Facelift Rough Idle; Misfire?

Hi Guys,

I’m having a bit of an ongoing issue with my car, it’s been into the dealer 3 times. First time it was suggested I change my spark plugs and see what that did, not covered by warranty. I wasn’t very happy with that outcome and sent it back in, they did a fuel management software update which didn’t resolve the issue and has since been in again where I’ve had to pay for new spark plugs.

The issue started at about 15,000 miles, spark plugs aren’t recommended to be changed until 40k. I’m on 17,500 miles now and it’s the same, if anything worse. No fault codes stored, drives faultlessly but can’t comment on whether it’s making this noise while driving or not as I can only hear at idle. I’ve noticed the engine when it is making this noise is jolting pretty much in sync with the louder noises the exhaust makes. Can feel it through the the car when sat in traffic!

Audi have refused to look at it any further as god knows how but they have discovered my exhaust has had the PCW Mod so they have wiped their hands of it, until it has a standard exhaust fitted. The exhaust was fitted in July last year (8500 miles), absolutely no issues between then and around February when I noticed this first of all. If it did it from day 1, the exhaust wouldn’t be on there.

Coil packs came in at £47 each, would rather not replace those just on a whim...

It’s booked in with my independent on Saturday but I can see this labour totally running away with itself as one day it does it terrible, the next it’s silent. I am hoping to gather some knowledge/experience from you friendly bunch.

First clip below is shortly after it began in February, second is from a couple of days ago when it was the worst it has ever been one after another but still no fault.. argh! It can happen at any point, it happens if left idling when cold, the other day started up with the oil temp at about 60 degrees and it was doing it, but mainly arises after a drive whatever the kind. Have had assistance out when it was really bad, didn’t happen at all.





One things for sure it definitely isn’t right, sounds really rough.

Thanks in advance,

Matt.

DW81 said:

First of Matt just wait until the specialist as looked at it as you will no doubt get bombarded with 101 reasons why this is happening, as for the pcw mod I honestly believe Audi staff frequent these forums and if not word on the street is slot of owners are having this mod done and now know where to check so voids the exhaust warranty and therefore could effect the engine one to.

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That’s correct they are on the forums, but this was a new dealer to me and they had no reason to go looking me up.

Been told by Audi before engine warranty will be unaffected by anything cat-back, that’s why Audi sell a res delete pipe for the S3. Been told it is simply a baffle and will only affect sound, actually got told by a parts department to go and have it done in a backstreet garage and save some money as it wouldn’t be an issue.

JamesBaby said:

Could it just be unburnt fuel popping in the exhaust? Perhaps running a little rich?

If you have VCDS check fuel trims in Engine, measuring blocks 032. See if it’s pulling any fuelling.


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Unfortunately I don’t have VCDS, Audi don’t appear to look at live data in the dealership but just for fault codes.

Yes the car throws faults, but this was my point that the car won’t always know when there is an issue as it may not quite reach that threshold for a management light.

First of all, wow

Leo-RS said:

James has it above.

AudiNutta, you come across like an owner of a car that will never be happy. I see this going on for the rest of your life with all future car purchases. You appear to find the littlest of things and then waste a huge amount of everyone's time trying to rectify them.

How many call outs to Audi assist have you made since you purchased? How many calls to the dealership have you made? How many times have you visited the dealership since purchase and how many hours, days and weeks of your life have you wasted complaining or reporting things to Audi?

What tells you this car is misfiring? Do you have a flickering engine management light under hard acceleration? Do you feel hesitation? Have you VCDS fault code scanned this car and its come back with hundreds of misfire warnings? If not, why on earth would you even consider changing spark plugs and coil packs? Why would you bother phoning audi assist, dealership etc and tell them your car's misfiring?

In summary, you have a modified exhaust (to make it louder) and you are now getting these noises (small cracks/pops) from the exhaust? Tell me how this is Audi's problem? You have modified your exhaust, not Audi, so why should they spend their time troubleshooting issues coming from a modified exhaust and why didn't you tell them that it was modified to save everyone's time?

