Ransford2987

I have a 1990 Camaro IROC 5.7 that is my DD and I bought some tuning stuff (APU1 AutoProm) to tune my car for the most efficiency I can get out of it. I've enabled Highway Mode, and done some minor tuning with the VE tables to get my BLM's to stay at/near 128. I'm fairly new to this and I do my best to understand some of the threads posted here, but I'm trying to figure out what else I can do to increase those MPG's and see what some of you have achieved with tuning. If there's a already a thread on this, kindly point me in that direction and we won't have to bother with this one. Thanks!

EvelBist

iTrader: (1)

you can try locking the tcc at lower speed, play with higher afr in highway mode. but mostly, the old heads around here have written a ton of stuff regarding lean cruise (highway mode). poke around in the archives.

Ronny

iTrader: (1)

deacceleration fuel cut off enabled and parameters to allow earlier

" enleanment enabled " " "

Dont go too lean on highway mode or the engine may misfire. I see 16.8 on my WB and is Ok.

I am not sure if you would want to command stoich to 14.8 instead of 14.7 and change the rich lean median swing to 6% lesser values. This might lean out CL running.

Gears

Doing all of the above incl hyway/lean cr will possibly cauuse you to fail emishions.

Ransford2987

Thanks for the help, guys. I have leaned out HM more than the stock table did, but I didn't go as high as 16.8. I'm using TunerPro RT, and my table looks like this,
MAP AFR
30 17
40 16
50 15.5
60 14.7

I'll lean out the 60 kPa a bit more, but what MAP value do you have for the 16.8? Or is it the whole time, as long as you're in HM?

I've attached a screenshot showing DFCO parameter values for any comments or advice. Forgive me here, but what other parameters are you referring to? I'm kind of new to this and some of the parameter names I see in TunerPro mean absolutely nothing to me. When I do understand them, I don't know how or what the value affects.

I've read a little bit about going WB with my O2, but can I just pick up any WB sensor and plug and play? I know I can use my AutoProm to hook up a channel for WB O2, and I've read about how to get TunerPro itself to read a wideband O2, but will the ECM recognize it? Is the voltage produced the same for the same AFR? I've read some links, like this one: https://www.thirdgen.org/forums/dfi-...o2-advice.html, but I can't find a direct answer to this. I keep reading about needing a controller, but that might be for gauge or some other display.

One more thing on the O2 Sensor: if I use a heated O2 sensor in the stock bung location, I can enable closed loop sooner, right? Should I put it further downstream somewhere in the exhaust with the same idea? https://www.thirdgen.org/forums/tpi/...o2-sensor.html
I understand the advantages, but is the time difference between both as far as enabling CL significant enough to warrant using a heated O2 is my main question.

I've changed my Stoich AFR slightly and haven't noticed any issues there, but I'll probably get up to the 14.8 AFR. I appreciate the concern for emissions, Ronny, but luckily FL has none that I have to worry about.

For the median swing, are you talking about the "Idle O2 Rich/Lean Slow Zero Error Low" and "High"?

As a minor question, does locking the converter at lower speeds put too much strain on the trans? I know this shifts will be slightly rougher, but if I remember correctly, the efficiency of the converter at lower engine speeds is much less than higher engine speeds, so maybe the trade off is worth it?

Please bear with me as you guys read this. If you know of links that will help answer my questions, those are well appreciated, as I don't expect you to waste your time posting something here that's been posted before.

Ronny

iTrader: (1)

What MAP value? Dont Know. I dont have lap at office. I think I cruise at 50 MAP 72 MPH. I see my WB in hyway move from 14.7 + or - b4 HWM to high 15's low 16's to 16.8 or so.

I did once experience in HY-M engine break up at 17.x for a few seconds but then came back to 16's. I think I enrichened the following day possibly 0.3.

The disable enable can be changed to allow sooner disable later but I see not by much.

WB can be used in place of a NB. The a/F can be patched into the datalog. I have not done either. Yet.

Yes on the heated. Will go CL sooner and keep CL in cooler temps. Especially for headers. Use stock location. Not so on the WB sensor.

Rich median lean I believe is a diff table. They are the swing points in Volts above and below .450.

