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Lane A/B Issue

F

Frostbite023

Member
Okay so I have been battling a lane A issue recently. My mechanic and I recently swapped out all the spark plugs and immediately following that I got a lane A fault for cylinder 3/4 ignition (picture attached). We have been trouble shooting and today we unplugged the spark plug connectors, unscrewed them from the wires, then screwed them back on. We also removed the spark plugs for cylinders 3 and 4 for inspection, finding nothing wrong we put them back in. Now when starting it shows a lane B fault, same message, "cylinder 3/4 ignition fault". Lane A no longer illuminates. It does sound quite rough now when starting as well. As a hail mary we unconnected the a connections on both the ignition coils for cylinders 3 and 4 and sprayed them out with contact cleaner, the issue persisted with lane b. Tomorrow we will be straight up replacing all the spark plugs in cylinders 3 and 4. I am also tempted to unconnect the spark plug connecters from the wires again and try reseating them. Any thoughts on what else we can try?


20251202_132622.jpgwapped out all the spark plugs recently and following that I started to get a lane B issue
 
Lane A 3/4 -> #3 and #4 bottom. Lane B 3/4 -> #3 and #4 top.

You must have mixed up either a plug boot or a plug when you re-installed them to make it change Lanes.

The test below may help. Also note each boot has a 5k resistor inside. Each plug has a 5k resistor inside. Perhaps you can narrow down the problem.

My #4 bottom boot had corrosion inside (and no dielectric grease either).
One of my wires (Coil 4 bottom -> Cyl 4 Top), was rubbing on the intake manifold.. the harsh surface finish of the manifold rubbed most of the insulation off one of my wires - others have had this problem too. But if your problem changed Lanes, then its probably not a coil or wire, likely a boot or a plug that got moved.

1766466030266.pngIMG_1232.jpg
 
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Swapped the boots on cylinder 3 and it went back to a lane A fault. So I'm assuming I have a bad boot? Easy enough to replace I guess.
 
Frostbite023 said:
Swapped the boots on cylinder 3 and it went back to a lane A fault. So I'm assuming I have a bad boot? Easy enough to replace I guess.
Click to expand...

Sounds like it. They're about $70. Take it back off the wire.. stick your ohm meter on both sides of it and see what it reads. Here's what my bad plug looked like inside. It would read 5k ohms when the probe was on the non-rusty parts of the screw inside it.
 

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