I have had 11 Audi's in 10 years, I can honestly say, the only time I've ever visited or phoned my dealer has been service time. There have been creaks and squeaks here and there, sensor lights come on and off etc etc but you know what, I've just always scanned, cleared the codes and they've never came back. A bit like when a Windows PC has an issue, you reboot it, it disappears and if it comes back then you have a problem. Other small issues like creaks and squeaks I've ended up rectifying myself as I loathe wasting my time back and forward to the dealer on trivial issues.

These videos are just unburnt fuel popping and cracking, go for a really hard run, abuse the sh*t out the car, lots of 30-100 runs over and over again, pull over, listen to the exhaust and it will be a hundred times worse than these videos. Your ECU richens your fuel mixture when the engine gets hot, it does this to cool the engine (EGT's) down. Excess fuel in the exhaust will cause these little pops. Absolutely nothing to worry about. (Unless you have the VCDS scans to state that you have a fuelling/misfire problem)

Sorry mate, just saying how it is, you appear to be an absolute nightmare of a customer. I bet they have a dartboard in their staff canteen with your face on it.

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Yep extremely unlucky with cars, brand new Fiesta had a bottom end rattle, S3 was plagued with suspension clicks and clunks and the RS is suffering from the tyre issue and now this. Yeah I’ve been a total t**t of a customer in the past and I’ve learnt my lesson, more than one Audi Centre that I’m not welcome in at this point in time, well not comfortable in. I’ve chilled out big time with the RS, sit back and take the majority of the rubbish I’ve been spouted.

How is this a little issue? The car didn’t do it before February, took 15 months for it to start doing it in the same conditions hence I wanted to investigate. Not to be a pain in the backside but to make sure the car is running the best it can be, for longevity and enjoyment. I don’t plan on selling it at any point, I don’t have the usual attitude if it’s a car on finance and it’s going back so to hell with how it’s treated (as some do). Yes the car is on the road, but I don’t think it’s uncalled for to try and find out why after 15,000 miles it’s started this.

Far as dealership visits go;

- One visit because of exhaust rattle, follow up visit to replace faulty exhaust as confirmed by Audi.

- 10k service at Audi, tyres worn to cords.

- Call to Audi assist sometime between with a scraping noise when driving which I couldn’t clear from movement, 100 miles away from home and no jack in the car.. free’d stone.

- 16k, geometry check at Audi for continued bad tyre wear. Audi agreed it was making this spluttering noise and advised I changed spark plugs (Audi advised this!!)

-16,5k, spluttering issue so back in following them advising I change spark plugs once I had the keys back in my hand. Audi Technical suggests software update which was done

-17k, back in to change spark plugs at my cost, Audi’s recommendation. Then announced the exhaust was modified and because they are listening to this through the exhaust, wanted that taken off to rule it out which makes sense and I’m not arguing that just know myself it wasn’t like it for the first 6/7 months. At this point booked in with my indi.

- Call to Audi Assist on the day of the second video because the engine was visibly jolting forwards in the engine bay to an extreme extent, hence exhaust was doing the same and could feel a shudder through the whole car when this was happening. AA patrol out, listened to the video and said that’s absolutely not right and offered to follow me into Audi as a recovery, which I declined.


Audi weren’t told about the exhaust initially because they didn’t ask, they asked if it had been mapped which it absolutely has not so that was that. If I thought it was the exhaust I’d totally bypass Audi and take the bloomin thing off.

I haven’t actually told the dealer it is misfiring, my mistake in how I wrote this thread. It went in defined as rough running at idle and I described it as a popping/spluttering. A You Tube search this morning allowed me to compare other misfires at idle and according to those home mechanics it seems pretty definitive that is the issue but appears I got sucked into that, sorry let’s return to rough running.

