Tachometer/Cutting Out Problem
 

Did tons of searching and haven't found anything. Car runs a little rough at idle on startup but once I get going it runs good. It will run strong until I get to normal operating temperature and then all of a sudden the tach will go to zero and it is like the car has turned off. Radio, oil pressure, volts all read fine like it is on but there is no pedal response if I push the gas. Just as sudden as it cuts out, it cuts back in and starts running fine. It will do this a few times in a 30 mile drive. I believe it to be an electrical problem coming from the coil. I think this because I believe the Tach needle is just a proportional output from the coil. Therefore it seems like the coil is cutting out, causing the Tach to read zero. These are the things I have checked.

Spark plugs - replaced, 0.04 gap
Spark plug wires - good condition
Coil - replaced
TPS - checked, seems fine, connections were cleaned
CHTS - checked, seems fine, connections were cleaned
Distributor Cap and Rotor - checked, seems fine, connections were cleaned

I am going to open up the AFM to see if the tracks are ok, but I don't think this is the problem since I feather the pedal and get no response when it cuts out. I have a suspicion that it is the IC Ignition Unit that is connected to the distributor, but that is an expensive part and I don't want to just throw money at parts. Anyone else have any insight?

1983 280zx NA

Had a similar issue, only the engine would not die, but my fuel gauge and tach would drop, and the temp gauge would max out.

What I did to fix this was to pull out the dash console. Then I took some sandpaper/Scotch pad and clean the copper traces around the connector pins. Applied some flux around the base of the pins where they contact the copper traces and then flowed solder into the pin/copper interface. (This was a pretty common procedure on 2.2l mopars).

Now the gauges are rock solid and I now have faith in their readings.

You may want to clean all the electrical connections on the passenger side by the fuse box also. Before reconnecting, apply some dielectric grease to the pins.

Get the '81 EFI Bible and verify the resistance and elecrical tests. (Do the tests both with the engine cold and hot, after it 'dies'. It could be a pinched wire or connection that when heated causes the problem).

Just a little tip... if you can remove the old solder with a desoldering braid will give you the best long term results. The problem with old solder is that it will oxidize especially if you have over heated it. The oxidized solder doesn't conduct well and if you can remove as much as possible then it doesn't get mixed in with the new solder.

Nice to see someone recomending using the flux as well. Very important for a good joint. It's like trying to weld without inert gas...