E30 Zone

My 320i isn't idling right, and worse, the econometer goes haywire.

Start the car, let it idle, and the econ needle swings all the way over to the right. Then it will start surging, and the needle will swing back to the left.

Once you're out and moving, it takes about three minutes for the engine to "cough" and then the econ needle is out of order completely, never coming back until you shut the engine down and restart, and then it only works for a few seconds.

Any causes? Does the econ get its reading from the TPS, or from the AFM?

I had a similar "cough" with my car , it turned out to be a faulty tps it was on a m50 engine but the econometer did just what you are saying , I would a tps , the econometer gets its signal from the ecu

Yeah, it was my gut instinct as well, so I just took it off and did the hole-drilling trick, filled it with contact cleaner, blew it out and tested it with a multimeter.

In one position I get 0 ohms across pins 2 and 3, and infinity between 1 and 2. If I move the shaft past the "click", all pins will read infinite resistance, so I guess the whole switch has gone duff.

That'll be fifty quid then

I guess so