It's possible; the wires that are shielded on my car are the cam sensor and crank sensor; probably on yours too.
Both of those signals are sensitive to edges, or transitions in the signal, not a voltage level; so this is a good place to look.
They care about When it changes, not What it is or changes to. (A TPS wants and tracks a voltage; the crank sensor wants to know when the timing mark passes.)
These voltages are from magnetic reluctance sensors, so they are tiny.(https://en.wikipedia.org/wiki/Variab...uctance_sensor
This is a fancy name for a coil of wire, wound around a pole piece; some of the pole pieces are magnetic, some are not, and if that's not correct it won't work. I think they all have magnets now.
To check the circuitry wiring, the best way is to untape them and separate them as far as you can from each other, and everything else. Then see what happens.
You can then wiggle individual wires, and see what effect it has.
You can replace those with Coax cables, but it needs to be rugged stuff to handle the heat. And it's a pain.
Covering them with aluminum foil with a bare (ground) wire to a bolt on the chassis should reshield them as good as you can for troubleshooting purposes.
Just wrap the foil around the wire, with a piece of bare wire crumpled inside; that will work for a few days without solder or whatnot.
It will eventually corrode where the copper hits the foil and lose the grounding effect, so then you rip it out and do it again with fresh foil/wire.
I use some of this stuff, that I rescued from a dumpster after it was removed from a project: https://www.thorlabs.com/newgrouppag...tgroup_id=7902
Aluminum foil works just as good, but it's hard to solder to.
Another thing I do to sensitive electronics, is take a large heavy AC drill or side grinder that sparks a bunch, and hold it nearby, hitting the trigger, and see if it screws up when you hit the trigger; nothing causes interference than an old 15A drill sparking next to it.
Doing that may give you an easy check, and after you separate the wires, pinpoint where the problem is.
A handheld 'taser-like' device works well too.
If the ignition triggers in time to the interference, it's a pickup problem for sure.
You might also try the AM radio check.
Find an old AM battery powered radio, tune it to a blank spot, and with the car running, wave it around and see where you pick up noise. If you hear the ignition coming thru, you have a spark leak Somewhere; it will get louder the closer you are to the source.
(I use this a lot on electronic interference problems; some of my preamp prototypes have shut down all the cell phones in an area before.)
If you hear other noises, suspect the grounds; that means a fast moving signal is taking a longer path back to ground than it should.
Sticking the antenna inside the loop formed by the signal from source to ground makes that one louder.