2008 1.6FSI lumpy between 2/3000 rpm

[Irishoctavia1976]

 

Its a first post , sadly it's to ask about a slight fault I'm suffering at the moment. 

Car is a 2008 mk2 Octavia 1.6fsi. It seems to have an issue when hot. It basically behaves like a pig between 2/3000 rpm or thereabouts. To the point where it feels likes it's about to run out if petrol. Then once above about 3000 it's absolutely fine. 

Idle is fine, in fact very smooth. 

There are no warning lights and no fault codes. 

A mechanic replaced one of the coils recently. But still no difference. He also tweaked the throttle adaptation (his words,) still it's hesitant at 2/3000.

Ive not had it too long. But am running it on super UL to see if that helps. 

Sorry for rambling, hope it makes sense? 

Cheers 

 

 

[TheClient]

fsi so no turbo operation which would normally be one thing you look at 2k-3k.... Fuel supply problem. Is it really ok at higher rpm under hard throttle? Replaced plugs?

[Irishoctavia1976]

Hi there 

It does seem fine when pushed hard. Brisk acceleration seems to be fine. Although it's possibly got a slight lumpiness when cruising on the motorway. Apologies for being a bit vague, it's my first Octavia so I don't have a point of comparison.

it did have new plugs put inat the same time as a new cool pack, as one plug seemed to be browned a little with heat. But the problem is still there. 

Hope this makes vague sense. 

[TheClient]

It can be a bit tricky when there is a noticeable fault but no fault codes. Before digging further one approach would be to replace the consumables:

 

Plugs (you say they've been done);

Airfilter

fuel filter

Coil packs as it could be one is playing up under loading. Be better if you could switch a set from a functioning car so that you don't have to fork out if it is not them, but they are not hugely expensive.

Have you changed fuel / petrol station lately? 

 

Has the problem persisted for more than one tank of fuel?

 

Apart from that I'm thinking fuel delivery - check fuel pumps

Or Injectors, which starts to get pretty expensive to replace and even diagnose.

 

What did your mechanic suggest to do next?

 

Edit: Some data logging when the problem occurs 2k - 3k may help.

Edited 17 May, 2017 by TheClient

[jong123]

Should be smooth acceleration through the rev's, I had similar when a coil pack started to fail , a scan showed up which coil and it was once replaced no problems.

If your mechanic pulled the coil packs off one at a time to identify the faulty one this could have caused a spike which led to the beginning of another to fail.

I now carry a spare coil pack and spark plug just as a precaution.

It has been 4 years so far and all is well.

[Irishoctavia1976]

Hi all

 

Cheers for all the replies. 

Well, I replaced the air filter and plugs. Still the same. So I took the plunge and changed out the coils. Dealer had claimed to have changed one. So I went and did the rest.

Now runs bang on  

Seems It looks like one of the others failing under load might have been it.

Cheers for all the help. Glad I came across this forum  

 

[TheClient]

Good result. Yes, I have seen them ok at idle but intermittent under load so your problems are hopefully behind you.  Thanks for coming back.  BTW, if you find a post useful or want to show thanks, there is a like button to click on the response, which goes to a members profile. All the best.

[jong123]

P.S. Don't get caught out carry a spare.

[Curvy]

 

On 21/05/2017 at 19:17, jong123 said:

P.S. Don't get caught out carry a spare.

If you carry a spare coil pack, and have a failure, how would you know which one to replace? I've had three of my four replaced and wonder if I should change the last one as a precaution. 1.6 fsi with 80k miles . . .

[TheClient]

If it goes completely faulty and not firing really at all properly, you can tell at idle by removing the harness to each one and listening for when there is no change. That will be the faulty one.

 

Or, if the miss is persistent enough, it may give a engine light and the stored fault often indicates the cylinder number.  If all the others have gone faulty I'd change it. I prefer to try and change things like that as a set.

 

It is trickier to identify when they start only playing up under load or in some circumstances and don't trip the CEL.

[Curvy]

Many thanks for the info 'TheClient' I'll have to look into changing it then!!

[Ootohere]

If you have Ignition Coils needing replacing i hope you are checking the spark plug is OK before doing that.

[Curvy]

I've decided to replace the one coil pack that hasn't been replaced. Is there a preferred make of coil pack that forum members could recommend? Also what is the designation/part number?

 

2006 1.6 FSI estate elegance.

 

I should be able to tell from receipts which cylinders have had the packs replaced, but I need to know how the cylinders are numbered . . . Left to right? Right to left? Looking into the bonnet from front or in direction of travel?

 

Thanks in anticipation . . . 

[TheClient]

Take a pick really, any good OEM spec coil pack. Genuine item or Bosch or NGK et al. Ideally you should match the 3 that are in there, assuming the 3 are all the same and matched up but a decent replacement will work. 

 

1>2>3>4

Front of Car

Lhs - Rhs (when standing in front of car)

 

I would just look at the top of the coil packs or pull them out. The oldest one should look older, plastic more heat stressed and dirtier, depending on how long ago you had replacements. I'd be surprised if you have been supplied detail for cylinder number on all invoices involving replacing coil packs but then I have been surprised before!

Edited 12 July, 2017 by TheClient

[Curvy]

Wicked buddy thanks for your help!