Sounds like you’ve been extremely likely, we have 3 VAG cars in warranty and every one has been in for at least 2 warranty claims in the last year, clutch pack, headlight levelling motor, water ingress due to failed speaker seals, turbo solenoid rattle and that’s without even mentioning mine. Lucky lucky you! That’s not me either that’s my Mum and grandparents picking up on all 4 of those issues, who have very little knowledge. One Audi out of warranty that we are working to a solution with gearbox issues at the moment but that’s an older car.

Thanks for your input, I know you are very well experienced and appreciate what you’ve got to say on the matter. If it is the engine running rich to keep temps down, it is interesting how it did it in the height of winter late at night time after time in February and then from a cold start on multiple occasions but there we go that’s just what I’ve experienced. I will send it into the independent on Saturday as it’s having a Haldex oil change at 18 months, half the recommended interval as I am doing with every item on the service schedule and they can scan it then and cast their well trained eye on the live data if they say it’s ok not to worry I will run it as it is, after all I’ve got a 5-year warranty and I’d always extend it after that anyway as I’m sorry to report that my pockets aren’t deep enough to pay for any major issues which may arise down the line.

Leo-RS said:

For 99.9% of other users on this forum the reply would have been a little more tactile

There's a pattern and theme with Audinutta's posts though. Comes across as never being content and always complaining, I'm not actually sure why he drives an Audi RS to be fair.

Anyway, Audinutta, don't take this the wrong way fella, I've just hopefully saved you a lot of money, time and effort. The video's you have posted are entirely indicative of unburnt excess fuel in the exhaust. You may be more aware of it now due to modding your exhaust and it getting warmer outside. Honestly, go out drive the car hard, pull over and listen to it and it will be a lot louder than it is in those videos. Completely normal.

What surprises me is that you have wasted 3 trips to the dealership to troubleshoot this "issue". What did Audi say when they discovered your exhaust was modified? You're extremely fortunate that they didn't send you a bill. You should have told them your exhaust was modified on the first trip and then you wouldn't have wasted everyone's time (including your own) on the 2nd and 3rd trips.

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The thing that upset me most about your responses is how you question you don’t know why I am in an RS? Where the hell has that come from, what a strange and unnecessary comment to make

As previous I’ve settled down and of late most of my complaints have been on behalf of the majority of the owners of the FL RS3 on here as some just don’t seem to have the get up and go to pursue an issue themselves, more fool me because I’m back to square 1 again as always when dealing with the poor Audi CS team, all is well until something is wrong. Why the hell I still live and breath the brand I’ve got no idea, the reason why I distance myself from the forums has become apparent again today. Head. Bitten. Off.

Again, genuinely thank you for your input on the over fuelling being normal.

T-800 said:

I actually posted about the PCW mod then thought better of it and deleted it.

Knowing the PCW mod squad would jump all over it.

Good post Leo though

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Nice to see you back T-800.

Had wondered where you’d gone in recent absence, I was funnily enough thinking of you when I posted this as I know you are pretty switched on as is Leo.

Everybody is on the PCW band wagon now, so probably least stressful to stay out of that as I doubt anybody will have the power to change the opinion on what he does.

Leo-RS said:

When did you have the exhaust mod carried out? I haven't looked at what that involves but suspect it removes baffles/sound deadening to heighten the exhaust note? The upshot of this is that in addition to the more fruitful exhaust note you'll hear more noises and "issues" too.

Cold start, your engine should run rich to begin with and you may have unburnt fuel still present in the exhaust system from last switch off. With outside temps now increasing, intercooler being heatsoaked in standing traffic etc, then your engine will begin to run hot (and rich) rich means more fuel than required which means these type of noises coming from the exhaust. The exhaust modifications will have heightened these noises making you more aware. In the colder winter months, once the car is warmed up you may not run the car too hot under normal driving (heatsoaking intercooler etc) We have had temps of 25c over the weekend there, sitting around in stationary traffic will almost certainly get the engine hot and the car running rich.

