Persistent misfire – 2.0tfsi

[Pure:Torque]

Had a misfire appear on the car a few weeks back. Having scanned the car for codes I managed to figure out it was cylinder 4 that was misfiring. Having taken the car to a garage on Saturday, and after some switching of the coils, had the spark plugs changed. That seemed to solve the issue, the car had regained it’s power, mpg and was a joy to drive again.

Come Monday afternoon and the eml appeared again, along with the misfire symptoms. A quick scan reveals p0304...again. So in short the spark plug change didn’t work. I’ve now been advised to see an auto electrician to check wiring. I’ve heard the spark plug wires are common faults on this engine?

Having booked in with an auto electrician, he’s coming on Thursday. He mentioned it could be a faulty ecu, could it be this serious? I’m assuming with a new way I’ll lose my map?

Thanks for any advice, hoping someone out there’s had similar issues and can offer advice.

 

[Pure:Torque]

Update: The car has driven horribly all day, misfiring badly. Flashing eml and very poor performance.

Just drove the car 10 minutes ago. Misfire gone completely. Drives like a dream again. Mpg back to normal.

What the hell is going on?

 

[GhulamAfzal11]

You mentioned your car being remapped, if you don't mind me asking where was the work carried out when it was done?

I have a 2.0 TFSI Cupra and I've never had any of these issues, it could be when the remap was done maybe one of the wires got damaged or the work wasn't carried out correctly?

I'm just throwing it out there it could just be wear and tear but all my friends who have Cupra's haven't had this issue.

 

[Dan FR]

If you've changed the coilpacks and plugs around, then you need a new injector. Get a proper diagnostic on there and look at the misfire counter for the problem cylinder..... you'll likely have consistent misfires at idle

Get it changed before you kill your engine

Here's a list to go through/rule out first: http://wiki.ross-tech.com/wiki/index.php/16688/P0304/000772

 

[Pure:Torque]

You mentioned your car being remapped, if you don't mind me asking where was the work carried out when it was done?

I have a 2.0 TFSI Cupra and I've never had any of these issues, it could be when the remap was done maybe one of the wires got damaged or the work wasn't carried out correctly?

I'm just throwing it out there it could just be wear and tear but all my friends who have Cupra's haven't had this issue.

Thanks for the reply man, but I have no idea where it was mapped. It was done before I got the car I'm afraid and I have no way of finding out right now.

If you've changed the coilpacks and plugs around, then you need a new injector. Get a proper diagnostic on there and look at the misfire counter for the problem cylinder..... you'll likely have consistent misfires at idle

Get it changed before you kill your engine

Here's a list to go through/rule out first: http://wiki.ross-tech.com/wiki/index.php/16688/P0304/000772

Thanks for the link mate, I'll have a look at that. I'm kinda convinced it's the injector too, I'm heading to a garage that specialises in modified cars tomorrow so maybe they can throw some light onto it. I'll post an update tomorrow.

So driving to work this morning...without any misfires. Car drove reasonably well with no EML, however I have noticed one thing. When the misfire isn't present, setting off from a standstill, or pulling away at low revs, there's a huge cloud of smoke in my rear mirror. I'd love to say the smoke is white, but it's kind of got a blue tinge to it... The exhaust pops a lot too...but as I say, no sign of the misfire. May I point out that there's no smoke whatsoever when I'm experiencing misfire symptoms...just when they disappear.

 

[Pure:Torque]

So I thought I'd post an update on this. The car is still misfiring terribly, worse than it ever has. The fault codes appearing now are P0304, P0420 and P2626. Remember the car is decat so I'm not so worries about the latter 2 which I assume are down to this, I'm no expert however so could be wrong.

I'm booked in at a decent rep garage who specialise in modified cars on Thursday. I'm not driving the car until then. The garage is about 7 miles away, I'm hesitant to actually drive it there Thursday.

I'm one of those people who Google's a lot when I have a problem. I shouldn't really. However I'm going out of my mind with worry. The prospect of a huge repair bill (1000+) along with the worry that I might need a new engine or possibly even worse...scrap the car. If anyone out their has had similar problems, I'd love to hear from you.

