Open Loop Question
10-24-2004, 06:00 PM
#1
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Open Loop Question Hey everyone. I posted this in the truck section with no luck. Hope you all can help.
Ever since I put on the supercharger i've had trouble with open loop. Sometimes it hesitates and stumbles when moving from a stop when the engine is cold and hasn't reached operating temps yet. It does not do this in closed loop (which is why I don't think it's a fuel pump or fuel pressure problem) and never did this before the supercharger. Anyone have any ideas? Should the egr be open or closed during open loop? I'm asking this because I once got an insufficient egr flow code thrown, so maybe the valve gets stuck closed sometimes. This problem occurred with the original superchips programmer that came with the kit and is still there with Allen Nelson's tune. I'm totally stumped since I don't have any scanning stuff and it only does this some days. The last thing I can think of is maybe it's trying to go into closed loop too soon (I have a 160° thermostat)???
Ever since I put on the supercharger i've had trouble with open loop. Sometimes it hesitates and stumbles when moving from a stop when the engine is cold and hasn't reached operating temps yet. It does not do this in closed loop (which is why I don't think it's a fuel pump or fuel pressure problem) and never did this before the supercharger. Anyone have any ideas? Should the egr be open or closed during open loop? I'm asking this because I once got an insufficient egr flow code thrown, so maybe the valve gets stuck closed sometimes. This problem occurred with the original superchips programmer that came with the kit and is still there with Allen Nelson's tune. I'm totally stumped since I don't have any scanning stuff and it only does this some days. The last thing I can think of is maybe it's trying to go into closed loop too soon (I have a 160° thermostat)???
10-25-2004, 04:42 PM
#3
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Originally Posted by Slowhawk
Are you sure the fuel pressure is constant?Also make sure the bypass valve on the driver side of the blower moves freely.
10-25-2004, 05:13 PM
#4
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Thermostat action happens well after closed loop
threshold (94F, stock). The open loop vs ECT tables
do command some piggy richness when cold and at
high MAP. Which you would expect a supercharger
to produce. No telling what your various tunes have
done there.
threshold (94F, stock). The open loop vs ECT tables
do command some piggy richness when cold and at
high MAP. Which you would expect a supercharger
to produce. No telling what your various tunes have
done there.
10-27-2004, 04:34 PM
#5
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Originally Posted by jimmyblue
Thermostat action happens well after closed loop
threshold (94F, stock). The open loop vs ECT tables
do command some piggy richness when cold and at
high MAP. Which you would expect a supercharger
to produce. No telling what your various tunes have
done there.
threshold (94F, stock). The open loop vs ECT tables
do command some piggy richness when cold and at
high MAP. Which you would expect a supercharger
to produce. No telling what your various tunes have
done there.
10-27-2004, 05:32 PM
#6
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Open Loop Fuel/Air vs ECT vs MAP is the table. There is
a pretty abrupt swing from small enrichment to 1.3
fuel/air multipliers, at the higher MAP levels, across a
pretty small (few columns) temperature span. If you
have just picked up this problem as the weather turns
colder, this could be where it's at.
It's worth a try, anyway. If you can see your Fuel Air
Multiplier PID (don't know what-all you can scan with
your SuperChips unit) that would tell you whether it's
rich on account of being told (see FAM of 1.3 or whatever)
or rich on account of being wrong (fat O2s but a 1.00
commanded multiplier). Even if you can't scan that, try
looking at your ECT at the point where it "gets better".
94F is the closed loop enable temp (stock). If it gets
right, right there, abruptly then that implicates your
open loop fueling. If it gets better more gradually, and
at a higher temp, then it may be more to do with some
other player.
I have to wonder about the EGR in all of this, seems
like it ought to just go away; why keep this silly
economy / pollution kludge in place with a blower on
there?
a pretty abrupt swing from small enrichment to 1.3
fuel/air multipliers, at the higher MAP levels, across a
pretty small (few columns) temperature span. If you
have just picked up this problem as the weather turns
colder, this could be where it's at.
It's worth a try, anyway. If you can see your Fuel Air
Multiplier PID (don't know what-all you can scan with
your SuperChips unit) that would tell you whether it's
rich on account of being told (see FAM of 1.3 or whatever)
or rich on account of being wrong (fat O2s but a 1.00
commanded multiplier). Even if you can't scan that, try
looking at your ECT at the point where it "gets better".
94F is the closed loop enable temp (stock). If it gets
right, right there, abruptly then that implicates your
open loop fueling. If it gets better more gradually, and
at a higher temp, then it may be more to do with some
other player.
I have to wonder about the EGR in all of this, seems
like it ought to just go away; why keep this silly
economy / pollution kludge in place with a blower on
there?
10-27-2004, 08:10 PM
#7
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Originally Posted by jimmyblue
Open Loop Fuel/Air vs ECT vs MAP is the table. There is
a pretty abrupt swing from small enrichment to 1.3
fuel/air multipliers, at the higher MAP levels, across a
pretty small (few columns) temperature span. If you
have just picked up this problem as the weather turns
colder, this could be where it's at.
It's worth a try, anyway. If you can see your Fuel Air
Multiplier PID (don't know what-all you can scan with
your SuperChips unit) that would tell you whether it's
rich on account of being told (see FAM of 1.3 or whatever)
or rich on account of being wrong (fat O2s but a 1.00
commanded multiplier). Even if you can't scan that, try
looking at your ECT at the point where it "gets better".
94F is the closed loop enable temp (stock). If it gets
right, right there, abruptly then that implicates your
open loop fueling. If it gets better more gradually, and
at a higher temp, then it may be more to do with some
other player.
I have to wonder about the EGR in all of this, seems
like it ought to just go away; why keep this silly
economy / pollution kludge in place with a blower on
there?
a pretty abrupt swing from small enrichment to 1.3
fuel/air multipliers, at the higher MAP levels, across a
pretty small (few columns) temperature span. If you
have just picked up this problem as the weather turns
colder, this could be where it's at.
It's worth a try, anyway. If you can see your Fuel Air
Multiplier PID (don't know what-all you can scan with
your SuperChips unit) that would tell you whether it's
rich on account of being told (see FAM of 1.3 or whatever)
or rich on account of being wrong (fat O2s but a 1.00
commanded multiplier). Even if you can't scan that, try
looking at your ECT at the point where it "gets better".
94F is the closed loop enable temp (stock). If it gets
right, right there, abruptly then that implicates your
open loop fueling. If it gets better more gradually, and
at a higher temp, then it may be more to do with some
other player.
I have to wonder about the EGR in all of this, seems
like it ought to just go away; why keep this silly
economy / pollution kludge in place with a blower on
there?
Kyle
