S6 timing

[HMS-S6]

Hi. Thank you. Yes. It was also lifted off my good S6 before it went. I also had a new one somewhere. It really is though as if it's receiving an incorrect signal from the MAF but the MAF itself checks out ok and the female pins have just been renewed also. A value on vag com at WOT for that would also help me.

[twoqu]

Actually have you physically checked the Maf for being standard. I think some people have used the similiar looking early VR6 one which as I recall did effect the mixture by leaning it out.

[HMS-S6]

Would poor spark cause the same AFR reading? If so I need to rule that out first too.

[twoqu]

Agreed!
That would be the issue even if we had a comprehensive data logging capability unless they was enough accumulated data/wisdom to say otherwise. It does seem that the ecu is happy with the signals its receiving as there are no fault codes.
As the ecu is a virgin then that also rules out anybody having altered the R201 resistor which the RS2 SW uses which may have wreeked havoc on stock SW as it effects both mixture and timing.
I would think the only people who would know the 951 injector lag would be either Paul N or Dmitri. I agree it would be nice to confirm that the ecu is operating them correctly because if that is confirmed then it would add extra weight to the injectors somehow either a physical blockage in the filters or some sort of electromechanical detioration. Of course it doesen't explain why substition does not improve it.

[HMS-S6]

Yeh I agree. The ECU is totally Virgin. I'm not saying the ECU is at fault, I'm saying the same as you, somewhere the ECU is receiving the wrong info and not trying to fuel enough. However if that open time is normal for WOT I have to look elsewhere.

[twoqu]

Quite agree, wish I could help further! However if ecu is completely untouched, how likely is it that any of the SW that controls the injectors is corrupted? Besides which unfortunately we need some more data to interpret any logs.
Whereas how much more likely is it that a 20 year old electromechaical device has an issue. Even if it opens at the required rate we don't know for sure it is flowing the right amount for every squirt! So far we have determined that the fuel pressure and volume is adequate.
Considering what you have spent so far, for piece of mind, I would have a set cleaned and tested and KNOW they are OK.
Annoying I can only find the RS2 data not stock for the latency/lag/deadtime/offset as it is variously refered to!

[HMS-S6]

Yes by this I was trying to determine weather it was an injector CONTROL problem or not. Ie; is that the correct open time and fuel is not getting through or is the ECU not opening them enough.

[AndyP]

For what it costs I'd get them cleaned and flow checked on an ASNU machine.

[twoqu]

Here is an example from an RS2 injectors. You can see why you need some other data to get accurate figures. You would need the lag time of stock injectors which might be on here somewhere.

http://www.s2forum.com/forum/showpost.php?p=607149&postcount=35

Guess you could attempt to log the rpm/voltage/inj time and see whether that gives anybody a clue as too whether its ok. Us ordinary mortals have nothing to refer to.

[HMS-S6]

Anyone?

[twoqu]

Its not really a case of just swapping things out, for yours (and ours) sanity, we need to know definitively that they function correctly and flow the required rate. After all you have been thoroughly testing the rest of the fuel system to eliminate it.
The inj opening time is a valid question but unfortunately its not the type of data that is in the general domain. Perhaps one of the few people who know might chip in!

[HMS-S6]

I can swap them again but it was under a year I swapped them and BOTH cars performed just as they did before the swap. I'm not dismissing the suggestion but I would have thought if it's cure it now it would have then too.
What open time would you roughly expect to see for the injectors under WOT? Mind are showing 16-17m/s

[twoqu]

Well the injectors are the last part of the chain on the fuel side. It wouldn't hurt to elinimate them by getting them or a spare set cleaned and tested so that you know they are in spec. I know you have substituted them previously but anything we can comprehensively eliminate from our enquires would be useful.
Has the ecu ever been opened or is it a complete virgin?

[HMS-S6]

Ah. Not that then. I checked them on Friday and had perfect continuity. By rights this car should NOT be lean. I have good fuel pressure, and all vag-com readings are ideal for WOT

[UrS4boy]

Also while I'm checking stuff. Where do the ECU's grounds attatch to the body on the S6?

You're not listening. The ECU grounds are in the engine bay harness and are attached to the intake manifold.