a/f richer in higher gears?
Thread Starter
Teching In
Joined: Mar 2006
Posts: 8
Likes: 0
a/f richer in higher gears? hi, i am fairly new with ls1 edit tuning and am trying to dial in a tune
that was done through mail from cartek racing. i have a 1999 c5 frc 6spd
with a head and cam package. mods include cartek stage two heads, 224/228 567 113lsa, headers with no cats and xpipe, ported throttle body,
granitelli mass air and other bolt on mods.
i live in montana and there are no shops or anyone who has any knowledge of tuning anything without a carburator. so i bought a wide band and ls1
edit. anyway the car runs fairly good i have been primarily tweaking wot
on the tune but am having a problem that may be easy to approach and
solve with a little help.
the problem is the tune air/fuel at wot is accurate in 1st and 2nd gear at
a reading of 12.6 afr but when i hit 3rd afr drops to 12.0 and 4th gear even
hits hi 11s afr. this is a 6spd car and it does have 4:10 gears, i dont think
this would effect it. i am assuming ve is correct based on 1st and 2nd are
correctly responding to my adjustments at wot, mostly pe table. i am thinking
maf frequencey may need tuning at higher frequencies because the only
changing factor i can this of is air temp at higher speeds. i would be glad to
email copy of tune for anyone to look at who can help or any suggestions to
point in the right direction would be awesome. i am new and any advice would be a great help. i have searched forum but cant find anything specific enough to help me so i included as much info as i could think of.
thanks for help,
xclr8ingc5
that was done through mail from cartek racing. i have a 1999 c5 frc 6spd
with a head and cam package. mods include cartek stage two heads, 224/228 567 113lsa, headers with no cats and xpipe, ported throttle body,
granitelli mass air and other bolt on mods.
i live in montana and there are no shops or anyone who has any knowledge of tuning anything without a carburator. so i bought a wide band and ls1
edit. anyway the car runs fairly good i have been primarily tweaking wot
on the tune but am having a problem that may be easy to approach and
solve with a little help.
the problem is the tune air/fuel at wot is accurate in 1st and 2nd gear at
a reading of 12.6 afr but when i hit 3rd afr drops to 12.0 and 4th gear even
hits hi 11s afr. this is a 6spd car and it does have 4:10 gears, i dont think
this would effect it. i am assuming ve is correct based on 1st and 2nd are
correctly responding to my adjustments at wot, mostly pe table. i am thinking
maf frequencey may need tuning at higher frequencies because the only
changing factor i can this of is air temp at higher speeds. i would be glad to
email copy of tune for anyone to look at who can help or any suggestions to
point in the right direction would be awesome. i am new and any advice would be a great help. i have searched forum but cant find anything specific enough to help me so i included as much info as i could think of.
thanks for help,
xclr8ingc5
Are you comparing AFR's for the exact same RPM range when you say it goes richer?
I guess considering you have a vette, make sure you watch on the data-logs that your throttle isn't closing on you for some reason.
Also verify your pulse-widths, manifold pressure, spark advance, and commanded AFR when comparing the same RPM range.
You my find something changing like a big drop in spark advance that would have the effect of making you richer.
I guess considering you have a vette, make sure you watch on the data-logs that your throttle isn't closing on you for some reason.
Also verify your pulse-widths, manifold pressure, spark advance, and commanded AFR when comparing the same RPM range.
You my find something changing like a big drop in spark advance that would have the effect of making you richer.
Check the things above, but I know what you are talking about. In my mind, a car should be tuned only using higher gears...it presents an accurate load on the engine that 1st and 2nd gears just can't do. If you think about it, you could theoretically tune your car without it even moving by just revving the engine...wouldn't be accurate though, would it? You can draw a parallel (at least I think) between that and tuning using only 1st and 2nd gears.
I can tune WOT doing a 2nd gear run, and I can tune it doing a 3rd gear run...doing the 3rd gear run is more accurate because it stays in the cells of the histogram longer, and is giving the engine a good load (i.e. not spinning the crap outta the tires).
Just revving the engine shows some lean values in the histogram, but it certainly ain't lean cruising in 5th gear.
I can tune WOT doing a 2nd gear run, and I can tune it doing a 3rd gear run...doing the 3rd gear run is more accurate because it stays in the cells of the histogram longer, and is giving the engine a good load (i.e. not spinning the crap outta the tires).
Just revving the engine shows some lean values in the histogram, but it certainly ain't lean cruising in 5th gear.
Maybe he's pumping the gas pedal during the shift into third.
I know exactly what you mean about the loading and the piston speed changing in the different gears though. He seems to be getting a fairly large change for whatever reason.
I know exactly what you mean about the loading and the piston speed changing in the different gears though. He seems to be getting a fairly large change for whatever reason.
The MAF is a slow instrument and this sounds to me like
airflow in lower gears (what with 4.10s, hot motor, etc.)
is changing too quickly for the MAF to track real-time.
That means the MAF airflow number will always be
"yesterday's news", lower by some amount than in-the-
moment real air (with less error, the slower you rise up
in RPM).
Look at the commanded AFR you log; does it resemble
more the 4th gear wideband result, or the 2nd gear?
airflow in lower gears (what with 4.10s, hot motor, etc.)
is changing too quickly for the MAF to track real-time.
That means the MAF airflow number will always be
"yesterday's news", lower by some amount than in-the-
moment real air (with less error, the slower you rise up
in RPM).
Look at the commanded AFR you log; does it resemble
more the 4th gear wideband result, or the 2nd gear?
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Teching In
Joined: Mar 2006
Posts: 8
Likes: 0
rpm range in gears i am comparing exact rpm ranges in all gears. i assume the is a load
difference in each gear and 3rd and 4th are more accurrate when tuning.
however 1st and 2nd are accurate to my wot settings. i will log above
and see if there is any spark drop as suggested. any other advice will
be helpful so please feel free to ask more questions about my tune if
it will help.
also it looks like my maf is not the main problem in my tune if little adjustment
is made there as stated above. do the map values change in the higher gears
do to air change? could they be correct in 1st and 2nd and off in third and
fourth? i am new and open to suggestions. i want to figure this out and
learn as much as possible.
thanks,
xclr8ingc5
difference in each gear and 3rd and 4th are more accurrate when tuning.
however 1st and 2nd are accurate to my wot settings. i will log above
and see if there is any spark drop as suggested. any other advice will
be helpful so please feel free to ask more questions about my tune if
it will help.
also it looks like my maf is not the main problem in my tune if little adjustment
is made there as stated above. do the map values change in the higher gears
do to air change? could they be correct in 1st and 2nd and off in third and
fourth? i am new and open to suggestions. i want to figure this out and
learn as much as possible.
thanks,
xclr8ingc5