Guest KEINsm Posted October 17, 2003 Share Posted October 17, 2003 I've tried searching for an answer to my problem but came with no clear answer. It seems like FI cars have the same problem. My car is an early 1970 240Z with all stock components (except an alternator from a newer car, electric cooling fan, stereo, and alarm) Almost a week ago, my car ran perfectly with no problems. Now, it is difficult to start and seems to misfire. The engine revs roughly up to 3000-4000rpm when cold then it hits a "rev limiter" and refuses to go any higher. I figured it would be driveable, but it lacks too much power and I must slip the clutch to get the car moved out of the way. (I need to do this at "full throttle" doing 3000rpm) When the engine warms up, the idle gets very unstable and stalls only after a few seconds. It also gets more difficult to rev past 2000rpm. What is wrong!?!?! When cold I can hear the timing belt slip with a high pitched screech. The car does not seem to be running rich. The exhaust is clear with a familiar gasoline scent. Here is what I have done. I replaced the fuel filter under the hood because I figured it was clogged. This changed nothing. Next, I pulled the sparkplugs for an inspection. I found the plugs from cylinder 4, 5, 6 were in good condition with a nice amber color. However, the plugs from 1, 2, 3 had a dark brown/black color. The front carb may be running richer but it still didn't explain the bogging. Next, I pulled the oil filler cap while it was running. The engine hesitated and quickly stalled. From what I read on this forum, this indicated that there should be no vacuum leaks. Next, I tried pulling the sparkplug wires one at a time while the car was reving at 2000rpm to see if the cables and distributor were working. Funny thing is...there seemed to be no change in the rough revving with or without any single spark plug. This confirmed (to me at least) that it was a misfiring problem caused by a timing error. Before I spend money to check and reset the timing, would there be any other causes of this problem or anything else I should check out? I know my little diagnostic and theory may be completely wrong so please don't hesitate to poke fun and correct me! Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 17, 2003 Share Posted October 17, 2003 Check the distributor cap for cracks (replace if it's still the original). Replace points and condensor and coil (if suspect). Replace plug wires. For your screaming fan belt, check that the tension is correct (should be about 1cm of deflection at the longest section. If it still screams, it might be glazed on the contact surface. You can try rough it up with a pieve of sand paper (while running, but be carefull!!). Or get some belt dressing from the parts store. Tim Quote Link to comment Share on other sites More sharing options...
Guest KEINsm Posted October 17, 2003 Share Posted October 17, 2003 The distributor cap, sparkplugs, and sparkplug wires look pretty new. All the contacts still have that brand new shine. Would you still recommend a replacement? As for the coil.....that thing looks lke the original from the factory. Would I be better getting an OEM replacement or getting one of those hyped up aftermarket ones such as MSD or Crane? Just now, I checked if I can see any sparks while running the car in the dark. I saw some small blue flickers on the ignition coil wire contacts. I will try to clean those up and see what happens as well. Thanks for the help! I hope your idea works! Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 17, 2003 Share Posted October 17, 2003 Don't get a powerfull coil. Get one designed for points. You could always upgrade your distributor to an electric one from a early ZX. That gets rid of the points variable and you can runa stronger coil. I did that mod to my old 73, and used an Accel super coil. Worked great. Tim Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.