I have an 83 maxima with the L24e engine. 165,000 original miles. Ran like a top until it started fouling the plugs on cyls 5 and 6. The plugs are fouled with carbon, not oil and are not wet - appears to be incomplete combustion.

The compression on all 6 cylinders is good and the engine does not burn any oil.

I would like to do a L28 conversion with this car, but need to get it running and driving again so I can smog and register it. First thigs first...

Any ideas as to what might be causing this?

 

Since this prob has been answered in a diff thread ( https://www.zdriver.com/forum/showthread.php?t=16958 ), and since this has nothing to do w/ 280zx's... can we delete this?

 

Sounds like leaking fuel injectors... How old are they?

Rod.

 

I wanted to see if I could get differing opinions.

Not everyone that visits the 240/260/280 forum comes onto the 280 forum specifically.

L24, L28 very SIMILAR engine, with similar issues. Input would be nice...

Any ideas?

 

The fuel injectors are not original. I replaced all 6 injectors about 30,000 miles ago.

They were rebuilt units. Not new.

 

Check the gap on the plugs if you haven't already. Also, what heat range are they? Too cold a plug will do this. And what Rod said too makes sense. A fuel fouled spark plug is usually covered in carbon deposits. It's not usually wet. A wet spark plug is a sign of oil fowling. But if you're sure the injectors arent leaking then check for sticking valves, that will cause the same problem. Also, inspect the wires to those two cylinders. Usually if it's isolated to 1 or 2 cylinders it's something like the wires.

 

Thanks. I will certainly check the gap, but that is something I always do when I install the plugs initially.

The wires are aftermarket NGKs and it is possible that something might be wrong. It has been a while since the car has been in storage, but I installed the wires right around the time this problem reared it's head.

I need to check the injectors for consistency bet cylinders, so I will put that on my list as well.

How would I go about checking for sticking valves?