LS1UltraZ

iTrader: (3)

Ok just did some WOT blasts with ATAP running. I monitored all the important stuff and this is how im running.
o2's: .90-.95V (It varied with each WOT run)

LTrims: 10.2% ( WTF i thought i should be around 0?) <img src="images/icons/mad.gif" border="0">

Timing Advance: 24-32deg. (stays within that range, just jumps around during run)

KR: 2.5deg max (only happened during once of three runs)

So I am glad KR is not a problem, however what is up with my Ltrims and should I tune for a leaner setup. I have an MAFT running at 4% rich at wot, so i should back it down a little? Not sure what the LTRIMS mean so fill me in!! Thanks guys.

Sean

kewlbrz

[quote]Originally posted by LS1UltraZ:
<strong>Ok just did some WOT blasts with ATAP running. I monitored all the important stuff and this is how im running.
o2's: .90-.95V (It varied with each WOT run)

LTrims: 10.2% ( WTF i thought i should be around 0?) <img src="images/icons/mad.gif" border="0">

Timing Advance: 24-32deg. (stays within that range, just jumps around during run)

KR: 2.5deg max (only happened during once of three runs)

So I am glad KR is not a problem, however what is up with my Ltrims and should I tune for a leaner setup. I have an MAFT running at 4% rich at wot, so i should back it down a little? Not sure what the LTRIMS mean so fill me in!! Thanks guys.

Sean</strong><hr></blockquote>

Were your LTrims + or - ?

Fuel Trims are registers that are updated via the PCM. The PCM gets feedback from the O2 sensors in closed loop (non WOT) mode. If the O2 Sensors detect that you are running rich or lean, a change is made either + or - in the fuel trims which is added real time to the base pulse width equation which is sent to the injectors.

The PCM does this to achieve a stociometric ratio of 14.7:1 air/fuel ratio at non WOT operation no matter what.

You should tune first with the maft using the BASE setting during non WOT runs. I personally like to tune at or near zero, erroring slightly to the positive side of Ltrims if necessary. Once you drive a WHOLE bunch to ensure everything is normalized, you will then do some WOT runs, and begin to monitor O2 sensors to fine tune WOT, and KR if any.

Your timing will be all over the place during non WOT operation. So ignore that then. During WOT it should level out somewhere in the upper 20's without KR.

-shawn

for more info see:

www.vetteguru.com/mods/howto

LS1UltraZ

iTrader: (3)

They are +10.2% during WOT. So i think that means it is compensating for a rich condition. Guess i should drop the WOT a few percent on the MAFT to correct it? I mean evetything else seems to be ok, so no harm will be done either way.. Thanks for the reply!

Sean

kewlbrz

[quote]Originally posted by LS1UltraZ:
<strong>They are +10.2% during WOT. So i think that means it is compensating for a rich condition. Guess i should drop the WOT a few percent on the MAFT to correct it? I mean evetything else seems to be ok, so no harm will be done either way.. Thanks for the reply!

Sean</strong><hr></blockquote>

Actually a postive shift in fuel trims is correcting for a lean condition that was previsouly picked up by the O2 sensors.

Remeber that its extremely important to tune BASE first while WOT is at 0 during non WOT driving.

Then fine tune WOT pot for WOT operation.

Rob98Z

Guys LTrims don't mean squat at WOT only during normal cruising (fuel cells 1-19).

Using a MAFT - first tune Base using fuel cells 1-19 on the LTrims, once you get your LTrims as close to 0 as you can then begin looking/working on your 02's at WOT (fuel cell 22 only). This is not something that you can just hop in your car and make a run and adjust one then move to the next, this takes some time to get the LTrims and 02's dialed in. It takes me at least 2-3 days to get a car tuned in with a MAFT. <img src="images/icons/wink.gif" border="0">

kewlbrz

[quote]Originally posted by Rob98Z:
<strong>Guys LTrims don't mean squat at WOT only during normal cruising (fuel cells 1-19).</strong><hr></blockquote>

is there an echo in here... hehe <img src="images/icons/wink.gif" border="0">