Stuttering and hesitant on full boost

[Rhod_S3]

Hi, I was hoping for some help with my S3 8L.

It's been suffering from hesitancy and has been stuttering on full boost, ESP light flashes on whilst it's happening. Initially I though the standard usual problems ie, MAF, coil packs. I unplugged the MAF and the problem was still happening so that ruled out a knackered MAF. I bought a new set of spark plugs with the intention of whipping the old ones out seeing if there was any remedy.

As I started to get at the Coil pack bolts I had a look at the hoses and found that one of them was almost totally split at the joint. I was hoping that someone could let me know which hoses this is. I am intent on getting some samco or forge hoses to add a but of future durability for these, but I'm not sure what hose it is exactly. I cleaned the hose and printed on it is "PA12< VW Spa"....Please see the pictures below and if anyone knows what the part number is for me to replace it I'd be extremely grateful.

For a very temporary / half fix for the problem I've ductaped as best i can and the problem seems to have been alleviated slightly but obviously I want to replace it ASAP.

Cheers

 

[Gizmo20VT]

That looks like one of the n249 lines, which would cause a boost leak as it controls your DV. Replace the hose or do a n249 delete. There is a DIY afaik in the stickes.

 

[Westy]

Split n249 hoses shouldn't make the EML flash though. Get a new set of coil packs, if this doesn't solve it then you may have cracked coil pack wiring. Though I'd still guess at coil packs as when I was getting misfires from cracked wiring the EML never flashed.

 

[daz-20vt]

yeh mine did this. it missed fired badly at the same time the engine light was flashing and it was a coil pack. had it happen twice in 4 weeks. both with identical symptoms.one coil pack on each time.

 

[Rhod_S3]

Hi gents,

Since patching up with the Gaffa tape, the problem seems to have alleviated a bit but still not running right. One thing that has changed since is the ESP light is no longer coming on. Before attempting to diagnose the coil packs I've ordered silicone hose and a T piece and going to attempt to bypass the N249 as suggested. I'll do this and if the problem still persists I'll start checking the coil packs, at least they'll be easier to get to without all the N249 malarkey in the way.

Will keep you posted once I've done the N249 bypass to let you know the results. Cheers

 

[Rhod_S3]

Ok, well I've done the N249 Bypass and that went ok, with the help of some guides (with good photos) on here...however the problem still persists.

I had one new Coil Pack, so went about swapping it out for each one and went for a drive after each swap and the problem is still there. I've read that the coil pack loom can become brittle after years of being exposed to heat and that they can be bought from the US for a reasonble price. Wondering if this is the problem. Although I'm doubtful as the problem only seems happen under full boost, which, if it was the loom, surely this would be an intermittent problem.


What about a clogged up fuel filter? Could this be a bit clogged, and when giving it some with the right foot the ECU's requested fuel amount is not what is actually being provided?

I've had a look for boost leaks but I can't seem to find any. I replaced a few hoses with silicone ones while i was bypassing the N249. I'm thinking it has to be an ignition problem, either a fueling issue or a boost leak issue.

I do have VAG COM, but will have to have another read on the guidies in the stickies to see how to log fueling and boost pressure.


Any ideas in the meantime would be very welcomed.

Cheers

 

[Westy]

I had the hesitation under full load only and it was the coil pack wiring. Only one way to find out and that's to check the wiring. If that is cracked and damaged you'll need 1 of these:

ECS Tuning Coilpack Wiring Loom Replacement - A3 (8L) - Audi - Shop By Car

and take a look here:

http://www.audi-sport.net/vb/a3-s3-...53-w3stys-progress-thread-34.html#post1726135

 

[Rhod_S3]

I had the hesitation under full load only and it was the coil pack wiring. Only one way to find out and that's to check the wiring. If that is cracked and damaged you'll need 1 of these:

ECS Tuning Coilpack Wiring Loom Replacement - A3 (8L) - Audi - Shop By Car

and take a look here:

http://www.audi-sport.net/vb/a3-s3-...53-w3stys-progress-thread-34.html#post1726135

Cheers for this Westy. Since i'm likely to be keeping the car 'forever' this is something that may as well be done as you mention it's only a matter of time before it becomes a problem. Mine is a W reg (2000) so is likely to be in the same state if not worse than yours was. Your diagrams and guide make it look pretty clear (good work!!) but the electrical side of things does daunt me a fair bit so may try and find someone a bit more competant than myself to do it.

Feel like I'm chasing my tail.

Cheers