HP Tuners Epiphany

[StopGap]

Well, this is all coming together for me now. I think I've spent more hours over the last ten days and have read more about tuning with HP tuners than I did getting my Engineering Degree. and, my wife hates me now!

A few posts ago I was struggling trying to get a safe start tune I had for my 2009 LS3 Vette with a small A&A kit a little more stable. I had LTFTs lean exceeding 25%. Now, I have LTFTs close to zero throughout the entire power side of the CL range. +2.9/+3.1 highest. This is a MAF tune BTW, if that wasn't obvious. I did this the hard way via MAF tables, but now I am getting ready to tackle the VVE routine in the next round of finer tuning (VVE my next learning challenge).

On the higher RPM range, I've made several adjustments to my PE entry point, have adjusted high octane spark table to correct a few KR spikes I saw (4/5%) little ones I let go, did a little backing and forthing with the spark table in general, and spent at least a tank and a half of gas DLing. I am confident I am safe in all ranges, but especially boost. I have PE coming on now at about 3800 rpm; boost just appearing. At first, I saw a couple of DLs where I was still in CL at 4900 RPM. Once in PE I am seeing .86/.89 Lambda.

Simply forcing myself into tune changes and getting past the flash scare and overall confidence with the SW makes a very big difference! I still have a lot to learn, just want to say thank you to this forum for some of the guidance you've given.

BTW, my goal in this project, was to FI an otherwise stock LS3 with a small kit. I didn't want a barn burner, just a reliable LS3 with more HP/torque. I estimated 6/8 lbs boost, tune to perfection. In my DLs, the highest boost I've attained is at redline is 6.2lbs....perfect!


All the Best,

[GHuggins]

Shoot for a -2 or -3 on long terms. Anything positive gets carried into power enrichment and will throw off your wide band tuning at that point.

[StopGap]

Shoot for a -2 or -3 on long terms. Anything positive gets carried into power enrichment and will throw off your wide band tuning at that point.

Thanks - I actually think I can do that!

[StopGap]

Followed Ghuggins advice - did a number of iterations of tweaks and 10 or 12 more DLs Friday and today. I have very stable LTFTs now and consistently entering PE with -0.8% to -1.6% trims. I've been working on the PE end too and other than some minor KRs that are less than 1.5% I have no KR spikes that I am fighting in boost. I might be at the risk of entering PE too soon, about 3200 to 3800 RPM, but I am also already into boost at that point too. I don't think I am over fueling into boost. I've seen Lambda .82 to .89. Of course, correcting out some places earlier where I found 5% KRs, I don't want to over correct at the cost of HP/Torque.

Two things I am working on now:

1. Understanding VVE. I am part way there and working on building a scan chart. I get the idea about DLing and hitting the VE table in as many places as I can, but working on what to do with that data then.

2. I need to learn where the HP and torque opportunities are in PE - The right AFR/RPM/Boost; right max timing at these points. At what lambda does the LS3 under boost run best (without wearing it out in 30hours of operation); and what are the spark timing limits?

Thanks for the advice guys!

[07GTS]

dont worry about entering PE to soon its more load related then RPM so if ur at boost or high load u want to have more enrichment straight away, i have mine come in reasonably easy with the PD blower cos it can boost up in an instant so u want the fuel to be there but also be able to cruise around at stoich when u need too, do u have the 2bar OS..? maby not if ur wondering bout VVE, but if so u can use the BE as well as PE so set up PE for the n/a side of load and then BE little richer for boost side and its also good if u dont meet PE quick enough the BE will kick in, most of the timing to find best will need a dyno

[StopGap]

Thanks for info 07GTS. Much appreciated. You've given me other things to consider, and this is going into my "database". Your comment about "boost up in an instant" is so true. I am still trying to get used to reading data logs after the actual street pull event as it is like watching what happened in a time warp.

I don't do hole shots and not into drag racing. Not into 100% throttle from a dead stop, so all of my DLs reflect my driving, I am rolling into boost from second gear, sometimes 3rd. I've already become used to a much different DL from the extra load in a 3rd gear rolling pull. But, tuning on the street, I need 2nd or 3rd as first is simply useless and I cannot control the car trying to roll into boost in 1st.

When I first loaded a start tune I was given, I was very cautious, but blipped a few times into boost to get a couple of readings. My first couple of DLs showed PE coming on 4700, 4800 RPM, but I am boosting already 3100, 3200 @ 100% commanded throttle. So, I took a drastic measure and in one adjustment got PE around the time I see 1 lb of boost. So, I am already seeing a .85 Lambda at 32, 3300RPM. Feels right to me...safe, but I am curious what an experienced LS3 tuner would say.