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Discussion Starter · #1 ·
OK so I just started tuning my car,
first time.
here's the setup
jdm d15b vtec, allstock except exhaust, no cat.
cx d15b8 injectors(why i have to tune).
ostrich, lc1, crome

OK so here's the deal, when i'm cruising around at partial throttle, afr is at high 14's, which is cool, but when i give it LESS gas it immediately dips down to 11-12afr then dips back up.

so say i'm cruising at around 12hg, then drop the pedal back to 20hg real quick, i'll see a huge increase in fuel, EVEN THOUGH if I cruise at 20hg steadily at that same rpm, afr will be at a normal 14somethin.


so basically when I let off the gas completely, I see my afr curve drop WAY down, then jump WAY up(as injectors cut because i'm in gear).

any thoughts???

thanks!
 

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its normal.. just a slight delay with the ecu, still giving you the same amount of fuel fro 12hg for that first half second or so before the vacuum gets to 20hg. same fuel, less air, gonna run rich..
 

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Discussion Starter · #3 ·
ooh ok, i kinda had a sneaking suspicion thats what it was.

so basically if i've got my afr's correct while my throttle/vac is at a steady state, then I should be ok?
 

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by anychance, are u running open or closed loop? did u by anychance leave it clicked to open?

if you did, your car is running off the tables and not off the o2, so it might be causing you to run rich as you are.

-tony
 

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Discussion Starter · #5 ·
i have debug mode checked all the time,
but disable o2 sensor is not checked at the moment(been playing with this on/off but havent seen much diff.)

not entirely sure wut debug mode does, but I do know that I get a solid cel if I don't have it checked(doesn't flash a code just throws cel always)
 

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if the o2 sensor is disabled the youre running in closed loop, so you should be ok...which is weird, since it should auto-compensate itself...

have you been tuned or just self tuning little by little? datalog a 3rd gear pull from around 2500rpms to redline and see what your afr's are thru the power band, you might be running too rich in your part throttle.

your cruising/power afr's should be around 13.5 and 11.5-12.5 while in your boost colums. you are using a wideband, so atleast youre getting very accurate readings. and since you are supercharged, you create boost quite quick.

i havent tuned my D with crome (im just using a xenocron bin for now), im just applying concepts i have used tuning my own kpro...so i might not be 100% accurate as far as what each program can do...but they are very similar.

-tony
 

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If the O2 sensor is Disabled then he is running in Open Loop, When the O2 is Enabled he is in closed loop. Cruising at 13.5 afr's? that thing would suck gas so bad, cruise you want like 14.5-15.2 and Full Throttle you want 13.5
 

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If the O2 sensor is Disabled then he is running in Open Loop, When the O2 is Enabled he is in closed loop. Cruising at 13.5 afr's? that thing would suck gas so bad, cruise you want like 14.5-15.2 and Full Throttle you want 13.5
*edit* EG8SIR is correct on the open loop, my bad on the type-o

but if you read above, i put crusing/power (i actually meant going from crusing-to-power band) you want 13.5's and 12.5's or richer into boost...remember he is supercharged, so he creates boost pretty quick, and running lean for FI is not an option...

the number's you speak of are ok for an N/A...

*edit* hadnt read Tad switched or is using an n/a motor.

so yea, the most you should be at wot is 13.5 and at around 14.7 at part throttle.

-tony
 

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great info here by everybody .
 
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