Roe VEC1 Technical Questions: 12v source revision, Key-On BARO, 12v Vampire Piercing Connectors

12 volt source:

It was an early 96 GTS install with the BK/OR wire as 12V source.

BK/OR is 12v in the RUN position only.

Roe's installation manual revised the BK/OR Run wire to the DB (Dark Blue) RUN & START wire.

WHY?

I can see issues with the RUN-START-RUN cycle which if BK/OR, energizes the VEC1, they de-energizes during START, then re-energizes finally in RUN (engine running.)
I see 2 considerations:
*) Interrupting VEC1 energizing during START could pose issues.
*) During START, battery voltage is drawn down by starter: this could cause VEC1 low-voltage issues

Why did Roe revise to use the DB wire (RUN & START)?
Power to VEC1 is continuous during engine start up.

BV still has the early BK/OR 12v source.
What are the issue(s) with this and should I change it to DB (I'll just an Add-A-Fuse in the fuse block.)

Key-On BARO:​

Never thought of this until a few days ago:
There is no BARO sensor.
PCM measures BARO from the MAP during Key-On.
NOTE: I think it was HexDummy on HPTuners forum that mentioned PCM will update BARO from MAP under certain conditions. One way might be: WOT @ Low RPM: MAP should be just slightly lower than atmospheric. If this value is higher than the Key-On, it would be safe to update BARO.
NOTE: Also, BARO is only used for the pressure at the end of the exhaust system. Giving a ΔP across the engine.

Now we have a race between the VEC1 coming up and the PCM measuring the MAP.
Who wins and if VEC1 translation is in effect when PCM measures BARO, what then?

Power Loss & Vampire Clips:​

QUESTION: What happens if the VEC1 (and A/F display) loses 12v power:

QUESTION: Clearly sensor connections should be soldered, but the VEC1/AF are electronics with high impedance - is it possible the 25 year old 12v source vampire clips could become noisy or fail?

I have Z-E-R-O faith in those Scotch-lock taps. The conductors on our cars are already somewhat marginal and anything that compromises the integrity of the wires is practically guaranteed to cause you problems down the road. I've tried with low success to solder broken door wires, but they just don't have an affinity for what I'm using. Perhaps the answer is a flux treatment.

GTS Dean said:

I have Z-E-R-O faith in those Scotch-lock taps. The conductors on our cars are already somewhat marginal and anything that compromises the integrity of the wires is practically guaranteed to cause you problems down the road. I've tried with low success to solder broken door wires, but they just don't have an affinity for what I'm using. Perhaps the answer is a flux treatment.

Click to expand...

Vampires have a better chance of working if there is some current - otherwise corrosion becomes a "contact resistance" which low current cannot burn thru.

Soldering door wires where they break should be problematic since they broke where the bending stress was the greatest. The solder makes a portion of the wire rigid which makes the transition to flexible have even more stress - it's like fusing vertebrae for a back injury - the next one takes a beating.

Dean's Wet Noodle wire used for RC and robotics would be the awesome choice. 12ga has 1666 strands (!) You cannot flex break this wire. NOTE: unfortunately this hyper high strand count wire is only available in 12ga. High strand flexy 12ga is 680 strands and available everywhere in colors also in smaller gauges with same fine conductors - it's also silicone insulation. If you spliced 6" of this stuff in the bending area of door hinge wire, it would solve everything.

Thinking more about triage fix door wire (not pulling harness), crimp connectors (or solder) inserting a 360* loop section might last.

Way ahead of you there.

UPDATE: FYI: The 12v VEC1 & Air Fuel LED Display piercing connector tap had failed and was "barely" intermittent (meaning mostly failed.) Also, the eary instructions identified the BK/OR RUN ignition switch wire which was corrected to the DB RUN+START wire. Mine was an early install so I corrected that too. Add-A-Circuit piggy back fuse holder of fuse #11 is an easy no-brainer tap.