I guess my dig about being in an RS is that you are constantly finding issues with it rather than just driving and enjoying the car.

What I will say is, be careful and don't fall for the sales pitch of replacing perfectly working and serviceable items. Garages are there to make money and if they can fit a set of plugs early and charge the labour and mark up as a preventative measure, they will. Saying all that, I am only going off your 2 videos, I am not there in person to listen to the exact noises, I'm not there to scan your ECU and im not there to check how smooth the car is under acceleration so I may well be wrong. My input is solely based on listening to the 2 vid clips carefully.

Good luck in resolving this issue (or accepting it as normal as part of the exhaust modification)

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I bought this exhaust modified already, but it was fitted in July 2018. I had my old exhaust up until about 6 weeks ago, absolutely gutted I sold it.. put it up for sale as I thought I’ve no reason to want to put it back on. The exhaust mod involves gutting the resonators and opening the backbox up reworking some piping so it bypasses sound deadening. You do get more ‘natural noises’ crackles etc that you haven’t heard before and I love that, makes listening to this easier but it’s loud enough that it would be there with a stock exhaust.

We have had blistering heat and queuing up into a show yesterday saw 106 degrees on the oil with no trouble, they do run very hot in this weather and I’m conscious of that.. give it plenty of time to cool down after a spirited drive.

The car gets driven, more than I’m comfortable with haha and it gets used properly as well, as far as I can explore it’s limits safety on the public roads anyway. Will be on 20k miles before I know it, scary quick for a car that isn’t a ‘daily driver’ as such in the sense I don’t need a daily car.

My car will go to Audi for all the fixed schedule items to retain the FASH status for any goodwill / if I did ever sell it, anything between is at a specialist documented comprehensively to use genuine parts etc as Audi are not cheap.. mind you Audi halved the price of my specialist for the S Tronic oil. I had a shock the other day when AUDI told me their labour rate is £156 an hour, wtf... I thought the old £120 was bad enough. The engine gets an oil change every 5k and that’s how I will continue to run it, look after it and it should hopefully look after me haha.

Thanks very much

T-800 said:

I stopped bothering because it’s tiresome reading the same old guff again and again.....

Your looking for faults that don’t exist I think and it’s ruining your ownership of the RS3.

It’s a highly strung car and you have to accept it’ll sometimes behave out of what you perceive to be ‘ordinary’.

As Leo has already said you are most likely to be hearing noises you’ve never clocked before.

Selling your standard Sports exhaust was a mistake, now you’ve no way of putting the car back to factory spec.

If you can’t enjoy the car what’s the point in having it, you’ll always be worrying about any little thing.

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Yeah I figure, I stay mostly out of new threads now just because I don’t have time struggle to keep on top of my own.

The car is great but yes no doubt the tyre issue is p’ing me right off as it is for a few others as well. It’s the response from Audi that’s even mor infuriating than the issue itself.

Yeah I’d understand if I had heard this in the weeks after the new exhaust, but it’s months and 3 seasons later so I’ve experienced all these heated conditions before.. oh well.

I sold my standard exhaust because it was taking up a lot of room in the shed and I had no intention on putting it back on or selling the car. If it comes to sale I can buy another, or can even pay to have the PCW mod undone... or sell it like it is because it sounds awesome.. is loud inside though. My exhaust is actually back up for sale, but truth is the money went on my third set of Pirelli’s and then replacing one of those brand new tyres 150 miles later afternoon a irreparable puncture.. poof, £600 gone.

I enjoy the car, just if there is something wrong I’d like it put right not because it is my right but because it can’t be good to run with any issue long term if there is one.

terminator x said:

Sparks were every 19k on the PFL, not sure why Audi pushed it out so far for the FL ...

TX.

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I found that strange also, but interestingly I noticed from the part number the plugs that came out are also compatible with an RS7. I thought the RS7 plugs were always an upgrade? Maybe a new addition?

terminator x said:

If you ask me Audi perhaps have guessed re the PCW mod and maybe you confirmed it? No way Audi can tell from the underside of the car. As for Audi frequenting the forums how on earth will that help them when plates are blurred and we all have usernames ...

