mk3cn4

iTrader: (3)

Taking to track tomorrow night for the first time since build was completed *IF* I can get it safely down in the high 12's AFR at WOT after work tomorrow, am VERY close!!!

Car is a 99 fbody with Lq4/799 heads/ls6 intake/LTs

Tuning was going amazingly well until I hit this limit of 4063 lb/hr in my MAF Airflow/Frequency table.

In other words, as I was WOT tuning the MAF, I needed to add a few more percent at 9125hz but that value is already 4063.5 in the table.

I'm real close, even pegged it's still doing low/mid 13's AFR according to wideband.

So I guess I could bump up my PE at the higher RPMs? Would that work and is that the "right" answer? Seems kinda hacky to do that. This is probably a newb question but didn't see the answer searching, kinda didn't know what to search for

Thanks everyone.

gametech

iTrader: (1)

There are tons of different ways to do this. You could scale the MAF, scale the IFR, hack the PE, etc. Any time you have to alter a table from reality you are making the choice to give that one priority and hack the others. Choose one and go.

fst100

iTrader: (5)

what type of MAF are you using, LS1 or LQ4? also one method of scaling the MAF is using a third party/piggyback and using a MAF translator or AFC controller. in the wbody world there was a company called easy performance that made a MAF Air Fuel Controller and you could scale the MAF frequency for ppl that went above the value in the LQ4 MAF(normally the turbo guys exceeded the values using the LQ4). the downside is that you're adding in another component in tuning and the afc does cost like $150 or so from ZZP. I was fortunate enough to hold on to mine when I sold my gtp and currently use it in my Z for on the fly fuel adjustments.

mk3cn4

iTrader: (3)

Thanks, will google MAF scaling and IFR scaling and the PE tweaking and figure out which seems less hacky and easiest to work with. Never heard of those other two. Appreciate the input.

If anyone wants to chime in and let me know what "most people do" I'd appreciate that, would prefer going with the most tried/true method and also the one that I'd likely find the most information on when Googling, especially since I am so new at this.

*IF* it would work, I guess I could just take the higher RPMs and bump up the PE for those, right? If that would do the trick then I'd just have to remember that my PE isn't a fixed number across the board when troubleshooting. Searching didn't outright say this would work if the MAF table is maxed out, I'd expect it to be OK. Normally I'd just try it and see but time is running out and I really want to see how strong this car is. I brought my laptop and everything to work today so will try this at lunch maybe. I'll have an hour to tinker then and maybe an hour after work to get this working. My plan is to just roughly "paste special" the % error in the PE tables to add fuel at the high RPMs that parallel that airflow Hz in the histogram.

Thanks again. I appreciate everyone's help. As I mentioned in other posts, because of this site I took my DD that had rod knock and swapped in the LQ4 and now will have a fast reliable cheap DD that runs like a champ. I got nearly all my information from LS1TECH and HPTUNERS.

mk3cn4

iTrader: (3)

I am using LS1 MAF.

MAF scaling, I remember years ago my buddy had a turbo buick and had MAF scaling hardware like that which let him use an LS1 MAF. I think I'd rather just do some tune trick and live with it being a little hacky I think but will keep that idea on the back burner. Thanks for reminding me that solution exists!!

mk3cn4

iTrader: (3)

Latest update, lunch run showed no improvement at all. I bumped up the PE a full 10% from 4k RPM and up, and the Wideband showed basically the exact same 13.5ish AFR.

One thought is that the tune I am using has a bunch of stuff disabled (including forcing MAF to fail) as described in MAF tuning howto's, didn't think of this until I was in the middle of the run, but maybe I'm not supposed to see the improvements until I turn all that junk back on.

Problem is that I am out of time. After work I will burn in the normal working tune that has MAF and DFCO and everything enabled with the PE upped 10% and will log on the way home. If results when I get home show no improvement maybe I'll bail on track day.

I guess I need to Google, maybe this high 13ish AFR isn't that dangerous and I go anyway...?

Posting my tune and latest run in case anyone wants to peek. I've got commanded AFR way down into the 11's at PE on this one I think. I also tinkered around with the MAF curve and rolled it back to the last curve that showed improvement. The MAF numbers look good up until about 6500hz then AFR error goes way up. You'll see my wideband AFR almost touch 14 at times during WOT

Luke19901

if you reduce the stoich value by 10-15% you will add 10-15% fuel across the board. you can reduce your MAF table by 10-15% and that should provide the resolution to populate the higher frequency cells with numbers that are less that 4063 lb/hr

you could add 10-15% to the IFR vs KPA injector table and it would likely do the same thing

mk3cn4

iTrader: (3)

Nice technique! If you can't raise the bridge then lower the water!

EDIT: changed plan and added questions. If someone could answer the questions before 5pm I'd really super appreciate it.

PLAN:
So I will change FUEL-->GENERAL-->Stoich AFR to, say, 13.17 instead of the 14.63, then bump the ENTIRE MAF curve DOWN 10% across the board, that makes the MAF tune just the way it was except shifted down and now I have headroom for adjustment. Any free time I have will be to try to do some MAF tuning to verify it's still good otherwise.

QUESTIONS:
1) Does the VE table need modified too, in case of MAF failure? I had VE tuned in pretty good. If nobody answers will leave it alone assuming trims will handle if it's only 10% off.

