Skip ahead 6 months of being swamped between being a full time engineering student, physics lab assistant, and racecar pitcrew mechanic who has no time to work on his own cars LOL:
Probably reiterating some stuff from before, but I want to revisit the symptoms I'm experiencing
(and possibly some new ones? IDK I've slept since then ¯\_(ツ)_/¯).
As it sits currently, it’ll idle and cruise fine after initial cold start. I’m down on power in acceleration and top end, often having to floor it to get the beans
(Oftentimes it feels like there's a dead zone in the pedal, in most generic scenerios this would point to a fuel pump issue. It's *possible* that could be my problem, but if you've read up to this point, I've tested fuel pressure per FSM before overhauling the fuel system AND after overhauling the fuel system).
Smells like it’s running rich. (No current codes as one of my battery cells died during the Texas freeze
(I suppose 6 years on a battery would do that!) and had to install a new battery, been driving it here and there to get the codes to resurface).
It won’t shift into 4th (overdrive) gear on the highway, at least I haven’t been able to drive it long enough to get it to as I was before. Currently educating myself on this system as it functions by locking up the torque converter and intend to dive into it when I have some free time as I believe it may lead me to the issue I’m trying to find, given that I believe everything under the hood is as it should be. Regarding the 'TCM ESA communication codes' (electronic spark advance). In every documented case of these, it’s due to a recall issue in the ’93 ECUs and is fixed by replacing with the newer ’94 ECU, and doesn’t really cause huge issues outside of slightly low idle and an annoying engine light.
HOWEVERRRRR I already have a ’94 ECU in the truck, and have a spare ’94 along with my original ’93. I’ve tried swapping all previously and the issue was not resolved. I’ve metered the wiring for the ESA circuit (just goes from ECU to the TCM and they’re all good) and swapping to my spare TCM didn’t resolve it either. From the thousands of online threads I’ve read, I’m the only one to ever have this issue. Should note that I never had these codes prior to my very initial issues with the truck, only after I got it to be driveable. I’ve basically just been fixing one thing after another without truly getting it to 100%. In my mind, it’d make sense if this were the entire issue, as the ESA controls spark advance (although it’s set by adjusting the distributor? Not sure how it actually functions). It could be that it's forcing a very advanced spark and thus causing a rich condition.
Once in awhile, after driving and having parked, I have to crank it constantly for like 40 seconds before it fires up
(apologies to my new starter. Putting it to work
). This happens totally randomly. I thought it may be due to a leaking/sticking injector issue, so I installed more modern Bosch 4- hole injectors from CruiserParts that I’ve had laying around (same flow rate) which many install on their Cruisers to gain like, +1 MPG hahaha.
I want to point out that I had previously installed a different set of the same injectors, and it caused the truck to run wayyy rich. Cruiser Parts sent me a new set to replace them (wish I could've bench tested the flow on them myself, but I don't have the equipment nor the time to build a bench rig to do it).
Since that swap, on initial cold start up/driving, the truck is pretty much the same; driveable outside of a little missing power and no 4th gear. However, when I turn it off and restart it, it runs like s***—like it’s missing a cylinder. I don’t recall this issue prior to swapping injectors, however it had been a long time since I last drove it before the swap.
It's so weird, to have it be driveable and just down on power from cold start to driving on the highway fully warmed up--but as soon and you turn it off and turn it back on it falls on its face and feels like it dropped a cylinder. I need to drive it more to verify the consistency of this, but in in both of the two times driving it since the new injectors, it's done this.
Some other notes: The transmission is designed to not shift into overdrive until the ECU reads that the engine is warmed up from the ECT. However, my issue is at all temps
I was able to get my hands on a TOYOCOM live data unit (if you don't know what this is, go find out. It's sooooo amazing! GAME CHANGERRRR). Waiting for it to arrive in the mail. Hoping that being able to read out live data while driving will show me some things I didn't see before. If anything else, I'll be able to read sensor outputs without having to manually do it because I'm spoiled

.
I plan to reevaluate the entire fuel system (including all the lines), look into the transmission electrical system (torque converter lock-up and solenoids), as well as re-re-re-recheck a few of the engine sensors. Also would like to try a known-good VAF and (94) ECU just to see if anything changes and to rule them out.
To be frank, I've had a hunch something's up with the
Ebay reman VAF I bought. It bench tests within all FSM parameters, but these are finicky to being tampered with. Given that the VAF has direct control of the fuel system, it wouldn't surprise me. I'm going to either send one of my old units to Bavarian Restoration or possibly find a known-good used unit. In a perfect world, I'd be buddied up with some local 80-Series guys whose VAF I could slap on temporarily just to see what happens before forking out the moolah. But alas, do not.