Has anyone here heard of this one : I went to tune my AFR today and the dyno shop guy claimed that my air/fuel curve will be different in 3rd than 2nd...


... when I made my passes in 2nd gear I tuned around 12.3-12.5:1.. however when making some runs in 3rd, I hit 10:1 without changing anything .


Normal? I called bull$hit but then again I guess it's *possible*



And the results were pathetic : I was hitting everything from 220fwhp to 240fwhp... about 30fwhp off from what I had BEFORE the straight thru 2.5" exhaust/straightening the af curve/high stall TC. Torque was stuck at 220lbs-ft to the wheel as well. Very wrong....

 

Defientely not. The a/f ratio should be the same in every gear. You push the same amount of boost in any gear. But its still very odd to see the a/f drop in 3rd gear. Unless his gauge is completely off.

Dixit

 

could be the FMU's abality to react to the boost. On a longer pull it is exposed to a longer duration of boost pressure.

Hence, the FMU is c r a p!

 

Yeah I was wondering - gear has no relevance to mixture/throttle/airflow... the only difference between 2nd and 3rd is that the gear is longer..

Does anyone else with a Vortech FMU wanna try a 2nd and 3rd gear dyno to see what they get? I'm curious if this is a general FMU thing... if my FMU were defective beyond spec it shouldn't work at all.

I'm gonna have the data files from the dyno on wed or thurs hopefully (just the a/f portion however - it was logged individually on a laptop at the shop)... I'll ask Vortech about it and see what they tell me.


PS. I'd like that dyno shop to explain to me how 240hp/220lbs-ft gets me a 14.5 on a 2000 SE with heavy 17"'s, full car, running smoldering hot after a 1.5 hour drive at 80+mph...they maintain that all their corrections are properly done, except everyone lost 15+hp MINIMUM today... FEH!