2) Is this going to throw off my WB since it's referencing stoich at the 14.x value? Asking because I saw a thread where that happened to someone apparently when they tinkered with underlying Stoich. Seems to me that an external LC-2 wideband as an external logging source on the side of the HPTPro box should be an unaffected independent measurement...?

THANKS.

Russ K

iTrader: (1)

No way you are maxing the airflow of the Maf table. Check your fuel pressure at WOT to redline. Most likely the pressure is dropping due to a plugged fuel filter or a weak fuel pump.

Russ Kemp

mk3cn4

iTrader: (3)

Thank you Russ. Yea that didn't cross my mind because the car itself and all parts on it were from a solid bolton LS1 that had about 350RWHP and had no problems, but who knows what can happen in a swap. Makes perfect sense that there's a fueling problem now I think about it because the MAF adjustments were responsive low/mid table, but the upper Hz I just kept throwing fuel at it over and over and it didn't seem to be helping much. Might be because I'm not able to deliver it mechanically. I actually hope that's the case because I absolutely HATE this hacky tune, even though it appears to work for the night.

Right now I did do the Stoich reduction, and adjusted the MAF table accordingly and added some fuel, and my WOT runs are all staying in the low/mid 13's AFR according to 2 or 3 test runs I've made. Searching around it seems general consensus is that this is safe for now, but I will absolutely find out what is going on. ON MY WAY TO THE TRACK!

Anyone else feel free to chime in, I will be checking here from my phone frequently in case someone has some major warning for me LOL

Thanks Russ, I feel like I am in the presence of greatness, googled your name many times while doing my idle config LOL... Thank you for that by the way, your idle config really helped me.

mk3cn4

iTrader: (3)

Russ, I think you nailed it. Just now did a quick blast at WOT with a gauge attached and popping out the rear of the hood LOL and although the fuel pressure stayed up near 60 most of the time, when really under load it sank down to 40psi up top. I didn't google it yet to make sure but almost certainly that's a problem! I'll try fuel filter first then fuel pump, pump is cake to change since I have the trap door mod.

But the good news is that using that stoich hack in the tune I was able to get it down the track while keeping 13.XX AFR and lower, so was able to make some safe passes. The scanner actually showed it commanding 10.xx at times even though the WB showed much higher actual.

My homebrew LQ4 with cheap 799 heads and 228R did best of 12.48 at 111, will do better because it's also bumping rev limiter between shifts, and it's very rich down low in order to keep it safe at high RPM, both problems I now feel I have a handle on.

Thanks guys for saving my track day, after all this work doing this build I needed some success and payoff. I can't go racing again for who knows how long because of my hectic schedule next two months, that's why I tried so hard to make it this time.

Russ K

iTrader: (1)

And there's your problem, check the fuel filter first. If the filter is good, then it's the fuel pump.

Russ Kemp

fst100

iTrader: (5)

If you end up taking the fuel pump out also replace the fuel pressure regulator.

edit - did your fuel pressure do whats in the vid link below?

mk3cn4

iTrader: (3)

Nope, mine "stuck" way higher at around 60 almost all the time even maybe 80% throttle, then when I would wind it way out, way up high it would just drop right down to 40ish. It's hard to tell because I had this acctron tester that had like 18" hose so I had to have to just barely sticking out of the rear of the hood where I could get glimpses of it. But it looks like yours "eases" into the lower PSI way earlier and gradually and kinda smoothly, mine hung at 60ish pretty solid and I had to really get it up there and then it seemed to snap down to low 40's pretty quick.

BUT, I did change my fuel filter and first initial test showed it hold solidly at 60 almost all the time but dropping maybe to mid-low 50's WOT near redline. I need to try it again to validate those results and need to search to see if that's OK. I didn't get a chance to do anything with the tune because my schedule is so crazy with stuff, but my logic is that now FOR SURE it's gotta be richer than it was if anything so I still feel like it's safe to run until I get go back in my saved tunes and try to find the newest tune where I believe was all done at the 60PSI. (I'll probably just roll back to the last good VE table tuning and start all over on the MAF tuning)

Plus, like an idiot, when I took my wideband out (it's portable car to car), even after it sat for like 20 minutes I put that plastic protector cap on the end and it melted and destroyed my WB sensor. It was still THAT HOT after 20 minutes? Strange. But ordered a new one just the sensor from Ebay for like $40 surprisingly, from innovative themselves apparently.

Once I get some time I'll test and update here in case anyone's curious and also for future new tuners who may run into this disguised problem.

subeone

iTrader: (5)

Theres no way in hell you maxing out the maf, either wrong injector data or weak pump or small injectors that cant keep up.

ddnspider

iTrader: (26)

ding ding ding.....couple boltons maxing a stock MAF thats good to 600+fwhp

PS....welcome back. what'd you get banned and unbanned? LOL.

mk3cn4

iTrader: (3)

Just wanted to update the thread for future searchers. This definitely fixed my problem!

I was able to finally do some more testing and can now quite easily get the AF to 11's even at nowhere near the top of the MAF scale. It was apparently that fuel filter as demonstrated by the fuel pressure dipping to 40's at WOT. The MAF tuning is now responsive up high and the pressure gauge reads maybe 55ish lowest at WOT. Thanks again to all who chimed in. Put my stoic back to normal and am dialing it in to 12.8 now.

ddnspider

iTrader: (26)

Excellent, congrats.amazing how some as stupid as a fuel filter will throw off the tune.