testing optispark
Race Director
Joined: Sep 2001
Posts: 14,651
Likes: 750
From: NEwhere Ohio
If your car wont start...watch the tach needle while cranking.
If it doesnt jiggle while cranking, the ecm isnt getting a signal from it. The ecm gets the rpm from the optispark.
All that said, that is not the end all test. You could be getting a signal for the tach and ecm, but could be getting shorts on the high voltage side. in those cases, the car usually runs, but misses/stumbles, especially when warmed up and under a load
If it doesnt jiggle while cranking, the ecm isnt getting a signal from it. The ecm gets the rpm from the optispark.
All that said, that is not the end all test. You could be getting a signal for the tach and ecm, but could be getting shorts on the high voltage side. in those cases, the car usually runs, but misses/stumbles, especially when warmed up and under a load
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Thread Starter
Instructor
Joined: Sep 2008
Posts: 119
Likes: 3
From: Ohio
opti spark
thanks all great info. Tach is not responding. The car will run for 10 minutes and then stall. Will rollover but not start for a few hours after sitting. Replace opti spark 2 years ago (within 2k miles) ecm also rebuilt 2 years ago.
