Wide open afr accuracy.
Thread Starter
On The Tree
Joined: Mar 2010
Posts: 112
Likes: 0
From: Iowa
Wide open afr accuracy. O.k. so I've been playin around with hp tuners for awhile doing the maf/ve tuning. I'm at the final stage here with wide open afr tuning. I was running leaner than commanded at first. After a few runs and tweaks I'm closer to target afr at wide open. I'd say anywhere from 1-3 % lean of target of 11.5:1 on average. For a brief moment spot on. but I'm wondering what some you are seeing at wide open afr. When this is dialed in correctly do you all see your commanded afr pretty much flat lined at what you command or do you see the afr slighty move rich to lean and so on?
Thread Starter
On The Tree
Joined: Mar 2010
Posts: 112
Likes: 0
From: Iowa
I tuned ve then maf for up to 4000 rpms. Now doing wide open maf. Data logging the afr % error and adjusting the table. Is the afr supposed to stay steady at commanded or is it normal for it to move around a bit?
There's a lot of bodies in motion and picking the right one(s)
to mess with is the trick. Fuel pressure is fading, exhaust
back pressure is rising, etc. I'd bet on the MAF being the most
realistic out-of-the-box, and avoid faking it lower especially
on an automatic.
In the end you are not tuning for a specific AFR, you're
tuning for performance and safety and you don't know what
the real AFR or indicated AFR "right answer" is for your setup
aside from avoiding ping and determining what makes best
output.
to mess with is the trick. Fuel pressure is fading, exhaust
back pressure is rising, etc. I'd bet on the MAF being the most
realistic out-of-the-box, and avoid faking it lower especially
on an automatic.
In the end you are not tuning for a specific AFR, you're
tuning for performance and safety and you don't know what
the real AFR or indicated AFR "right answer" is for your setup
aside from avoiding ping and determining what makes best
output.
Thread Starter
On The Tree
Joined: Mar 2010
Posts: 112
Likes: 0
From: Iowa
The car is an m6 so I understand that there will be some spikes (percent error) lean or rich while shifting. And I see that the % error is a little higher at the moment it enters w.o. and at the end just as i lift off the gas at 5000rpm. What I mean is through out the duration between 2000-5000 rpm area that im in p.e. tps at 100%. I can't post a log because Im at work, but right at the moment it enters p.e. the error is 3% rich. Then steadily moves toward target. Stays close to target. Then moves on up to 3% lean. Then right as I hit 5000rpm and shift, it touches 7% lean. So my afr goes from 11.0-12.3. So maybe if i copy paste special by half % one more time it'll be closer. From what I understand 12.5-12.7 w.o. afr.is where these engines make the best power. I want to be more on the safe side as this is just a cruiser. But if I command 12.5 the way it is, it would be in the 13s up top. Thats what I'm gettin at here. Is it possible to get the commanded and actual to stay say within 1% of each other through out the duration while at w.o.?
Do your trims lock at 0? The a/f ratio will move some. What is your wide band compared to the demanded? Is it a few tens off? If it is like 12.6 to 12.8 then you are good.
Thread Starter
On The Tree
Joined: Mar 2010
Posts: 112
Likes: 0
From: Iowa
Fuel trims i think were zero or maybe .5 at most i believe. I commanded 11.5 afr wideband is going from 11.0 to around 12.3. Which i feel is too much movin around but i dont know how much is normal.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Yes, you should be able to get the actual closer to the targeted than that... Did you disable the MAF and correct the entire VE table? Then disable the VE and correct the entire MAF table? If you do that, you should be able to get actual almost dead on commanded...
Also, what Jimmyblue is saying is correct - however, I set the commanded tables to a conservative safe value, then correct the VE and MAF tables so that actual equals commanded - then I go to the dyno and work the commanded fuel and spark tables to get the optimized torque/power on the dyno. Basically, it saves expensive time on the dyno by getting things in line before hand...
Also, what Jimmyblue is saying is correct - however, I set the commanded tables to a conservative safe value, then correct the VE and MAF tables so that actual equals commanded - then I go to the dyno and work the commanded fuel and spark tables to get the optimized torque/power on the dyno. Basically, it saves expensive time on the dyno by getting things in line before hand...
