280zx intermittently dies then restarts
 

At my and my mechanics wits end.

1982 280zx n/a manual.

After reaching normal operating temp the car will intermittently die like a switch was turn off and on. The tach drops to zero then usually car fires up again on its own. Sometimes I have to turn the ignition to off then back to start and then it will restart.

It's been into the auto electric shop twice with no change. Tried a second ecu, 2 other distributors and ignition modules, wiggled wires while it was running, replaced weak coil, installed new electrical connectors, cleaned all connections, brand new JECS AFM and injectors because of high CO & HC. Had it re-smogged 2 weeks ago and came in extremely low on all readings. Checked the ignition switch, checked out OK.

There's no pattern to it dying. Started about 5 years ago with just a little bump when driving and the tach bouncing to zero and back up without shutting off.

I've research this and other forums for an answer. The ignition module doesn't seem to be the problem in that it did it with two other modules and fuel, filter replaced, doesn't seem to be the issue because it typically take less than second to occur on most occasions.

Someone steer me in the right direction. Thanks

OK, let's get at least half a response in here. I'm assuming your ECU is reliable since you switched it out. If your Z was a Z31, I would say it has to be sensor/signal related, meaning that there is either a sensor that is intermittent, drops out for a bit, then reconnects - and this means it is dying and needs to be replaced. Your call on the sensor. The guilty party on a Z31 is usually CHTS or TPS, fairly replaceable. When they send bad or no signal to the ECU, Z31 crap occurs. Makes you crazy. Your call on the S130 sensor to blame.

OR (the big OR) is just a bad connection that can be vibrated to break and then reconnects. This says dirty/corroded/broken connector, loose wire, etc. and is a pain in the butt because it can only be found by checking the entire harness from one end to the other. But you have the service manual from XenonS130 - S130 Reference and can print out the detailed electrical circuit diagrams on 11x17, use colored markers to trace every connector in the harness between your sensors and your ECU. Use your circuit tester, disconnect, clean and reconnect every connector one at a time, testing circuits as you go.

On an old car, sensors get tired and connectors corrode, get grimy. I hope a S130 guy shows up and knows an instant fix for your problem. Until then, sorry for the mixed (Z31) input. :120:

My bro had a MkII Supra doing the exact same thing you described: It had a short to ground on a wiring harness from the ECU to the engine bay, took a mechanic 5 hours to find it after he got tired looking for it... I hope it's something simple!!!