Ransford2987

Thanks for the help! I think I'll do some tuning this evening and see how it does on the highway this weekend. I'll get back on here with any other questions and thoughts I have during the testing. My goal here is 25-26 on the highway. I'm not sure if it's possible, but it's a nice target.

Ransford2987

I ran the car today as I had to make a trip to autozone. My idle seemed rougher than usual. I did some datalogging and found that on initial startup, the commanded AFR reads near 16.59 for a bit, then drops to 14.79, as I have it set to 14.8. When it warms up, it tends to idle fine but randomly jumps back up to 16.59-ish very briefly and then back to 14.79. That's the only issue I'm really having. I noticed that my MAP never fell to 20 kPa to activate the DFCO, so i raised it to 28 kPa for enable and disable at 31 kPa. Although, I did manage to fix my cruise control, as it had a broken vacuum line, so maybe I should run it back at the normal settings to see if my MAP values are lower since the fix. Does anyone have any thoughts as to why my AFR starts/jumps at/to the mid 16's? The only AFR setting I've changed is the Highway Mode AFR vs. MAP. I know it's difficult to diagnose an issue with a custom tune, but if you guys have any thoughts, they would be much appreciated.

On a side note, I've ordered a heated O2 sensor and the harness to go with it, so I'll splice that in next weekend. Anyone know how soon you can go into closed loop after startup with a heated O2 sensor?

Schrade

Your BEST fuel economy will START with a good spray pattern from the injectors.

AFR maintenance by ECM is based PARTLY on what's already burned (or failed to burn).

So, on the highway, you'll get ok economy, even with a bad burn.

But idle and low RPM burn quality STARTS at the injectors. Good STATIC fuel pressure (motor off), and no FP leakdown after 10 minutes, 20, 30, etc. Dynamic fuel pressure usually follows suit of static, IF the vacuum supply to FPR is PERFECT, and STEADY!!!

Yours an LB9? Or L98? My '87 L98 stock was good for just under 28 highway, and '94 LT1 held JUST under 33 at 54mph. Sure didn't take long to go down when the hammer fell

Ransford2987

I know what you mean. If i drop the pedal to the floor, I can watch my gas gauge drop . I had considered replacing the injectors, as I've owned the car for a few months now and enjoy doing maintenance that will help in the long run and give me a better running car. I've replaced a lot of things and fixed almost everything else on the car thus far, other than the valve guide seal that's leaking, and I've noticed that the injectors look to be mismatched, indicating that the PO replaced a few here and there. I'll probably end up buying a set and swapping them out in the future, but that's difficult to do in an apartment complex in Tampa where it rains every day. It's nice to see someone getting in the high 20's with their mpgs on an L98, which is the same thing I have, btw.

On a side note, what kind of mileage do you see in town or city driving? I'm averaging around 19-21 mixed highway and city, but that's before the recent tuning I've done.

What other tunes have you done to your stock L98?

Any preference on injectors?

Are you still using the recommended 91-93 octane?

As always, thanks for the comments and advice from all!

Schrade

I think JonB / FIC Injectors is probably the best. He has good turn-around time, even for flow match and clean your OEM's (for any who still have them installed).

You can Ohm-spec the injectors (when hot) for starters. They get electronically 'lazy' after a while, and you get bad spray. Think water dripping from a leaky water hose sprayer.

Make sure there's no vacuum leaks in the TPI. MUCH is governed by vacuum... http://www.corvetteactioncenter.com/...ml#post1126308

I went with 87 fuel in the '87 L98; I don't remember if the squeeze called for premium.

Replacing parts is fine, but good vacuum, and good grounds in the harnesses is FAR more important. Get scanning software, and see both of those things in the computer, as voltages, then compare with spec voltages in your FSM factory shop manual. They're hard to 'see' otherwise.

Ransford2987

I'll have to check voltages the next time I do some datalogging. I have yet to check the resistance on the injectors, but since some were swapped before, and to prevent constantly having one fail or another and not being 100% sure about all of them, I'll just replace them all.

I'll give that vacuum leak test a try in the near future when I have some time.

