The one on my old Rover is faulty, and is no longer available new. It's basically just a pot. Goes open circuit at low throttle openings and causes the engine to loose power - although it will idle fine, and wider throttle openings are also ok. But made it difficult to trickle through town traffic smoothly. Got worse with the engine very hot.
Decided to open it up, after removing the epoxy that sealed the screws.
It's two large lumps of carbon, with twin wipers either side of the spindle which then connects these in series. Travel is only about 90 degrees.
There was some wear where the wipers touched the carbon, but not that deep.
Cleaned it all up, and it's better, but not perfect.
The question. I was surprised to find them dry - I was expecting a light coating of grease. Conductive plastic is usually dry, but this looked to me like carbon. Would there be any benefit in using one of the normal switch/pot lubricants?
I have found that dusting the tracks of TPSs with ground up graphite (From a pencil or old carbon brush) works wonders and ekes these things out for a few more thousand miles. Also try cleaning the tip of the wiper with WD40 and wiping with a dry cloth.
The worn bit is obviously where it is used most. Can you reverse it end for end so the wear sits elsewhere ? This way your repair will hopefully last longer.
Although I used to have a Rover with similar sensor I never had occasion to take it apart... however, my experience of switch cleaner / lubricants in audio applications is pretty awful. Unless the thing is hermetically re-sealed (difficult with a pot, or a fader as I more usually met) cleaning the thing with something vaguely oily or greasy worked well for a period of time, but actually made things worse in the long run because any bits of dust and fluff floating about tend to stick to the tracks.
In consequence we tended to use isopropyl alcohol almost exclusively for cleaning jobs, though the P&G conductive plastic faders we mostly used more commonly needed new wipers due to abuse from the jocks. The occasion when IPA wasn't suitable was the one when one of the jocks had tipped half a pint of cider into the desk - such sugary things clean up best with water.
...and the desk stayed on air right through both the tipping and the cleanup, a process which lasted a good couple of hours.
So, personally, I'd be tempted to clean it up with some IPA, possibly grind some soft pencil or drawing charcoal onto it if really
*really* desperate, and then use the reprieve to search for an alternative. Is there any chance of kludging a standard part from another (related) engine to fit?
My Rover was a 214 with 1.4l K-series 16V engine. I doubt it was actually an engine problem, but from very soon after I got the car, right up to the day I PX-ed it for something newer, it had this weird problem where if you had less than (about) a quarter of a tank of petrol you had to be very careful going around left hand bends. Too quickly and the engine would cut out, picking up again when you were back on the straight (or turning right). The less petrol you had the more severe this problem was. I never had anyone give me a satisfactory explanation for the symptoms :-)
I cleaned mine when looking for a problem. However, the thing that really benefited the car was cleaning the advance / retard vacuum pipe. After finding such an improvement I did it every few months.
The fuel pick is probably towards the left hand side of the tank, and as you turn hard left, the fuel tends to swill to the right, allowing air to be sucked into the pick up, which unsurprisingly does not help to keep the engine running. If this were happening with as much as 1/4 tank indicated, I'd suspect the fuel gauge to be overreading somewhat.
There's a certain (once) popular small diesel engined van around that if slightly overfilled with oil and driven hard whilst turning right, (for example on a large fast roundabout) would have the tendency to flood the oil seperator and suck copious quantities of engine oil into the intake through the breather. Of course being a diesel this is a nearly good as injecting more fuel, producing an unexpected boost of uncontrolled power along with an enormous cloud of filthy black smoke (more so than usual), accompanied by a rather frightening machine gunning noise. Declutching (I can say with some authority!) is not the thing to do in this instance as the engine will continue to run away until either something breaks or the unintentional fuel/oil supply stops. Apparently one should try to stall the engine, but this is an easier said than done bit of hindsight advice when you unexpectedly find your van developing a life of it's own.
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