HELP Tuned VE Tuned MAF But Runs Awful

[gmachala404]

I tuned the VE in open loop and it ran good after that was done. I followed the tutorials.

Then I plugged the MAF back in ran it in open loop tuned the airflow vs frequency and it ran good.

Then, I opened my tune and plugged in the new MAF and VE tables and it runs terrible.
Mind you I am still in open loop with O2 sensors disabled. I attached my AFR Error table
you can see it just is nuts. No where close to the 1% errors I had before when tuning them
individually.

What on earth is going on. I have redone this over 3 times and got a new wideband and
it is the same result. When I put the two together MAF + VE it runs like crap.

My combo 418 LS3 stroker with 235/247 113LC cam, long tubes no cats standalone in
a 72 Z28 manual

[5FDP]

I would suggest not unplugging the MAF sensor unless you wired in a separate air intake temp sensor. The factory MAF's have the IAT built into them. Fail the MAF within the tune file instead and do not log any MAF based channels while VVE tuning with your wideband.

[gmachala404]

I would suggest not unplugging the MAF sensor unless you wired in a separate air intake temp sensor. The factory MAF's have the IAT built into them. Fail the MAF within the tune file instead and do not log any MAF based channels while VVE tuning with your wideband.

I hot wired the IAT to keep the IAT reading. It did log the correct IAT temps all the way. I wanted to be absolutely sure the
MAF was out of the equation when I tuned the VVE table in HPT 3. I failed it in Engine Diag as well. I do have a curved
pipe ahead of the MAF with a universal conical filter on the end of the curve could this throw the MAF off that badly to hose
up the tune? It is the stock 2014 Camaro card style LS3 MAF. I have heard you are not supposed to put a curve near the MAF
but I can't do it any other way in the old car.

[gmachala404]

I did notice when tuning the MAF it would switch back and from from rich to lean below 2500RPM every time I would paste and multiply by % minus 1/2 and make another run it would be 5% rich then do the same and it would be 5% lean. The low flows seem to be very sensitive to change.

[GHuggins]

Are you correcting for rich after flash? Waiting for injector tip temp to come back down to operating temp before logging for corrections?

[gmachala404]

Are you correcting for rich after flash? Waiting for injector tip temp to come back down to operating temp before logging for corrections?

No I am not sure what you mean. However, the VE tuning instructions I am following state to put a "1" in all the open loop gains such as the injector temperature gain for VE tuning. For normal driving, should I use the injector temperature gains from the 2500 Sierra HD 6.2L Flex Fuel tune (as I am using those injectors) or should I use the values from a 2014 Camaro SS tune file for normal driving? They are radically
different.

I have never let the engine cool back down while tuning the VE or MAF.
I would apply the AFR changes by multiplying by % minus half. Reflash. Drive for 30 minutes, stop, save the log, apply the % minus half. Restart after about 5 minutes, wait a minute or so for the wideband to warm up then start logging again and drive around another 30 minutes. rinse and repeat. For both the VE and MAF
tunes.

The MAF and VE tune is open loop and I am commanding a constant 13.5 in all the open loop tables (even in PE which I am not entering anyway as I am focusing on below 4K) and the log shows 0 STFT and 0 LFTT . I am also going in the VCM controls and selecting force close loop off and turn off LTFT and reset the LTFT every time just for kicks.

[smokeshow]

You can plot airflow from MAF, VVE, and the dynamic combination simultaneously so it will be easy to see where the error is coming from. It really isn't necessary to disable MAF while calibrating VE anymore. It was helpful on the gen 3 and older due to the slower bus speed, but these days CAN is a little less slow. And if you intend to re-enable closed loop, you're better off calibrating with the narrowbands to start with.

[gmachala404]

Not sure what you mean by "plot airflow from MAF, VVE, and the dynamic combination simultaneously". So, I can leave the MAF plugged in and not bother hotwiring the IAT and just do set Engine Diag->Airflow->MAF Fail High = 0?

Also when tuning the VE and MAF in open loop do I still neeed to put a 1.00 value for all the open loop
gains?

