Running Lean

[bentaw]

i had my car dyno'd at JKM today and found it was running lean 13 over 1 if that means anything to anyone. What could cause a car to run lean i know the MAF is the main cause and i am changing this soon but what else apart from the MAF could it be

 

[Balf2k]

Lambda? You need to vag-com it mate, that will show up a faulty MAF.

 

[ans4r]

vag.com

 

[bentaw]

so i log airflow for maf which i aready know is low at 178g/s what do i log for lambda

 

[m0rk]

is it 178g/s now? not last week etc

that's still low though.

what's the air filter like? do you have a 4 bar FPR (check that it actually says 4 bar on it)

 

[bentaw]

yeah now and last week, air filter has done 1000miles bmc panel filter, dont have 4 bar as dont have stage 2 yet mark

 

[cuprablue]

Air leak in the induction will cause lean running. Dirty airfilter will usually cause rich running. partially blocked injectors can cause lean running also. Of course this is what I've experienced on motobikes which don't have complex ECU electronics measuring fuel mixture etc. I would guess that on a car with a MAF which determines the air flow in to the engine any leak after that point would cause lean running.

cuprablue

 

[bentaw]

here is my graph from that rolling road day

http://www.seatcupra.net/users/pabs/RR_Day/Results/BenLCR.gif

 

[bentaw]

not very smooth at all

 

[wild willy]

i had my car dyno'd at JKM today and found it was running lean 13 over 1 if that means anything to anyone. What could cause a car to run lean i know the MAF is the main cause and i am changing this soon but what else apart from the MAF could it be

I'm confused by this, as i interpret this as meaning 13 parts air to 1 part fuel. If this is the correct interpretation then this represents a rich mixture and not lean because rising above 14.7 : 1 represents going lean and falling below represents going rich.
This reading wouldn't concern me as running slightly rich under load is good.
Log lambda output with VAGcom and do a searchy to find out how.

 

[ibizacupra]

they would run richer than 13:1 on WOT normally.
what lambda is logged?

 

[bentaw]

http://www.seatcupra.net/users/pabs/RR_Day/Results/BenLCR2.gif

this is the graph they gave me showing my fuel/air mix

 

[virdi]

I think, what you are talking about here is Air/Fuel Ratio (AFR)

12:1 is usually optimum for max power....