Correct AFR

[HMS-S6]

Hi all,

I've finally dug my S6 out and fitted the wideband I bought for it over two years ago!
What figure would you typically expect on wot from 3,000 to 5,000 rpm?

[Jaswan]

out of curiosity what brand have you/did you go for?

thanks

[UrS4boy]

Hi all, I've finally dug my S6 out and fitted the wideband I bought for it over two years ago! What figure would you typically expect on wot from 3,000 to 5,000 rpm?

Hey there!! Long time no post? Hope things are good.

As for your question, my off the top answer was going to be an AFR of around 11. Here are some UrS AAN dyno results that back that up:

[HMS-S6]

Yeh, mines dipping to 10.8 or so on WOT so obviously not a fuel trim issue it would seem. Still edging for a hiding boost leak maybe!?

[twoqu]

http://www.s2forum.com/forum/showthread.php?t=68814&highlight=afr

[Rusty]

High 11s low 12s

[ineora]

Idle

Is that a correct value on idle too? On a stock non modified Engine?

[prj]

Depends on the software it's running.

Stock runs mid 12's on WOT, but there's hardly any boost.
Most power on these engines is at about lambda 0.8, which is 11.8 in AFR terms.
Of course on the top of the rev range, it makes sense to go richer for EGT control.

After about lambda 0.78 or 11.4 AFR you start massively losing power.

Idle should always be lambda 1, 14.7 for gasoline.

[ineora]

Right on startup, when the engine is cold, should it still be 14.7?

[EspenW]

Right on startup, when the engine is cold, should it still be 14.7?

14.7 when the sensor has warmed up and the ECU reads its signal. This takes a little while.

[Laaf]

Right on startup, when the engine is cold, should it still be 14.7?

As the ECU is running cold start enrichment then, no.

[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?

[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]

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

a slowmo log of the stock ecu in 3rd

[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 ?