Tune Issues on 2015 Corvette Z06

[ShawnC7]

Hi all,

First post on this Page. I was instructed to do so by an acquaintance assisting with issues I've been having on a 2015 Z06 I just picked up recently. Build list is posted at the bottom of the page. I'm very new to this type of stuff, but very enthusiastic about learning new things, so any input given is 100% appreciated. I was pretty much told by acquaintance to post the 2 files attached below and give a summary of some issues I'm seeing, and hopefully you all can correct any potential issues or at least point me in the right direction.

Okay, for the background info.

Vehicle has about 55k miles and dyno'd at 630whp, shortly after picking up the vette I received trouble codes; P0171 and P0174 lean bank 1. Immediately following that I reached out to a tuner and inquired about fixing this issue. I brought the vette in and he ran it on the dyno and reported it was running 38% lean. He made the adjustments necessary and sent me on my way.

After a few days of driving I began to notice it was not running smoothly at all. Most noticeably was a VERY rough cold start, to the point that the entire car would shutter and shake for 1-2 minutes until it was up to operating temperature. Also noticed at WOT the car would sputter and kick out black smoke. This went on for about another week before it suddenly started back firing on cold start spewing out large puffs of black smoke and a strong scent of gas, immediately after I received trouble code P0301 cylinder 1 misfire detected and was followed with a CEL and then Reduced engine power mode (limp mode). I removed the cylinder 1 spark plug to trouble shoot and seen it was covered in carbon build up (not oil), I removed cylinder 3 to compare and noticed it was also fairly sooted but not as bad as Cylinder 1. I replaced both and the car stopped misfiring (still ran rough on cold start). Please note the previous owner replaced plugs 2000 miles prior and should be in good condition.

Without drawing this post out any longer (apologies for the essay), I began seeking assistance with trouble shooting the issue. Including, reaching out to my tuner (who recommended I go to Chevy Dealer and have them test fuel injectors), a certified corvette mechanic at the local chevy dealer, and other knowledgeable corvette owners locally. The dealership turned me down due to being catless unfortunately so no shot at testing fuel injectors, they also told me the cost just to TEST the injectors was $400 and would require flashing my ECU which would remove the tune on it. I think right now the goal is to determine if this issue is a tuning issue or a mechanical issue. The acquaintance that assisted with comparing my tune to his similarly modded 2016 Z06 noted that I was running very rich but did not know what the issue could be (again back to mechanical or tune related). I believe we have it narrowed down to 02 sensor issue messing with AFR, bad fuel injectors, or potentially a bad tune.

Thank you for taking the time to read this post. If any other information is needed please let me know.

Edit*- also note that data logging was done between idle and 4k rpm. At the time of data logging it was raining. Once the weather clears I will be doing data logs at WOT.


Build List;
PERFORMANCE -
* Lingenfelter 15% Lower Pulley & Idler Pulley
* Cordes 5" Intake
* Cordes Expansion/Ice Tank
* MPI Billet Blower Lid
* LT5/ZR1 Throttle Body w/ Lingenfelter Adapter Plate
* Hand Ported Blower Snout & Case -Port Matches to Throttle Body
* Katech 160* Thermostat
* New OEM Plugs & Wires
* Gates HD Belt
* EOS Cat Delete Pipes
* Speed Engineering X-Pipe
* DSX Auxiliary Fuel Pump Kit
* MGW Short Shifter

[JASON11WS6]

If you're tune was that far off all 8 spark plugs probably need to be changed. On modded LT4 cars I tell guys to change them every year. The carbon build up on LT cars is crazy. You probably still have 6 bad plugs in the car.

[1scls1z]

You need log more channels. But one thing I see off hand is the ECU is going in and out of Open/Closed loop on light throttle transitions.

[edcmat-l1]

The data log looks like you may have a miss on bank 1. That would go along with your P0301.

The tune file looks very aggressive from an ignition timing standpoint. The high-octane table has been increased, the recovery table is way more aggressive than I like, the IAT table is worthless under 150* and the worst of it, the knock sensors are desensitized. That's a dangerous combination.

I'd take it back to whoever last had their nose pickers in it and ask them to do a compression and leak-down test and document the results. Verbal description of the running problems sound like you may have damaged a piston.