I've got a supercharged b16a an aem wideband and a hondata s300. When I'm cruising the gauge shows around 16 or 17 air fuel but when I stop at a red light it shows around 13. When its showing lean I can give it gas and it will jump to about 14 then drop back to 16 or 17. The car has been tuned but another tuner looked at my tune and said that my tune was basically a basemap with all the fuel tables increased by 20 or 30%. If it was wouldn't my car run a little rich instead of lean. I'm just trying to make sure its the tune before I waste money on getting it tuned while it could be something else.

 

That's a normal idle and cruise af reading... you don't need a lot of fuel at idle nor at cruise. how do you think most cars get such good highway mpg? lean cruise af...

It's also normal to have a leaner than normer af if you give the throttle quick partial blips as there isn't enough load.

as for the rest it could be the tune. it could also be anything from a fuel or ignition system issue to a vacuum leak or bad o2 sensor.

The most important thing is what is the af in boost and wot? that's all that matters. the idle and part throttle fueling will always be very lean and fluctuate.

 

If it's in boost it shows around 15 or 16. My main relay is going bad could that be causing it to be lean in boost?

 

wow... Has the car always ran that lean since the tune?? Or is this a new problem?

 

It was tuned before I bought it and since I've had it it's ran lean.

 

dont boost your car!! with afr at 15-16 at fool boost and throttle, your engine is about to explod!!!

check fuel filter, then check your injectors, and if they are ok go to an expert that can remap your CPU...

dont go to the first chiptuner you find, do some research first...

remember, your afr is ok when at full throttle is about 11.5-12.5

 

How do I check my injectors.

 

you have to take m off and place them at a special machine that it cleans them also
usally the injectors must be checked each 80.000 miles, so if yours are new it is possible to be your bad ecu mapping, or a bad petrol filter...

is your engine stalling?

if yes it may be also the fuel pump, but this will be the last you will check after fuel filter, ecu mapping and injectors..