Thanks for the tips!

DENN_SHAH

iTrader: (1)

there are a ton of things you can do to help fuel mileage.
playing with idle fuel & timing can even yield a little bit.
you may even find 15.0~15.2 gives a bit better idle.

getting BLM/INT to 128/128 is a start.
with fuel good, ignition timing is next for good fuel mileage & driveability.
depending on how close is close enough for you, you can probably expect to bounce back & forth a few times.
when tuning fuel & timing, turn off HM.
when tuning hiway mode, don't focus just on hiway mode fuel & forget about HM ignition timing.

if you haven't read them yet, a couple of threads with some info on hiway mode,
https://www.thirdgen.org/forums/diy-...hway-mode.html

https://www.thirdgen.org/forums/diy-...-best-mpg.html

also you can do a search for the user names Grim Reaper and RBob and you should find some more on running HM.
search for Grumpy (rip) he posted a lot of great info including but not limited to titles of "tuning 101" & "Final answers".

if your tuning the factory bin, you may want to take a look at AUJP_V4,

https://www.thirdgen.org/forums/diy-...-released.html

Ransford2987

Thanks for the links! I have been tuning the stock BIN, and haven't yet seen the S_AUJP V4. I've read a little about it and tried to dl it, but I have to register I guess.

I've considered pushing the AFR a bit higher, but cautiously thus far. I like to learn from other's mistakes instead of making them myself, but since it's at least recommended, I'll give that a shot.

As far as the timing, is this the same adjustment normally made for power? Should I be advancing it as much as possible to maintain the lowest MAP at a given speed/gear/etc.?

I read one of the threads linked about logging the amount of fuel used per distance traveled and I'm trying to find that fuel used counter in TunerPro, without luck. I must be missing something here...

I'm waiting on that heated O2 sensor to show up, and waiting for this thursday when I have to drive from Tampa to Orlando to get some good datalogging and to test the changes I've made thus far. That will be a good test with some mild tuning to see what I get. Fingers crossed!

One last question, what are some benefits to tuning the AUJP V4? I saw some benefits in the thread posted, but how are the "selectable" features utilized in the BIN itself? I get that you can select certain things for viewing in TunerPro or Tunercat, but how the engine's ECM is able to use this information is my main question. Should I stop tuning the stock BIN and just get the V4?

Thanks again for all the input. Even if what's posted is something I've seen before, it's still nice to know I'm going about things the correct way and it helps in case I missed something.

Ransford2987

After a few times of trying to drive from Tampa to NW Orlando on I-4, I constantly found myself in traffic on the highway. Needless to say my mpg's weren't very accurate to what my tuning might have provided me with better traffic. I managed to average around 20 mpg's with city and highway. I'm also finding it difficult to put the same amount of gas in the car every time. The needle always seems to be in a different place after I fill up. I still plan on replacing my injectors, but that will have to wait until I have some time available. Once I replace those, I'll see if that makes a difference to my mpg's. I also need to check fuel pressure and make sure that's accurate and holding pressure correctly.

What are the rest of you getting as far as combined city/highway driving with the 5.7/A4?

Ronny

iTrader: (1)

I am about 20 on average but 3.07 gears with a 5 speed manual trans. However I run 75 lbs injs at 21 lbs FP. My WU shows under hyway mode(16.9/1) about 25-27 MPG at 70 mph. funny at 4th gear of five WU whows nearly same gas mileage yet I am taching 2400 vs 1900

Ransford2987

I have 3.27 gears, and the 4 speed, so I wonder if I'm capable of achieving that 25-27 mpg's. I still have yet to set my AFR that high for highway cruising, but I'll get to that soon. I'm trying to leave certain things constant so I know exactly what kind of change I get from installing new injectors and the heated O2 sensor. I'm not expecting much by way of the O2 sensor, but it should definitely help. I hate the idea of losing mpg's just for warming up the car. Thanks again for your input, Ronny!