Last edited by BLK02WS6; Sep 18, 2012 at 01:30 PM.
Thread Starter
On The Tree
Joined: Mar 2010
Posts: 112
Likes: 0
From: Iowa
Like I stated earlier, I did tune v.e. first while maf disabled and then tuned maf with v.e. disabled. Did both up to 4000 rpm like what ive read. Because they say not to go w.o.t. while doing those areas of tuning. I got my ltft down to practically zero while cruising. So I believe that part is about as good as its gonna get. I've made 4 scans now and at wide open my % error has gotten better each time. So I believe its goin in the right direction. I just simply dont know what to expect as far as whether or not the afr will move around a bit or should it be locked in at whats commanded. This is my first tune. So if the afr on the wideband should be more steady at whats commanded I will continue. But if what i have now is considered normal then I will quit whipping the poor car and move along. Lol
My commanded a/f ratio is within .2 or .3 of commanded. My histogram only logs data if A/f is less than 13.5 air/fuel ratio. I did not want closed loop data, just WOT.
I dont normally get into these discussions any more because there is a lot of info posted on how to do this properly already...
its real simple...
MAF and VE are blended all the time at Part throttle...
MAF us used 100% only when it exceeds the values set in the dynamic airflow tab.
stock, this value is 4000 rpm... this can be changed to suit the needs of your vehicle...
I actually like to set it to a lower value like 1400 rpm so its 100% MAF all the time and VE is really just there for idle, off idle, and a backup plan for when the MAF has issues
this being siad..
start with the MAF Disconnected/failed in the tune...set p0101, p0102, p0103 to set mil on first error, and set MAF fail frequency to 0
start with tuning your VE table at ALL RPM's...including WOT
Just get as close to 0 as possible and slighly on the negative side(better to be slightly rich rather than slightly lean)
if you use fuel trims, then you want to see negative numbers anywhere from 0 to -4%
then you can re-enable your MAF and begin your tuning process on it....
this is where setting that RPM value can be very useful... set it to 400 rpm... well below idle rpm...
then go about tuning your MAF table the same way until you are within a few % of zero error... preferably on the rich side.
then you can set the MAF dynamic airflow rpm value back to whatever you feel comfortable with...Stock being 4000 rpm, or lower like I prefer somewhere in the 1400 rpm range
remember, whatever value that dynamic airflow rpm value is set to, is when your MAF will take full control....
its real simple...
MAF and VE are blended all the time at Part throttle...
MAF us used 100% only when it exceeds the values set in the dynamic airflow tab.
stock, this value is 4000 rpm... this can be changed to suit the needs of your vehicle...
I actually like to set it to a lower value like 1400 rpm so its 100% MAF all the time and VE is really just there for idle, off idle, and a backup plan for when the MAF has issues
this being siad..
start with the MAF Disconnected/failed in the tune...set p0101, p0102, p0103 to set mil on first error, and set MAF fail frequency to 0
start with tuning your VE table at ALL RPM's...including WOT
Just get as close to 0 as possible and slighly on the negative side(better to be slightly rich rather than slightly lean)
if you use fuel trims, then you want to see negative numbers anywhere from 0 to -4%
then you can re-enable your MAF and begin your tuning process on it....
this is where setting that RPM value can be very useful... set it to 400 rpm... well below idle rpm...
then go about tuning your MAF table the same way until you are within a few % of zero error... preferably on the rich side.
then you can set the MAF dynamic airflow rpm value back to whatever you feel comfortable with...Stock being 4000 rpm, or lower like I prefer somewhere in the 1400 rpm range
remember, whatever value that dynamic airflow rpm value is set to, is when your MAF will take full control....
Thread Starter
On The Tree
Joined: Mar 2010
Posts: 112
Likes: 0
From: Iowa
Thanks soundengineer. The stock setting for w.o. was 11.77. When I made my first run at w.o. the afr went up to low to mid 13s. So to play it a little safe I decided to target 11.5. My long termfuel trims are damn close to zero when cruising part throttle and so on. Ltft are a tad rich at idle but thats it. So I feel my v.e. and maf below 4000 not at wide open are good.
