I'm all out of ideas on what to check next. 90 sohc 240sx. What its doing is, get the car up to about 80 mph the car shuts down, falls flat on its face like the gas was turned off. The car shuts down. Don't know how else to describe it. ALWAYS around the same MPH. I have replaced the following:

ECU
Injectors
FPR
MAF
TPS sensor
Fuel Pump
New cap, rotor, plugs and wires

Any idea what I should check next? He is about to take it to S&R to have them fix the problem. By the way, except for exhaust, the car is stock.
Thanks.....

 

fuel filter?????
and i would still drive it around lol there is no need to go 80mph

 

New fuel filter with all that stuff as well? I'm no expert, but have you checked the timing? Does it do this at a particular RPM?

 

Yes, he did replace the fuel filter. I have not personally checked timing. As for RPM, it does it only as you hit the upper 70's-80 mph mark. You can drop it in forth get the RPM's up and still does it at the upper 70's-80 mph mark. He had the head rebuilt and Im sure the shop he took it to set timimg. (Car was doing this before it had the head rebuilt.) BUT I'll double check timing.

 

Could it be the speed sensor going bad and thinking it is hitting speed-cut? Just an idea.

 

I disconnected the speed sensor since it was cutting out at the same MPH each time and no change

 

I did notice there were 2 sensors going to the air box. 1 to the Mafs and the other I have no clue what it does. Anybody know? Some kind of air sensor.

 

strange...

how does it die? quickly shuts off or stumbles over itself and dies...

does it do it every single time, without fail, or is it just most of the time?
does it matter if you've been driving for a while or not?
What about load, if you creep up to 80 is there a difference rather than if you floor it up to 80? does it still do it going down a hill?

I know those all sound pointless, but it could help point to something...

 

Also, did you replace all of those parts with brand new, known to be good parts, or did you rape a junkyard 240?

it is possible that you replaced a bad part with another bad part...

 

Intake air temperature sensor I think?