armos

I think you might be misunderstanding the stoich air/fuel ratio setting. This doesn't actually set the desired ratio. Due to the way a narrowband O2 sensor works, it will always switch at the actual stoich point.
What that setting does is tells the computer what the stoich point is. It's not a target, it's a reference point. When it sees the O2 signal switching between rich/lean, it will assume that the current A/F ratio must be whatever you defined as the stoich ratio.
So if you set that to 14.8, it believes that the switching point is 14.8, even if it actually isn't. With ethanol-gas, the stoich point might actually be more like 14.3 or whatever.
The O2 sensor isn't accurate outside of stoich, so the ECM has to rely on the indicated stoich value as a reference point. By blindly adding or subtracting some amount of fuel from stoich, it will attempt to hit a non-stoich value, such as highway lean cruise or power enrichment. So if the indicated stoich value isn't accurate, it would throw off the accuracy of hitting the lean cruise or PE ratios.

If you have the stoich value set leaner than reality, I believe the effects would be:
1) It will make the base fuel calculation less accurate (too lean), and then feedback from the O2 would cause BLMs to increase.
2) Due to the reduced distance between the stoich value and the commanded highway lean cruise ratio, the actual mixture at lean cruise would be less than commanded.
3) Likewise, because of the inaccuracy of the stoich reference, the actual ratio in power enrichment mode would be richer than commanded.

Points 2 and 3 would both happen because it's using the stoich value as a reference point. If that reference point isn't accurate, it throws off it's calculations when trying to hit a non-stoich value.

I'm not sure if I explained that very well. And if I'm misunderstanding something, somebody please correct me.
The basic point is that changing the stoich value doesn't change the actual switching point, only the ECM's perception of it.

Ransford2987

So, if I'm understanding this correctly, the ECM will always find the switching point to be 14.7/1, and changing the stoichiometric value to 14.8 doesn't actually change that switching point. In O2 sensor language, that's around 450 mV that's always going to be the switching point between rich/lean that the ECM will identify.

When you refer to base fuel calculation, are you referring to the VE tables? If I have the above correct, and feel free to let me know, what does changing that stoichiometric value actually change, referring to parameters or how the ECM uses that input? Can you give some clarification here?

Referring to point #1, can you help explain why the BLM's would increase? Is that based on my question above, and as far as the VE table values? Or does the ECM reference the 14.8 I've input, get to the switching point at 14.7/1, and then lean it out from there to what MIGHT/SHOULD be 14.8? #2 makes sense, and #3 makes some sense, but I haven't really delved into PE mode as of yet.

Your comment on ethanol enriched (mixed I think is a better term, as it doesn't enrich anything...) fuel brings about a good topic of conversation. What values need to be adjusted to correctly tune for the types of gasoline used today? Does anything need to be adjusted, or is there any way to account for the 14.3 stoich point mentioned, or any other effects of the added ethanol? Granted, I could just go down to some marine gas station and pay a dollar more for unmolested gas, but financially I don't have that option.

RBob

iTrader: (1)

Good reading material:

https://www.thirdgen.org/forums/diy-...ng-points.html

RBob.

Ransford2987

That is an excellent read! Thanks for that, although it's probably something I should have read on my own, though it wasn't until recently that I realized I didn't quite understand this correctly.

Now, as I read this info, I tried to find the correct tables referred to so that I can adjust the upper and lower rich/lean O2 thresholds, but I can only find one in tunerpro: O2 Rich/Lean Upper Zero Reference Error Slow Vs. MAP and it reads as such (why aren't these values closer to .45V?):
MAP Volts
20 .62
30 .65
40 .67
50 .67
60 .65
70 .63
80 .58
90 .56
100 .55

A quoted excerpt from the link above: !) The slow filtered O2 error term is the delta of the current slow
filtered O2 value and the proper window boundry, upper or lower. This
term is then used to lookup the proportional gain error from another
table.

The lower window boundry is used to calculate the error term whenever
the O2 Sensor is below that value. The upper window boundry is used
whenever the O2 Sensor is above that value.


This error value is then used to lookup various proportional values. If
the Slow Filtered O2 value is within the window, no proportional
correction takes place (prop term = 0).

