Change your spark plugs and wires!

[SURF RUNNER]

Yeah, I know... Captain Obvious, but not so obvious in my case.

My 4Runner was running really rough for the past two weeks. It started with severe vibrations when accelerating between 52mph and 68mph. I just had brand new tires balanced and installed, so I didn’t think that was the issue.

I changed all of my fluids with REDLINE last month, so I knew I wasn’t low on gear oil or ATF.

I started researching my issue on this forum and decided that it was probably a bad u-joint, unbalanced drive shaft, and/or the transmission. I was hoping that it was a bad u-joint, because that seemed like the cheapest repair.

All of the sudden my 4Runner started idling rough and the check engine light went on. The trouble shooting tool from Auto Zone read that it was a bad CPM, but I really didnÂ’t believe that.

I did some more research on this forum and realized that there was a decent chance that it was bad spark plugs/wires. I checked my service records and I was way overdue.

When I picked up my 4Runner it ran as smooth as butter... I took it up to 80mph and it still ran as smooth as can be.

I think that bad spark plugs/wires can imitate the symptoms of bigger problems. Now I know... what a relief!

 

[MaineRunna]

These vehicles are super reliable, but the plugs, wires and coil boots are one of the main causes of misfires, bucking, rough run on start up, etc. Always good to do regular maintenance on them and start there first when there is a misfire problem.

 

[pluton]

I changed the wires as soon as I got the vehicle, and I change the plugs every 2 years...right before smog check time.

 

[VincentGsrq]

I purchased my 4cyl 98 with 225k on it and non working AC, when I replaced the AC system I also changed plugs, wires and coils. It had a bit of a rough idle and I ran 2 tanks of double dose Gas Shok before the new plugs and then 2 tanks after, now it purrs.

 

[brillo_76]

Yes there is even a thread that has the specs for the coils and wires. As I have seen wires resistance check good and still be bad.

Sent from my SM-J337V using Tapatalk

 

[TheDurk]

Yes there is even a thread that has the specs for the coils and wires. As I have seen wires resistance check good and still be bad.

Sent from my SM-J337V using Tapatalk

Pretty common, actually. Many fails are due to leakage to ground, often at the boots at the end. A leaking plug wire can still show perfect on a resistance test.

 

[shadow247]

I think I am going to change my wires. The PO had the spark plugs replaced with OEM Denso 10k miles ago, but the Wires and original from 2001. It's actually running a tad rough at idle in gear compared to my 99 with an extra 200k miles on it. I'm hoping that fixes it.