open loop f/a vs coolant temp
05-31-2005, 08:08 PM
#1
open loop f/a vs coolant temp how should i go about adjusting this table so my car isnt really rich on cold starts? car is burning too much fuel in open loop and it about maxing out my IAC counts and its really weird until it starts to hit closed loop. plus the idle trims are adding a lot more air so im assuming im running really rich.
06-01-2005, 07:32 AM
#3
Man, you and I must think along the same wavelength. If you have the VE in line, wouldn't you just be able to screw with this table and tell it to command something leaner? I would think the car is only listening to the VE table on a cold start...
06-01-2005, 07:51 AM
#4
The table represents the lambda ratio.....or the ratio difference between the commanded a/f ratio and the stoich. a/f ratio.
To determine what a/f ratio your car is commanding with the OL/AF table just devide 14.7 by the value on the table.
14.7 / (value in OL AF table)
ie
14.7 / 1.13 = 13.00
To lean the car out decrease the value for the coolant temperatures in which the car is having the rich condition.
This table is referenced any time the vehicle is in open loop operation (unplugged O2 sensors, cold/warm starts, Power enrichment......kinda).
To determine what a/f ratio your car is commanding with the OL/AF table just devide 14.7 by the value on the table.
14.7 / (value in OL AF table)
ie
14.7 / 1.13 = 13.00
To lean the car out decrease the value for the coolant temperatures in which the car is having the rich condition.
This table is referenced any time the vehicle is in open loop operation (unplugged O2 sensors, cold/warm starts, Power enrichment......kinda).
06-01-2005, 03:46 PM
#6
yeah im gonna try to get a wide band too but right now i think im going to set my idle and low map areas closer to 1 so it wouldnt be so rich. with the cam in there right now i am running about 12.3:1 at idle where as before it was more like 14.2:1 and im gonna see how that works out. should save me on some gas too
i notice when the car is hot it doesnt use much gas but open loop starts i see the needle drop the most
i notice when the car is hot it doesnt use much gas but open loop starts i see the needle drop the most
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06-01-2005, 05:25 PM
#8
well the ve table is good, closed loop the fuel trims are actually a little on the lean side. but the way that the open loop f/a table was is reeeeeeeeeeeeeeeally rich. just started it up and the pulse width on the injectors went down and it seems smoother and not so much gas is burning
06-01-2005, 06:42 PM
#9
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Couple of problems.
One is, who knows what the car really wants for
mixture when cold? I think here you just have to
back into it, drivability / startability based until you
find where it starts not to like going leaner, and
then back out.
Two, you have a situation where you are grossly
over-enriched. This makes the engine even less
efficient at idle, needing more air and raising MAP,
making for more enrichment, positive feedback. As
you lower the enrichment the MAP will come down.
Back in the old days one school of shade tree thought
was, you should tune idle mixture for the highest
vacuum gauge reading (lowest MAP). This is probably
not a bad way to go. Problem is in getting any much
cold idle time. But log idle MAP and ECT every morning
right after you knock the OLFA, cold part of the table
down by 0.95X per day, and you should shortly find
a minimum MAP curve (clip and scatter-plot MAP vs
ECT at idle as you slide through warmup). You can
then pick from the best result, the table scaler you
should have stuck with. If the lines cross that would
tell you to borrow some from one table and some from
another, whichever produces the lowest MAP and the
happiest motor.
Note that this table also likely supersedes PE vs RPM
if you have a habit of getting on it, cold, so your limit
to leaning out may come from cold ping rather than idle
quality. It's just unfortunate that big cams elevate idle
MAP into the area where you also need enrichment for
high actual cylinder pressures, at higher rpm. There
you would have to compromise in favor of power I
expect, but you might as well set about finding the
line, and see how much improvement you can stand.
One is, who knows what the car really wants for
mixture when cold? I think here you just have to
back into it, drivability / startability based until you
find where it starts not to like going leaner, and
then back out.
Two, you have a situation where you are grossly
over-enriched. This makes the engine even less
efficient at idle, needing more air and raising MAP,
making for more enrichment, positive feedback. As
you lower the enrichment the MAP will come down.
Back in the old days one school of shade tree thought
was, you should tune idle mixture for the highest
vacuum gauge reading (lowest MAP). This is probably
not a bad way to go. Problem is in getting any much
cold idle time. But log idle MAP and ECT every morning
right after you knock the OLFA, cold part of the table
down by 0.95X per day, and you should shortly find
a minimum MAP curve (clip and scatter-plot MAP vs
ECT at idle as you slide through warmup). You can
then pick from the best result, the table scaler you
should have stuck with. If the lines cross that would
tell you to borrow some from one table and some from
another, whichever produces the lowest MAP and the
happiest motor.
Note that this table also likely supersedes PE vs RPM
if you have a habit of getting on it, cold, so your limit
to leaning out may come from cold ping rather than idle
quality. It's just unfortunate that big cams elevate idle
MAP into the area where you also need enrichment for
high actual cylinder pressures, at higher rpm. There
you would have to compromise in favor of power I
expect, but you might as well set about finding the
line, and see how much improvement you can stand.
06-01-2005, 07:32 PM
#10
Originally Posted by NoGo
The table represents the lambda ratio.....or the ratio difference between the commanded a/f ratio and the stoich. a/f ratio.
