My 86 non-turbo Z, 5-speed will idle fine then when taken out on the road, after about a mile, will loose most of it's power and barely make it back. Changed the fuel filter, replaced the ECU, spark plugs/wires and some vacuum hoses. The codes give me a 31 while on the road but switches back to 44 when I get it back in the garage. Been beating my head for 6 months over this. Sometimes it even looses power while idling but not for to long.

Any ideas will be gratefully taken.....

Engine power or Electrical power?

Engine Power, sorry.

After it loses most of its power, if you turn off the car and try and start it does it start and idle ok?

Yes, got an idea? Thanks

Not sure man, im stumped(thats not saying much). Try posting this on www.z31.com , youll get many more responces.

i had a similar problem though FAR less severe, i bought a can of GM top engine cleaner and after i filled about 4 city blocks up with smoke i regained most of my power.

I was talking with this guy one time about his 280z and it did the same thing...he said it was Airflow Sensor....senses/controls the amount of air coming in to mix with the engine.....MASS AIR FLOW SENSOR...something like that!
david

My best bet would be the fuel injectors. NISSAN FUEL INJECTION SUCKS! z31's were recalled for it, and i believe so were 280s after 75. at least my brothers was ****ed up.