So if I understand this table correctly, this is the upper error threshold that is used if the slow filtered O2 value falls outside these values, and thus references a proportional value necessary to adjust the PW of the injectors? Is there only an upper limit? I can't seem to find anything else, other than idle R/L O2 lower and upper threshold, which again from the link above, is to adjust the idle to make it slightly richer? The lower is .56V and the upper is .6V from the stock bin I'm currently editing.

I'd like to adjust the upper and lower thresholds here so I can actually adjust the AFR, but I'm unable to find the correct label in Tunerpro....has anyone else encountered this? Maybe I'll try a different XDF.

On another note, I think I'll also adjust the idle R/L O2 upper and lower thresholds to see what changes are noted during idle.

thanks again for the info!

Ransford2987

Armos,
I definitely appreciate this info, and after more reading I now understand it. I'm glad you could see that I was misinterpreting and were able to help me correct my deficiency .

kevm14

Yes, armos nailed it. If our ECMs did more on the basis of lambda and less on the basis of specific AFR, we would be in better shape, at least for fueling. Highway mode also will need more spark advance, so keep that in mind. I did some playing around with lean burn on an LT1 (8051) which does not have highway mode code, so I first played with O2 switching points and that went terribly. Then I went OL and that went better except there was no way to control the AFR by MPH. I had it idling lean with a bunch of extra spark advance. I got it running alright but I don't think I increased fuel economy more than 1 or 2 mpg so I ultimately put it all back to stock. This was in a heavy Fleetwood, also.

RBob

iTrader: (1)

The other two tables aren't in the super_8D ECU file. They should be added.

The reason the table values are high is that the AIR system when in divert or goes only to the cat-con, subtracts about 100 mV from the table values. See this value:

AIR Rich/Lean Reduction Volts

RBob.

armos

No problem, and honestly, I need to look over the info in the last few posts myself sometime because those O2 threshold settings are new to me. I don't think the ECM in my car has any tweaks for that, or at least it's not exposed in Tunerpro.
This tuning stuff gets really confusing. It's mostly this website that has helped me to make some sense out of it.

Earlier you asked why the stoich value would affect BLMs - I'm not sure if you are still wondering about that. The reason is because the indicated stoich value is one of the parameters that influences the fuel pulse calculation. If the ECM expects stoich to be a leaner ratio than it really is, then it will calculate accordingly, and end up lean. Then the feedback from the O2 sensor causes higher BLMs, which push it back to the actual stoich point.
I changed that stoich value on my car a few months ago, and was kind of surprised how much the BLMs were affected by it. Of course I have no idea what the correct value really should be, other than rigging it to make the BLMs look good. To answer that question, I almost think it would be worth doing a test to find the local gas' actual ethanol content.

Ransford2987

So if I have AIR disabled, then I should probably adjust these tables accordingly to remove the ~100 mV offset added by the AIR diversion.

My goal now is to figure out how to adjust the Upper and Lower O2 thresholds to completely adjust the actual stoich point for the AFR. In the meantime, after what I've read, won't adjusting the AFR value still lean it out, if slightly? It may not be the complete or correct way to do it, but it should work for the time being, right?

kevm14, I haven't added any spark yet for HWM, and haven't had any issues, but that doesn't mean it can't be improved. How much do you recommend advancing it, up into the 1800-2500 RPM range? I've added a small amount of timing to the spark tables-no more than 2* in any cell-and don't want to run the risk of detonation

Armos, I just want to be sure I'm understanding correctly: with inputting a leaner AFR, the ECM will adjust the PW of the injectors, causing it to be leaner. This in turn causes the BLM's to rise, as the ECM responds to the O2 sensor feedback sensing that leaner exhaust. A question to follow, though, if the change is slight, won't the increase in BLM's cause the INT to attempt to bring it back to 128, and thus the normal 14.7/1 AFR?

RBob

iTrader: (1)

Only if you also zero out the AIR correction for the O2 voltage.

Read through that fueling paper again regarding your other questions.

RBob.

kevm14

It's funny, as I recently realized this myself as I've been tuning this 292 truck with TBI. Adjusting stoich from 14.7 to 14.1 did make BLMs go down, so I had to remove fuel (I think). The most important thing for EVERY reader to realize is that the narrow band's job is to always target stoich, though you can certainly mess with that with the swing thresholds and such. If the BLM has adjusted, it found stoich in CL, regardless of any other settings, and importantly, regardless of what stoich actually is for your fuel. But without knowing the actual stoich AFR, your VE table will be wrong. Which is obviously not a good way to run the show.

