Thanks, GeorgeSanJose, I have now focused on ignition for the reasoning you mention.
And Rod Knox: there is a cold start injector which tested good previously and I just tried to eliminate it (again) from consideration by eliminating it from the the engine equation - cut off fuel flow to it with no change in running behavior. (at least now I’m working with an engine that will run, sort of)
Just to update. did a complete check of the cold start/TT switch functioning and it all looks ok. Car was firing up quickly but still with that erratic miss and rough running.
I was in the process of checking all of the temp sensors, the last being the 45 degree switch. Checked the switch, cold and hot which was good (no continuity at <86, continuity 105>), reconnected the switch, started the engine, —no miss, no hesitation, ??. Bad switch? Did I heal it with my magic wand (DVOM)?
[ One add’l detail, I pulled a connector from the switch while engine running at temp (before doing the continuity check), and the idle went up immediately (probably to be expected), on re-connection it did not come down until I stopped and restarted the engine. ?]
Given the erratic nature of this problem over the last 1.5 years, I’m not ready to declare a healing yet. Am gonna renew that switch.
Pulling and reconnecting electrical connectors can sometimes result in a “miracle” cure.
At least you know its not timing probably unless the chain got back on the right cog again.
My 2003 Olds Silhouette had an intermittent ABS light. I disconnected the front connectors at the wheels and sprayed contact cleaner into them. After reconnecting the circuits, I have had no more problems. For a 1985 car corrosion in the connectors, even if they are weatherproof, is not out of the question.
It wouldn’t be that unusual for a temperature switch like that to be intermittent. I had a radiator fan temp switch on my Corolla that would work fine when I pulled it out of the engine and bench tested it, but would fail intermittently when it was installed. This is especially true if the active part of the switch is in the coolant path.
@GeorgeSanJose just bought a floor jack at a flea market…maybe it’s yours.
I always thought he was a shifty looking fellow.
Yosemite
These BMWS are VERY SENSITIVE to holes or rotted rubber intake tubes… when they crack the suck air without pulling it thru the MAF sensor… a Big No no on this engine.
Remove and inspect that rubber intake tube for cracks or holes…replace if you find any and see what you get. This is of course assuming all else is healthy…like the Timing chain etc…fuel pump and ignition system.
DUH…I read almost all other posts except the LAST one from Circuitsmith… LOL… Hey at least we are on the same page. Yup…that intake tube was a MAJOR source of issues on this model.
Blackbird
lol … yeah, @Yosemite might be right about the source of my new $2 floor jack … lol