[kumiko1]

After I drive my '83 280ZX for approx. 20 minutes, it starts hesitating like that of a fouled plug or bad throttle sensor, but if I let the car sit over an hour, it drives fine, but after awhile it does the same thing.

I'm thinking the problem is related with the car warming up...any ideas?

Kumiko

 

[MeloPark]

Check that your water temp sensor is connected. If it is disconnected it will try to run rich until it thinks the car is warmed up. It is by the inlet hose on the front of the motor. Good Luck

 

[shane280z]

Hi Kumiko.
You might also install a new fuel filter. Your old one would appear to be dying.

 

[john cross]

It could be the above, if in fact it is related to it warming up. However, it does not seem right to me. I would think the car would warm up sooner. One possibility is an electrical problem. This is heat-related, in that ehwn transistors go bad they fail after they warm up. THis implies either the trignition unit or the ECU. The way I would approach it is, fix everything else, do a total tune-up, and if it still fails look at the computers. It is difficult to diagnose this, unlkess yo are prepared to get into ghooinhup and oscilliscope.

 

[johnh240]

I would agree with the total tuneup, plugs, rotor, cap, wires. But also look for very small vacuum leaks. They could be covered up during warmup by richer mixtures then still cause a lean misfire after complete warmup. Next thought would be looking at the ignition module on the side of the distributor. Also have the O2 sensor tested for output at full warm up temp. It doesn't light off until it reaches something on the order of 600d and if old or cruddy enough it may be giving an incorrect feedback signal.