economy tuning
Honestly... I'd say that the only advantage to doing it w/ the WB would be not having to mess w/ the OE closed loop. Actually... I can think of a way that adjusting via WB is potentially harmful. If you are setting some threshold that says "Whenever the WB sees 14.7 or greater, it outputs 14.7 to the narrowband output, to fool the ECU into thinking it has the right cruise AFR" then what if you go lean during cruise sometime and you just happen to not be logging? (many of us don't have an AF light show gauge) Your ECU would think everything is dandy with 14.7AFR, but you could be cruising at like 17 or more and toasting your gaskets. I'm thinking that switiching over to open loop cruising sounds like a better idea... especially since I've already got my EGR disabled.
All the narrowband simulator does is changes the point in which the narrowband output tells it to go rich or lean. The readings on the WB are still the ACTUAL real-time AFR's. The advantage to the zeitronix option is that your aren't trying to continuously dial in the fuel cells to get a round-about AFR result in open loop. Besides, you have such a broad range for each cell that you won't get it perfectly dialed in. By using the NB simulator, you're taking advantage of the ECU's closed loop capabilities to keep your target AFR in check. Its far more reliable than adjusting the cells for open loop, trust me. Your car won't magically go to 17:1 while in closed loop cruising...the entire point of the closed loop O2 sensor monitoring is to always keep the AFR in check. If it lets it go lean, its because the parameters say that it is allowable. There are many variables that affect the AFR changes in closed loop, you are removing a ton of them when you go to open loop. Would you rather set ONE cell and call it a day....or would you rather have the ECU monitoring a crapload of stuff and keeping things in check at all times??
Last edited by Jack_of_Trades; Feb 14, 2008 at 04:45 PM.
It doesn't work that way. It doesn't "output a different AFR". All you do with the Zeitronix is tell it at which point it will switch from lean to rich. A NB O2 sensor is nothing more than a 2 way switch when you really break things down. If it sees that the mixture is above 1.0 lambda(just so happens to be 14.7:1 for gasoline), it triggers the ECU to lean the mix. If it sees its BELOW 1.0 lambda, it triggers the ECU to richen the mix. Thats all it does, thats why you never see it staying still on a NB sensor while in closed loop because the ECU is doing nothing more than adding too much fuel and then removing too much fuel very rapidly to try and stay in a very small window.
All the narrowband simulator does is changes the point in which the narrowband output tells it to go rich or lean. The readings on the WB are still the ACTUAL real-time AFR's. The advantage to the zeitronix option is that your aren't trying to continuously dial in the fuel cells to get a round-about AFR result in open loop. Besides, you have such a broad range for each cell that you won't get it perfectly dialed in. By using the NB simulator, you're taking advantage of the ECU's closed loop capabilities to keep your target AFR in check. Its far more reliable than adjusting the cells for open loop, trust me.
All the narrowband simulator does is changes the point in which the narrowband output tells it to go rich or lean. The readings on the WB are still the ACTUAL real-time AFR's. The advantage to the zeitronix option is that your aren't trying to continuously dial in the fuel cells to get a round-about AFR result in open loop. Besides, you have such a broad range for each cell that you won't get it perfectly dialed in. By using the NB simulator, you're taking advantage of the ECU's closed loop capabilities to keep your target AFR in check. Its far more reliable than adjusting the cells for open loop, trust me.
You need to cut the front O2 sensor wire at the ECU (pin #71 for you) and connect the narrowband simulator wire from the wideband control unit to the ECU side of the wire. You're replacing the front O2 sensor signal with the simulated signal from the wideband controller.
Cool, thanks for schooling me. Makes much more sense to think of it as an on/off switch. So, do you know if the LC-1 works this way at all? I think somewhere on this forum (perhaps in this thread) someone mentioned it. But like I said, I couldn't find it in the PDF manual...
I know it can simulate the narrowband output but I don't know if you can adjust the narrowband switching point like you can with the Zeitronix unit. Best bet would be to drop the company an e-mail.
I've done it for almost a month now. Definetly an improvement in gas. I went from 200 to the tank to 220-230 depending if I boost or not.
It should work just as well, god knows E85 can use all the help it can get for gas mileage. Whether you use gasoline or E85, the lambda target ranges generally stay about the same at:
.82-.85 (best torque/power)
1.0 (best emissions)
1.05-1.09 (best fuel economy)
1.05-1.09 on a standard wideband gauge set for gasoline (14.7:1 = 1.0 lambda) would read between 15.5-16.0:1 AFR. In reality, this is in the 10.2:1 to 10.6:1 AFR ratio for E85 since E85 has a stoich ratio of 9.765:1.
Last edited by Jack_of_Trades; Feb 18, 2008 at 09:41 AM.
Yep, no matter what fuel you use with a standard WB gauge, 14.7 will always be the ideal stoich mix for that fuel. The sensor ONLY reads lambda, the control unit uses an equation to digitally dispaly the readings in an air/fuel ratio for gasoline (14.7:1 stoich). O2 sensors are actually called lambda sensors but along the line they got dubbed O2 sensors. The best way to tune with alternative fuels is with lambda, rather than AFR since the variances from diffrent fuels is so different. Google a little about lambda, its rather useful info.
