looking for guidance, experienced tuners please help

[LS ROB]

posted once with no luck. attached is a log and a tune file. my issue is after the car is started and idles down, my vacuum drops hard to roughly 9.7" now im not sure if this is a mechanical issue or if its in the tune. ls7 ,johnson short travel lifters (pushrod possibly tad long?) my cam is a stage 2 ls7 .635/.635", 234/246, 115lsa +3, msd intake, stock injectors, long tube headers, nw102 dbw ls7 heads milled .020. car starts well hot or cold, idles good, throttle blips return to idle well but the rpms DO FLARE UP when changing gears. now i dont have a wideband and have not even began to tune this thing but have just been focused on the idle and timing, so with that said, roughly how much will engine vacuum increase with this thing tuned correctly? at this point im weighing cost effectiveness of purchasing a wideband and tuning vs having an experienced tuner tune the car. recommendations are welcomed.

best idle low vacuumbaf.hptfindingidle.hpl

[kevin87turbot]

That's a pretty healthy cam...pretty good choice for the LS7. Just looking at the tune and datalog, the tune is pretty good...but not perfect.
The MAP sensor averages around 56 kPa at a warm idle at 800 rpm and around 22 degrees timing. That's about what I would expect. That's approx 13.03 inHg. Nothing to be concerned about for sure. If you want more vacuum, you can increase the idle speed a bit more. I don't see where it dipped to 9.7 inHg in this datalog. That would be around 67 kPa.

As far as the flare up during gear changes, it appears that the min airflow table is simply too high at higher rpm. Should be an easy fix.

[GHuggins]

You'll want to get the fueling dialed in before addressing the other issues as the MAF and VE tables will be the route calculation control of a lot of the tables. Doesn't look like any of them have been touched and it is currently 6% out just in the startup idle log.

[LS ROB]

Thank you Kevin87turbot. that gives me a little more hope and alot more information on what to expect. i can definately work on that airflow table.

[LS ROB]

ghuggins i thank you for your direction! you are correct, i have not even touched on tuning MAF and VE. that would require a wideband to do correctly i am assuming?

[kevin87turbot]

ghuggins i thank you for your direction! you are correct, i have not even touched on tuning MAF and VE. that would require a wideband to do correctly i am assuming?

You can utilize a wideband to do it, or you can use the stock oxygen sensors in order to dial in the part throttle portion of the MAF and VE tables. Let me know if you need help getting it dialed in.

[LS ROB]

i am interested in the procedure on how to do this with the stock oxygen sensors if you are willing to share. also, should my MAP kpa read 100 or 105? my tune file is showing 105 as the estimation but im only reading 97. is it possible to tweak the linear/offset to get it to read up to 100 and is that the best way to do it?

[GHuggins]

You don't want to mess with your map sensor settings as long as the factory sensor is installed and your still using those settings. In order to adjust fueling without a wideband you'll first need to pull roughly 12 to 15 degrees of timing out of your wot sections of the timing tables and then log fuel trim stft+ltft against a MAF plotted histogram in your scanner. Highlight/copy/paste special percent into your tune and then smooth or hand edit adjacent cells. Honestly the easiest way to tune a NA vehicle... Right now you can multiply your entire MAF table by 1.08 and it'll be close enough to start this. Just use steady throttle and change PE settings to something like 95% pedal until your done.

[LS ROB]

ahh.. ok. ill leave the MAP settings alone. i added 8% to the MAF table but im honestly not sure where to take out 15 degrees of timing on my timing tables. also, this will be for the high and low octane tables only?

as for the histogram, LTFT+STFT (Math) is the parameter and Mass Airflow Frequency (Sensor)is the the column axis logged in Hz?

[GHuggins]

I'll make some adjustments for reference when I get back to the house and get my work done up if nobody else does by then. Yes for the histogram. You can right click on the maf table in the upper left corner in the tune then copy column axis "I think" then paste into your scanner to save time.

[GHuggins]

Just keep in mind timing will change fueling, so once you go back to your regular timing you might have to tweak fueling a touch to get things back in line. PE is almost disabled, so keep that in mind too - watch and listen for knock. Use one of the math formulas for back calculating your VE table while dialing in the MAF and use light small throttle movements for steady state logging.

[LS ROB]

Tune for MAF Only closed throttle.hpl

huggins are you suggesting i tune the MAF and VE at the same time? ive uploaded the tune and took a drive. i may have to venture a little farther out in the countryside to get some smoother logging in. there are some rolling hills around where i live. could you take a look at the VE vs FUEL TRIMS graph to see if it will work for backcalculating the VE table? if this is correct do i do copy-paste-multiply by half % on the VE table and smooth as well?

thank you Sir!

[LS ROB]

Tune for MAF Only closed throttle.hpl2.hpl

log 2. any suggestions on how to hit the higher Hz cells? Also, if I seem to be too aggressive on the throttle just let me know and I'll try something different. im actually adjusting airflow min. table as well. the flare ups are nowhere near as bad as they were, but im not sure if that skews the MAF tuning or not.

[GHuggins]

https://forum.hptuners.com/showthrea...ation-for-gen4

Read up on this for tuning the GMVE at the same time as the MAF...

Use the cars gears for hitting the higher cells. Just put in a higher gear and hit a hill if you have any then you can go to next lower gear doing the same to get as high an airflow cell as possible - just multiply the rest of the MAF table going beyound what your able to hit by the last few cells and remember to smooth everything.

Also important - rich after flash - drive for roughly 12 to 15 minutes before even beginning to collect data as it will be skewed until that point - sorry for not mentioning that sooner...

[LS ROB]

ah..ok.. ill do a couple more logs then. no worries. i really appreciate your help.

[LS ROB]

t.hplTune for MAF Only closed throttle4.hpt

so i logged a couple more times remembering to drive for a bit before i started logging. the attached files are what i have came up with.

[GHuggins]

Looking very good - I'm attaching a minor tweaked revision that should have you really close other than more of your VE table. Looks like it's time to put your timing and PE settings back in, do some final tweaking of your min airflow and timing tables

[LS ROB]

maf tuned.hplcurrent tune.hpt
awesome! I've put PE and Timing table back in as well as tweaked on the airflow. seems rich now. I haven't really tried to mess with the high-low octane tables but only the base timing. i will see if i can find some info on tuning timing tables or should i tune something else first?

[GHuggins]

You flashed it while the engine was still hot so it'll be rich for the 12 to 15 minute time span it takes to "reset/re calibrate" itself. Made a small change to your timing table to get you started for the cam. Might want to multiply your knock tables by 1.2 too unless you don't want to. Knock sensors from factory are super sensitive.

[LS ROB]

i see. you did mention that earlier. when you say knock tables are you referring to theknock tables.PNG

i do want them somewhat sensitive but i didnt realize the cam would/could trigger them so if you say 1.2 then 1.2 it is unless this is not the tables haha