What does vapor lock look like in a data log?

I went to the track today for some roll racing, and had to sit in staging for like 20 mins.. I made a pass, noticed it was down like 10mph, checked the log and it was insanely lean, idk how it wasnt breaking up and idk how it didnt blow up. Anyway after checking everything over I couldnt find a good reason as to why it went lean. I noticed trims at idle were lean as well. I shut it off let it sit for an hour came back started it up and trims were in line, so I made another pass keeping an eye on the wideband this time around. Spot on.. Only thing I can think of is e85 vapor locking in the lines. The lines are like 2 inches from the header coming up to the rail, but Ive ran this car for over a year now and never had any issues like this.. It was 90 degrees out today and i usually dont take the car out in the heat with no AC.

first log is where it went lean, second log is good. Same tune file and ran an hour or so apart. Kinda worried about this situation lol.

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All those pids and you're missing the most important one for this problem. Injector on time.

Yeah I know. Was not expecting this issue lol. Fuel pressure pid is generic too just stays a constant value. I would think you would not have issues cooking the fuel if it?s flowing. I could understand if it was stagnant fuel in the line next to a header.. I pulled the relay for each pump individually and it did not go lean on trims at idle like it was before that pass so I?m pretty confident it?s not a pressure or pump issue.

You can relieve some pressure at the fuel rail with the shrader valve. if it starts immediately after that it was likely vapor lock.

If you have a gauge on the rail they will often be wrapped around/maxed out.

I recently installed two Aeromotive 340s (replaced a single Racetronix 255) and I have a boost-referenced return style regulator on the rail. The second pump only comes on under boost. I live near Savannah where temps are between 95 and 100. I have a 40 minute commute to/from work and I have a very hot engine bay (twin turbos). I have no problems when I drive to work pre-dawn. In the afternoon, after 30 minutes of driving, my fuel pressure drops from about 52psi at idle to under 40psi. Fuel trims show about 10 to 15% lean when this happens. I never had the problem with the little Racetronix.

My problem is with the fuel going into the pump vaporizing and pump efficiency dropping, not with high pressure lockup at the rail. I run 93 octane and I’ve heard this particular condition is much less of a concern with E85, although I haven’t tried E85 yet to prove that out. I’ll be moving my canister style fuel filter out of the engine bay and then try a fuel cooler if that isn’t enough. I’ve already added a pump speed controller to keep flows down under 2500 RPM.

All of this to provide you with another datapoint. Good luck.

Sounds more like a pump failure unless maybe if you are running the tank mostly empty. Or did you mount pumps somewhere outside of the lower portion of the tank.