My 5.2 l van ran fine when I parked it in early December; went back in February to restart it but no luck. The engine cranks but no spark (it initially ran for a few seconds after changing the PCM but rough and but wouldn't continue-now only cranks and still no spark) Changed engine control modules (the latest was supposedly remanufactured), also changed coil, distributor/rotor, and crankcase sensor. The sensor shows 3.81 volts at the connector. Checked relays and replaced the fuel pump/ASD relay. The key dance shows a faulty MAP sensor (showing 0 volts at a/b pins of connector and 4.92 volts at the a/c pins.). My old PCM has been sent to SIA Electronics for testing and repair. Any thoughts would be appreciated.

 

Where did you check for spark, at the spark plugs or at the wire coming off the coil and going to the distributor?

 

Both. Thanks for your inquiry.

 

UPDATE! Checked the voltage at the CAM sensor connector which is fed from the same PCM 8 volt input as the crank sensor: it also read 3.8 volts. Would seem the PCM is bad?? Also checked continuity on the MAP sensor at the connector; 4.7 ohms between pins 1 and 3, open line between pin and pin 1 and 2; likewise for pin 3 and 2. Time for replacement of the MAP sensor? Thanks.

 

That voltage might be being pulled down by a bad sensor in the loop. You can unplug sensors while monitoring the voltage and when and if the voltage goes up you have found the bad sensor. Not saying the pcm is not the issue, but there are other possibilities. Mine was insulation worn through on the 5 volt reference signal.

 

Thanks, I'll check it out.