so this weekend we were fooling around with my map trying to get my idle fixed. we ended up getting some of the maps confused, yadi yadi yada and ended up finding an untouched copy of the map. we put the new chip in and went for a test drive. the car seems to pull like usual, spins 2nd and 3rd hard. just for ***** we put it on the dyno - originally i made 323hp 270tq @12.5psi with a 11.8-12.2 a/f (4months ago). after reburning the map and going on a test drive i put it on the dyno .. 268hp 240tq @12psi with a 10.0-10.5 a/f. i have no freakin clue what happend .. the car still pulls just as hard - just don't understand the a/f changes. i guess its for the good!!

 

Temperature change can cause that Warmer air = less dense. You'll run a tad richer.

Was there a big temp difference when you dynoed?

 

like 60 degree winter day the first time .. this time prolly 85-90 degree humid rainy day.

 

that make a big difference, but i don't think that big.

 

anyone?

 

humid rainy day would make a pretty big difference. Rainy air is a LOT less dense

 

not 55HP worth of difference. the change in a/f was probably caused my the change in temp. a 10-15hp drop is not unusual to see with changing air temps as is 1pt of a/f also...but with 55hp your problem lies elsewhere. id say possibly a boost leak or the motor is on its way down compression-wise

 

i went from 11.0 in shreveport to a 12.5 in fort worth same week............ I think this is a common thing people overlook. Shouldn't your air intake temp sensor do some of the math and keep it close?

 

There is no sensor to measure humidity though. All that moisture in the air takes up space that could have been used for more Oxygen rich air to use. So going from a cool winter day(it's also usually very dry in winter to) to a hot and probably close to if not 100% humidity raining day could make a good size difference. so that with a half a psi less boost might have been the culprit or maybe your engine is taking a dump.