After short running time, the carbon deposits on the plugs short out. I installed the hottest plugs I could find (NKG4's) and advanced the timing a little. Is there any way to adjust air-fuel mixture? Is there a problem with advancing the timing too far, like 5 degrees past recommended of 10 degrees?

I have a '77 280z fuel injected; compression is 140psi.

Thanks for any help. Ron

I wish I could give you a definitive answer that would make this issue just go away, but I can't.

However, our neighbors to the North have assembled a great resource:

http://www.atlanticz.ca/zclub/techtips/EFI&fuel.htm

www.atlanticz.ca

Be sure to download the EFI Bible, it's in .pdf, and should be considered required reading.

Good luck, and be sure to post how things go for those that come after.

If your car is running rich (plugs fouling) then they are obviously getting a bit too much fuel. Check your cold start switch, coolant temp sensor, TPS, and O2 sensors first. Make sure these are in running order. If so, then you have at least narrowed it down a bit.

Next check your AFM and make sure it is operating correctly and not sticking. These are all the easy checks.

Check your fuel pressure and make sure that it is at the correct operating range. Too much pressure yields too much fuel. Things that affect fuel pressure are the fuel pump and fuel pressure regulator.

If everything else checks out, the last thing to check is your injectors.

Good luck.