devolution

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.

Im using an Autronic SM2, so the following may also be useful to some;
Right now i am mapping my engine as TPS/LOAD this way I can target economy or Power AFR dependent on TPS postion (driver intention) rather than just load. For instance on highway cruise and a moderate hill you may near 100% load and would rather target leaner, beacase you are just trying to maintain cruise, not accelerate, When at other times you are at the same load site but want max acceleration. by putting "wrong" values in the fuel table at less than 100% TPS you can have econmy AFR's, yet when you go to 100% TPS it can target best torque AFR's. On the Sm2 one has to compromise on the ignition advance because that is only load/rpm based. The SM4 would be nicer for this...

Jack_of_Trades

iTrader: (17)

Unfortunately, different engine, different fuel so it isn't comparable at all in that aspect. What it does show is the very small "ideal" window you are trying to find. Preloading the car to simulate cruising conditions and dyno tuning is by far the best way to controllably tune for such a thing.

Did you happen to log cruising EGT's? Thats definitely important here.

tkklemann

iTrader: (6)

For the 96940011 ROM, what are the correct addresses for both of the Throttle Based Tables?

Mine display something different than what it seems you insinuate yours do.

Profoxcg

iTrader: (9)

Im not insinuating, I am stating what mine does. Evo IX. I don't know what your rom looks like.

devolution

i did not log egt's, but i was watching them, egt's were about 600 deg C, at wich point i stopped monitoring them since i had plenty of head room , and the cruise target power was what was important.

I'll be interested to see the egt's when i do some power tuning, wich will be a long time into the future probably.

tkklemann

iTrader: (6)

Thats not what I meant.

I meant that what you are insinuating is that the values in your table are different than what are in mine, and I know it was a IX vs. a VIII. It's in no way saying it's right or wrong, just different as I am trying to get mine to be "Correct" if they are wrong.

You insinuated that your values in those tables are % based. Mine have a range of 3.01 to 1.72 (With the exception of zero), which do not follow your insinuated "%" of your table. My values don't seem to be in a %, so i am worndering if my tables are coorect now, thats all. Not trying to be a pain in the **** or anything here...

pltek

iTrader: (33)

so if you do the NB similation and set the switching point to say 15.5, you dont touch the afr table in the rom,

what about the closed to open loop transition tables (based on load and tps) what load would you assign there for the cruising rpm range of say 1500-4000?

THanks

EE

iTrader: (9)

that's exact, your ecu will take care of keeping your afr's at 15.5 instead of 14.7 (for the ecu it's still 14.7...)
I hvn't tried it yet (got the lc-1 but didn't install it yet), but i guess as long as you hv no knock when transitting from closed to open loop you are fine...

Tek3Evo

iTrader: (11)

does it help to change the 14.7 fields on the fuel map to the new target afr set by the simulated NB for fuel trim sake?

Jack_of_Trades

iTrader: (17)

I never alter the stock settings and it hasn't ever had a problem during the transition between closed and open loop. For me anyways.

I never changed them personally but you could if you wanted. I would personally keep them where they are, so if the ECU sees a problem with closed loop operation, at least you know you are getting enough fuel in the open loop fuel map.

pltek

iTrader: (33)

but those tansition tables have pretty high load and TPS% settings (below is the stock Open Loop Load values b/w 1500-4000RPM) so that thells me that i would be running 15.5 afr until or even beyond when boost comes on, would that not be slightly unsafe?

I guess i am trying to understand the difference / benefits of either altering the rom or going the NB simulation, in terms of safety and accuracy/


Load
90
100
110
110
95
78.125

Jack_of_Trades

iTrader: (17)

By all means, edit the tables if you want. It won't hurt any. Don't go too low or you'll be flip flopping between closed and open loop too often which would be worse. This is totally a fuel economy mod so as far as performance is concerned, I would say it comes second. I'm using Tephra's new Map Switching Patch so I technically could have a switch setup that also switches between the stock O2 sensor input and the NB simulated input when I switch maps. One flip could do everything. So if some punk is messing with me on the highway and I'm cruising to save gas, I could just flip the switch and wave bye bye.

There are tons of ways to set it up, just mess with your tables until you feel better. Datalog and see if you ARE having any safety issues at all.

pltek

iTrader: (33)

thank you

EVIL MR

iTrader: (5)

keep the info coming guys.

tkklemann

iTrader: (6)

I finally got some satisfactory results on my VIII (05).

I have been playing with all 4 of the maps in my 96940011 map, and here is what I came up with.

In the Open Loop Load #1, I only have 500-1500 changed to a load value of 30. (Reason is last I read this map was thought to be a start-up/warm-up map. My car is acting as though it is) The values are set to 30, because at *warmup* idle, the car is reading load values of 42-47. Coolant temp was at 98.6 degrees, and climbing. The car was idling warming up with an AFR of 15.4-15.6.

In the Open Loop Load #2, the values of 500rpm to 3000rpm are changed to 30, and 3500-4000rpm are at 40. Set these this way because at a steady state cruise of roughly 55mph the load values are 40-55. AFR is reading around 15.1-15.3. (I am going to increase this slightly to around 15.4-15.7)

The Open Loop Throttle Low has the 500-3,000rpm set to 15%, and 3500-4000rpm set to 20%. This gives me the low throttle percentage I needed to get the car over the load values from the Load #2 map, and over the throttle percentage in the Throttle Low Load map. If I didn't adjust the Throttle Low Load map, the car didn't respond to the changes I made in the fuel map.

The Open Loop Throttle High is set the same as the Low. I am going to remove these changes to see how the car reacts. I don't think that I need the High map changed, as I only want the car to run lean when under low loads.

But, the car is finally acting the way i want it to now, only a few small things left to clean up and get the lean cruise/idle set up perfectly.