AFR what am i looking for?

[Dan s3 audi]

Hi

Well i brought myself a PLX wideband afr gauge the other day just as i have the crap ecu that wont give me no warnings for a lot of things so i thought its best to be safe than sorry. So i am going to be fitting this item tomorrow if its dry, but my question is what should i be looking out for figure wise? for example full on throttle and boost what reading would you consider safe?

Cheers

 

[jonno123]

when crusing off boost 14.7 afr

when coming onto boost a few psi (2-3 psi) around 13.7-13.5 afr

when on big boost full throttel say 21 psi 12-11.5 afr

all depends on air temps, egt ,

 

[Dan s3 audi]

when crusing off boost 14.7 afr

when coming onto boost a few psi (2-3 psi) around 13.7-13.5 afr

when on big boost full throttel say 21 psi 12-11.5 afr


all depends on air temps, egt ,

Thanks for that info, so basicaly if i say go full throttle and its above 12 its running to lean ?

Cheers

 

[<tuffty/>]

Assuming you have an APY S3 then these run very rich as std... can go into the 10's even when mapped.... the above would be an ideal tuned but in reality is not likely to be that on yours so I wouldn't get too upset if your actual figures are not the above...

14.7 afr is lambda 1 which is deemed to be the most economic afr to run, any figure above that is lean and any figure below that is richer...

<tuffty/>

 

[<tuffty/>]

Thanks for that info, so basicaly if i say go full throttle and its above 12 its running to lean ?

Cheers

not really... if its running over 14.7 under boost you have issues...... see my post above for what to expect...

<tuffty/>

 

[jonno123]

ive mapped mine to 12.5 afr on full throttle on my low boost map only running 5-7 psi

just depends on how much boost ur running

 

[Dan s3 audi]

not really... if its running over 14.7 under boost you have issues...... see my post above for what to expect...

<tuffty/>

Okay so if i am understanding this correctly, if i ever see it go above 14.7 under boost i have a problem somewhere along the line. I will be going back up too bills soon once i get myself some new injectors as i think he said my standard injectors were maxed at 305bhp, my fuel pump must have been struggering as i was running the 4bar reg and i went to change the fuel filter a few weeks ago to fined it was soo blocked i could hardly blow through it. I decided against going for the water meth kit i just worry that its something else that could go wrong, resulting in a poor head lol.

 

[Dan s3 audi]

ive mapped mine to 12.5 afr on full throttle on my low boost map only running 5-7 psi

just depends on how much boost ur running

Its running top's 20 psi but stays around 18psi mark.

 

[jonno123]

id be looking at that boost for low 12 to 11.5

 

[<tuffty/>]

ive mapped mine to 12.5 afr on full throttle on my low boost map only running 5-7 psi

just depends on how much boost ur running

Key word here mate, you have mapped... assuming the OP's car is std or even fairly generically mapped then from experience APY's won't run ideal AFR all the time... for a start they run very rich as std under boost as K04's turbo'd engines run hot... they have EGT protection of sorts from calculated EGT's but every one I have seen run on the dyno just seems to go straight in there and run to 11's at peak revs...

Later wideband S3's with EGT probes run a different fuel strategy and I have mapped mine along the same lines as you have... 12.5afr on boost with my EGT protection maps running richer than thatso as EGT's increase then afr runs richer as ME7 is set up for this...

Generally speaking 12.5 afr is best power and 13.5 afr is best torque but as revs rise and heat increases then afr needs to be richer to help keep the cylinders cool...

Point I am trying to make is while the figures discussed here are 'ideal' ones, in context of the OP's current setup I wouldn't want to worry the guy unduly by suggesting he should expect to see these values else he is in trouble...

<tuffty/>

 

[jay1601]

mine is 14.5 - 15.1 on idle and crusing.

when on boost will be around 10