As far as the wide open maf afr error goes, its been coming along. A little slow probably because when I got within 5% error I've been pasting it by 1/2%. I was just unsure on what to expect out of this and I dont want to waste time tryin to get the commanded afr and actual to be perfect if its not likely they will ever match up perfectly throughout the time im at full throttle. That and I dont want to break something making several wide open runs a day tryin to get it PERFECT if its not possible. Ive read a ton on this stuff ovef the past couple years but this is my first real go at it. And there are a lot of things that arent mentioned either that a person just has to learn from using hp tuners or whatever.
All that said, im gonna mess with it more tonight and hopefully get it pretty close and then try and target around 12.5 afr and hope it stays close to that mark.
Thanks for the help all.
Hopefully I can post up later its all good.
As far as the wide open maf afr error goes, its been coming along. A little slow probably because when I got within 5% error I've been pasting it by 1/2%. I was just unsure on what to expect out of this and I dont want to waste time tryin to get the commanded afr and actual to be perfect if its not likely they will ever match up perfectly throughout the time im at full throttle. That and I dont want to break something making several wide open runs a day tryin to get it PERFECT if its not possible. Ive read a ton on this stuff ovef the past couple years but this is my first real go at it. And there are a lot of things that arent mentioned either that a person just has to learn from using hp tuners or whatever.
All that said, im gonna mess with it more tonight and hopefully get it pretty close and then try and target around 12.5 afr and hope it stays close to that mark.
Thanks for the help all.
Hopefully I can post up later its all good.
you want to set it so that your Target, is what you want it to be...and then correct the fueling tables till it lines up properly...
again... 11.5 is a lot rich... not just a little...
if you want "a little rich".. shoot for 12.5
I've never toasted a motor NA from being too lean....
I know lots of people that have destroyed a motor from being too rich...
again... 11.5 is a lot rich... not just a little...
if you want "a little rich".. shoot for 12.5
I've never toasted a motor NA from being too lean....
I know lots of people that have destroyed a motor from being too rich...
Thread Starter
On The Tree
Joined: Mar 2010
Posts: 112
Likes: 0
From: Iowa
Ok I'll change it and make it leaner. Stock was 11.77. So when i saw it go up to 13.5 it made me nervous. I didnt show any kr but still made me nervous. The way i understood this was that you calibrate the maf for wide open and when done you can command anything ya want. So do you have to scan and log error everytime you want to tweak the afr?
in theory... once you get the fueling tables dialed in... you should be able to just change the PE table and fuel should follow... but its not a perfect world, and the pcm isnt the greatest at correcting for the uncontrollable mother nature...
so yes, you should always log/scan when you want to change the AFR to make sure its correct.
13.5 is not an issue...maybe a little on the lean side for what a lot of people think... but its not bad, and it wont hurt anything...
detonation on the other hand.. will hurt stuff
and being lean can lead to detonation from too much heat being created in the cylinder and the flame front moving to fast and doing its job before TDC.
tons of completely stock never even looked at vehicles running for 200,000 miles and running at 13.5 or leaner at WOT...
so yes, you should always log/scan when you want to change the AFR to make sure its correct.
13.5 is not an issue...maybe a little on the lean side for what a lot of people think... but its not bad, and it wont hurt anything...
detonation on the other hand.. will hurt stuff
and being lean can lead to detonation from too much heat being created in the cylinder and the flame front moving to fast and doing its job before TDC.
tons of completely stock never even looked at vehicles running for 200,000 miles and running at 13.5 or leaner at WOT...
Thread Starter
On The Tree
Joined: Mar 2010
Posts: 112
Likes: 0
From: Iowa
I set the afr to 12.3 and did another scan. The afr % error dropped to -4%-5%. Staying around 1-2% rich/lean throughout the wide open portion. At the very start and end it showed 12% lean. But that was at the part where i was first in and out of the gas. So it looks better. Maybe tweak just a bit more.
Also my fuel trims went to 0 stft and 1.6% ltft. Someone asked earlier.
I will play with it more tommorow.
Also my fuel trims went to 0 stft and 1.6% ltft. Someone asked earlier.
I will play with it more tommorow.
Did you clean the MAF before you started tuning? If the MAF is dirty it will read lower than actual airflow. The problem with the high end of the maf table is you don't get many cell hits so collecting enough useable data on the street is difficult.