Open loop/ SD tune is killing me
10-05-2004, 10:00 PM
#1
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Open loop/ SD tune is killing me Now, I'm not a good tuner at all. But the shop I work at is experienced as they come. Problem is, we have never done a SD tune. Here's the setup:
No O2 sensors
No MAF
90mm FAST TB
Big big big cam
Open headers
OK, idle is great, no codes are thrown at all. WOT is also good. It will hold timing where I want it, and the A/F is perfect during a WOT dyno run. The problem is part throttle. I need a place to start here. Granted, I stay away from tuning, but need something to tell my tuner, like a starting place. Any suggestions? Running it on the street is not going to happen. I can only tune on the dyno. Drag only car here.
No O2 sensors
No MAF
90mm FAST TB
Big big big cam
Open headers
OK, idle is great, no codes are thrown at all. WOT is also good. It will hold timing where I want it, and the A/F is perfect during a WOT dyno run. The problem is part throttle. I need a place to start here. Granted, I stay away from tuning, but need something to tell my tuner, like a starting place. Any suggestions? Running it on the street is not going to happen. I can only tune on the dyno. Drag only car here.
10-05-2004, 10:37 PM
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I just need part throttle. It really gets crazy when I'm driving back to the pits, or if you just try and hold it at a certain rpm to launch.
10-05-2004, 10:46 PM
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I've made a few passes, and it runs damn good at WOT. Really surprised me. But yes, the surge is unbearable if I hold it at say, 4000 rpm in neutral. I'm using edit right now.
10-05-2004, 11:05 PM
#6
You're gonna have to do some serious work on your ve table. Why did you decide to go with open loop. Speed density's not that bad but SD with open loop is making it really hard on yourself.
If you had access to a load bearing dyno i would say set it to hold your rpms constant at whatever, like 4000 rpm. Then press the throttle until you get the manifold pressure you want, say 60 kpa. Then write down the a/f reading there and adjust the ve table for that cell up or down based on that.
The thing that sucks about this way is you have to do that for every combination of rpm and manifold pressure in the ve table. That is where hptuners with the wideband cable will come in handy, cause it will pretty much do that for you and sort it for you while you drive.
If you had access to a load bearing dyno i would say set it to hold your rpms constant at whatever, like 4000 rpm. Then press the throttle until you get the manifold pressure you want, say 60 kpa. Then write down the a/f reading there and adjust the ve table for that cell up or down based on that.
The thing that sucks about this way is you have to do that for every combination of rpm and manifold pressure in the ve table. That is where hptuners with the wideband cable will come in handy, cause it will pretty much do that for you and sort it for you while you drive.
10-05-2004, 11:22 PM
#7
can you send me your current operating edit file? as a start try holding steady throttle in nuetral at 1000-2000-3000 rpm etc and record the MAP at those places. Try richening up those places, and if it doesnt improve, go leaner. I usually move things richer first if I have no instrumentation. Try the same thing in first like your footbraking the car... unless its a6 speed
once you get a couple points roughed in, and if your WOT is set good, you shoudl be able to move your stock VE table up or down in large quanties to get you close. No load timing should be low to mid 30 degrees I beleive. What gas you running
once you get a couple points roughed in, and if your WOT is set good, you shoudl be able to move your stock VE table up or down in large quanties to get you close. No load timing should be low to mid 30 degrees I beleive. What gas you running
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10-06-2004, 07:46 AM
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I liked the suggestion from (Chris?) on the HPTuners
'board. That being to set PE to 1.0, open the loop
(sensors disconnected or just raise the enable temp)
and use the open loop fuel/air table dialed to 13.0:1
(1.129 fuel air multiplier). Then you log as much of
the driving envelope as possible with the wideband,
bin up the results on the same basis as the VE table
and you can use that (via Excel) to straighten the
VE table right up.
It might be as simple as putting a cinder block on the
gas pedal and a shim under it, and do pulls at 10, 20,
30, ... 100% TPS to redline or flatline RPM.
A poor boy's alternative would be instead to set the
OLFA table to all 1.0s and pull back maybe 10 degrees
of timing (to extend the load range you can hit w/o ping),
put it open loop but log the O2s, and run the driving
cycle on the street; use the rising part of the front O2
curve as a roughly-right guide, 0.5=14.7, 0.2=15.0,
0.8=14.0:1 and trim the VE table up/down by that
(bearing in mind that low-flow narrowband readings are
for **** when you have headers, so favor idle / cruise
feedback immediately after hot running and ignore the
"settled" state). You would probably not want to exercise
WOT this way but could get the low to middle end of
the VE table trued up in a couple of cycles of this.
Bit more work than the wideband but $400 less expense
in the short term for the shade tree types.
Just be sure to put it all back when you're done
'board. That being to set PE to 1.0, open the loop
(sensors disconnected or just raise the enable temp)
and use the open loop fuel/air table dialed to 13.0:1
(1.129 fuel air multiplier). Then you log as much of
the driving envelope as possible with the wideband,
bin up the results on the same basis as the VE table
and you can use that (via Excel) to straighten the
VE table right up.