TX.

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After the first visit the tech said something along the lines of “standard other than the exhaust?”, I just said that it hadn’t been mapped and ignored the exhaust question.

Second visit they looked into it and did the update no quibbles, when it didn’t work booked it back in no worries.

2 days before taking it, called me and said that they weren’t willing to progress with it under warranty because of the non-standard exhaust. I said it was a genuine one which the guy on the phone by his response didn’t realise that, but I explained then what had been done. Called Audi Technical and it was a no, would not progress any further so the outcome of that phone call was that they would contribute to the cost of spark plugs but that was it until I was able to fit a stock exhaust. Courtesy car was forcefully cancelled as the work didn’t warrant it, so I had to wait for the plugs to be done and be gone the same day as there wasn’t even a test drive done (not that I’m complaining about no test).

I confirmed I’ve not lost my warranty, just won’t look until the exhaust is changed. Audi have been great with discounting the plugs and I appreciate that, but obviously I’m a little frustrated by the whole thing. I want to be driving it not on pins every minute it’s in their possession, if it was immediately after the exhaust I would have taken it back off. If I wasn’t concerned I wouldn’t be trekking up and down the motorway to this new to me Audi Centre, but it’s worth it because the wait times are very very short compared to any centre I’ve ever come across before and overall seem more organised.

Will be glad when Saturday is over and hopefully I will have a definitive answer as to whether to be concerned or not.

T-800 said:

I changed my plugs a few months back

Around £70 for the plugs.

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That’s a good price, they quoted me just over £120 for the plugs! Usual price is £212 for the plug change at Audi. I’d rather not release on a public forum what I paid, but they did a good deal.

Wouldn’t have been an issue doing the plugs myself have done plenty of them before but not on a car like this and with my bad luck haha! I’ve got a torque wrench but it’s only a cheap Sealey option that I use on wheels, it would be my luck I’d snap a plug off in the head.

Just checked and my plugs are the same number as yours

Dan_DJT said:

Sorry to hear you are having some more issues with your car Matt.

Have you tried different brands of fuels ? or same brand but different garage ?? Have you checked the air filter and pipework up to the turbo compressor ?? These cars dont have a MAF and leaks not always easy for the on board diagnostics to detect. I can also recommend swapping out the air filter, I did mine at 15k miles and it was very dirty (see pic), it wont be the cause of your issue but it wont do any harm to change it.

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Different fuels are a good idea, it’s always had Shell V Power without fail and most of the time from the same station 1.5 miles away. Next nearest is about 15 miles, will go there and get a tank to try it and see what happens.

Air filter was checked a couple thousand miles ago and it was actually really clean, definitely didn’t need replacing yours was very dirty! Anyway I’ve got it noted down to change it at 20k, but if it’s as clean as it was before I don’t think I will.

When the AA came out he was looking for the MAF and said it was right by the intake on the engine rather than closer to the air box as normal?

jaysrs4 said:

I have an FL with a PCW mod and a Stage 1 map and it definitely doesn’t do this on idle. IMO you’d here that with a standard exhaust too. It’s not out of the realms of possibility that you wouldn’t notice a slight drop off in performance if there was a small issue and it was retarding timing for some reason.

I had a similar issue with an R32 I had once, no fault codes, no EML. It went back to the dealer 3 or 4 times and they couldn’t find the fault. I went to a specialist and they changed two lambda probes (post and pre cat) still no change. After a load of grief, it turns out it was a lambda fault but one of the new lambdas i’d been sent was faulty!

Chasing faults can be an utter nightmare but what I will say, you leave it long enough, something else will fail due to that fault and it’ll all show its head. Until it causes a noticeable problem I wouldn’t waste my time.

