Nothing to add, except for wishing you and your Dad have a great time. 👍

Thank you sir.

Good luck! If I were a bit closer I'd come watch.

Good luck!!!

Well I guess I brought bad juju on myself making this post. It has been a very long time and hundreds of passes since my car hasn't run right and tonight I broke the record. Never got one good pass in.

Every single thing we can check checks out but it is falling on its face right when the G-force would probably be peak. It falls on its face sputters a little then takes off. Went a best of 10.96@126.85 with a 1.84 60ft. Shook everything we could down at the track but this wouldn't go away. The 02 sensor was also acting up but we disabled its ability to make any changes and the problem still persisted. The 02 sensor was old so it might have just been its time.

Open collectors vs having any kind of exhaust on the car did do some things I wouldn't thought of. I had to make some pretty drastic changes to the idle control valve. It didn't need near as much air valve open to idle at the target RPM.

To make sure it wasn't a lean bog I added a good amount of fuel both to the map and to the "accelerator pump" and it didn't really change anything, maybe made it worse.

The problem can't be duplicated on the return road so I think something is loose somewhere. I built this EFI controller my self so maybe it has cracked a solder joint or something after 8 years of trouble free performance. The best air I saw was around 800ft and I bet we won't see that again until the fall.

I'll get a new 02 sensor and put the exhaust system back on and see if I can shake this problem down then maybe try again.

That’s a frustrating trip to the track, ugh. At least it came home in one piece!

Do you measure/log fuel pressure?

Yes, I have had some trouble with the SD card so I was using my laptop to log. It takes a slower sample rate but it logs everything. Fuel pressure it rock steady, same for battery voltage, those were the first two things I checked.

Looking over logs this morning I do see it had a sync loss like it missed one tooth right when this event happened. However, its only in one log, the other logs are clean. I also logged a tooth counter on the last run. I have that posted over on the megasquirt forum because I get lost in that stuff. Caveman understand air fuel, caveman understand horsepower, caveman get lost in data not related to those things lol.

Little update on this. I finally made it back to the track last weekend. The only thing I changed was that I put the exhaust system back on the car. The car ran perfect and the data logs never missed a meat. It even ran a little faster than last time I had it in crappy July air.

My conclusion is that the open exhaust was scrambling the guts on my home built EFI system. I relocated it to the bottom of the dash for better access and a friendlier environment. I plan to try the collector extensions again before we make the haul to drag week.

Another thing I have learned is that the exhaust dumps don't matter(not a big surprise) near as much since I removed the tailpipes from the car. Even running without the dumps the car was .03 faster than last time it was out in similar air where the exhaust dumps were open.