280z Misfiring When Warm

[SkunkTeeth]

Hi Everyone,

I am having a problem with my FI 76 280z. It runs great when cold, but once it warms up it will misfire around 2500rpm then run smooth again at 3000rpm. I did a sensor check as per the FSM, and everything was good except the main temperature sensor was reading about 30°F high. I had cleaned the connection terminals prior to this. Could the temperature sensor be reading too high and leaning it out once it warms up? The plugs, wires, and distributor cap are new.

 

Thanks

[george.bryant]

Hows the coil?

[SkunkTeeth]

I will check out the coil, but I have a MSD sticker under my hood from the PO but the coil does not look like it is the MSD blaster. It also has the fireball xr3000.

 

Another weird symptom. I was driving today with the AC on. When it was could and I would tap the gas, the idle drops to about 500 then goes back up. Then will constantly bob up and down from 700-1000, and there would be that same misfire sporadically. But when I almost got to work the idle would stay steady and there was no misfire. Sometimes when its warm its good and sometimes its bad I guess.

 

It seems when it is cold outside in the morning it runs good when the motor is still warming up. But in the afternoon when it is warm outside and the engine is cold it will misfire. This is why I am thinking it may be the water temp sensor.