Why are most professional "tuners" doing Flex Fuel timing wrong?

[mJolnir]

Ok that makes sense - e85 loves timing in the mid airmass areas where your adding a lot - not sure you needed that much, but that will fix take off stumbles - negative timing for deceleration stumbles - don't know - haven't had that problem before?

its a stock flex fuel spark table from a 5.3, i just added a couple degrees on the 0.64-0.92 region when i was at the dyno trying to extract a bit more power out of it.
on that same table 0.40g and under its taking timing away, i will set all that to 0 and see if the stumble comes back.

just downloaded a stock tune from a 2011 6.2 silverado and the flex fuel spark is totally different

[gmtech16450yz]

Good discussion guys!

I have a couple quick thoughts and a link to throw in here. The first thought was what I previously mentioned about the factory guys building these tunes having their hands tied. I still say much of what they put in these flex fuel and pump gas tunes/tables is constrained by emissions laws. They can only run the engine so "dirty", it puts more load on things like the cat converters and increases the chance that their tailpipe emissions will be too high. I'm sure if they could build these tunes without worrying about what comes out of the tailpipe that these tables would look a lot different.

Second is how advanced/retarded ignition timing effects the way the engine "feels" and a lot of the time it won't show those differences on a dyno. Retarded ignition timing makes an engine feel sluggish and lazy. On the other side, ignition timing advanced more makes the engine a little more "revvy". (lol. Is that a word?) I always describe engines as being "happy" or "not happy". Weird I guess but when I find an engine that runs clean and feels like it just wants to rev and make power, it usually has a healthy dose of ignition advance.

So much of this stuff can be felt with experimenting with BIG changes. Even I can't say I can feel the difference of a 1 degree ignition timing change. I can guaranty 99% of us all can't feel those small changes, even though you SWEAR you can. The placebo effect on stuff like this is huge obviously, it's the hardest part of tuning. Set up a double blind test and there's no way in h#ll most people could tell when the timing is changed only 1 degree forward or back. So when you're experimenting with this stuff, go big! You want to see if retarded timing with E85 makes more power or makes the engine run differently? Put in -5 or even -10 degrees in those modifier tables. Can't feel a difference? Try going the other direction. (As long as you're not talking about WOT and your knock system is working, adding 10 degrees in the low or midrange load areas and just going for a quick drive shouldn't kill anything.) If at that point you can't definitively tell which works better, you should probably quit tuning!

Just a quick example of the placebo effect and real effect. I have a dual mode ignition timing map switch on the handlebar of my YZ450. I can change between several different maps, but the handlebar switch is only programmed to switch between my best curve and the stock curve. My best curve is advanced pretty much all the way through the rpm/load range. Anyway, when you flip the switch back and forth the difference in the way the engine runs is obvious. But how do you know you're really feeling a difference and not just assuming it's stronger because you put the switch in the hi power position? Sometimes when I'm riding I'll bump the switch and it will go to the stock position. Within a minute or two I'll be riding along and start thinking "damn this thing feels sluggish, wth is going on?" I then look down and realize the switch got bumped to the stock position. THAT'S a solid test and indication that there really IS a difference that's not clouded by the placebo effect.

How can you do that with this tuning thing? How about this... Make 3 tunes, one what you're running on now, one with the flex fuel timing advanced and one with it retarded. Have your wife or somebody else name them with random names and close them so you don't know which is which. Like "tune joe", "tune sam" and "tune fred". Now try all 3 of them in your car and see if you can rate which one is best to which one is worst.

Lastly, here's a link to a PDF I found awhile back. There's a ton more like this on the web, you just have to look for them. I really like tests or studies like this because they're usually done at Universities by smart people that know how to conduct proper testing and comparisons. None of this "Well my buddy tried E85 and his mileage and power doubled" cr#p!

Enjoy!...

https://www.researchgate.net/publica...aust_emissions

[LSxpwrdZ]

I'll have to try the negative timing in the adder table again next then - I haven't seen any benefits to negative timing in this table before or negative timing benefits to the flex spark table either - I've been getting about as good a fuel economy from E85 as I do from 93 minus 1 to 1.5 mpg of course with the minor positive timing...

As far as keeping the timing tables smooth - I always paste special add to the main timing table and adjust timing according to this - no weird feelings at all when switching between the tables... Would be curious to see how this would turn out with James's table above...

I'll re-evaluate for any benefits once again for doing the negative timing...

This is what I meant using the tools within the editor to make sure your flex spark is dialed in properly. I will paste special add into the main spark table to get a visualization of what the timing table actually looks like when in ethanol fuel is being used. You can then adjust that table and open a compare file with the regular gas spark table and view the difference and there is your flex fuel adder table.

As you can see in the timing tables below, the mid range cylinder airmass has quite a bit more timing advance.

