Couple of problems

[andrewc53]

90 E 30 with the 6 banger. My tach has just started bouncing around lately. It's close to right but not steady. and the econometer goes wild or does not work. Is it the tach or board? also looking for an AFM. My car wont idle right when it's cold and if I bang on the afm it will settle down. Any help Thanks . ACurtis

[jlevie]

The behavior of the tach and mpg gage could be a failing SI board. The first thing I'd do would be to replace the SI board.

The vane bearings in the AFM could be dirty and the vane sticking. Dismount the AFM and use carb cleaner to clean it. Then lube the pivot points with 3-in-1 oil. If that doesn't fix the problem there is an excellent chance that the cause is intake leaks. Have the intake smoke tested.

[andrewc53]

I tried cleaning the AFM with no luck. Where can I get the SI board? Thanks for the help. A Curtis

[jlevie]

The most common problem with the SI board is battery failure. The batteries can be replaced, but if they have leaked and there is any corrosion on the board the chance of success from a battery replacement is close to zero. In that a replacement board is needed. You can get a used board and replace it's batteries or get a new board from a dealer or on-line vendor.

[blunttech]

if you want to do away with the batteries I have replacement boards sans batteries.
they have capacitors in place of the batteries and the si lights work with this set up