Guest yTTyTee Posted October 27, 2003 Share Posted October 27, 2003 I pulled out my plugs the other day to check um, and they are black sootey. I take it this means there is too much fuel going into the mixture. I have noticed that the exhaust smells very rich, but I thought this was becuase it was old and had no cat. I have the stock L28E in my 1976 280z. I did fix a mixture problem before when I had an air leak in my intake hose before the throttle body, but after the air pressure sensor. I patched that up, and the idle problem I had was fixed. I'm just wondering where I should start looking, is there any common mixture problems with this engine that I should check out first? Just kinda lost as to where to start. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 28, 2003 Share Posted October 28, 2003 Check fuel pressure and the pressure regulator - most likely cause, unless you idle the engine too much, and idle mixture is way off. If fuel pressure is OK, your AFM may be jacked, and you might be able to adjust it. But check fuel pressure first. Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted October 28, 2003 Share Posted October 28, 2003 I have the same problem- sooty spark plugs, sooty tailpipe. the dealer tekkie said the AFM was all messed up and I need to install a new one -> $600! I adjusted the TPS (throtle position sensor) myself to give rich on idle or WOT, but I'm not sure what the dealer tekkie means when he says it was too rich. What throttle position(s) do they measure the mixture at? I can live with it for now, but will probably go at it in the spring. Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted October 28, 2003 Share Posted October 28, 2003 Here's a procedure I found on the Internet someplace: http://www.network54.com/Forum/thread?forumid=149594&messageid=1050639430&lp=1051927272 1. take the cover off the left side of the afm 2 there is a wheel with teeth on it held in place by a small screw on the top left corner(on my 78 it was a phillips) 3 hold the wheel FIRMLY!!!!!! while you loosen the screw just enough to be able to move the wheel , there is a spring in the center of the wheel and if you let go you will be in a whole heap of trouble the spring holds tension on the flap inside so the tighter the spring the less fuel 4 twist the wheel forward (as if it where a wheel on the car while it was moving forwad) I wouldn't move it more than 2 or 3 teeth at a time Use at your own rick, obviously. Quote Link to comment Share on other sites More sharing options...
Guest yTTyTee Posted October 28, 2003 Share Posted October 28, 2003 Sounds like a good temporary solution for now, the rainy season has caused me to lose a little modivation to get out there and really work on it. Thanks Quote Link to comment Share on other sites More sharing options...
Guest Boyd Posted October 29, 2003 Share Posted October 29, 2003 I turbo'd my '77 and spent waaaayyy too much time trying to tune by adjusting the AFM. It's pretty easy though. I also recommend small changes, only 2 or 3 teeth at a time. It also helps to have a fuel pressure gauge. That way you can see what pressure your running and if it is correct (typically 37psi). If you are the adventurous kind, you can purchase a MegaSquirt kit for $120 and have fully programmable! As far as the $600 for a new AFM, hit the junkyards! I picked up a 3" one for $30. Quote Link to comment Share on other sites More sharing options...
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