Gas Spark.pngEthanol Spark.png

If you see gains adding timing with ethanol at very light loads then you probably don't have nearly enough timing in the gas table. With ethanol and too much timing at light loads you'll see your oil temperature rise. I use an eddy brake dyno that I do all my timing adjustments on and if power isn't going up when I'm adding timing then it's at the limits of that fuel at that particular load point. A Plex combustion analyzer is on my list of tools that I want for calibrating spark tables much more closely. But I don't have enough pennies in my piggy bank to get into that system yet.

[schpenxel]

A Plex combustion analyzer is on my list of tools that I want for calibrating spark tables much more closely. But I don't have enough pennies in my piggy bank to get into that system yet.

How much do those run?

[Area47]

i have run into this as well. most recently on the V cars. the FF table is there for a reason and is active when done right. most of them have the mentality of "get it in get it out, money money money" hold on padre, all you're doing is cheating the customer in the end. There is variations in the fuels and the timing that need to be done. Whats going to happen when it is at 40% mix, or 20%? too many what if's and not enough time working with it. stop being lazy and give the engine what it wants, not what you think it needs.

[GHuggins]

I know that these comments weren't meant towards me. I know there isn't anyone who spends as much time dialing this stuff in as I do.

James your saying that you put the difference of the tables into the adder table? Just wanted to clarify that's how it's supposed to be done.

[gmtech16450yz]

I know that these comments weren't meant towards me.

Interesting comment I wanted to respond to even though it had nothing to do with me.

I've noticed something about this forum and tuners in general. If you're a professional tuner AND you're a contributing member on here, you're one of the good ones! Honestly, it's the professional tuners that never come in here or contribute that are the ones you have to question. Think about it, if you're not really that good and you know it, you sure as h#ll aren't going to be on here where you're exposed and vulnerable. Like I previously mentioned, the way I worded this thread guaranteed that no professional tuner was going to come in here and say "Oh I NEVER work that flex timing table, it's stupid and GM makes things more difficult than they need to be". lol. How many guys on here that really know what they're doing would have a problem with that and would probably stomp all over it? I would think a bunch. So the guys that are doing this kind of shoddy work aren't the ones that are going to be in here discussing it.

So in other words, I wouldn't ever worry about somebody on here questioning your tuning abilities. In my opinion you wouldn't be here if you didn't care about doing a good job. And if you are doing things that might be the "wrong" way, you wouldn't be on here discussing them if you couldn't admit you can always learn how to do things differently. It's the ones that think they already know everything that won't be on here. After all, if you already know everything, why would you be on a forum that's all about learning and sharing information and knowledge? In my humble opinion, you guys aren't the "problem".

[gmtech16450yz]

stop being lazy and give the engine what it wants, not what you think it needs.

Excellent post but I especially liked this comment. We had a discussion elsewhere about working with a tune file vs. a log file. That's pretty much what you just said, basically look at the logs and don't just throw some numbers in a tune. Anyone can copy and paste values into tables in a tune. Heck, a lot of these "tuners" simply copy and paste tables from one car into another with similar mods.

They only really know how to work the tune file, they don't really know how to interpret what the logs are saying. The tune file is simply what you "think it needs", the logs are what it's really getting. Is it getting what it needs? How would you know if you're not very good at looking at logs. I've always been amazed by looking at config/layout files from tuners. Half of what they really need to be looking at isn't even being logged. Why? Because they don't know what all those squiggly lines mean. Understanding the nuances of logging traces is exponentially harder than simply throwing some numbers in a table in a tune file.

So yeah, they need to concentrate more on seeing if the engine is actually getting what it needs instead of simply changing some tables and sending the car on it's way. Will that happen? Doubtful. I will say this though... There's a vendor/tuner on the CTS-V Owners forum that's gonna wish he spent more time looking at and understanding his customers logs though. An unhappy customer just blew them and their reputation out of the water.

[Area47]

Excellent post but I especially liked this comment. We had a discussion elsewhere about working with a tune file vs. a log file. That's pretty much what you just said, basically look at the logs and don't just throw some numbers in a tune. Anyone can copy and paste values into tables in a tune. Heck, a lot of these "tuners" simply copy and paste tables from one car into another with similar mods.

They only really know how to work the tune file, they don't really know how to interpret what the logs are saying. The tune file is simply what you "think it needs", the logs are what it's really getting. Is it getting what it needs? How would you know if you're not very good at looking at logs. I've always been amazed by looking at config/layout files from tuners. Half of what they really need to be looking at isn't even being logged. Why? Because they don't know what all those squiggly lines mean. Understanding the nuances of logging traces is exponentially harder than simply throwing some numbers in a table in a tune file.

