Coil Pack Failure

[JakeUK]

Hi folks,

So about 10 days after having my res delete fitted, the car had some issues with misfiring when giving it wide open throttle.

Took it to the garage (warranty) and as expected, I had a cylinder misfire on 1. They replaced all 4 coils (apparently) and I also asked for 4 new NGK plugs too. This was billed accordingly and the receipt clearly shows 4 coils and 4 plugs.

Now I always check the garages work to keep them honest and I suspect that only 2 coils have been changed. 2 physically look brand new and 2 look old. This is quite obvious due to the brightness of the lettering on 2 of the coils. Sadly the numbers on the coils don't really give me timestamps etc so I will be taking the car in to discuss. I will also pull a plug this weekend and check to see how new these are looking.

Regardless of the above, I am almost certain the car isn't pulling as well as before. I tried my best to time a 0-60 on the lap timer function and got 3 pretty quick times.

4.5, 4.3, and a 4.5 again. So in terms of 0-60 we are looking quite well but I just feel the car isn't moving that quick after 60 and it seems to be taking a while to hit redline in 3rd gear. Perhaps I have just gotten used to the power now but it honestly feels like the car was running a stage 1 remap and the fault code reader work / diagnostics the garage has done has removed this.

Before I take the car back to the garage to potentially tear a strip of them for not doing the job I paid for, is there anything specific I should be asking / looking for with the symptoms described above? I am not sure if this is of any benefit, but after the res delete, the car pops really frequently when coming off throttle and revving. I actually don't mind it as it's only a second ish and sounds pretty cool, but there seems to be a mixed bag of people saying they don't get exaggerated popping, and some that do. When the coil was nearly dead, I was getting popping on throttle which is when I knew something was about to die. I tried overtaking someone and the car went into limp mode and the EML came on.

After the garage did their work, I can confirm the issue with popping on boost and EML etc have indeed gone away. I just can't help but feel I've got about a 20% ish power loss!

I've stuck some injector cleaner in too but I am not expecting much of a return on this. Could it be that the plug on cylinder 1 has become fouled due to the failing coil and running rich? And if the garage have been extra naughty and not replaced the plugs then that could be the answer? I will be checking though but just looking for ideas. Or I'm going mad...


Thanks in advance!

 

[Matt Titanium]

I'd expect all the new coils to be the same make and look new. Did the garage just charge for the plugs or three coil packs as well (if you asked them to change them all whilst they were in there replacing the faulty one)?
Always ask for the old parts back. That way, you have more confidence they have been changed and you would have had three spare usable coil packs.

 

[JakeUK]

It was a bit of a weird one to be honest.

I specifically said that if it's a dead coil, I want 4 new ones and 4 new plugs. They called to say it was a misfire on cylinder 1 so they've done all the coils and the plugs for me. He then said that as they already had a new coil, they've chucked that in for free so the invoice states 3 coils and 4 NGK plugs.

I took the cover off the engine and noticed the 2 coils looked box fresh, and 2 looked faded. They are all however the same coils in terms of brand and model numbers.

I wish I had marked them now to be honest, silly really as I always do that when using garages.. ah well. I will pull a plug and if they look old, I'll be taking it back down and kicking up a bit of a stink.

I just took the car on a drive to really push it and aside from lots and lots of popping, it doesn't seem to be missing or hesistating at all. It still just feels a little flat though. Again I tried to time a 0-60 and got at least 5 seconds so I'm confident it's delivering a 0-60 in line with advertised speeds. Another thing I noticed tonight was that when driving in D mode in about 3rd or 4th gear, I would plant my foot down to the "kickdown" button area and sure enough the car would do as it was told, however, when actually waiting for the gears to drop, the car was choking up, nearly exactly what it was like when hesitating before the coil died.

I did Google this and found several posts to say it's normal so I guess that's just paranoia for now... driving in manual hasn't caused any issues no matter what gear or rpm I use.

I'll update the thread after a visit to the garage. Hopefully I'm just used to the power is all now but if anyway has any ideas then I'm all ears could really do with another code scan..

 

[Damo S]

Regarding feeling flat. I had exactly the same after a service which included a plug change (like for like NGK Racing plugs). I wondered if the garage doing the service hadnt gapped the new plugs properly so I contacted the tuner (who fitted them originally) for advice. Supposedly, they are pre-gapped from the factory there is nothing to screw up there other than complete mistreatment / damage to the plug. I never did get to the bottom of it but the car sorted itself out.
The ECUs are sophisticated bits of kit and I wonder if it just goes into some kind of learning mode if it detects a significant change to sensory inputs. This is just a guess.

But the other stuff you mention is underhand by them. Definitely check out the plugs and make sure they have actually changed them. if they have you may just have to give your car a bit of time to adjust and see what happens. Go and give it a nice long up a motorway.