 

[GhulamAfzal11]

So I thought I'd post an update on this. The car is still misfiring terribly, worse than it ever has. The fault codes appearing now are P0304, P0420 and P2626. Remember the car is decat so I'm not so worries about the latter 2 which I assume are down to this, I'm no expert however so could be wrong.

I'm booked in at a decent rep garage who specialise in modified cars on Thursday. I'm not driving the car until then. The garage is about 7 miles away, I'm hesitant to actually drive it there Thursday.

I'm one of those people who Google's a lot when I have a problem. I shouldn't really. However I'm going out of my mind with worry. The prospect of a huge repair bill (1000+) along with the worry that I might need a new engine or possibly even worse...scrap the car. If anyone out their has had similar problems, I'd love to hear from you.

I'm really sorry to hear about this mate its one of the worst feelings in the world hearing and seeing your car misfire. I haven't got a clue when it comes to stuff like this but what I would say is don't overthink too much.
Of course it is good to google and do your research but everyone's situation is unique and will lead to a different solution. I'd prepare yourself for the worst just in case but fingers crossed it won't require a new engine as if it does I'd just get rid of the car and use that money for something else.

Keep us updated mate

 

[Pure:Torque]

I'm really sorry to hear about this mate its one of the worst feelings in the world hearing and seeing your car misfire. I haven't got a clue when it comes to stuff like this but what I would say is don't overthink too much.
Of course it is good to google and do your research but everyone's situation is unique and will lead to a different solution. I'd prepare yourself for the worst just in case but fingers crossed it won't require a new engine as if it does I'd just get rid of the car and use that money for something else.

Keep us updated mate

Thanks for the words mate.

Yeah I don't know why I worry so much. I really like the car and would hate to see it go. It is what it is though I suppose. Only thing that get's me down is knowing if the repair bill comes in at £1,000+, I'll struggle to afford the repairs, therefore the replacement car will be a major banger...a fall from grace indeed.

 

[Pure:Torque]

Update:
So I had my car in at a VAG specialist the weekend just gone. Apparently when switching the coil packs around, the misfire stayed on cylinder 4. The mechanic then switched the spark plugs around and guess what, the misfire moved with them. He also told me that cylinder 3 & 4 had oil in the spark plug hole, he suspects bad valve stem seals are the culprit and are fouling the plugs.

He fitted a new set of plugs and coil packs and the misfire was cured. Albeit for 2 days, when the misfire returned with a vengeance. I took the car back to the mechanic and he inspected the plugs again, and confirmed they had been fouled and again there was oil in cylinders 3 & 4.

So, it looks as though I’ll need to get the valve stem seals replaced in order to prevent this. He gave me 3 options.

Option A) have him source me a replacement engine, which after doing slight research will probably set me back £1000ish plus labour charges.

Option B) have him replace the valve stem seals, which again would probably cost not much less than sourcing a replacement engine.

Option C) he says it COULD, possibly be a faulty injector. There’s a pungent raw fuel smell from the exhaust when the misfire is present. The oil in the spark plug holes also has a slight smell of fuel. He thinks that maybe the map on the car is causing the injector to over fuel, coupled with it being faulty, and this is causing fuel to also enter the spark plug hole.

Now, obviously option C is the cheapest option, however, I threw £200 at the problem when changing the spark plugs and coil packs. There’s no guarantee that replacing the injector will fix the problem, and I’m obviously hesitant to throw more money at a ‘possible solution’.

I’m really stuck for what to do. Selling the car isn’t really an option as in it’s current state it’s not worth much, plus then I’d need to find a new car, and in the end I suspect the cash I’d have to part with wouldn’t be too dissimilar from just repairing the car.

Any advice would be hugely appreciated.

 

[ZiggyEP3]

I was reading the thread and was going to suggest oil in the plug tubes as i had the exact same symptoms due to a faulty rocker cover leaking oil into the plug tube on my old calibra V6.

 

[GhulamAfzal11]

Sorry to hear that pal, I think in this situation you've got to ask yourself is it really going to be worth spending the money.

Even with option C you will have to spend money and if you feel its worth the spend then go for it, otherwise I think you might have to look at a new car.

