factionos Posted May 12, 2015 Report Share Posted May 12, 2015 we are having a similar problem, about 2 weeks ago upon start up it started intermittently idling rough and driving poorly, the next time it was started it ran fine, then again it ran rough and finally the check engine came on. I got the code P0203 - Injector circuit / open cylinder #3 I thought that testing the #3 injector would be the first thing to check, I switched the #3 and #4 injectors and nothing changed. This leads me to believe the injector itself isn't the problem but perhaps the wiring? so I removed the intake manifold and did a couple things to determine if the spark plug or coil where part of the issue. switched the #3 spark plug with #1 switched coil pack from #2 and #3 neither had any effect and still had the same DTC of P0203 Tonight i wired in a replacement plug for #3 injector, unfortunately it did not fix the issue and i am still getting an open condition on #3 I'm starting to think its the PCM at this point, I really want to try and trace the wires for #3 back to the harness but everything is so tightly wrapped i am not sure what to do. Quote Link to comment Share on other sites More sharing options...
macbwt Posted May 12, 2015 Report Share Posted May 12, 2015 I am not an electrical engineer but you should be able to test the wiring at each plug to determine if you have the juice going to each coil. This would most likely be the best first step. Maybe someone here can outline how this is done. Quote Link to comment Share on other sites More sharing options...
factionos Posted May 14, 2015 Report Share Posted May 14, 2015 I am not an electrical engineer but you should be able to test the wiring at each plug to determine if you have the juice going to each coil. This would most likely be the best first step. Maybe someone here can outline how this is done. the problem I am running into with checking the wiring is that it requires the car to be running, but cylinder #3 is under the intake manifold which has to be on the car to run. This leaves me with very limited ways of checking it Quote Link to comment Share on other sites More sharing options...
macbwt Posted May 15, 2015 Report Share Posted May 15, 2015 I believe the option would be to remove the intake. Remove the fuel injection fuse then connect the voltmeter or engine analysis computer to the injector wiring. Then crank it to obtain a reading on the the voltages. A lot of work for a snap shot but it would confirm the wiring is either good or bad and allow for a better determination as to the direction you would have to proceed. the problem I am running into with checking the wiring is that it requires the car to be running, but cylinder #3 is under the intake manifold which has to be on the car to run. This leaves me with very limited ways of checking it 1 Quote Link to comment Share on other sites More sharing options...
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