I thought Haulin did a pretty good job explaining his methodology on this stuff: https://www.thirdgen.org/forums/diy-...ime-6.html#258

Very thorough approach. I like how he tunes in VE using 13:1 commanded AFR, then re-enables closed loop and tweaks the NB O2 parameters. Problem is, even the WB is still a lambda sensor, I believe, so you still need to tell it the stoich AFR. Someone could figure out how to rig up an ethanol sensor from a flex fuel GM. Ideally, this would feed into EBL for an on-the-fly stoich reading. The extra mile would be to get lambda out of the TT-1, then when EBL did the final figuring for AFR, it could take the current stoich into account for the log. Though evidently GM has moved to a software ethanol sensing solution, which seems kind of crazy. http://www.autos.ca/auto-tech/auto-t...x-fuel-system/

Adjusting the stoich AFR value won't do anything if you have closed loop fuel control. You need to change the NB O2 swing points if you want to target a CL AFR other than stoich OR if you have a situation where there is excess oxygen in the exhaust (AIR, lots of cam overlap, or for the really lazy, tune around an exhaust leak!).

What do you have for heads? High swirl should get by with maybe 2° at high load, tapering down to a few more at low load. A less efficient head may need more highway SA to get your peak cylinder pressures back where they need to be on the stroke. The burn is slow. Not enough highway SA would probably drive up EGT.

You're saying inputting a leaner stoich AFR? Yes it would be leaner, but you end up back at stoich. It's only 14.7 if you are running straight gas.

Don't think of it as targeting. It's more for the ECMs information. Stoich is stoich, and it's one thing if that's 14.7. But if it's actually 14.1 (E10), your learned VE will indicate the engine was more efficient than it really is. Correct the stoich value and your 128 BLMs should suddenly decrease to 123 or so. It was always running at 14.1 (or whatever stoich is) but your VE was set as if stoich was 14.7. Think of it this way: if you tuned your VE for a 128 BLM, and your REAL stoich value was 14.1, but you told the ECM 14.7, then when you finally tell it the truth (14.1), it says, "oh, all this time I thought I was running 14.7 but I was really running 14.1" which is why it ends up lowering the BLM. It thought it was getting by on less fuel, but it was really more fuel (lower actual VE than it thought).

I can see I am still struggling with this concept myself as I attempt to explain it. Going to extremes may help. Imagine a scenario where you thought stoich was 20:1 and you told the ECM that. But stoich is actually 10:1. Meaning it needs TWICE the fuel just to burn at lambda = 1. If you tried to fill in your VE tables like that, you'd probably end up with VE of nearly 200% at the torque peak. As you drive around, your BLMs would be going nuts, pegging at 160, because it's doing a calculation of targeting an AFR of 20:1 in CL. So you end up increasing your VE all over the place just to get the BLMs under control, making the engine look all kinds of efficient. But 20:1 isn't nearly enough. If it assumes a stoich AFR of 10:1, it'll add a TON more fuel, and your VE will actually reflect reality.

jjcuff1

Ransford I am in the tampa area too. Post hp n Clearwater

Ransford2987

Hey guys, I definitely appreciate the information you've given, and the attempts to dumb it down for me. I thought I understood things well, but my lack of understanding exactly how the ECM calculates the PW and uses the stoich input AFR has had me questioning other things as well. I've been away from my car all week, but the changes I've made to my BIN will be tested tomorrow. I have:
Changed the AFR back to 14.7
Adjusted the VE tables back to stock
Disabled HWM for the time being until I can get good BLM counts and CORRECTLY adjusted VE tables
Disabled AIR and set the voltage offset to 0 (the GM dealership that replaced my cats didn't reconnect the AIR Lines correctly, and instead plugged them...)

If you have any other recommendations, let me know. For now, I need to get the BLMs adjusted correctly and get a good baseline.