Go for option C not only because its the cheapest option but you have no guarantee that you do actually need a new engine. At least then if you go for it and it works it will save you the grand needed for a new engine and then if it doesn't work you can fit a new engine in.

 

[Pure:Torque]

I was reading the thread and was going to suggest oil in the plug tubes as i had the exact same symptoms due to a faulty rocker cover leaking oil into the plug tube on my old calibra V6.

Really? Thanks for the input, I'll mention this to the mechanic as I've heard this being mentioned by a friend who happens to know a lot more about cars than I do!

Sorry to hear that pal, I think in this situation you've got to ask yourself is it really going to be worth spending the money.

Even with option C you will have to spend money and if you feel its worth the spend then go for it, otherwise I think you might have to look at a new car.

Go for option C not only because its the cheapest option but you have no guarantee that you do actually need a new engine. At least then if you go for it and it works it will save you the grand needed for a new engine and then if it doesn't work you can fit a new engine in.

Thanks for your reply again mate! I've booked the car in for Monday for the injector replacing. I've no confidence that it will rectify the misfire but what do I know, lol. Even if it doesn't, and I need deeper engine work, I genuinely can't justify buying a new car over having the repairs done. A new car would set me back a few grand. Even then I may have problems with a new car, I've been told the Leon is in great shape apart from the misfire. When it's running well, its a beauty of a car to drive. I just get the feeling I'd be out of pocket more should I opt to get shut. Just wish I could have a car which didn't have problems!

 

[Darbo]

It doesn't sound like an injector to me simply because of the oil, that's either valve seals or rings mate, you'll get unburnt fuel because an oil soaked sparkplug won't ignite the fuel.
Test compression on the dodgy pots compared to the other two, if it's significantly lower then that points to rings, if not then possibly stem seals.

 

[Bony]

I too have just had a read, sorry to hear your problems. I've had a car that leaked oil into a spark plug hole and it would misfire with monotonous regularity as it gradually filled the hole. The key was regularity, it was a predictable pattern. If the plugs and coil packs have been changed around and the misfire followed them then that may suggest more than one injector is at fault? Or the new coils/plugs are faulty? Or the map is so horrendous its forcing the engine to do things it doesn't want too?

I think there is/was a problem with tfsi engines and coking up on the back of the valves due to the position of the injector being changed and therefore possibly not 'washing' the valves. If this is so I wonder if this can create running issues? I'd ask a few more questions before shelling out, perhaps a compression test to see if all is well/equal, fit a spare set of plugs to double check and I'd be tempted to remove the inlet manifold and investigate if it was my car.

I understand we're all different when it comes to taking bits of engine apart etc, but I'm a bit old school and like to get as many answers as I can before spending big money! That and I'm a skinflint

Hope it's simpler and cheaper than it sounds, keep us updated and all the best!



Sent from my Nexus 6 using Tapatalk

 

[Pure:Torque]

Sorry about the delay in responding with an update but here we are.

I had the car in for a head gasket replacement, along with valve stem seal replacement last week. I got the car back yesterday.

So the misfire seems to have gone. The car drives brilliantly again and has so much power. It's a joy to drive, and I had the work done for a very reasonable price.

Now, as I say, the car drives great with no misfire what so ever. However, there's still blue smoke from the exhaust. My mechanic said this could be due to oil residue in the exhaust/intake system. He says this should burn off in the next few days and hopefully should stop smoking. Having put up with the misfire for so long, I'm always pessimistic. Has anyone heard of this before? The smoke is mainly at start up, however is still present in higher gears, low down in the rev range. It's worrying me. This morning I let the car idle and gave it a bit of revs, maybe 3/4 times up to around 4k revs. As I checked the exhaust, I could literally see dry carbon shooting out of the exhaust. It actually made a 'dry puddle' on the floor although I'm sure there was a little water in there too. I could see small balls of carbon in the exhaust tip.

Can anyone advise?

 

[Darbo]

Give it a couple of days then check your plugs again, if they're clean enough then it probably is just residue in the exhaust, if they're dirty clean them up and check again couple of days later, if they're dirty again then...well, y'know.

 

[Pure:Torque]

Thanks, I'll do just that. I'll come back and update in a week.