a/f ratio leaner in lower gears?
04-09-2003, 03:13 PM
#1
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.
04-09-2003, 04:45 PM
#3
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.
04-09-2003, 05:14 PM
#4
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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).
04-09-2003, 05:20 PM
#5
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.