Ransford2987

I haven't updated this in a while. Since the last post, I have changed the injectors and tuned the VE tables a bit more. The southbay injectors I bought made it harder to start, which is probably an adjustment of the crank pulse width, though I don't know which way to go, longer or shorter pulses. All in all, I'm getting somewhere between 26-29 mpgs on the highway, so I'm more than satisfied with highway mode and the other adjustments I've made. My next goal is to get the city driving mpgs a little better. I average around 16 now, which is normal.

Does anyone know how to adjust the O2 swing points using Tunerpro? That's probably limiting most of the progress I could make to increase city mpgs...

Dominic Sorresso

One thing about this board is how it is so cool to re-read things you "think" you know about. Always some little nugget you pick up or do a face palm DOH!
I forgot about that. Really valuable resource.
Anyway, reading this thread it brought up a couple of things.

1. The INT delay - so with long tubes, is there any guide as to how much additional delay you should consider?

2. When it comes to the AFR using 10% Ethanol, which we have in abundance in the Midwest, I have my stoich is set at 14.3. With my ZT-2 WB, I can see the AFR sitting around 14.7 w a Lambda of 1, but just to clarify. Lambda is actually reporting on a 14.3 AFR even tho the WB shows 14.7. My 128 BLM is also reporting on the 14.3 stoich since I made that change in the cal. So in tuning for E85, as an example, I need to focus on Lambda, not the AFR. If I were to set my cal at 9:1, I would tune so my Lambda shows 1.0 even tho the WB AFR reads 14.7? Would the NB O2 sensors still be useful for C/L in this case, or do you just run O/L for something like E85?

Ronny

iTrader: (1)

Dominic nailed it as usual. When WB set to 14.7 for lambda E10 when completely burned will show 14.7 or 1.0 L. I run E10 and my WB defalt is set to 14.7 for Lambda. So i never changed it. I probably will when I have more time.

My stoich is set to 14.1/1 in constants. My rich lean median is 5% above stock values in my .bin. Typically I see 14.0 on my WB at idle at 700 rpms.

Dominic Sorresso

Ronny,

Then the question becomes when using E10 for example, should Lambda for WOT (shooting for say 13:1) be .86? ie (14.3/14.7)*(13/14.7) =.86. Or is it 13.0/14.3 = .909 Lambda. Am I tuning using Lambda only and if I see 13.0 AFR, is that leaner than my target AFR?

Ronny

iTrader: (1)

14.13 is stoich for E10. so 13.0/14.13 = .92

I believe the above is quote is correct

hhmmm. Is not 13.0/1 a bit on lean side? I am thinking 10% ethanol may burn hotter raising the combustion temp from say 1250 degF to ? We dont have jetting but I recall my sleds needed richer jetting and lower timing for E10.

Dominic Sorresso

Ronny,

I have found w dyno runs that the LT-5 develops more power as the AFR is leaned out. What's interesting is that power is not knock limited. If you run it leaner and/or increase timing, power just drops off but you don't see knock. Knock shows up at about torque peak which comes in between 4500-5500rpm. Timing there is at 23-24d, then cranks up to 31 thru 7500rpm.
The CR on the motor is at 11.5:1.
So on the dyno, I'm tuning to an indicated 13:1 on the WB. I have not watched for Lambda but will from now on. If the WB is showing 13:1, is it actually 12.6 (14.3*.884) w the corresponding Lambda?

RBob

iTrader: (1)

Best power Lambda is typically in the .86 - .88 range. Going between Lambda and AFR is easy. Using 14.7:1 as stoich and 12.8:1 as best power (gasoline):

12.8 / 14.7 = .87 Lambda

So if E10 stoich is 14.1:1 then:

14.1 * .87 = 12.3 AFR for best power

Although, as noted need to reprogram the WB controller for the different stoich value. Otherwise it will still output gasoline AFR's.

RBob.

Ronny

iTrader: (1)

Makes sense to me!

Dominic Sorresso

So RBob, my WB 13.0 is actually 12.6 using a 14.3 AFR for E10.

