EA Slope Calculation Offset Input Option

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skunk
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EA Slope Calculation Offset Input Option

Post by skunk » Fri Aug 10, 2018 7:06 pm

I had an epiphany moment today. I have been experimenting with hego switching trying to lean out my ride CL and decided to give EA another go on calculating slopes to clean up fuel on a near perfect overlay of scaled factory settings. In the past, slope calculations have always calculated me leaner and leaner regardless of how lean im already running. So off I went anyway, ran the calculation and drove with those slope settings for about an hour. Sure enough running the log through EA confirmed the new slopes ran me lean. I figured, run the calculation again on the lean datalog, maybe it will self correct...…..NOPE! I didn't even bother running it in the car......it was going to be even leaner.

I started messing around trying to find the why.... I calculated the lean error against my MAF and came up with an average of 1.01402 increase in required fuel using the new slopes. I decided to experiment by reducing the slopes and breakpoint EA provided by the same factor to get fuel back inline. Turns out....the calculation worked well once corrected.

I believe the WHY is due to the fact that my engine runs rich CL because of exhaust arrangement and placement of the HEGO. The help document indicates EA uses fuel trims and calculated fuel to determain slope output. I will always report richer than what EA calculates I am supposed to be, therfore it will always calculate leaner and leaner unless I can give it an offset. Having the option to give it an offset may also help those with Long Tube headers and maybe give some insight to those who like to tune OL and cant figure out why their tune turns to garbage once they switch to CL.

No disrespect to Clint.....It works as its supposed to, but sometimes no matter how hard you try, you cant get things to line up. I had to cheat to get CL to work by calibrating my wideband to what the ECU said was stoich. If I didnt the MAF looked like I was tuning for two different size injectors.

I don't know if anything will come of this so Im putting it out there for those looking for information on using the Slope Calculator in EA. Key point is making note of what the ECU says is stoich and what your WB is telling you. Calculate the difference eg; WB 14.40/Lambse 14.64 = 0.983. Apply the multiplier to the slopes and breakpoint results in EA. You can also do it the long way like I did and dial in the MAF then calculate an average molesting.

Thanks for looking
John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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Re: EA Slope Calculation Offset Input Option

Post by cgrey8 » Sat Aug 11, 2018 10:50 am

I could be misinterpreting what you are saying, but the fact that you say you are tuning for two different size injectors suggests that your slope values aren't right. When this occurs, you get conditions where a given MAF value is lean at certain RPM/Loads and rich at others. As you might suspect, you cannot fix this via the MAF transfer because you'd have to choose which conditions you want to fix while making the other conditions worse.

What you want is for all MAF conditions to result in the same condition, even if the condition is rich or lean. But in this case, you can actually fix that with the MAF transfer.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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Re: EA Slope Calculation Offset Input Option

Post by skunk » Sat Aug 11, 2018 3:23 pm

Chris, thanks for responding. I agree 100% with your post but only in a perfect world which my car doesn't live apparently.

What I meant about tuning for two differnt size injectors is in refrence to making closed loop work. It really has nothing to do with slope error in this case. I had the issue of my OL tune efforts turning to garbage when moving into fine tuning CL. I didn't want to run FTOL because Im stubborn so I had to jack up the closed loop portions of my MAF transfer to get KAMs at or near 1. I then had to blend the transition to what my WB said was good OL fueling. To exaggerate the point picture a hard step at lets say 2.5 MAFv for entering OL. Essentially the bottom of my MAF Transfer looked more like 44# injectors but the top portion was reduced to represent my actual 42# injectors.

After a great deal of experimentation I found its all due to HEGO error. Just like Long Tubes, my turbo setup really messes with the HEGO feedback. I decided I was ok with running a hair rich all the time. I calibrated the offset into my wideband transfer in BE and was able to get near perfect Lambse/Kams without the messy transition to OL. Ran like this for a long time and this year I thought I would try and fix it best I could.

I may have been premature posting my Offset suggestion. Sometimes I need to say things outloud to force me to think about solutions. As I stated in my original post, manually applying the offset to the slope results in EA works very well for me to get appropriate values tuning in CL. If I don't, EA basically leans me out equally by the amount of the offset. I actually needed to find a way to get rid of the offset to do this right. I tried applying the offset to reduce the HEGO switch voltage and it appears to have reduced the AFR offset by half. The latest EA calculation with that change appears much closer to whats actually needed. I will run the engine with a further reduced HEGO switch voltage and see where I end up, I dont want to overshoot otherwise I have to burn more fuel.

