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I did some tuning yesterday and this morning I had my laptop hooked up, I started the car and proceeded to load a tune. A message came up asking if smec ecu is correct, I clicked no. However now my tach is running backwards. Have you seen this before? I had two tunes in place on mptune yesterday but only used lm tune.I
I got it working again but it is unsteady at times at idle. Probably just being cantankerous because it's 35 years old or a problem at the distributor plug pins which I recently cleaned.
I revisited this problem and fixed it. Here's what the problem looked like...The tach needle would bounce and then steady to be useable. It continued operating like this until one day the needle just sat at "0" rpm. It wouldn't move until a small amount of throttle was applied at which point it moved towards the gas gauge needle. Increasing throttle would make the needle bang over against the gas gauge needle.
I pulled the Rallye package instrument cluster and inspected. A couple of pins on the circular array of pins were loose including pin "C" which is the tach input. The fix was to solder each of those pins to the trace and I also soldered the back of the pins even though they were just crimped over from the factory. I counted on the solder wicking past the crimp and making further contact with the traces.
Reassembly and test showed a perfectly operating tach.
nice fix
Similar problem I had on mine. I am using a 1989 J body dash in my 1986 LeBaron convertible, every one of the pins were loose in the board. I still had an erratic tach until I sprayed the pins with Radio Shack contact cleaner and tightened the female connection side springs.