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Thanks for confirming that, another forum member local to me also doesn’t have this issue with the PCW mod. You would hear it with a stock exhaust as well, inevitably it would be a little quieter but it would still be there.

Interesting on your R32 issue, I think it’s one of those where it will take something else for us to find it. That is why id like to get it done, don’t want it to cause any other damage but might just be a case of waiting until the car thinks something is bad enough to tell me about it.

T-800 said:

AA are a waste of time, when using Audi Assist you can actually insist on an Audi specific tech guy.

The first time my PFL had it's Fuelling issue they sent out a 'normal' yellow van AA chap and it was a waste of time because the minute he showed up he said he couldn't access the RS3 systems with his code reader, he called in and got the silver VAG van breakdown guy to come out instead, these guys have access to Odis etc.....

Before leaving the VAG breakdown guy told me i could ask for a dedicated VAG tech, it may take a few hours longer depending upon their workload in the area, but he told me they had access to better systems.

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Correct, waste of time.. the patrols just don’t have the knowledge to look into issues like this it either runs or it doesn’t.

I’m aware of the VAG patrols, learnt of that when I had the steering rack issue on my S3. I always request them, but on this occasion I was calling on a Saturday and the next available guy they had was on Monday so unfortunately wasn’t an option wanted it checked for my long drive the day after.

In my experience the VAG Patrols have worked in main dealers.

Jefecito said:

@AudiNutta I don't think what you're doing can be called investigating. The first thing you should do whenever you suspect anything going wrong with the car is plugging an OBD fault code reader. You can get a basic cheap one but acquiring VCDS would save you a lot of time and money overtime.
If your ECU is fault free, in your case I'd check short and long term fuel trims, and also misfire counters for each cylinder.
Your car can be misfiring but not enough to trigger a check engine light, and a lot can be happening before that damn thing illuminates.

I'm having an actual nightmare with my owernship, I've had a huge fuel leak, no CEL. The fuel pump controller failure created tons of misfiring, no CEL.

I've had some knocking noise at idle in the engine bay. After full days of data logging and investigation, I've got the whole piston set shot from the same are (piston skirt), no CEL.

Most dealers would never put much effort to track down issues for you because for them no CEL = no problem.

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That is why I booked it into the specialist, for access to VCDS and somebody who actually knows how to operate it to it’s potential. Audi plugged it in and there is no fault, I have a Carista OBD reader which is only ever any use if there is a fault code not live data.

Anyway, the car went in to the specialist today and didn’t make the noise which is the norm.. frustrating. BUT, not all is lost.. we went for a drive and it drove fine, trims are all ok and no confirmed misfire readings. Only one confirmed misfire reading when I downshifted to 1st coming to a stop.

Then they moved onto the individual misfire cylinder count.

Cylinder 1 - 682
Cylinder 2 - 1172
Cylinder 3 - 628
Cylinder 4 - 696
Cylinder 5 - 541

That was when it wasn’t making the noise to its full potential, so I hope that will back up my concern that there’s is an issue and this isn’t ‘normal’.

Plan of action, I’m going to swap the coil pack from Cylinder 2 to Cylinder 5 later on today run it for a while and then go back for it to be read again. If my problem has been transferred to cylinder 5, replace the coil pack for £47 (quote for one from Audi).

I am so happy they found something, would have been happier if they’d heard it too but can’t ask for too much. Hopefully can isolate that coil pack and hopefully, that will be the rough running solved.

Jefecito said:

That would be a good start, swap coilpack and keep check the counter a few days later to see if the pattern changes from Cyl 2 to 5.

What didn't the specialist say about the amount of misfires recorded ? Isn't it "high" for a 17k miles car ?

Regarding fuel trims, what's the long term figure like ? I guess within the -10 to 10% range but the actual figure gives you an idea about how rich/lean the car is running.

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The coil pack has now been swapped, the car will be out of my hands as of Monday for 3 weeks unfortunately so I can’t have it looked into until after then. They told me to drive it for around a month anyway and then go back.