Alright, went out today to get some milage from my racecar. I'll be taking it on a trip this weekend and didnt want to stop 4 times on the way.
First I tried the Open loop thing.... It seems that the same fuel cell would net a different AFR under different conditions. Long story short: There's a reason for closed loop. So I dug into my ECU+ manual and used its variable front 02 switchpoint. That was amazingly easy to hook up.. only changed one wire and it now hovers around 15.7 predictably. Works very well. I don't have an EGT gauge, but driveability and knock don't seem to be a problem. The LC-1 does emulate a NB output (which is what I was doing previous to today), but per the manual it doesn't allow for adjusting the stoich switchover point... but obviously the ECU+ did, so that was cool. I'll see if I can get a MPG this weekend... chances are I won't because even though I'll be working this event at VIR you can bet that I'll be out for touring laps.
First I tried the Open loop thing.... It seems that the same fuel cell would net a different AFR under different conditions. Long story short: There's a reason for closed loop. So I dug into my ECU+ manual and used its variable front 02 switchpoint. That was amazingly easy to hook up.. only changed one wire and it now hovers around 15.7 predictably. Works very well. I don't have an EGT gauge, but driveability and knock don't seem to be a problem. The LC-1 does emulate a NB output (which is what I was doing previous to today), but per the manual it doesn't allow for adjusting the stoich switchover point... but obviously the ECU+ did, so that was cool. I'll see if I can get a MPG this weekend... chances are I won't because even though I'll be working this event at VIR you can bet that I'll be out for touring laps.
First I tried the Open loop thing.... It seems that the same fuel cell would net a different AFR under different conditions. Long story short: There's a reason for closed loop. So I dug into my ECU+ manual and used its variable front 02 switchpoint. That was amazingly easy to hook up.. only changed one wire and it now hovers around 15.7 predictably. Works very well.
"The advantage to the zeitronix option is that your aren't trying to continuously dial in the fuel cells to get a round-about AFR result in open loop. Besides, you have such a broad range for each cell that you won't get it perfectly dialed in. By using the NB simulator, you're taking advantage of the ECU's closed loop capabilities to keep your target AFR in check. Its far more reliable than adjusting the cells for open loop, trust me"........"There are many variables that affect the AFR changes in closed loop, you are removing a ton of them when you go to open loop. Would you rather set ONE cell and call it a day(and just hope for the best)....or would you rather have the ECU monitoring a crapload of stuff and keeping things in check at all times??"
Thats what I've been saying. Glad to see you got it to work well
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Random E85 economy data:
Not a SUBE, but a SAAB 900 16v, but it has a slightly larger turbo and the Normaly aspirated compression ratio pistons.
anyway maybe this data will help someone
I spent some time on the dyno today, I did not do any power tuning, I was doing an experiment to find the best AFR for economy with timing optimized for that AFR. (ALL AFR's noted here will be on the gasoline scale even though i was using E85, which at this time of the year here is supposedly E70). (Colorado Springs)
I logged my rpm and load at about cruising speed on the highway at 3000 rpm fith gear , so that i could go to the dyno and then get an idea of my HP required at cruising speed.
I went to the dyno and loaded the car to my cruise conditions, and noted the tractive effort (say 30 lbs). This number represents the "power" that my car needs to maintain cruise at 3000 rpm 5th gear on the highway.
I then loaded the car at this point at different AFR's and then experimented with the timing with fixed AFR until i found the timing that used the lowest msec of fuel while still making 30 lbs.
I repeated this for different AFRs.
The results: (only listing the least efficient tested to and the most efficient)
3000 rpm, 30 lbs tractive
manifold kpa=about 55 for all
AFR 15,best advance=28,msec required=2.27
AFR 16.8,best advance=40 ,msec=2.07
i experimented past 17:1 and between 15 to 16.8, but 16.8 was the best
timing seemed very critical 1 degree either way lost 3 lbs or so tractive force.
Not a SUBE, but a SAAB 900 16v, but it has a slightly larger turbo and the Normaly aspirated compression ratio pistons.
anyway maybe this data will help someone
I spent some time on the dyno today, I did not do any power tuning, I was doing an experiment to find the best AFR for economy with timing optimized for that AFR. (ALL AFR's noted here will be on the gasoline scale even though i was using E85, which at this time of the year here is supposedly E70). (Colorado Springs)
I logged my rpm and load at about cruising speed on the highway at 3000 rpm fith gear , so that i could go to the dyno and then get an idea of my HP required at cruising speed.
I went to the dyno and loaded the car to my cruise conditions, and noted the tractive effort (say 30 lbs). This number represents the "power" that my car needs to maintain cruise at 3000 rpm 5th gear on the highway.
I then loaded the car at this point at different AFR's and then experimented with the timing with fixed AFR until i found the timing that used the lowest msec of fuel while still making 30 lbs.
I repeated this for different AFRs.
The results: (only listing the least efficient tested to and the most efficient)
3000 rpm, 30 lbs tractive
manifold kpa=about 55 for all
AFR 15,best advance=28,msec required=2.27
AFR 16.8,best advance=40 ,msec=2.07
i experimented past 17:1 and between 15 to 16.8, but 16.8 was the best
timing seemed very critical 1 degree either way lost 3 lbs or so tractive force.