John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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Re: EA Slope Calculation Offset Input Option

Post by cgrey8 » Sat Aug 11, 2018 8:04 pm

You mentioned offset, is there a chance you have too much Injector Offset messing with things? I had that, but it didn't present as you are describing. On my setup, excessive offset resulted in EA calculating VERY steep low slope values and a transition to a slope closer to my actual injector sizes. This made getting the breakpoint a must to make the transition correctly. A 0.1 change was a noticeable difference in performance. When the high and low slopes are relatively close, you should be able to make whole number changes and get, maybe, the same change I was getting with a 0.1 change. Once it finally occurred to me to change the offset curve, I was able to get my low slopes down to values almost identical to my high slopes. As it turned out, my newer EV6 style injectors just didn't need the same amount of offset that the old EV1 injectors from the 80s did (i.e. the stock values in GUFx tunes).
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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Re: EA Slope Calculation Offset Input Option

Post by skunk » Sun Aug 12, 2018 10:42 am

Thank you again Chris, your response is forcing me to think through the possible scenario.

Unfortunately, Battery Offset is a global adder. It will effect both HS and LS the same. Reducing your Battery Offset allows for closer slope values only because you have less slop during very low pulswithdths. Personally I don't like this approach, I feel Battery Offset should be calibrated around HS requirements and LS used to clean up the slop. If you think about it, battery voltage should never fluctuate much anyways. The only time I see a steady consistent dip in voltage is at WOT full boost when the fuel pump is working hardest and injectors peaking in duty cycle, which brings me to my next bit of enlightenment.

Its entirely possible I need to add Battery Offset to voltages of 13 and lower to create a steeper adder around the 13.5v WOT I usually see. This may actually give a little better balance to the transition into OL using corrected slopes without touching the MAF. Ive been hesitant to do this because of how I have already gotten the near perfect overlay of my expected vs actual MAF transfer using the stock offset and scaled breakpoint/slope values. Let me clarify, my slopes and breakpoint were adjusted based on running the stock calibration and me overlaying the stock MAF Transfer scaling down slopes and breakpoint until I had a good overlay......then scaled everything up based on real world injector values (Fuel Tuning the EASY WAY 101 lol). Lambse never seems to vary more than 0.20 AFR in either direction. Sorry back on point, so Its likely Fords Battery Offset wont account for the additional loading.

Even considering the above...… EA slope calculations for me are off by a definite factor equal to the ratio of Lambse vs AFR. I know that sounds like an odd issue since the whole point is to make them match. The issue I have is Lambse is naturally commanding a richer mix represented as stoich due to the HEGO feedback it receives. EA has no idea there is an offset to commanded Lambse and therefore will always calculate leaner slopes based on its calculation of required fuel vs actual fuel pulswidth.

LOL....If I am sucessfull in eliminating the offset via HEGO switch voltage, I suppose the point is moot.

Crap.....Thinking out loud again here, I may have figured out a solution after reading through this post. I had considered at one point setting the Z_AFR to E5 which is very close to the error I see even though the fuel I use claims pure gasoline. I talked myself out of it due to the theoretical Lambda 1 = Lambda 1 regardless of fuel used. Now it occurs to me that the way EA calculates slopes.....it has no idea required fuel pulsewidth has changed indicated by the error if in fact my fuel is not pure as claimed. Is it possible I am chasing my tail and changing Z_AFR is really the answer? (lol....rhetorical, you know im going to experiment). My first thought is NO.....if HEGO feedback is in fact the issue, the error will remain.

Thanks guys.....sorry for the public rambling
John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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skunk
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Re: EA Slope Calculation Offset Input Option

Post by skunk » Sun Aug 12, 2018 5:47 pm

Ok more ramblings,

I have talked myself out of using the Z_AFR for the time being and continue down the HEGO voltage path. I know my engine is rich based on the amount of carbon coating my O2 (wiped down every oil change) and stain on the garage floor at the tail pipe (turn down tip).

Using the Z_AFR method should work to address my initial concern regarding the offset to the slope calculation in EA, but gets me no closer to proper fueling...…… Ya, ya, I know, I wasn't concerned before and was happy just dialing it in rich..... this exercise in critical thinking set my OCD in motion, it appears I can fix the rich condition, get my slopes a little cleaner.....and my favorite part, (some of you will understand) I will have a benchmark.

Thanks
John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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Re: EA Slope Calculation Offset Input Option

Post by cgrey8 » Sun Aug 12, 2018 6:01 pm

Ramblings are OK. Sometimes we need a sounding board just to throw our ideas up and then see how they land.

As for Z_AFR, think of that as an alternative to adjusting your slopes. Logically, they are doing something very different. But in practice, they do pretty much the same thing. In fact for tunes that don't have a Z_AFR available, your only option for adjusting for alternative fuels like E85 is to adjust the slopes to claim smaller injectors than actual in order to get more E85 sprayed for the same amount of air.

