Question about 1999 Ford Ranger SuperCab
OK - For the last 10 years the Ranger has started perfectly every time. Last week, for the first time, I turn the engine over and it would not run. It sounded like none of the cylinders were firing so I pulled a spark plug, grounded it and turned the engine over, no spark. After half an hour of fiddling with connectors and swearing under my breath the engine started and ran like it was new. This all happened (BTW) when I was 40 miles from home so after the engine started I drove it home without any trouble. The next morning, same thing, the engine would turn over but not run. No spark. Between then and now, I've checked the coil pack by ohming out between the Batt+ terminal and each of the three coil primaries (same connector) and I get 2.5 to 3 ohms. No opens or dead shorts. Next, I checked the crankshaft sensor for output by looking at the two terminals with an o-scope. While cranking the engine over I'll see a steady sine wave output - proportional to the crankshaft RPM. Outputs everytime so I rule that one out. BTW, when the engine is in this failure mode the PCM does not generate any error codes or check engine light - nothing.... So I'm thinging that may it's a wiring harness connector problem or perhaps a flaky ground connection. Any suggestions as to the root of this intermittent problem would be greatly appreciated.
I would have to suspect a crank sensor and-or connection there.
i see you checked it with an "o-scope" but i would be willing to
bet you dont have injector pulse either. without the crank signal, there is no rpm input, the pcm doesnt even know its cranking!
i have replaced many crank sensors with this intermitent concern....
Posted on Jun 02, 2010
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