Intermittent holding back on boost.

[S3 Ed]

Hi all, done a search but can't find what i'm looking for.

Noticed last night that it was slightly holding back between 3-6 RPM's seemed to go fine then would hold back then go fine then hold back. I have altered the boost setting lower and nocked the timing down from 6 to 5 but still the same. Sometimes its fine though which makes me think it could be a coil pack on its way out? It drives spot on below 3 RPM's so could it be a issue with the turbo? Any feedback would be great.

[S3 Ed]

Just had a thought. I filled the tank (£62) last night and its the new fuel from Tesco's called Momentum 99. It started to play up a few miles after leaving the fuel station and it does run better now the settings have been lowered.

Anyone think it could be dodgy fuel? Just it seems to run perfectly not under load.

[Sunglasses Ron]

Come on tech boys, we need your help on this one.. 
I was in the car with Ed yesterday and it isn't a general holding back like when you have the settings set to high. It's a very fast intermitent series of pauses through the revs (like 4 or 5 times each gear) and seems to do it more when in the lower gears..  I don't think it's anything to do with the Revo settings as we have lowered them to B7 T5 F8 and still exactly the same and it has been running fine on higher settings for a while now.

I'm a bit baffled anyway and until we can gain access to VAGCOM we thought we'd ask you chaps..

[KRL]

Very difficult say without VCDS.

If the problem started straight after filling up with the Tesco fuel then that would be the logical candidate.  With VCDS you would see lots of timing pull if it is bad fuel.


My other thought from your description is misfires so I would be checking plugs and and coils.

Post up what you see with VCDS.

[Sunglasses Ron]

Cheers Kristiian  Misfires would be a logical suggestion mate, your right. Especially as there have been other who have had the same problem. Can this start straight at any point though, as he has been mapped for well over a year now and been stage 2+ for about 6 months.. 

[S3 Ed]

I'm going to ring Audi up tommorrow and get them to look at it, still under warranty til next month and they seem to be good when it comes to warranty claims (had steering rack, air con comp and both seat bases done in last 7 months with all mods on) The stuff i've had replaced all have been things that my mods shouldn't effect anyway so they might spit their dummies out with this one due to the engine mods my car has. I work in the car trade myself so i'd say that they might do it if its a common fault.

The more I drive it the more I think it is the coil or coils, I sell loads where I work and it seems to be a problem on all new engines, coils on petrols and EGR valves on diesels.

[KRL]

Can this start straight at any point though, as he has been mapped for well over a year now and been stage 2+ for about 6 months.. 

Yes can happen at any time whether you are mapped or not

[Top Cat]

My guess would have been coil packs. 

[Sunglasses Ron]

Quick update regarding Ed's car. Car has been in to Audi today and after being plugged in, it has returned with no faults.   This would indicate that it pretty much has to be the fuel he put in at Tesco's last Friday, as it started straight after that...
Not good, as it's the same Tescos I have used for years..  

[Top Cat]

There have been a few cars on here Ben were the coil pack faults havn't shown up in VCDS as well. 

[Sunglasses Ron]

There have been a few cars on here Ben were the coil pack faults havn't shown up in VCDS as well. 

Really? So what would you recommend him do mate?  He only has about 80 miles worth of this fuel left and will try some V power to see if that helps. But if it doesn't, how do you diagnose a knackered coil pack?

[gazbutS3]

There have been a few cars on here Ben were the coil pack faults havn't shown up in VCDS as well. 

Really? So what would you recommend him do mate?  He only has about 80 miles worth of this fuel left and will try some V power to see if that helps. But if it doesn't, how do you diagnose a knackered coil pack?

You need a known good coil pack really and swap it into each position 1 at a time and try it each time and see if the problem persists

[Saint Steve]

Come on tech boys, we need your help on this one.. 
I was in the car with Ed yesterday and it isn't a general holding back like when you have the settings set to high. It's a very fast intermitent series of pauses through the revs (like 4 or 5 times each gear) and seems to do it more when in the lower gears..  I don't think it's anything to do with the Revo settings as we have lowered them to B7 T5 F8 and still exactly the same and it has been running fine on higher settings for a while now.

I'm a bit baffled anyway and until we can gain access to VAGCOM we thought we'd ask you chaps..

Traction control on ben??

[Sunglasses Ron]

Well, just put a full tank of V power in her and the problem seems to be near enough gone already even after a few miles. So looks like it's Tesco's new fuel which isn't good.. 

[S3 Ed]

Seems to be ok now, hopefully it'll get better when I've ran this tank out, still probably had a gallon or so left it the tank so its still messing around a little. Got some new plugs also so will bang them in after this tank has gone through. Not ever going to Tesco again, V power all the way.