So i finally got my jdm d15b to start up on my ek. But there's one problem, the engine is stuttering? idk if that makes sense and when i take out my spark plugs they are black! meaning the fuel is too rich. my mentor (senior project) thats helping me on my car said that its spitting too much gasoline. If i unplug one of plugs to the injectors it stabalizes but when i plug it back in it wants to die. someone help me! i hope i explained it pretty well...if any questions just ask!

 

Any CEL codes? Is the timing set to spec? Have you inspected the cap and rotor? Are the plug wires old?

 

we basically made the wiring harness. cel codes? im using a p2j ecu. idk anything about timing set up.

 

Soot on the plugs doesn't always indicate a rich condition. It also happens with incomplete combustion. I'd start by checking the fuel pressure. Disconnecting an injector shouldn't make it run better unless you have a fuel supply problem and doing so frees up fuel to supply the other injectors. Inadequite fuel supply can also cause injector sputtering which produces soot. Post info about how the car runs at higher RPM, once it warms up, etc.

The phrase "fuel supply" was used rather than "fuel pressure" since a clog can sometimes increase pressure while decreasing fuel supply.

 

Click on the CEL sticky at the top.

Jump the service connector, hook up an inductive timing light, and check whether the pointer on the lower timing belt cover aligns with the red mark (middle in group of three) on the crank pulley.

 

Timing is everything. If you haven't yet, set it properly with a timing light. Search the forums, there are many how-to's.

 

it runs a lot better when the rpm is higher. i think he might have done timing already.

 

Timing problems will get better or worse with RPM and throttle position because they change how quickly the charge in each cylinder explodes and where the piston is when it does.