AIR / FUEL ratio...issue..

[rs200]

hy.
yesterday I finally get wide band lambda sensor in my car..

and I think that running lean ..
at idle (hot engine) 14.10-14.80..
normal drive 16.05-14.50 , than slowly accelerating from 2k - 4.5k rpm (low boost 0.1-0.4bar) and values where 14.80-13.09.
at WOT ,full boost ,first 15.40 ,13.30 , and in one moment at 6000rpm 12.30..
I think that is lean..
what can cause that problem , and how to fix that..


can you please tell us how is on your car, that I can compare with my car..


thanks

[prj]

Uhm, it would be nice if you would take some logs.
Not write what numbers you see...

Also, comparing these values between cars is pretty useless. It depends on many things - IAT, fuel quality, coolant temp to name a few.

[willg54]

14.7 would be stoichiometric. under that would be rich, over that would be lean.

[prj]

14.7 would be stoichiometric. under that would be rich, over that would be lean.

[Rocco]

with WOT we need 11 to 12.3 (more or less) with normal 98 ron fuel..as a base

14.7AFR with WOT will destroy the car

[willg54]

was just stating how to define lean and rich! realise at WOT 14.7 would destroy it!

[prj]

was just stating how to define lean and rich! realise at WOT 14.7 would destroy it!

Yeah, that's how a narrowband sensor sees it, not how it is used when describing mapping an engine though.

[willg54]

Yeah, that's how a narrowband sensor sees it, not how it is used when describing mapping an engine though.

please educate us...how is it used when mapping an engine?

[prj]

please educate us...how is it used when mapping an engine?

By your logic an engine always runs rich.
In the current context "rich" is meant as "too rich" and "lean" is meant as "too lean".
Maybe that makes sense to you.

Example:
Running 10 AFR under 1 bar boost would be referred to as running rich, running 14 under the same condition would be referred to as running lean.

[willg54]

By your logic an engine always runs rich.
In the current context "rich" is meant as "too rich" and "lean" is meant as "too lean".
Maybe that makes sense to you.

Example:
Running 10 AFR under 1 bar boost would be referred to as running rich, running 14 under the same condition would be referred to as running lean.

Our formula student defo runs lean on a lean map >14.7. we use lambda more so tend to map for 1.05 lambda for lean. all varies through the rpm and throttle % to get the BMEP we want. rest of the time we're at 0.88-0.9

so basically you're saying you refer to lean and rich around the 'ideal' AFR of the rpm/boost/throttle site?

sorry for hi-jacking the thread

[prj]

so basically you're saying you refer to lean and rich around the 'ideal' AFR of the rpm/boost/throttle site?

Exactly. This is how it is referred to most of the time when tuning...
Really, just replace your definitions of "rich" and "lean" with "too rich" and "too lean" and you'll arrive at the same point.
"Ideal" AFR does not really exist though... too many variables, but that's nitpicking.

[willg54]

Exactly. This is how it is referred to most of the time when tuning...
Really, just replace your definitions of "rich" and "lean" with "too rich" and "too lean" and you'll arrive at the same point.
"Ideal" AFR does not really exist though... too many variables, but that's nitpicking.

Cheers

[rs200]

one stupid question .. I'm NEW in that..

what is 0.89, 0.90, 1.05 lambda? 14.7 is 1.00 lambda , and under it or upper is AFR in % ? or ?
thanks..

[willg54]

Lambda is Actual AFR / Stoichiometric AFR

[prj]

Lambda is AFR divided by Stoichometric AFR.
Because stoichometric AFR is different for different types of fuels, it makes more sense to actually note lambda.

For example the Stoichometric AFR for gasoline is around 14.7. For E85 it is around 9.8.