One thing I did noticed looking back at my MAF tuning log is frequencies 3000Hz and below will change from -5% rich to +5% lean in the same cells. I am looking at a 30 second zoomed in slice of the log and page through it. However, frequencies above about 3000Hz ar consistently rich or lean with similar
cell values as I page through the log.

I may run closed loop (or a hybrid) just depends how it runs. It is not a factory car at all.
Its a 418 stroker in a 72 Z28...no cats 1-7/8 long tubes 235/247 113LSA .651 cam 15deg overlap at .050.
It is very strong WOT and the AFR is great above 3K but the under 3K driveability is killing me. Honestly,
after 3 weeks of trying I don't think I made any improvement at all below 3K. Nothing is working
like any of the tutorials say it should be. So much mixed information too it is hard to know what
is good advice and what is bad. I was able to tune a crate LS 3 in 2010 with just a cam and long tubes
and I don't remember it being this difficult to do. So, I guess I got brave and figured I would try a stroker ls3.

[gmachala404]

I made a new layout to plot dynamic vs MAF vs VE airflow. Is this what you mean:
I also made a histogram that plots the percent diff between MAF vs VE airflow at
different MAP/RPM values.

mafvsVE.png

[gmorris]

Search 'rich after flash' or after you flash and start it, watch your fuel trims and see if they are crazy negative (like -20) for the first 15 minutes or so of running after the flash. Don't log until they come back down and stabilize.

[gmachala404]

OK, should the tune be in open or closed loop? My VE and MAF tunes are all open loop with all the open loop gains set to 1.00. So, fuel trims still work even if your in open loop? Won't that mess the actual AFR Error up? Or, when I am ready to start logging just open the scanner controls and force open loop, reset LTFT and turn off LTFT learning? Kinda confusing.

[gmachala404]

I searched for "rich after reflash" and got the following...is this the current procedure?"

First off - dial in your injection timing as this changes fuel atomization and burn efficiency... After this kill long term fuel trims and change the IVT table to something really close to 1's in the map cells where your engine normally idles - your doing this to help yourself out and keep temperature swings fueling more in line... Picture posted below to illustrate...

Click image for larger version. Name: Intake Valve Temp.jpg Views: 441 Size: 639.0 KB ID: 73066
At the same time your doing that your going to put it into MAF only or SD only if it's a SD tune... Your also going to close the hood so the intake is sucking in air like it normally will everyday of the week - make sure you do that part... ALSO at this time multiply your injector tip temp table by the size increase of your current injectors - in other words if you increased them 50% - take 50% out of the injector tip temp table - this will help things go quicker...

With the engine idling at an elevated 1200 rpms your going to log injector tip temp just like it is in the tune - once the temp comes all the way down to as low as it's going to go - usually 50 to 60 degrees Celsius - this will be where you will make corrections to fueling for here on out..

[gmachala404]

I read the "rich after flash" post and logged my injector tip temp and flashed my last MAF only tune
into the car. When I started it, it did indeed peg the injector tip temp at 212F degrees or 100C. So,
I drove around for a good 20 minutes before it dropped to 150 (which is the 0 injector temp offset
in my tables). Then I started logging my MAF tune and yes it was way way lean. I was tuning the
MAF way too early after flashing. I will keep going forward and see what happens when I put the new
VE table and MAF table together again and log the dynamic air, mass airflow and VE airflow. Thanks
all for the help so far!

[jsllc]

150 is too high. Your normal driving temp will be below that and used for zero. 131 or 140 would be more normal. Some like mine run 122. And no, that is not how to tune the injector tip temps. You will want to leave all of your tables alone. Kill all FTrims if you have a WB. Start the car and measure the error if injector pulse width from xx to 130F. Subtract the error from your cell you are going to use as ZERO. Let's say 131F value from all captured cells. This then get updated. After flash temp will be high. Measure error down to 131 at same RPM and repeat. You want to make sure that at least the cell above and below your zero cell are every accurate and that there are no lean cells. If MAF is tuned right you should see next to ZERO error in these three cells.