It might be as simple as putting a cinder block on the
gas pedal and a shim under it, and do pulls at 10, 20,
30, ... 100% TPS to redline or flatline RPM.
A poor boy's alternative would be instead to set the
OLFA table to all 1.0s and pull back maybe 10 degrees
of timing (to extend the load range you can hit w/o ping),
put it open loop but log the O2s, and run the driving
cycle on the street; use the rising part of the front O2
curve as a roughly-right guide, 0.5=14.7, 0.2=15.0,
0.8=14.0:1 and trim the VE table up/down by that
(bearing in mind that low-flow narrowband readings are
for **** when you have headers, so favor idle / cruise
feedback immediately after hot running and ignore the
"settled" state). You would probably not want to exercise
WOT this way but could get the low to middle end of
the VE table trued up in a couple of cycles of this.
Bit more work than the wideband but $400 less expense
in the short term for the shade tree types.
Just be sure to put it all back when you're done
10-06-2004, 07:51 AM
#10
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Originally Posted by GrannySShifting
can you send me your current operating edit file? as a start try holding steady throttle in nuetral at 1000-2000-3000 rpm etc and record the MAP at those places. Try richening up those places, and if it doesnt improve, go leaner. I usually move things richer first if I have no instrumentation. Try the same thing in first like your footbraking the car... unless its a6 speed
once you get a couple points roughed in, and if your WOT is set good, you shoudl be able to move your stock VE table up or down in large quanties to get you close. No load timing should be low to mid 30 degrees I beleive. What gas you running
once you get a couple points roughed in, and if your WOT is set good, you shoudl be able to move your stock VE table up or down in large quanties to get you close. No load timing should be low to mid 30 degrees I beleive. What gas you running
10-06-2004, 09:37 AM
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Originally Posted by P Mack
You're gonna have to do some serious work on your ve table. Why did you decide to go with open loop. Speed density's not that bad but SD with open loop is making it really hard on yourself.
If you had access to a load bearing dyno i would say set it to hold your rpms constant at whatever, like 4000 rpm. Then press the throttle until you get the manifold pressure you want, say 60 kpa. Then write down the a/f reading there and adjust the ve table for that cell up or down based on that.
The thing that sucks about this way is you have to do that for every combination of rpm and manifold pressure in the ve table. That is where hptuners with the wideband cable will come in handy, cause it will pretty much do that for you and sort it for you while you drive.
If you had access to a load bearing dyno i would say set it to hold your rpms constant at whatever, like 4000 rpm. Then press the throttle until you get the manifold pressure you want, say 60 kpa. Then write down the a/f reading there and adjust the ve table for that cell up or down based on that.
The thing that sucks about this way is you have to do that for every combination of rpm and manifold pressure in the ve table. That is where hptuners with the wideband cable will come in handy, cause it will pretty much do that for you and sort it for you while you drive.
10-06-2004, 09:38 AM
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Originally Posted by GrannySShifting
can you send me your current operating edit file? as a start try holding steady throttle in nuetral at 1000-2000-3000 rpm etc and record the MAP at those places. Try richening up those places, and if it doesnt improve, go leaner. I usually move things richer first if I have no instrumentation. Try the same thing in first like your footbraking the car... unless its a6 speed
once you get a couple points roughed in, and if your WOT is set good, you shoudl be able to move your stock VE table up or down in large quanties to get you close. No load timing should be low to mid 30 degrees I beleive. What gas you running
once you get a couple points roughed in, and if your WOT is set good, you shoudl be able to move your stock VE table up or down in large quanties to get you close. No load timing should be low to mid 30 degrees I beleive. What gas you running
10-06-2004, 09:39 AM
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Originally Posted by HumpinSS
Is your WB gettting accurate readings with the open headers. How close is the bung to the open collector...
10-06-2004, 09:41 AM
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Originally Posted by jimmyblue
I liked the suggestion from (Chris?) on the HPTuners
'board. That being to set PE to 1.0, open the loop
(sensors disconnected or just raise the enable temp)
and use the open loop fuel/air table dialed to 13.0:1
(1.129 fuel air multiplier). Then you log as much of
the driving envelope as possible with the wideband,
bin up the results on the same basis as the VE table
and you can use that (via Excel) to straighten the
VE table right up.
'board. That being to set PE to 1.0, open the loop
(sensors disconnected or just raise the enable temp)
and use the open loop fuel/air table dialed to 13.0:1
(1.129 fuel air multiplier). Then you log as much of
the driving envelope as possible with the wideband,
bin up the results on the same basis as the VE table
and you can use that (via Excel) to straighten the
VE table right up.
10-06-2004, 11:01 AM
#16
Originally Posted by LOnSLO
OK, we are on the same page so far. Do you think the HPtuners software is more user friendly for this type of tuning?
10-06-2004, 11:47 AM
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A few of us have tried with great sucess but we are in CL and using the o2's for modifying the ve table. when the cable comes out you will prolly see more of use start tuning using open loop and a flat ratio like 13.0
10-06-2004, 11:53 AM
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OK, so basically you're using ltft's to adjust VE, correct? I will be using the wideband on the dyno (I have unlimited dyno time) so no O2 sensors would be fine right?