So yeah, they need to concentrate more on seeing if the engine is actually getting what it needs instead of simply changing some tables and sending the car on it's way. Will that happen? Doubtful. I will say this though... There's a vendor/tuner on the CTS-V Owners forum that's gonna wish he spent more time looking at and understanding his customers logs though. An unhappy customer just blew them and their reputation out of the water.

now im very intrigued by this actually. {the v thread}

What it boils down to is people being lazy. pe rape, flat timing, carbon copy crap from car to car. I have always used the flex fuel adder table for the reason, it is there, use it! You're losing a lot of would be power, or mpg regardless of the blend. no two engines are identical and never will be. spend the time and do it right.

Most people look at the dyno graph as one purpose. numbers. they ignore the dips and peaks from the run and don't even compare that to the log from the car. THIS right here is invaluable information. There is a reason why it dips, or spikes. fix it!

[gmtech16450yz]

now im very intrigued by this actually. {the v thread}

What it boils down to is people being lazy. pe rape, flat timing, carbon copy crap from car to car. I have always used the flex fuel adder table for the reason, it is there, use it! You're losing a lot of would be power, or mpg regardless of the blend. no two engines are identical and never will be. spend the time and do it right.

Most people look at the dyno graph as one purpose. numbers. they ignore the dips and peaks from the run and don't even compare that to the log from the car. THIS right here is invaluable information. There is a reason why it dips, or spikes. fix it!

Haha, the V forum thread should be easy to find. A lot of the best stuff on that forum is in the members only sections, but that one isn't. Actually there's a been few on there recently about tuning. That V forum is a very unique place, not like any other forum I've ever been on. But like I said, most of the good stuff you can't see unless you're a member. And membership only costs between $40k to $100k. lol.

And again, excellent comment! That must be why I remember your screen name from years ago. (I haven't been on here much in the last few years.) It's nice to see an old name, knowing a guy that knows his chit is still on here contributing. It just backs up what I said, you wouldn't be on here for a decade or so if you didn't know your chit but still want to learn how to do things better or maybe a little differently. Or just to help others, which is still pretty nice. I've always had a lot of respect for contributing members here. Cr@ppy tuners/vendors elsewhere that never come in here because they know they suck? Not so much respect. lol.

[Area47]

sent you a pm btw.

The e85 stuff irks me actually. I see it on all gm platforms. "oh we can just do this and get away with it" yeah. no. stop.

"did you feel that?"
"no"
"how about now"
"yea, it's always done that"
"not anymore" ::fixes problem::



Spent years working with the flex fuel vehicles and testing and testing on my own stuff to see what works and what does it. This thread right here is one of the great mysteries for "tuners" for some unknown reason, and i am not even sure why actually. it's simple. spend time with the cars and figure it out. I am still doing this. Almost everyday, searching information to make the cars better. I learn something new to test out, and see what happens. 90% of the time it works in favor after tinkering. {there is a metric crap load of information on this forum, just need to know how to read it} Just because you make 7-800 whp, doesn't mean the car should drive like a race car. No need for that at all.

[dreksnot]

Soooooo.... Asking as a daily driver/weekend warrior wannabe tuner with open ears - what is the best approach to dialing in the timing for light load areas of the spark tables (low to mid RPMs and 0.20-0.60 air) without a dyno, using the wide open street? I've found it very easy to time the WOT spark demands as well as fueling there. But the daily driving stuff is where it demands the most time and effort, to ensure fueling it dead on steady state and during transients, but I've always feared messing with the timing. Does one need a dyno to get max torque timing?

I've attached my most recent street attempt, which I'm currently running 91 octane (E10). The tune does pull about 0.5-1* timing cruising and would add about 1* when getting into the throttle due to the FF spark table. When it warms up some here in CO, I'll put some E85 (actually E70) in the tank and play.

[LSxpwrdZ]

How much do those run?

IIRC around $7k. It's a pretty kick ass unit. I call it a wideband for spark advance! I know alot of people look at stock tunes and wonder why they look so shitty from a visual standpoint but they use these tools to develop the spark tables in a lab. There are lots of spark modifier tables based on various conditions. The afr spark modifier table is one of them. With the ability to monitor peak cylinder pressure in reference to crank angle every one of these tables could be populated. The spark advance per cylinder even could be dialed in. It'd take a few days and lots of logged hours to do but that would be the full on corect way. In this industry though most results are perfectly fine without that level of detail in just the spark tables. So this is why it's normally not done. Wot spark is easy and 90% of the people want power.

http://www.plex-tuning.com/products/...stion-monitor/

I know that these comments weren't meant towards me. I know there isn't anyone who spends as much time dialing this stuff in as I do.

James your saying that you put the difference of the tables into the adder table? Just wanted to clarify that's how it's supposed to be done.

Yessir. Save the tune file with the gas spark set. Paste Special Add the flex spark adder to the main spark table. Open the file your working on as a compare. This loads the 93 tune as the compare file with your flex fuel spark in the main tuning file. When you select difference view it shows you exactly what spark needs to be added to the main spark table to achieve the final result. Gives a nice visual of what the flex fuel spark table will look like when the flex adder table is fully utilized.