Your thoughts on the Offset drop on WOT is interesting. My voltage is way too variant than that. When I cold crank, the voltage is really high and backs off as the alternator gets warmer. When I'm at warm-idle sitting at a traffic light, I've had tunes that let the RPMs get really low and the alternator is barely able to maintain voltage. I can watch the volt meter on the dash bouncing as the small fluctuations in RPM around 550ish blip the alternator on and off. And even when on, when I have loads like headlights and blower motor, I'm getting just a tad over battery voltage until the RPMs get higher. Point is, my voltages are all over the place. And since I'm not boosted, I've never noticed anything unusual with voltage while at WOT. Then again, the stock Explorer 4G alternators are 150ish amps, which is WAY larger than the truck's stock 40a alternator. I looked into an undersized pulley for a 4G, but it doesn't appear anybody makes an undersized pulley for 4G alts. They just aren't popular enough on performance vehicles for anybody to make such a thing.

The thing I'm not sure I agree with you on is that offset is "set" and low slope makes up the slop. I agree that both low slope and offset are both components that have their greatest affect on small injector PW conditions. And while technically offset affects high slope, the PWs are generally higher and the portion of the PW from just the fuel demand starts dwarfing the offset contribution so that changes in offset contribution come closer to negligible. But ultimately, it doesn't matter what people's philosophy and opinion of what the controls are meant for. What's important is you know how to manipulate them in a way that gives the engine what it needs, when it needs it. If you can succeed at that, people's opinion of whether you used the controls correctly or not to get the engine tuned are not important. The only exception is if there's an actual scenario with your approach that you hadn't considered that is just waiting to bite you when the stars align and conditions are right.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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Re: EA Slope Calculation Offset Input Option

Post by skunk » Sun Aug 12, 2018 7:20 pm

Thanks Chris, that tidbit on Z_AFR is helpful. Boy 550 idle, ya that will swing your voltage around. I'm sure that big alternator is also creating alot drag down that low. I'm running the stock 65a 2g at stock 672 rpm with steady voltage. Like you it starts high cold just over 14 and settled down around 13.8 warm. I think the lowest I've seen it dip is maybe 13.2 at WOT. The blower motor flipped to high causes a dip, but it quickly recovers. If I ever go to a 3g, I will likely keep it down to 95a on this car. Anything more will be inefficient and overkill.

My outlook on the Battery Offset is based on setting both HS and LS identical then watching the entire MAF Transfer require the same factor of adjustment from top to bottom. I feel we were seeing the same thing except you didn't see the effect as drastically using varying slopes since you are applying an offset to the HS via the LS and BP. I'm not saying your wrong....I hope that's not how this comes across. I see this difference in opinion to be more like holding a quarter in the air one side facing me and the other side you. I see heads and you see tails......BUT we Both see a Quarter.

Thanks
John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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Re: EA Slope Calculation Offset Input Option

Post by cgrey8 » Mon Aug 13, 2018 5:17 am

BTW, I re-read my comments on offset after having sleep, and I realize I did a horrible job of explaining myself. What I was trying to say is that offset and low slope are dominant at low Inj PWs. And as PWs get higher, the high slope becomes the dominant decider of fuel delivery, and both the low slope and offset's contribution becomes less and less significant.

As for the quarter-flip thing. I agree. And I don't think there is a single "right" way to get things working.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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SOLVED Re: EA Slope Calculation Offset Input Option

Post by skunk » Mon Aug 13, 2018 2:38 pm

Update....SOLVED......Found purely by accident, the AFR/LAMBDA input box in the BFSC section of the Fuel Delivery Tab, directly effects Slope calculations. Therefore, the offset option is already included.

I was able to set the AFR to represent my error, in my case 14.85. Now I get useful calculated results instead of sloppy best guess factoring to work on consistent delivery, albeit rich. Thanks Clint!

As for actually leaning things out...….the HEGO switchpoint…..that effort has failed for now. It takes a very large change in voltage to force a change in AFR. Its like playing a game of keep away except the jumps and ramps are large enough to catch you without any effect on AFR. I may revisit this and the jump/ramp for fine tuning but I believe the BIAS table should provide better immediate results. If all goes well and I find an appropriate way to lean thing out in Closed Loop, I should be able to set my WB calibration back to real world values.


Chris, BTW, the new results indicate that a lowering of Battery Offset to be a definite possibility. Oh, and thank you so much for participating in my scatterbrained thought processes.

John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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Re: EA Slope Calculation Offset Input Option

Post by cgrey8 » Mon Aug 13, 2018 5:10 pm

Not a problem. It's why I hang around.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

Member V8-Ranger.com

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