One cylinder not firing
10-15-2013, 01:26 PM
#1
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One cylinder not firing Like the title says, I have one cylinder that isn't firing. Engine is an lq4, with factory harness in an 82 stepside. When I changed headers I noticed my #3 cylinder's spark plug was black(carbon), but all others were light tan/white. The primary tube on that cylinder was also not getting hot on #3, so I swapped the coil with #1, and #1 was still heating up/working. I swapped the plug wires with #1 and #1 was still heating up/working, then I replaced the #3 sparkplug with a new properly gapped one and #3 still doesn't fire. I checked the pink wire to #3 coil and it had 12v, I was thinking of hooking up an inductive timing light to see if it's making a spark, but I'm out of ideas after that. How do I check the signal going to the coil to see if there is a wiring issue or something else?
10-15-2013, 02:14 PM
#2
Mine was a wiring issue from the MSD, but I had two wires that were swapped in MSD's factory connector. Actually mine was swapped in the box, cause the colored wires were right, but when I swapped them it worked. OH, and then, another time at the track I had a bad connection in the pins that fired my #1 coil. I applied some dielectric grease and kind of mashed the female ends so they would grip the pin tighter. Been fine ever since.
10-16-2013, 01:28 AM
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One cylinder not firing Small update, I checked the coil's plug for continuity from the part that plugs into the coil to the PCM and didn't find any signs of a breakage, I also checked the ground by putting one lead to the pink wire and one to the black wire on the #3 coil and that checked out. When idling you can tell it is missing, but it hasn't thrown any codes. Is there any way a faulty injector could be causing my problem? Is there an obd2 scanner/program that can give me a readout for each cylinders spark/fuel?
10-16-2013, 03:03 AM
#4
Very possibly a stuck/clogged fuel injector. With a Tech2 you can do an injector test with a fuel pressure gauge and watch to see if the gauge falls, but most people don't have access to one. You could pull the fuel rail and crank the engine over to see if all the injectors are spraying.