Soooooo.... Asking as a daily driver/weekend warrior wannabe tuner with open ears - what is the best approach to dialing in the timing for light load areas of the spark tables (low to mid RPMs and 0.20-0.60 air) without a dyno, using the wide open street? I've found it very easy to time the WOT spark demands as well as fueling there. But the daily driving stuff is where it demands the most time and effort, to ensure fueling it dead on steady state and during transients, but I've always feared messing with the timing. Does one need a dyno to get max torque timing?

I've attached my most recent street attempt, which I'm currently running 91 octane (E10). The tune does pull about 0.5-1* timing cruising and would add about 1* when getting into the throttle due to the FF spark table. When it warms up some here in CO, I'll put some E85 (actually E70) in the tank and play.

Without a dyno or combustion analyzer it's a best guess at best. Some more experienced guys will have a good best guess based on prior work but still to get each combo perfect you'll need a dyno with very good resolution at light engine loads to map out the spark advance for both gas and ethanol.

[schpenxel]

IIRC around $7k. It's a pretty kick ass unit. I call it a wideband for spark advance! I know alot of people look at stock tunes and wonder why they look so shitty from a visual standpoint but they use these tools to develop the spark tables in a lab. There are lots of spark modifier tables based on various conditions. The afr spark modifier table is one of them. With the ability to monitor peak cylinder pressure in reference to crank angle every one of these tables could be populated. The spark advance per cylinder even could be dialed in. It'd take a few days and lots of logged hours to do but that would be the full on corect way. In this industry though most results are perfectly fine without that level of detail in just the spark tables. So this is why it's normally not done. Wot spark is easy and 90% of the people want power.

http://www.plex-tuning.com/products/...stion-monitor/

Very cool

[sevinn]

This is a great thread thanks for starting it and I appreciate the input from folks like GHuggins and LSxpwrdZ. It makes me feel a little better about how I developed my ff table (basically doing the add to main spark and compare method...it's always nice to see people have the same idea about things without ever communicating it), but also show that it will need some work and some dyno rental time to really get dialed in since all I have been using a my butt dyno.

Oh and I found the thread on the V forums...I'm glad the OP got his tune sorted out, but it sucks that he had to go through a motor to figure out he needed a better tune.

[GHuggins]

IIRC around $7k. It's a pretty kick ass unit. I call it a wideband for spark advance! I know alot of people look at stock tunes and wonder why they look so shitty from a visual standpoint but they use these tools to develop the spark tables in a lab. There are lots of spark modifier tables based on various conditions. The afr spark modifier table is one of them. With the ability to monitor peak cylinder pressure in reference to crank angle every one of these tables could be populated. The spark advance per cylinder even could be dialed in. It'd take a few days and lots of logged hours to do but that would be the full on corect way. In this industry though most results are perfectly fine without that level of detail in just the spark tables. So this is why it's normally not done. Wot spark is easy and 90% of the people want power.

http://www.plex-tuning.com/products/...stion-monitor/


Yessir. Save the tune file with the gas spark set. Paste Special Add the flex spark adder to the main spark table. Open the file your working on as a compare. This loads the 93 tune as the compare file with your flex fuel spark in the main tuning file. When you select difference view it shows you exactly what spark needs to be added to the main spark table to achieve the final result. Gives a nice visual of what the flex fuel spark table will look like when the flex adder table is fully utilized.


Without a dyno or combustion analyzer it's a best guess at best. Some more experienced guys will have a good best guess based on prior work but still to get each combo perfect you'll need a dyno with very good resolution at light engine loads to map out the spark advance for both gas and ethanol.

Sorry James,I meant the adder table up above the main spark table. How your describing tuning the ethanol flex advance table is exactly how I already do it. The torque adder table is what I was asking about.

Thank you

[GHuggins]

This is a great thread thanks for starting it and I appreciate the input from folks like GHuggins and LSxpwrdZ. It makes me feel a little better about how I developed my ff table (basically doing the add to main spark and compare method...it's always nice to see people have the same idea about things without ever communicating it), but also show that it will need some work and some dyno rental time to really get dialed in since all I have been using a my butt dyno.

Oh and I found the thread on the V forums...I'm glad the OP got his tune sorted out, but it sucks that he had to go through a motor to figure out he needed a better tune.

You don't have a link to this do you?

[Karch]

You don't have a link to this do you?

http://www.ctsvowners.com/forum/66-t...when-cold.html

[schpenxel]

Not a bad read

[sevinn]

http://www.ctsvowners.com/forum/66-t...when-cold.html

Also this one:
http://www.ctsvowners.com/forum/66-t...need-read.html

I think I misread someones comment about "engine issues" as having lost an engine here, but still bad none the less.