Open loop tuning vs. Closed loop tuning
Oct 25, 2007 | 09:35 AM
#1
Open loop tuning vs. Closed loop tuning
Can someone explain the advantages and disadvantages to each?
It seems that closed loop is the best for part throttle driveability and fuel consumption and it relies on short term and long term fuel trims alonmg with other sensor parameters. Open loop seems to be best for WOT performance where a wide band is used to tune the AFR at WOT.
How are most of the tuners out there tuning our engines?
It seems that closed loop is the best for part throttle driveability and fuel consumption and it relies on short term and long term fuel trims alonmg with other sensor parameters. Open loop seems to be best for WOT performance where a wide band is used to tune the AFR at WOT.
How are most of the tuners out there tuning our engines?
Oct 25, 2007 | 11:11 AM
#2
If you're using a wideband you need to force the PCM into open loop, because you want to get your VE tables as close as possible without correction from the PCM. Once you get your VE tables dialed in, you can throw it back into closed loop and let the fuel trims do their thing.
If you get your tune close enough it won't matter if you're in open or closed loop for part throttle. I ran my truck is open loop for about 2 years, just put it back into closed loop and I haven't noticed a difference in fuel consumption. WOT should always be open loop because you want your AFR richer than stoich. Closed loop is only good for keeping AFR's at stoich.
For you, being FI, I would recommend getting a 2bar MAP sensor and loading up a 2bar operating system. Are you still running a MAF? If so, are you close to maxing it out? The highest value the PCM will read is 512g/sec of airflow. There's nothing you can do to change that.
If you're running a MAF, put your truck into open loop and run it off the MAF only. Get your MAF table all set up the way you want it. Then disable the MAF and run the truck off the VE tables only. Get those where you want them. Then put it back to running off both the MAF and VE tables, and put it back into closed loop. That's what I would do, but there are lots of options available.
If you get your tune close enough it won't matter if you're in open or closed loop for part throttle. I ran my truck is open loop for about 2 years, just put it back into closed loop and I haven't noticed a difference in fuel consumption. WOT should always be open loop because you want your AFR richer than stoich. Closed loop is only good for keeping AFR's at stoich.
For you, being FI, I would recommend getting a 2bar MAP sensor and loading up a 2bar operating system. Are you still running a MAF? If so, are you close to maxing it out? The highest value the PCM will read is 512g/sec of airflow. There's nothing you can do to change that.
If you're running a MAF, put your truck into open loop and run it off the MAF only. Get your MAF table all set up the way you want it. Then disable the MAF and run the truck off the VE tables only. Get those where you want them. Then put it back to running off both the MAF and VE tables, and put it back into closed loop. That's what I would do, but there are lots of options available.
Oct 25, 2007 | 12:09 PM
#3
If you're using a wideband you need to force the PCM into open loop, because you want to get your VE tables as close as possible without correction from the PCM. Once you get your VE tables dialed in, you can throw it back into closed loop and let the fuel trims do their thing.
If you get your tune close enough it won't matter if you're in open or closed loop for part throttle. I ran my truck is open loop for about 2 years, just put it back into closed loop and I haven't noticed a difference in fuel consumption. WOT should always be open loop because you want your AFR richer than stoich. Closed loop is only good for keeping AFR's at stoich.
For you, being FI, I would recommend getting a 2bar MAP sensor and loading up a 2bar operating system. Are you still running a MAF? If so, are you close to maxing it out? The highest value the PCM will read is 512g/sec of airflow. There's nothing you can do to change that.
If you're running a MAF, put your truck into open loop and run it off the MAF only. Get your MAF table all set up the way you want it. Then disable the MAF and run the truck off the VE tables only. Get those where you want them. Then put it back to running off both the MAF and VE tables, and put it back into closed loop. That's what I would do, but there are lots of options available.
If you get your tune close enough it won't matter if you're in open or closed loop for part throttle. I ran my truck is open loop for about 2 years, just put it back into closed loop and I haven't noticed a difference in fuel consumption. WOT should always be open loop because you want your AFR richer than stoich. Closed loop is only good for keeping AFR's at stoich.
For you, being FI, I would recommend getting a 2bar MAP sensor and loading up a 2bar operating system. Are you still running a MAF? If so, are you close to maxing it out? The highest value the PCM will read is 512g/sec of airflow. There's nothing you can do to change that.
If you're running a MAF, put your truck into open loop and run it off the MAF only. Get your MAF table all set up the way you want it. Then disable the MAF and run the truck off the VE tables only. Get those where you want them. Then put it back to running off both the MAF and VE tables, and put it back into closed loop. That's what I would do, but there are lots of options available.
I think I may need to look into a 2-bar tune and go from there.
Oct 25, 2007 | 12:56 PM
#5
If you're using a wideband you need to force the PCM into open loop, because you want to get your VE tables as close as possible without correction from the PCM. Once you get your VE tables dialed in, you can throw it back into closed loop and let the fuel trims do their thing.
If you get your tune close enough it won't matter if you're in open or closed loop for part throttle. I ran my truck is open loop for about 2 years, just put it back into closed loop and I haven't noticed a difference in fuel consumption. WOT should always be open loop because you want your AFR richer than stoich. Closed loop is only good for keeping AFR's at stoich.
If you get your tune close enough it won't matter if you're in open or closed loop for part throttle. I ran my truck is open loop for about 2 years, just put it back into closed loop and I haven't noticed a difference in fuel consumption. WOT should always be open loop because you want your AFR richer than stoich. Closed loop is only good for keeping AFR's at stoich.
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Oct 25, 2007 | 06:53 PM
#10
ive been open loop for a few years now...no maf and no o2's, completely off the ve table..its an efi live custom operating system..it runs my desired a/f..i dont know why but alot of people dont like it..i have my a/f set to run 15.5 a/f and if i stay out of it i can average about 15.8 mpg for a tankfull..this is a 6.0, with my cam is sig, p&p ls1 heads, 3200 stall and 4.10's