To determine what a/f ratio your car is commanding with the OL/AF table just devide 14.7 by the value on the table.
14.7 / (value in OL AF table)
ie
14.7 / 1.13 = 13.00
To lean the car out decrease the value for the coolant temperatures in which the car is having the rich condition.
This table is referenced any time the vehicle is in open loop operation (unplugged O2 sensors, cold/warm starts, Power enrichment......kinda).
To determine what a/f ratio your car is commanding with the OL/AF table just devide 14.7 by the value on the table.
14.7 / (value in OL AF table)
ie
14.7 / 1.13 = 13.00
To lean the car out decrease the value for the coolant temperatures in which the car is having the rich condition.
This table is referenced any time the vehicle is in open loop operation (unplugged O2 sensors, cold/warm starts, Power enrichment......kinda).
06-01-2005, 07:44 PM
#11
Originally Posted by jimmyblue
Couple of problems.
One is, who knows what the car really wants for
mixture when cold? I think here you just have to
back into it, drivability / startability based until you
find where it starts not to like going leaner, and
then back out.
Two, you have a situation where you are grossly
over-enriched. This makes the engine even less
efficient at idle, needing more air and raising MAP,
making for more enrichment, positive feedback. As
you lower the enrichment the MAP will come down.
Back in the old days one school of shade tree thought
was, you should tune idle mixture for the highest
vacuum gauge reading (lowest MAP). This is probably
not a bad way to go. Problem is in getting any much
cold idle time. But log idle MAP and ECT every morning
right after you knock the OLFA, cold part of the table
down by 0.95X per day, and you should shortly find
a minimum MAP curve (clip and scatter-plot MAP vs
ECT at idle as you slide through warmup). You can
then pick from the best result, the table scaler you
should have stuck with. If the lines cross that would
tell you to borrow some from one table and some from
another, whichever produces the lowest MAP and the
happiest motor.
Note that this table also likely supersedes PE vs RPM
if you have a habit of getting on it, cold, so your limit
to leaning out may come from cold ping rather than idle
quality. It's just unfortunate that big cams elevate idle
MAP into the area where you also need enrichment for
high actual cylinder pressures, at higher rpm. There
you would have to compromise in favor of power I
expect, but you might as well set about finding the
line, and see how much improvement you can stand.
One is, who knows what the car really wants for
mixture when cold? I think here you just have to
back into it, drivability / startability based until you
find where it starts not to like going leaner, and
then back out.
Two, you have a situation where you are grossly
over-enriched. This makes the engine even less
efficient at idle, needing more air and raising MAP,
making for more enrichment, positive feedback. As
you lower the enrichment the MAP will come down.
Back in the old days one school of shade tree thought
was, you should tune idle mixture for the highest
vacuum gauge reading (lowest MAP). This is probably
not a bad way to go. Problem is in getting any much
cold idle time. But log idle MAP and ECT every morning
right after you knock the OLFA, cold part of the table
down by 0.95X per day, and you should shortly find
a minimum MAP curve (clip and scatter-plot MAP vs
ECT at idle as you slide through warmup). You can
then pick from the best result, the table scaler you
should have stuck with. If the lines cross that would
tell you to borrow some from one table and some from
another, whichever produces the lowest MAP and the
happiest motor.
Note that this table also likely supersedes PE vs RPM
if you have a habit of getting on it, cold, so your limit
to leaning out may come from cold ping rather than idle
quality. It's just unfortunate that big cams elevate idle
MAP into the area where you also need enrichment for
high actual cylinder pressures, at higher rpm. There
you would have to compromise in favor of power I
expect, but you might as well set about finding the
line, and see how much improvement you can stand.
so far i have just pulled out little bits to try and get the car leaner in the idle cells. it has worked but the map hasnt dropped off really at all, i didnt move it much, just closed to what the other stock idle was
i have the new hp tuners and i have my fuling cut back to 98% at 0% throttle and this really helps out with the fueling with the cam. i can tune the rest of my table at idle conditions and tune my idle issues out in the ve multiplier table.
now the pe table, doesnt that have a tps setting as well? so how would map play into that? does it have to meet those 2 conditions or what? how can i go about getting pe at the right times? also what would this have to do with cold start and running in open loop. im just a little confused by some of the things u said lol i get it but then i dont, im gonna try to reread it haha
thanks
06-02-2005, 07:33 AM
#13
Originally Posted by NoGo
The table represents the lambda ratio.....or the ratio difference between the commanded a/f ratio and the stoich. a/f ratio.
To determine what a/f ratio your car is commanding with the OL/AF table just devide 14.7 by the value on the table.
14.7 / (value in OL AF table)
ie
14.7 / 1.13 = 13.00
To lean the car out decrease the value for the coolant temperatures in which the car is having the rich condition.
This table is referenced any time the vehicle is in open loop operation (unplugged O2 sensors, cold/warm starts, Power enrichment......kinda).
To determine what a/f ratio your car is commanding with the OL/AF table just devide 14.7 by the value on the table.
14.7 / (value in OL AF table)
ie
14.7 / 1.13 = 13.00
To lean the car out decrease the value for the coolant temperatures in which the car is having the rich condition.
This table is referenced any time the vehicle is in open loop operation (unplugged O2 sensors, cold/warm starts, Power enrichment......kinda).
Sorry for the oversight.
