240sx runs rough. tried EVERYTHING

[SloS13]

1993 Nissan 240sx w/KA24DE

All emmissions stuff has been removed. Right now the only vaccum operated things are brake booster, FPR and secondary butterflies.

IdleCar starts and will idle great for a couple seconds then the idle will lower and it will start running very rough.

DrivingCar runs very smooth with very small throttle input, but as soon as you overstep a certain threshold of throttle opening, it will go into a mode of what feels like missing and retarded ignition, back your foot off a bit and voila it goes right back to smooth-runnign mode.

Compression is 180 across the boardI have also noticed that, when the car is idling bad, I can pull the #1 injector clip and it makes no difference whatsoever.

What I have tried replacing:Main engine harnessMain under-hood harness (From ECU to driver side floorboard)Sub-harness for IACV, etcIACVDistributor, cap, rotor buttonECUCoilfuel filterspark plugsMAFS

I NEED to get this thing running. Any help appreciated

[180fan]

You've already found your problem. The injector. Have you also tested the fuel pressure by any chance?

[SloS13]

Forgot to mention. I switched the #1 and #2 injector but the problem did not move with it.

Haven't tested fuel pressure yet but it's on my list of things to do. It has a walbro 255 and it *sounds* to be working perfectly normally.

[180fan]

then the problem is either your harness or your ecu. fuel pump sounds to be working but you haven't tested your actual fuel pressure.

[SloS13]

Yeah but the gay thing is, I've swapped all the harnesses in the car except for the one that goes behind the dash. I removed the dash and insspected it. Looks perfectly normal.

I've tried several ECU's too

[rogoman]

I have also noticed that, when the car is idling bad, I can pull the #1 injector clip and it makes no difference whatsoever.

Looks you definitely have a problem with the #1 cyl even though you exchanged #1 and #2 injectors.

Have you ever replaced the ignition wires because it's looking like an ignition problem with #1. You may not be getting spark at #1; something you need to verify.

[SloS13]

Spark is working on all 4 cylinders. Even tried putting ANOTHER set of brand new plugs in there. Wires are low-miles NGK wires but I have tried another set as well.

If I havent mentioned already, compression is ~180 on all cylinders

[180fan]

stab in the dark: have you checked your fuel pressure

[SloS13]

I'm gonna get a cheapo gauge from Advance in the next day or two. The walbro *sounds* perfectly normal to me and the stiffness of the feed line after the car is shut off feels about right and remains constant.

Sniffed the FPR's vaccum line, no fuel smell but oddly enough I removed the valve cover and could swear I smelled fuel but maybe that was just me. If the pressure checks out I might swing by the junkyard and get another rail/fpr/injectors assembly.