Mostly Stock C6 LS2 2005 Corvette Tune, For Your Opinions
Good afternoon all!
I have spent a good amount of time tuning my corvette since I picked up HP tuners and I am more or less happy with where I'm at with the latest revision of my tune. I had some serious issues which I wasnt aware of initially until I scanned it, I'll get to those later and see what your thoughts are...
Car: 2005 LS2 Corvette M6, been in 3 countries, an international salvage car, if you will. Picked it up because I now live near a track and I have always wanted to get into going fast legally.
Mods: K&N Intake, Flow-Master cat-back. (Headers en route)
Initial Tune/Diagnosis:
1. No issue with how it ran but at ~160-180 km/hr or so I would get a CEL for P0101 (MAF out of range). Seemed common for a CAI to have bad trim on the forums so flogged the car on the track for probably ~2 hours total over the last 8 weeks but made note to get a tune going. Honestly, thinking a CAI and cat-back are very minor mods I wasnt worried thinking the car would trim it out.
2. After running a scan I noticed my fuel trims were +10% on fuel trims everywhere. I also notice that my O2 was showing afr leaner than 14.7 at WOT. I found this highly concerning, as I had been tracking the heck outta the car with this tune. (See attached log from earlier this week pre-tune. Look at the pulls 2:10 in)
Current Tune Parameters:
1. First thing I did was add 10% fuel to the entire Low MAF range. This immediately brought it back in line for my trims. I did the same to the High table but left this for a while.
2. The usual, torque management removed, linear throttle, added the patches, etc.
3. Now I'm aware that I need a WB to tune WOT but I need to get it close to a target until I can get headers/wb and/or a dyno tune. Strategy here was use +15% fuel as a starting point and creep up the MAF frequency range without PE. This gave me more data higher into the range at what stoich fuelling will be, thus I ended up seeing ~12% at ~7500 hz.
4. (Bad quality of work warning on the following) From canvasing dozens of tunes on similar engines and checking NB to WB data at WOT to average my NB mV and tune on that I ended up running +25% across the board from ~7500 hz to my max, which is ~9500 hz. I found 125% was 880 mV as a (very rough) reference point. It pulls hard and feels good at 125-130% overall. None of the PE tables were touched, just MAF data.
My logic is as follows: With PE added I was seeing approximately stoich at WOT. Thus, the margin of PE was the margin of change required (how not to tune your engine, but logical). Thus, PE at ~20% plus a 5% margin and I land at ~125% overall increase in MAF calibration.
5. IAT's are very high here. Ambient is ~45C/113F regularly. As such, I'm not going to touch spark until I get WB/dyno dialed and Im sure this is affecting my fuelling.
6. I am slightly worried about running hard with my car lean, but nothing to do about that now. Put about ~1000 km on it since, no issue. So I think I'm in the clear, agree?
Questions:
1. I'm suprised to see a 10-20% increase in fuel trim and associated airflow from CAI, especially with PE being associated directly to the MAF calibration. Would this be considered a normal result? If so, scary to think the untuned corvettes running around like this. I have no history on the car though, so I dont know if it's been modified (but some evidence, cold thermostat, short shifter, ect...)
2. What do you think of my WOT fueling strategy overall? Is it too far in the rich direction in your opinion (+25% on MAF + PE is a huge jump from stock...)? I need to run some kinda tune this weekend on the track. Based on what you see you think I should drop to 115%, 120% or keep as-is? Running the car at +15% is giving ~850mV, which is
3. Overall, please critique my tune! I'm getting lots of KR. I posted two logs, one with 3 degrees pulled and still seeing KR. I'm not as worried about it now with fuelling much improved, though.
I'll post a new log with more data as I updated the dip in my Low Range MAF after the logs today.
Amazing forum, I'm learning a ton!
PS. For fun, heres a project I did back in the day. Roots blower on a civic with meth injection, tuned it myself as well. (https://imgur.com/gallery/nGcN5Vq)
I'm following your reasoning on fueling. There's just one problem. If you need 25% more fuel then you'd better be getting 25% more power. I recommend SD tuning. You're welcome to do MAF/SD, though. I see you've got a wideband coming.
Roots on a Civic. Reminds me of a friend who put one of those on an RSX Type S. It was funny because he could creep up to VTEC then it was like WHAM almost like he jammed the throttle.
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