Correct AFR

[S2central.net]

If coils from another (known good) car made no difference then rout cause of any misfire must be in the POS / BIM or the ECU itself - unless you have a wiring / earth issue between ECU and POS/BIMs... Have you tried swapping BIMs or ECU with a healthy car ?

I only suggest those methods as most cost and time effective way of component replacement that could help root cause this one.

As long as you do things in a logical sequence and take good notes of any different behaviour you should be golden.

There are only six things at play here...

0. mechanical timing (correct phasing of camshafts to pistons via timing marks and toothed belt)
1. air measurement
2. fuel delivery
3. spark generation
4. ECU software (which encompasses all the various sensor inputs and timing of course)
5. The wiring which links it all together

I would stick with OE software while you are fault finding to rule out one massive variable (especially as source of chips is unclear)

[HMS-S6]

I do not believe you have any issues with fuel pressure or MAF.

Can i get the Coil kit in the UK?

[S2central.net]

As per this - http://forums.quattroworld.com/s4s6/msgs/22623.phtml

You are looking for more than 650cc delivered with the pump held on for 15seconds and 12V at the pump... best done with a relay jumper in the fusebox - look at the graph in the link above.

[HMS-S6]

On the S6 - the correct fuel pressure is 4bar +/- boost/vacuum... so you would see 3.5bar at 0.5bar vacuum and 5bar at 1bar boost.

BUT - have you actually checked the fuel FLOW rate from the pump - its easy on the S6 as access to the lines is more user friendly.

prj has a valid point too on the coils... easy to check/replace with a 2nd car alongside before gambling on new set of COPs etc

I'll double check that pressure.

How do i check the flow and what is the correct value?

[HMS-S6]

I do not believe you have any issues with fuel pressure or MAF.

Dmitri, Would you take a punt at coil conversion kit if you were me?

[HMS-S6]

Dmitri, No, its pretty **** when cold too mate, just gets WORSE when its warm! I have tried a second set of coils from a car that ran perfectly and it made no difference though.

Is there and way i can determine whether its a fueling or ignation problem?

[S2central.net]

On the S6 - the correct fuel pressure is 4bar +/- boost/vacuum... so you would see 3.5bar at 0.5bar vacuum and 5bar at 1bar boost.

BUT - have you actually checked the fuel FLOW rate from the pump - its easy on the S6 as access to the lines is more user friendly.

prj has a valid point too on the coils... easy to check/replace with a 2nd car alongside before gambling on new set of COPs etc

[prj]

I do not believe you have any issues with fuel pressure or MAF.

[HMS-S6]

Ive had a fuel pressure gauge on there before and its reads exactly what id been advised it should on here (3bar plus boost??). Maf, i have tried three but now the boost leks are cured i may try another again.

[prj]

Dmitri, Just refitted the stock ecu to my car and went for a run with the AFR rigged up. As it comes 'on' at around 3000 rpm (1bar) the AFR goes to 13-13.2 as it is hessitating, as it clears at around 4,500-5000 rpm at goes to high 11's-low 12's. Would you say that its lean running causing my issues?

Sounds like you have a misfire there where it is hesitating. Misfire always shows as lean on the AFR gauge.
Also stock software does not run 11's anywhere, it should be 12 or up.

Btw, if it's fine from cold and then gets bad when hot, then it sounds very much like the coils at fault. When the coils start going, they start first misfiring when hot under peak torque.

What coils did you have again? Maybe time to order a plug and play coil loom from efiexpress.com?

[S2central.net]

Also worth trying a 2nd MAF to see if you get same behaviour !

[S2central.net]

Dmitri, Just refitted the stock ecu to my car and went for a run with the AFR rigged up. As it comes 'on' at around 3000 rpm (1bar) the AFR goes to 13-13.2 as it is hessitating, as it clears at around 4,500-5000 rpm at goes to high 11's-low 12's. Would you say that its lean running causing my issues?

Sounds lean to me... have you checked fuel pressure regulator and actual fuel flow capability from the pump ?

[HMS-S6]

http://www.youtube.com/watch?v=u-10I-yIGHc

a slowmo log of the stock ecu in 3rd

[HMS-S6]

Afr

It seems the mapped ECU aggravates the problem even more. At idle the stock ecu gives a figure of 14.5 and the mapped one 16.2!!

[HMS-S6]

Dmitri, Just refitted the stock ecu to my car and went for a run with the AFR rigged up. As it comes 'on' at around 3000 rpm (1bar) the AFR goes to 13-13.2 as it is hessitating, as it clears at around 4,500-5000 rpm at goes to high 11's-low 12's. Would you say that its lean running causing my issues?