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Re: Black smoke, dying car[240-260/84] posted by Don Foster on
Sunday, 5 July 1998, at 8:51 a.m.
A quick guess.... Check the air mass meter (AMM). With the ignition off unplug the cable at the AMM and try starting and driving the car. If the AMM's at fault, it should start and run OK up to maybe 20 mph. (With the AMM unplugged, the injection ECU generates (synthisizes) a signal as if the AMM was working properly at idle/low speed.)
Remember to unplug/plug the AMM only with the ignition off.
A second guess.... The fuel pressure regulator has failed. Possibly, the small neoprene hose connecting it to the intake manifold has become cracked or fallen off.
A third guess.... The wiring to, or connection at, the temperature sensor (in head) has failed, telling the injection ECU it's very cold. The ECU will richen the mixture to compensate. Possibly the sensor itself has failed.
A fourth guess.... The wiring harness (insulation) is failing creating shorts or bad connections, sending false signals to the injection ECU. Inspect the engine harness where it plugs into the main harnes at the firewall, and look for evidence of the plastic insulation crumbling and falling off. You might be able to patch it up (good approach if you intend to junk the car soon), but a better repair is to install a new harness. You can patch it by splicing in good wire or using "liquid tape".
Good luck. --