pentagrammaton
New member
Thought I'd share my newbie experience here. I have a '97 4runner SR5 V6 w/ 214K miles on it.
Backstory & issue
It's been hot & muggy here in the south and we've been idling with aircon on frequently. At some point, the engine vibrated really bad and there was a significant loss in power, fortunately we were close to home so I eased it to the garage and shut off the engine. The check engine light wasn't on. Visually checked the engine bay, nothing looked awry. Let the engine cool down for a few minutes and restarted the engine with the hood up, it was still vibrating strongly. That's when the check engine light popped up. Used one of those WiFi/BT OBD scan tools and it gave me P0306, a bit of googling indicated that it was a misfiring sixth cylinder. The spark plug wires looked old and doesn't seem to have been changed (I'm the 2nd owner) and I'm guessing that being exposed to heat for too long finally fried it. I didn't want to spend time diagnosing so I went ahead and decided to change the coils, spark plug wires and spark plugs (first time doing it myself, it looks simple enough when watching YouTube videos). Decided to forgo Denso coils and ended up with a generic 3 pack for $35 on Amazon, went for the blue NGK 4412 wires, and Denso 3194 spark plugs.
Disassembly
Removed the air box, then the air intake tube that goes from the airbox to the throttle body plus other vacuum hoses that were connected to it and electrical connector to MAF sensor, that gave me access to the coils (this is on the passenger side). Clearing up access to the driver's side is much more involved, I removed the diagnostics thingy (don't know what this is called), the ground cables(?) connected to the engine. Nudged a few hoses to gain access to the spark plug boots, tried removing the bracket that connects the manifold to the block but only managed to remove the bolt on the manifold. I was able to nudge it out of the way to access cylinder 6, so that was good.
Replacing parts
Now that I had access to the coils & boots, I removed the electrical connector to the coil, then the spark plug wire from the coil, then removed the coil, then the spark plug, replaced the spark plug, put in the coil, reconnected the electrical connector to the coil, then connected the new spark plug wire. On to the driver's side, removed the old boot, remove the old spark plug, replace with a new spark plug and then put in the boot of the new spark plug. I did it in this pattern 1 then 4, 5 then 2, 3 then 6. Visually inspecting the old spark plugs and boots, I didn't see anything wrong with them. I'll post pics later.
Reassembly
Reattached air intake tube to throttle body, reinstalled airbox, reattach vacuum hoses to airbox, electrical connector to MAF sensor.
Put in the key and put it in ACC, reconnect to OBD scanner and reset engine codes. Started the truck and it sounded good, vibration was gone, checked engine codes and got nothing. Drove it around for a bit and it ran great!
Now, just being paranoid, did I miss anything? I know I didn't apply dielectric grease on the boots or connector, but some say it's alright.
Backstory & issue
It's been hot & muggy here in the south and we've been idling with aircon on frequently. At some point, the engine vibrated really bad and there was a significant loss in power, fortunately we were close to home so I eased it to the garage and shut off the engine. The check engine light wasn't on. Visually checked the engine bay, nothing looked awry. Let the engine cool down for a few minutes and restarted the engine with the hood up, it was still vibrating strongly. That's when the check engine light popped up. Used one of those WiFi/BT OBD scan tools and it gave me P0306, a bit of googling indicated that it was a misfiring sixth cylinder. The spark plug wires looked old and doesn't seem to have been changed (I'm the 2nd owner) and I'm guessing that being exposed to heat for too long finally fried it. I didn't want to spend time diagnosing so I went ahead and decided to change the coils, spark plug wires and spark plugs (first time doing it myself, it looks simple enough when watching YouTube videos). Decided to forgo Denso coils and ended up with a generic 3 pack for $35 on Amazon, went for the blue NGK 4412 wires, and Denso 3194 spark plugs.
Disassembly
Removed the air box, then the air intake tube that goes from the airbox to the throttle body plus other vacuum hoses that were connected to it and electrical connector to MAF sensor, that gave me access to the coils (this is on the passenger side). Clearing up access to the driver's side is much more involved, I removed the diagnostics thingy (don't know what this is called), the ground cables(?) connected to the engine. Nudged a few hoses to gain access to the spark plug boots, tried removing the bracket that connects the manifold to the block but only managed to remove the bolt on the manifold. I was able to nudge it out of the way to access cylinder 6, so that was good.
Replacing parts
Now that I had access to the coils & boots, I removed the electrical connector to the coil, then the spark plug wire from the coil, then removed the coil, then the spark plug, replaced the spark plug, put in the coil, reconnected the electrical connector to the coil, then connected the new spark plug wire. On to the driver's side, removed the old boot, remove the old spark plug, replace with a new spark plug and then put in the boot of the new spark plug. I did it in this pattern 1 then 4, 5 then 2, 3 then 6. Visually inspecting the old spark plugs and boots, I didn't see anything wrong with them. I'll post pics later.
Reassembly
Reattached air intake tube to throttle body, reinstalled airbox, reattach vacuum hoses to airbox, electrical connector to MAF sensor.
Put in the key and put it in ACC, reconnect to OBD scanner and reset engine codes. Started the truck and it sounded good, vibration was gone, checked engine codes and got nothing. Drove it around for a bit and it ran great!
Now, just being paranoid, did I miss anything? I know I didn't apply dielectric grease on the boots or connector, but some say it's alright.
