Help Rb25de Neo Running Rich!

[JMUZZA_R33]

Hey guys, I've got an 96 R33 S2 with an RB25DE NEO in it.

The problem I have is it is running super rich, just above my exhaust on my bumper is black like solid black & I'm getting shit fuel economy. When I drive I can just smell fuel & the same when standing outside the car. I know Skylines aren't cars for fuel economy but it's N/A and I'm getting roughly 320kms to a tank. A mate of mine has a 96 S2 R33 GTS-T and he said he gets 350-400kms flogging it! I know it has a lot to do with the driver & the way I'm driving but I don't believe I give it to it a lot, of course every now & then, I change gears around 3k RPM.. For modifications I only have an X-force rear muffler, pod filter & super spark coil packs. I've just had the correct harness & ECU installed as it was running a GTST computer & R33 harness with the plugs replaced to suit the NEO from the old engine, performance wise it's so much better but fuel economy stays the same?

Sorry if I'm a bit oblivious guys bare with me, I'm a newbie to Skylines. Always been a fan it's just my first time owning one.

Any help on suggestions to diagnose the problem or things that may help improve it are appreciated!

Cheers,

Jordan.

[ErOR]

Possibly the O2 sensor needs replacing or maybe the thermostat. Does the car take a while to warm up?

Another thing that could be is the water temp sensor for the ECU, if it's giving a wrong reading (too cold), the car will think that it's still needs to warm up and will keep running rich to try and do so.

I find revving out the engine a bit more (3k) when cruising to be better for fuel economy as long its kept at light load to keep momentum.

What ECU are you now running?

[scotty nm35]

I would say you need to swap the turbo injectors out for NA ones, now you swapped the ecu over.

[JMUZZA_R33]

Hi guys thanks for the reply!

@ErOR my car does take a while to warm up now you mention it, about 10-12minutes if it's just on idle, also I pulled out my O2 sensor to clean it & it was black!! Big carbon build up I guess, that was about 4 months ago I cleaned it with sandpaper to get all the carbon off.

@scotty nm35, how do i check if I have turbo injectors? I have the part number with me, I have searched them up but I can't seem to be finding much.