is no new info from my side..
The dealer said that my car has the latest engine ECU software (done in 2019 when the turbos died)
I said that they should reset the engine adaptation values for testing, but they dont want.
Ive tried to reset it with VCDS, but no luck.
They have just done normal service ( Engine air filter and DSG oil change. Car has 32,397 Miles)


I will buy 8 used coils for testing.

I report back!


@gk1 Thanks for your help! I check every weekend for fault codes..VCDS is clean. When the pumps are starting dying, then i should have a code or not? The car is stumbling for months now..it doesn't get worse

Sorry that this one seems to be tough to diagnose.
I wasn't aware there was any new ECU software for older cars especially nothing from 2019 for a 2015 ECU. Maybe things are handled different in Germany.
Anyway, yes, when the pump starts to die you get the codes mentioned and the car is nearly undrivable. I was only mentioned the pump as a possible source, but if you have stumbles for months with no codes it is a mystery. Almost everything I have read if you have an audible or tactile stumble you can feel from the engine a code will be generated.
I know this is putting you on the spot and I mean no offense but are you perhaps more sensitive to such things than others? or has the techs who have checked it also confirmed they hear/feel the stumble? I know I can for sure hear and feel things with my cars more than say my wife. Sometimes it is nothing though, just my hypersensitivity to the running of the cars.
Also I know you have new turbos and they were only put in a couple years ago, but have they been re-checked? I've read instances also where turbos are failing and no codes are thrown.

[Gutek21]

Hello@all,

today was the day..Ive change my Coils and Plugs.
Driverside was not funny but doable.

The cars behavior is not better, its the same.

Here is a pic of the old plugs.
https://ibb.co/q1T8s66

I think that the plugs are looking fine.
There should be no leaky or faulty injector because the plugs are looking all the same.

no Codes in VCDS, the car is clean.

Here are my LTFT readings:

IDE00597 Long Term adaptation of mixture formation bank 1 -10.9%
IDE00598 Long Term adaptation of mixture formation bank 2 -8.6%

IDE01869 Long Term Fuel Trim @idle Bank 1 -1.92%
IDE03794 Long Term Fuel Trim @idle Bank 2 -1.41%

When the car hits 70°C (158 F) it starts to stumble. On stop you can feel a hard missfire but no CEL.

Greetings from Germany!

[gk1]

It is still really weird to have a hard misfire you can feel and no codes.
It is pretty much unheard of.
It implies a misfire that the car cannot detect.
...or the car is doing it on purpose so it doesn't detect it as a fault?
I've read plenty of cases where people have a misfire code for a specific cylinder but replacing plugs, coils injectors doesn't fix it and it end up being rings or valves, but still... they had a code.
Unfortunately LPFP is still my only wild guess. Even though your LTFT look ok compared to mine and those plugs look fine too. I'd hate to see you spend $1000 on LPFP replacement and it does not resolve your issue.
If you wanted to try you could see if you are getting spec pressures on the pumps. What they are for every situation I do not know.
Manual just says ranges 4.3 bar 62.3psi 800cm3/15s delivery rate. Line pressure 5-8 bar 72.5-116psi. Might need a shop and/or specialist equipment to make certain measurements.
GL

[Alabama]

It is still really weird to have a hard misfire you can feel and no codes. It is pretty much unheard of. It implies a misfire that the car cannot detect. ...or the car is doing it on purpose so it doesn't detect it as a fault?

Suppose the problem is just short of triggering a code. OP mentions "The car is driven much on short Trips. And very defensiv. No hard acceleration." Are there things a driver can to do "stress" the system and try to force a code, such as long drive, harder acceleration, and/pr put transmission in neutral, set brake, and push engine to high RPM??

[gk1]

Suppose the problem is just short of triggering a code. OP mentions "The car is driven much on short Trips. And very defensiv. No hard acceleration." Are there things a driver can to do "stress" the system and try to force a code, such as long drive, harder acceleration, and/pr put transmission in neutral, set brake, and push engine to high RPM??

Maybe, but if you can feel the miss it should be recorded. Unfelt misses I could see not tripping a code, but if you feel it when stopped then it should set a code I would think.

[csaba.meszaros]

I do have as well a very rough idle on my 16' RS7. I have the start-stop reversed so at the lights the engine doesn't stop. When outside is like 20°C the misfires are more noticeable, above 30°C when the AC kicks in harder you can barely notice. I've stayed with my laptop in the car and was watching the misfire counters in VCDS and from 50 noticeable misfires on idle only counted 1-2.

Car drives fine, accelerates hard, it's only noticeable on idle. I am thinking of reversing the start-stop back so factory setting so that the engine stops at the lights, but I find that super unhealthy for a v8.

[TexasDfwS4]

The fix is ever so often drive it like you a bat at of hell. It needs to stretch out ever so often

[jakubx80]

The fix is ever so often drive it like you a bat at of hell. It needs to stretch out ever so often

Funny you say that. I started having some slightly rougher idle and what felt like lower torque at lower rpm.

Used fuel additive recommended here in the thread and then took it to backroads on dynamic mode with some hellish paddle shifter action.
Tons of pulls, pops and and bangs started coming in louder and more noticable than throughout last few weeks (that was quite interesting) and now when I was at red light I swear I thought the engine shut down it was running so smoothly and quiet.

So maybe there's a lot of truth to this.

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