You know what's even better?That is such a good feeling, isn't it?
Discovering that the computer connection wasn't the problem, then finding the real cause.
When my truck died, a week ago, I was heading to the industrial supply place to buy a small sheet of aluminum to fabricate a perch, or hanger for the inlet and outlet tubes of my new heater core.
After thinking I finally found and fixed the culprit, that computer cable, I reinstalled the computer up under the dash.
NOW, it was time to head back over and get that aluminum.
I drove over there, six miles away and found a perfect scrap.. 3" X 30"..... $2. Perfect thickness and no cutting charge. It was 4:58, closing time. As they closed the big shop door, I started my truck...... And it began stumbling again.
It kept running as long as my foot was 1/2 way to the floor.
It died again in town 2 1/2 miles from home.
I folded the carpet back from the firewall, removed the computer from its position up in the dash and laid it on the floor.
The truck restarted and ran beautifully.
Once home, engine idling, I started gently tugging on each individual wire at the plug connection looking for the loose one. Nothing changed at all. I wiggled wires up under the dash... Nothing.
I folded the carpet back against the firewall and the engine immediately started missing, so I folded it back onto the floor.
I grabbed the wire bundle and held it steady, then twisted the computer left, right, up down..... The engine never missed a beat.
Ok, once again, I folded the carpet back into place against the firewall and the missing instantly reappeared.
There is a big, fat grommet where this bundle of 25 or 30 wires from the computer pass through the firewall. The hole in the metal firewall over time, had worn all the way through the grommet and was grounding a wire. That was my problem.
With the computer on the floor, there was no tension on the grommet and no shorting.
The wire bundle and grommet moved slightly as the computer was pushed up under the dash, so only with the computer in place did this short happen.
So yes, the plug not being connected may have contributed to the transmission shifts and idle speed never being consistent, but the misfires ant erratic tachometer was because of this short.
This grommet, on the lower side has become soft and sticky, almost like roofing sealant. The top half is still solid. I want to wipe off the goo and determine if the wire is good enough to be left alone, then devise a way to build up with some heater hose, or other stuff to shield and protect the wire. I'm hoping it's only a bared wire, not worn 1/2 way through.
Yes, its been a long way there, a long way....