He didn’t say it was abnormal, he said you expect some misfires and around 600 seems consistent for this car. But this isn’t a complete misfire count, from my understanding this is basically a reading from the knock sensor? He said if the cylinder has totally failed to spark you will get a confirmed misfire reading, as we got a single one of those coming to a stop on a downshift but he wasn’t alarmed about that. So from what I can gather the readings I’ve taken away could highlight a ‘poor’ spark rather than no spark hence no CEL. I could be interpreting that wrong and somebody with more knowledge of this data might be able to fill in the gaps. The “misfire count per cylinder” then, is that a TOTAL number in the life of the car is that what you are trying to say? I thought it was live information from that moment, not historical misfires?

I wish I’d taken a photo of all the data he pulled up, but I was driving and had little opportunity to look at specific values. He did say that one of the trims was between 1.5% and 3%, which he said when mapping they try to keep under 4%? So no issue there. He said all other values were perfect as to be expected at both idle and under 100% throttle.

When I have it looked at again, I will try and capture the information.

Jefecito said:

Regarding the trims that's certainly the short term fuel trim he was talking about. The long term one is basically what your ECU has learnt overtime regarding the air/fuel ratio and it give you more information regarding what you're looking for. If LTFT is "perfect as to be expected" then fine.

However from my understanding, the misfire counter is an actual TOTAL that your ECU recorded in your 17k miles. If you drive your car another 100 miles and check it again you'll see a couple of misfires will be added to the counter. (with the same pattern you're having, most probably Cyl 2 misfiring more than others) These cars do misfire and it's considered normal to a certain extent. The range set by the manufacturer of x misfire / specific time is unknown and when/if your car reaches that limit it will trigger a CEL.

There's a point that sounds weird to me though, he told you that was from knock ? If you're having knock the ECU will be pulling timing and that's super easy for him to have that information through VCDS live data while you're driving. If it was the case I assume he would have looked at that data because of damage detonation can have on an engine.

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Ah right that’s cleared that up then, yes he was happy with the LTFT during the drive.

That makes sense now as when he updated the boss, the boss turned around and said about it being historical. This also now makes sense why he’s asked me to drive it for a month, because if I went back tomorrow it wouldn’t have accumulated hardly any misfires and if at all noticeable.

It might take a little while to build the number of misfires on Cylinder 5, 17k Miles is a a long time so you are looking at a misfire for every 28 miles on a regular operating cylinder and every 14 miles on Cylinder 2. I will get some miles put on the car and take it back to them at the end of May and hopefully it will be noticeable that the fault has transferred onto Cylinder 5 and in which case I will happily buy a coil pack and totally bypass Audi main dealers.

It was just how he explained it, he said the knock sensor is used to detect misfires and it could be seeing nothing from one cylinder or pick up a slight misfire. When I drove it he had a decent number of values up probably around 10 and was happy with all the readings, the car wasn’t running rough at any point today and it was only what is now apparent to be the historical data that hasn’t highlighted cylinder 2. If I go back on another day when it is spluttering, we should see actual misfires being added to the count.

I absolutely trust these guys no end, if they say not to worry about it I will keep driving and forget. They are very good at what they do, I’ve got no experience with MRC etc but from what I’ve seen, they are on par in their section of the industry. Their business is Japanese cars, despite this they all own German cars and do an awful lot of work on the German stuff as well. Most of what they do is engine builds / custom remapping, so I’m confident they know what to look for.

T-800 said:

I wouldn’t get too hung up on VCDS mis-fires this is mine at 14k miles

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Hmm, well that’s thrown a spanner in the works

Not only do you have a large number but there is quite a large variation. My car had the software updated around 500 miles ago but chances of me having 600 normal misfires in that time looks slim comparing it to the rest of you guys.

My faith in the VCDS misfire count is slipping away now Only way I’m going to know now is in a months time when we plug it back in. It’s going to have PPF done on Monday and will be gone either 21/22 days... dreading it.