Inconsistent lambda readings between runs

[MichaelR32GTR]

I asked a while back how to go afew points richer in lambda, 

I made minor changes to the afr target table, but I noticed I’m getting different readings each run,

 

first run will show 0.77 lambda from full boost, then as revs climb will end up going 0.76 and then 0.75

even though afr target is 0.79

 

second run will show 0.795 at full boost down to 0.77 up top

 

any reason why it’s going so far off afr target values ?

ps I have not touched VE table as I just wanted to go slightly richer 

 

should the afr target table have MGP on the axis table or MAP ?

[Confused]

What lambda sensor/controller do you have?

A friend had an AEM, connected via analogue, and what the ECU saw compared to what the gauge itself was displaying varied massively from one minute to the next.

Replaced it with a Link CAN Lambda, repeatable results all the time.

[Adamw]

11 hours ago, MichaelR32GTR said:

any reason why it’s going so far off afr target values ?

I wouldnt call 0.02lambda "so far off".  That's about as good as most tuners would even strive for.  

There are a huge amount of variables, one confused has mentioned, there is also fuel temp, charge temp, turbine temp etc.

[MichaelR32GTR]

14 hours ago, Confused said:

What lambda sensor/controller do you have?

A friend had an AEM, connected via analogue, and what the ECU saw compared to what the gauge itself was displaying varied massively from one minute to the next.

Replaced it with a Link CAN Lambda, repeatable results all the time.

I run the onboard lambda in my link fury 

8 hours ago, Adamw said:

I wouldnt call 0.02lambda "so far off".  That's about as good as most tuners would even strive for.  

There are a huge amount of variables, one confused has mentioned, there is also fuel temp, charge temp, turbine temp etc.

So targeting 0.79 lambda and it falling down to 0.75 or 0.74 lambda is perfectly normal

 

in regards to that, would there be any issues running that rich in the top end on e85 ? Doesn’t misfire as is 

[Adamw]

22 hours ago, MichaelR32GTR said:

So targeting 0.79 lambda and it falling down to 0.75 or 0.74 lambda is perfectly normal

I wouldnt say perfectly normal, but certainly not uncommon and I see a lot worse daily.  It can take a lot of time to get the various compensations dailed in to cover all operating conditions and most dont care - as long as its safe and not misfiring...

 

22 hours ago, MichaelR32GTR said:

would there be any issues running that rich in the top end on e85 ? Doesn’t misfire as is 

    Not at all.

[k4nnon]

Just to add a little "make you feel better" info. Working in lambda is a learning curve if you are used to a normal AFR reading. .75 to .80 lambda are perfect AFR values for gasoline and E85. the difference between your .75 and .80 lambda are only 11.2 and 11.75 AFR on the gas scale and 7.3 and 7.8 AFR on the E85 scale. Anywhere within these areas is considered best safe for power afr.