IMO, if it was remapped and that had been removed you would really notice the difference in 1st and 2nd gears. On mine that is where the most difference was felt after tuning. It went from feeling somewhat underwhelming in 1st for a 300bhp car to pretty ballistic and sub 4 seconds to 60 even without doing a proper launch. One reason being that the stock car runs about 16 psi in the higher gears but reduces that in 1st (12psi) and 2nd gear (14psi) . Basically, the car isnt booting out 300bhp in 1st, perhaps 260, 270 at best. After a remap it runs full boost in all gears. Maybe not all remaps do that but mine does, its gone from running 12psi in 1st to 22 or so, and the difference in performance is awesome.

btw, get yourself a OBD2 dongle and torque pro or similar diagnostic app. You can scan codes yourself and look at things like misfire counts, boost levels, loads of other bits of data. I'd highly recommend this to all owners, and doing regular monitoring.

 

[JakeUK]

Hi Damo,

Really good advice thanks. I was looking at the OBDElevenPro actually as I'd like to carry out a few smallish mods such as exhaust valve coding etc. I'm sure I read this can also provide diagnostics so definitely a worthwhile investment I think.

I'm taking the car on a drive at the weekend and plan to drain the tank and fill back up with Premium. This plus the injector treatment is just good TLC anyway I think, plus I'll have a bit more time to really assess the performance. It's a great point on the gaps, I know that they are relatively easily adjusted with a gentle tap on the end so it could actually be that. I'll pull them all and use my dads shims to check the gaps just in case!

Glad to hear yours sorted itself out, hopefully I'll be able to report the same haha

 

[Harvey]

I can confirm the plugs will be pre-gapped and shouldn't require any adjustment but always worth double checking prior to installation. The OE gap is 0.8mm and uprated (one step cooler) plugs RS3/RS6/RS7 are 0.7mm. The reason for the slightly smaller gap is to stop the spark blowing out which can occur with higher boost. Incorrectly gapped plugs will cause misfires so always worth checking/swapping plugs prior to coils. As for the feeling of less power it could be just the placebo affect so I suggest you get it on a rolling road for a health check as that’ll be the only way to prove it for certain in a controlled environment.

 

[JakeUK]

Hi folks!

Firstly thanks for the input and advice here..

I pulled the plugs and can confirm they are in fact all new so I suspect the coils are too. The car was performing just as reported and I even took my dad out for a spin who said that he too could tell it was lacking. Felt like torque to be honest as it was still doing a very respectable 0-60. Unsure how just torque would be effected though so I imagine it wasn't quite as quick on the 0-60 as I timed..

I had an OBDEleven on order and that arrived yesterday. I scanned the car and found 0 faults which was a relief. While looking around I made some little mods to the vehicle including the throttle response one. Took the car out and felt absolutely no difference so removed it. Later that evening I popped out for a drive and as if by magic I have full power again! It's as if there was some sort of ECU issue at play and the tinkering has sorted it out. Or it was just a coincidence. No idea but I can absolutely feel the difference again.

Also as a side note, I'd strongly recommend doing a DSG reset if you can. The car is so smooth now. It was already smooth but I could feel the change between 2nd and 3rd and when in S mode it could be a little jerky when doing anything slow speed. I thought this was just the car but after carrying out a reset, it's noticeably improved. I'm not sure if the Basic Transmission Settings does the clutch packs too but I'll probably run through the settings manually to ensure it's all been done!

One happy S3 owner

 

[Damo S]

That's good to hear. Like I said mine just sorted itself out as well, and yes its the midrange torque that is a little lacking when it's having a hissy fit.

 

[JakeUK]

That's good to hear. Like I said mine just sorted itself out as well, and yes its the midrange torque that is a little lacking when it's having a hissy fit.

Exactly as you called it

It does however really make me want a remap at some point... just a Stage 1. He says...

 

[Damo S]

It really does transform the car.

 

[JakeUK]

It really does transform the car.

What are you running Damo? Stage 1?

I haven't done that much research into it but my car seems to have been a motorway mile muncher prior to me purchasing it so I would hope the clutch has plenty of life left in it. I only say that because I've seen a few videos of people needing to take a clutch and flywheel replacement after pushing the bigger numbers through. I'd hate to take a £500 ish remap and then meet a £2500 bill for that work! From what I read though, providing no underlying issues with the clutch, flywheel, and transmission, they are good to push the extra Stage 1 power through without an upgrade?

 

[Damo S]

Mine is stage 1 and a half if you like. Upgraded intercooler, intake, racing plugs then an MRC custom remap to run on 99 ron fuel. Exhaust side is stock. It made 390 on a hot summers day at 25C.

You don't need to worrying about the clutch as yours is an auto correct? a TCU tune is recommend for the DSG box its about the same price as the remap.