Coil voltage problem.


BSchrowang

Budget Builder
Apr 24, 2016
492
0
Peru Illinois
I have a 2010 crown civ police interceptor (i know cool right) and i just got it re assembled. And now i have a check engine light. So (i work at a mechanic shop) i put the obd reader on it and it says i have an ignition problem in cylinder 8. It usually means a bad coil. So i switched the coil hoping it would go away but no dice. So i replaced the spark plug and still same problem. So i took the handy harbor freight voltmeter and tested the input voltage to the coil. It has 2 wires ~ Constant 12v and spark control. The power wire is 2v lower than every other coil plug on the car. Can i run a cable from another 12v source to see if that solves the problem? I reallllly dont want to get a whole wiring harness, especially considering i just got this car put back together from bare block. Thanks

 

bump465

Senior VIP Member
Apr 14, 2014
172
0
Arizona
If it needs a constant 12v, then there shouldnt be any problems with hooking it up to a 12v power source.

Amplifiers dont care where their 12v comes from, I cant see a sparkplug being any different in that sense.

Never tried it, but sounds safe.

 
OP
BSchrowang

BSchrowang

Budget Builder
Apr 24, 2016
492
0
Peru Illinois
Well i looked at my problem again this morning.. Today the plug is reading the exact same voltage as all the others 12.4 car off and 14.03 running. So now i dont know what to do. Its still not firing on that cylinder at all. Its not misfiring. Its not firing at all. Ive tried new coil, new plug and tested voltage. What else could i do?

 
OP
BSchrowang

BSchrowang

Budget Builder
Apr 24, 2016
492
0
Peru Illinois
Update. I tried switching out fuel injectors for that cylinder and still nothing. So i put the obd reader on and loaded a cylinder contribution test. It measures the output of each cylinder individually. It showed 1-7 all good and 8 had no contrib. So i tried giving the motor some rev to about 1500-2000. And then cylinder 8 came on just as strong as the other 7. But when i let back off the throttle it dropped back to nothing. Any thoughts? Maybe a intake manifold gasket leak?

 

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