a/f ratio leaner in lower gears?
Thread Starter
single digit dreamer
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From: omaha ne
a/f ratio leaner in lower gears? check this out
<img src="http://members.***.net/parish8/DSCN1158x.jpg" alt=" - " />
tried to really dial in my tune last night doing WOT blasts in 3rd loging and adjusting the PE vs rpm. i was able to get a more even ratio and am able to prety easily minipulate the a/f ratio in 3rd but look what it does in the first 2 gears <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> , any ides on why it is much leaner in 1st, and a little leaner in 2nd?
the only off the wall idea i can come up with is i have 50lb injectors and never adjusted the offset table. i had to tell the computer the injectors were smaller then they are to get the ltrims right. i really dont think this would be the problem though because the computer prety much asks for the same pulsewidth for the entire run. somewhere in the 16ms range.
<img src="http://members.***.net/parish8/DSCN1158x.jpg" alt=" - " />
tried to really dial in my tune last night doing WOT blasts in 3rd loging and adjusting the PE vs rpm. i was able to get a more even ratio and am able to prety easily minipulate the a/f ratio in 3rd but look what it does in the first 2 gears <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> , any ides on why it is much leaner in 1st, and a little leaner in 2nd?
the only off the wall idea i can come up with is i have 50lb injectors and never adjusted the offset table. i had to tell the computer the injectors were smaller then they are to get the ltrims right. i really dont think this would be the problem though because the computer prety much asks for the same pulsewidth for the entire run. somewhere in the 16ms range.
Thread Starter
single digit dreamer
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From: omaha ne
Re: a/f ratio leaner in lower gears? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Cal:
<strong> I thought the PCM adjusted the AFR slightly richer as the load increases. The load would be lighter in the lower gears. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">i agree the load would be a little less. if this is true anyone know a way to counter act this? i am too rich in 3rd and too lean in 1st.
<strong> I thought the PCM adjusted the AFR slightly richer as the load increases. The load would be lighter in the lower gears. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">i agree the load would be a little less. if this is true anyone know a way to counter act this? i am too rich in 3rd and too lean in 1st.
Re: a/f ratio leaner in lower gears? I think maybe this relates to how fast you are
running up through RPM. When you're running
up fast, the PCM is always a little bit behind
and maybe squirting a little less fuel than it
should, next time because its calculation is
based on this time (but airflow is higher).
I wonder if you ran up and held it at a fixed
RPM, if you'd see it settle at the same AFR
as the high-gear pull segment.
I think too that maybe this is one reason why
"they" say to do your pulls in 1:1 gear. And
also why "they" say that dyno tuning isn't
the same as track tuning (which exercises more
fast-ramp operation).
running up through RPM. When you're running
up fast, the PCM is always a little bit behind
and maybe squirting a little less fuel than it
should, next time because its calculation is
based on this time (but airflow is higher).
I wonder if you ran up and held it at a fixed
RPM, if you'd see it settle at the same AFR
as the high-gear pull segment.
I think too that maybe this is one reason why
"they" say to do your pulls in 1:1 gear. And
also why "they" say that dyno tuning isn't
the same as track tuning (which exercises more
fast-ramp operation).
Thread Starter
single digit dreamer
iTrader: (6)
Joined: Mar 2002
Posts: 9,757
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From: omaha ne
Re: a/f ratio leaner in lower gears? that sounds reasonable to me, this is a road test run just in case you didn't know, a full 1/4 mile run.
now, any ideas on how to fix it? if i lean out 3rd to 11.5 or so like i would like to 1st might just be waaay too lean.
now, any ideas on how to fix it? if i lean out 3rd to 11.5 or so like i would like to 1st might just be waaay too lean.
