When is a tune absolutely needed?

Originally Posted by chrischhorn

i understand what you're saying and it makes sense. funny thing is you say maxed out A.k.a. running lean. My car with all my bolt ons was running so pig rich at points hitting 10.9:1 in the afrs. my car was straight up dumping fuel without a tune. my mpg was like 17-18 without the tune. got it leaned out to 13:1 afrs and my mpg is back up to low 20's and the pulls like a beast. Maybe my car is an oddball but without the tune i was running stupid rich and needed to lean it out bad!

Originally Posted by TerribleONE

super odd... glad its runnin good now!

Originally Posted by Sh0velMan

The engine will go into a 'mode' where it dumps fuel in open loop mode, if you add too many breathing mods without a tune.

The Nismo intakes (that I have) are one mod that if you put it on without a tune, it'll just go full rich, 10.5:1 or whatever the low threshold is on our O2 sensors. Even with their MAF spacers (which are just like the ones AAM includes in their intakes).

Strange, but I think it's a protection mechanism.

Originally Posted by jcosta79

I am going to keep this very simple (I have made other posts about this subject and I don't feel like re-writing everything again):

If your mod is anywhere between the MAF and the 02 sensors, you very likely need a tune.