RBob

iTrader: (1)

First convert 13.0 to Lambda based on gasoline at 14.7:1 (stoich):

13.0 / 14.7 = 0.884

Then convert the Lambda of 0.884 to AFR based on E10 (stoich of 14.1:1):

14.1 * 0.884 = 12.5

Just using Lambda, the 0.884 is a tad on the lean side.

RBob.

Dominic Sorresso

From 2008

Re-reading previous posts and re-confirming. So not necessary to reset O2 swing points for 128 when tuning for E10. Just change Stoich AFR in cal? Which is what I have done.

Ronny

iTrader: (1)

I found this above post by Grumpy in stickies.

It would appear raising the values in lean-rich-median would tend to make the car run richer than stoich. If that is your desire, then would you also need to set stoich value in .bin to say 13.9 for E10?

Dominic Sorresso

OK. I understand now. That's why just setting the Stoich AFR does the trick because the switching point will be for whatever fuel basically. And since AFR adjusts the PW, more fuel will be added(if lowering the AFR) correspondingly to hit 128.

jjcuff1

SO setting the scalar value to 14.2 say for E10 which here in florida is noticeable in the gas during the winter will richen things up?

That might help my lean 140 BLM

Ronny

iTrader: (1)

[QUOTE]SO setting the scalar value to 14.2 say for E10 which here in florida is noticeable in the gas during the winter will richen things up?[QUOTE]
I believe stoich for E10 is 14.1x. If running E10 it will place it(A/F) at stoich not richen it. If your BLM is 140 you are not lean you are stoich as the ECU is doing its thing(adding fuel). Low or high BLM is not rich nor lean

jjcuff1

I understand stoich and for E10 it is lower at 14.2 but if I am at 14.7 in the bin the ECM is running stoich for 14.7 and therefore lean. So at 14.2 it should richen it up to be stoich at 14.2? My questions is: if I play with the AFR in the bin up or down does it globally effect the ECm to go up or down driving the o2 switch points and the BLM conditions?

sort of like a changing the o2 switch points on a narrow band simulator.

Ronny

iTrader: (1)

See post #40. Setting the stoich to 14.7 in .bin when it should be 14.1 will drive up BLM and cause you to increase the VE table so as to show 128 + or -...

I believe to enrichen the CL A/F you need to change the stoich constant to a lower # than it should be for that fuel(E10 maybe 13.7?) and move the switch points approx 5% higher.

Dominic Sorresso

Forget AFR for a moment and think in terms of Lambda. Lambda is "agnostic" to the type of fuel being used. A Lambda of 1 is always stoich for that fuel. If you are burning E10, a Lambda of 1 occurs at an AFR of less than 14.7 for a WB calibrated to E0. By telling the ECM you are shooting for an AFR of 14.3, the ECM uses that as part of its PW calc, automatically making the mixture richer in respect to a 14.7 stoich, but correct for a 14.3 stoich.
Now I understand that when I see a Lambda of 1 on my ZT-2, it's saying that I am at 14.3(the AFR commanded in my cal) although my AFR gauge reads 14.7.

As an aside, anyone know if the ZT-2 curve can be changed to display the correct AFR? Haven't seen that on their website.

Ransford2987

I'm going to bring this back up for a sec for DFCO. I made some changes to my DFCO parameters and noticed my injector PW drops to 0 when decelerating from a higher speed, >50 mph, but jumps back up once I reach I mid 40s. Also, I see no change in the AFR during deceleration; it holds the same value for the lowest MAP highway mode until I reach 42 mph. I always thought DFCO would only cause the AFR to be extremely lean during deceleration, not necessarily zeroing out the PW. Is that what's causing this? Why am I not seeing a changing AFR?

RBob

iTrader: (1)

With the PW at 0, the reported AFR should be as high as can be shown on the WB.

Unless there are leaky injectors or a leaky FPR.

And a PW of 0 is correct when in DFCO.

RBob.

Ronny

iTrader: (1)

In DFCO my A/F is 20+/1 after the residual fuel is pulled off runners. As stated above WB is maxed out. I think it resumes pulse at around 40 mph otherwise it could stall the engine if I were to brake while at 40 mph to 0. I suspect I could reduce to 30 but dont see much value vs risk of stall.