Open Loop, Speed Density users chime in please.
03-13-2007, 06:19 PM
#1
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Open Loop, Speed Density users chime in please. My O2 sensors are pissing me off today, they are reporting .560 Volts(lean) yet my wideband is telling me its rich. I dont even fell like dealing with my O2 sensors anymore and am thinking of just running open loop SD when i go to get tuned. I will be tuning it on a dyno dynamics loading dyno using EFI Live so i figure I can put it on there and load the dyno and control RPM to hit all the cells that i need to hit.
My main concern is how accurate does it run in open loop? How much do external conditions such as air temps, weather, elevation, and stuff like that throw off your AFR? I would love to do it this way since it gives me much more control over everything, but I dont want to have to tune it once a month to keep it accurate.
My main concern is how accurate does it run in open loop? How much do external conditions such as air temps, weather, elevation, and stuff like that throw off your AFR? I would love to do it this way since it gives me much more control over everything, but I dont want to have to tune it once a month to keep it accurate.
03-13-2007, 06:24 PM
#2
It will stay pretty accurate, but I still keep on top of mine at least 3-4 times a year depending on my mood (whether or not my obsessive compulsive disorder is flaring up). The winter gas they use around here threw it off a little, but the air temps themselves didn't do a whole lot to the tune. I tuned it in 40 degree weather, and it was near 80 today, and the AFR was just as stable and accurate as it was when I tuned it. Never done much of an elevation change, so I can't comment on its effect.
I have done some alterations to many, many things in my tune to get it where it is, and I'm still experimenting to keep it as stable as possible. A big reason I'm going to an electric water pump is to keep the coolant temps as stable as possible as well, as that will also have a pretty decent impact on the AFR you get. Another thing to take into account is your fuel pressure...mine swings a LOT going from cruise to WOT, and that will have an impact on the stability as well as the pressure change doesn't really coincide with the slope of the IFR table as it came from the factory. I'll most likely being doing a return-style fuel system with a regulator at the rails in the next year or so along with a fuel pump upgrade to see if I can stabilize that.
All that said...I'd never tune someone's car open loop and SD without informing them that the tune will probably change throughout the year. I just can't get mine stable enough to do that yet (although that doesn't mean it can't be done).
I have done some alterations to many, many things in my tune to get it where it is, and I'm still experimenting to keep it as stable as possible. A big reason I'm going to an electric water pump is to keep the coolant temps as stable as possible as well, as that will also have a pretty decent impact on the AFR you get. Another thing to take into account is your fuel pressure...mine swings a LOT going from cruise to WOT, and that will have an impact on the stability as well as the pressure change doesn't really coincide with the slope of the IFR table as it came from the factory. I'll most likely being doing a return-style fuel system with a regulator at the rails in the next year or so along with a fuel pump upgrade to see if I can stabilize that.
All that said...I'd never tune someone's car open loop and SD without informing them that the tune will probably change throughout the year. I just can't get mine stable enough to do that yet (although that doesn't mean it can't be done).
03-13-2007, 06:29 PM
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Thanks man, I have no problem cleaning up the tune 3 times a year just as long as its not any big changes that need to be made. Im in GA so it doesnt get too cold here anyway. I guess I can just do it and give it a try and see how it works out for me.
03-13-2007, 06:35 PM
#4
With the software available today, retuning takes me about an hour, two at most if I'm being slow. I use HPT with their real time tuning solution, and since I'm open loop and SD, I only have to change the VE table to adjust my fueling. Quick, easy, simple.
If you had EFI Live with their Roadrunner, it'd be even faster. I'm anxious to see how the HPT autotune feature works, but that won't be for a little bit (next software release hopefully).
If you had EFI Live with their Roadrunner, it'd be even faster. I'm anxious to see how the HPT autotune feature works, but that won't be for a little bit (next software release hopefully).
03-13-2007, 09:17 PM
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You've got a Y2K vehicle and EFI Live? Get the RR and employ RTACS. Main drivability areas of the VE table as smooth as silk in minutes not hours. Goto the track for ~20usd for the day or ~60-100 dollars an hour for dyno time. Hmmm.
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03-14-2007, 06:04 AM
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Originally Posted by Doc
You've got a Y2K vehicle and EFI Live? Get the RR and employ RTACS. Main drivability areas of the VE table as smooth as silk in minutes not hours. Goto the track for ~20usd for the day or ~60-100 dollars an hour for dyno time. Hmmm.
How well does the rr work anyway?
03-14-2007, 09:10 AM
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Originally Posted by Country Boy
Ive never seen the point of staying OLSD?
I've run both ways. Good arguments for both ways. What swayed me to OLSD is:
Can run leaded racegas.
Don't have to worry about airleaks, bad O2's, etc messing with my part throttle tune.
Car starts, drives, idles very well OLSD.
Really just depends on your goals.
03-14-2007, 09:14 AM
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Originally Posted by Country Boy
Ive never seen the point of staying OLSD?
03-14-2007, 09:15 AM
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Originally Posted by Country Boy
Why not just use CLSD? I never hada problem with it and the PCM will still correct for the AFR. You can also use IAT correction to account for the weather.
03-14-2007, 09:22 AM
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Originally Posted by Country Boy
ahh.. now that can make sence. I guess with really large cams its near impossible to have a nice AFR with the O2s all wacked.
03-14-2007, 09:29 AM
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humm.. havent thought about that, but Ive only tuned my SD turbo setup. Why tune it on the dyno? Its going to be off when you get to the street unless its a mustang dyno.
03-14-2007, 09:31 AM
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Originally Posted by Country Boy
humm.. havent thought about that, but Ive only tuned my SD turbo setup. Why tune it on the dyno? Its going to be off when you get to the street unless its a mustang dyno.
03-14-2007, 10:10 AM
#20
Originally Posted by Country Boy
Ive never seen the point of staying OLSD?