I have many posts on this subject. This thread may help Ignore the BS comments of who is taking credit for whos work:

https://www.hptuners.com/forum/showthread.php?66837-Rich-After-Flash-Injector-Tip-Temperature&highlight=rich+flash

https://www.hptuners.com/forum/showt...ght=rich+flash

[gmachala404]

I copied the Sierra 2500 6.2L Flex Fuel injector temp offset table into my tune since those are the injectors
I am using. Right now I am trying to tune the MAF and VE. So, I want to be sure that the injector tip
temp offset isn't adding fuel before I start logging AFR Error in the MAF and VE tunes. I was doing hot
reflashes before and logging AFR error right away while the injector offset was defaulted to 212 and the
injector offset table was adding fuel. So, I was pulling fuel inadvertently leaning out the VE and MAF tunes.
Once I get the MAF tuned I will revisit the injector offset table settings. Thanks for the link.

Edit: I just read through those two threads. Yeah I was having that hot after flash problem and didn't know
it so it was really messing with me in a bad way. Tuning this motor is like being addicted to crack LOL. I
know what to do now if I get rich hot starts. I just want to get past the VE and MAF table already so I can
feel like I am making headway. I think this knowledge about hot after flash will help me tremendously.

[5FDP]

FYI 2500 series trucks never came with 6.2's, they only have the old 6.0's that are the LY6 or L96. I'm only saying this because they injector sizes from a 6.0 and 6.2 are different. So hopefully the data you have it from the right tunes.

[GHuggins]

150 is too high. Your normal driving temp will be below that and used for zero. 131 or 140 would be more normal. Some like mine run 122. And no, that is not how to tune the injector tip temps. You will want to leave all of your tables alone. Kill all FTrims if you have a WB. Start the car and measure the error if injector pulse width from xx to 130F. Subtract the error from your cell you are going to use as ZERO. Let's say 131F value from all captured cells. This then get updated. After flash temp will be high. Measure error down to 131 at same RPM and repeat. You want to make sure that at least the cell above and below your zero cell are every accurate and that there are no lean cells. If MAF is tuned right you should see next to ZERO error in these three cells.

I have many posts on this subject. This thread may help Ignore the BS comments of who is taking credit for whos work:

https://www.hptuners.com/forum/showthread.php?66837-Rich-After-Flash-Injector-Tip-Temperature&highlight=rich+flash

https://www.hptuners.com/forum/showt...ght=rich+flash

Page 2 is where Scott gets into the details of how to do this more precisely

[gmachala404]

FYI 2500 series trucks never came with 6.2's, they only have the old 6.0's that are the LY6 or L96. I'm only saying this because they injector sizes from a 6.0 and 6.2 are different. So hopefully the data you have it from the right tunes.

That is interesting. I am not sure what truck I got the tables from but the flow rate in the injector tables had
flow rate of 51lbs/hr at 408Kpa and my ls3 injectors had 42lbs/Hr at 408Kpa so I thought it was the right tables.
God I hope I got the right injector tables. I'll have to double check again.

Edit: I rechecked my injector part number is from a 2010 Silverado 2500HD 6.0L Flex Fuel 52lbs/hr. I did
get the correct tables thank god. I don't know why I thought it was a 6.2L

[gmachala404]

I made another discovery with the car (72 Z28 restomod). I was going to give up on the MAF
and go SD. Because the AFR is so stable in SD. However, I read where so many recommend
trying to keep the MAF. So, I thought about my cold air setup and was wondering if the 90degree
elbow in front of the MAF was causing the unstable readings. So, I decided to move the MAF
right behind the conical filter and put a 45degree elbow behind the MAF. You can see the
difference in the pics I attached. It made a world of difference too. The AFR is much more
stable with the MAF behind the filter. Huge difference. I was getting all kind of fluctuating
AFR reading from rich to lean before I did this. Hope anyone else doing a swap like this sees
this and it saves them some headaches. Apparently the MAF doesn't like a 90degree elblow
in front of it. Finally making some progress now after almost a month of tuning this thing.

[5FDP]

Ideally the MAF needs to be a straight piece of tubing with no bends before it for like 3-4 inches or more. Turbulent air causes havoc with the MAF readings. Even buying a airflow honey comb air straightener is a good idea sometimes.

Most stock setups have the MAF right after the airbox in a straight piece of plastic that is molded to the box, atleast in the truck applications it is.