new o2 sensor and a/f ratio
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Honda-Tech Member
Joined: Sep 2002
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From: gilbert, arizona, usa
new o2 sensor and a/f ratio
a few months back, i dyno tuned my vafc (no wideband o2). the hi-cam was tuned to around 5-8% across.. a couple weeks ago, i swapped out my o2 sensor for one sold at oxygensensors.com. no reason as to why i changed it other than i had over 95k on the stock one... the car was running awesome, together with an oil and sparkplug change, valve job, and coolant bypass, i almost gained 3 tenths and over 2mph in the quarter mile...
yesterday, i took the car to another dyno, this time with a wideband o2... to my surprise, (as well as everyone else who was there) we had to lean the fuel out with the vafc up to 18% at some points... my lowest point on the hi-cam side was 15%... with these settings i had solid gains across the band, and my a/f ratio stayed between 13.5 and 13.8... in lower rpm's (2k-3k) the ratio did run a bit lean into the low 14's
is this normal? should i worry? could these unusual settings be caused by the aftermarket 02 sensor??? and another thing, we did try out a couple things on the dyno...unplugging and corking the line that leads to the secondaries gains absolutely no hp anywhere... top (4.5k and up) hp remains identical while having a significant low end hp and torque loss... advancing my ignition timing yielded in hi rpm hp loss with a slight (im talking fractions of an hp) gain in the mid-range... actually the best numbers were gained with the ignition timing set at stock... who knows what high octane fuel would do, as far as gaining hp with ignition advanced...
with a wideband o2 sensor, i gained almost 6hp and 7hp in the midrange over the gains i had last tuning session... all gains were achieved through cam and vafc tunning... not bad, eh???
yesterday, i took the car to another dyno, this time with a wideband o2... to my surprise, (as well as everyone else who was there) we had to lean the fuel out with the vafc up to 18% at some points... my lowest point on the hi-cam side was 15%... with these settings i had solid gains across the band, and my a/f ratio stayed between 13.5 and 13.8... in lower rpm's (2k-3k) the ratio did run a bit lean into the low 14's
is this normal? should i worry? could these unusual settings be caused by the aftermarket 02 sensor??? and another thing, we did try out a couple things on the dyno...unplugging and corking the line that leads to the secondaries gains absolutely no hp anywhere... top (4.5k and up) hp remains identical while having a significant low end hp and torque loss... advancing my ignition timing yielded in hi rpm hp loss with a slight (im talking fractions of an hp) gain in the mid-range... actually the best numbers were gained with the ignition timing set at stock... who knows what high octane fuel would do, as far as gaining hp with ignition advanced...
with a wideband o2 sensor, i gained almost 6hp and 7hp in the midrange over the gains i had last tuning session... all gains were achieved through cam and vafc tunning... not bad, eh???
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Joined: Apr 2000
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From: Toronto, ON, Canada
Re: new o2 sensor and a/f ratio (ALTERED4)
That much correction with the VAFC is not unheard of and is fairly common. It's not something to worry about. The aftermarket O2 sensor may have a hand in causing the car to run slightly richer than normal.
The behaviour you saw with the secondaries has been known for a long time.
Thanks for the insight into your tuning session, it interesting to see what worked and didn't work for you.
The behaviour you saw with the secondaries has been known for a long time.
Thanks for the insight into your tuning session, it interesting to see what worked and didn't work for you.
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Westrock2000
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Feb 25, 2002 05:20 PM