AFR's at idle/light throttle

A

Animaldaz

Active Member
What are you guys getting at idle? I seem to be fairly lean (15-16ish) I cant see it being a problem as on boost fuelling seems to be fine im just interested to what others are seeing.
 
PobodY

PobodY

Moderators
Staff member
At idle aren't you on a closed-loop using the lambda sensor?
That will give you a different AFR from whatever you fuelling map is when you've actually got the throttles open.
 
Trip

Trip

New Member
I might not be of help here.

On N/A at idling with engine fully warm, it should play in the 14.7 region(stoichiometric). At light partial throttle while cruising, it will go to 15.5 for fuel economy. This data is from an F20C engine.

So i should assume that on a Turbo'ed engine, the AFR's should be slightly lower.
 
PobodY

PobodY

Moderators
Staff member
Depends what ECU your running. As I said, I think you're on a closed-loop but it's not uncommon to map a PFC to include the idle so that you don't need the lambda sensor (at least, I thought so anyway)... just as an example.
 
A

Animaldaz

Active Member
Thanks for the replies, im on the oe map and standard fuel system all be it with a walbro fitted. So im interested in what others with a similar set up (to which there must be alot) are seeing, and adding to my thread title what are you seeing throughout the rev range?
 
stumo

stumo

Active Member
I would have thought that anywhere between 14.7 and 16 on idle and cruise isn't going to cause any problems.
 
olliecast

olliecast

Active Member
IIRC the standard map has a closed loop section around idle. So via the sensor it should be aiming for stoic ~14.7afr.

Once out of that area, fuel wise line is set to richen up as the load increases. Think i`m seeing ~11 on full load. My timing is pretty reserved though (i`ll change when i can be arsed to spend a fortnight on the "private road / runway" with the lap top!).

ollie
 
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