Noob Ignition Coils Question

[Foehammer]

Hello mudders, ordering plugs for my rig. Was thinking of ordering all the ignition coils as well, but it's a bit pricey for all 8. Will the engine act funny if I end up replacing one or two of the potential bad coils? Should I just bite the bullet and get all 8? Going Denso for both plugs and coils. Thanks in advamce

 

[Bisho]

You can replace individual coils, no problem.

 

[Mikeybro]

I tried to replace all 8 at once but could only get 6 at the time. Still have the 2 old ones in it. I just pulled all of them and did triage on which where most cracked and threw those out accordingly. When you go back to start the engine, make sure you get all of them plugged back in. I did my TB at the same time and I thought I botched it and cooked my engine.

 

[Mikeybro]

Also inspect all of the ones your order as soon as you get them. DENSO kept sending me the wrong coils. The box label was right, but the coil in the box was wrong.

 

[Foehammer]

How do you tell that the coil isn't the right one?

 

[2001LC]

Also inspect all of the ones your order as soon as you get them. DENSO kept sending me the wrong coils. The box label was right, but the coil in the box was wrong.

This to me, would indicate bootlegs. As I really can't see a Denso distributor sending mismatched box content.

 

[GstacksLX]

I was in a similar boat - did 4 on the side where I had a misfire .
They aren’t cheap! 117 at my local Lexus parts dept, but something like 170 msrp…
The old ones were pretty cooked so I ended up buying 4 more for peace of mind and am doing that side this weekend. No issues with just doing half. Def a good thing to have a spare on deck if yours are old though.

 

[Joe422]

One easy way to freshen your coils is to change out the boot seals and the spring inside. They get fatigued, and the rubber seals dry, and get cracked. I did this for my 8 OE coils. The refresh kit were $6 each (NGK/Rockauto) and theyre working great @285k miles. That being said, i carry 2 brand new Denso coils in the car for emergency, in case 1or 2 fail. Someday ill replace all 8 with new, but not in a rush just yet.

 

[Hugh Heifer]

What year is the truck? I have replaced 6 of 8 on the road over the last 12 or 15 years. I think one I have replaced twice. Takes a few minutes at the side of the road. I carry 2 or 3 in the kit.

 

[dbleon]

Inspect very carefully if you want to re-install the originals. Take a careful look at the plastic.. not the rubber boots.. the plastic body of the coil. Almost all of mine had hairline cracks ( 265k miles- originals likely). No running issues or misfires but I opted to replace all 8 while doing plugs to be safe. Also used the TT iridium plugs recommended here by others. Truck runs better after this. Smoother idle and acceleration. Also cleaned the MAF, TB, and replaced air filter same time

Have fun it’s a nice easy1/2 hour job

 

[Foehammer]

I ended up biting the bullet and putting in 8 Denso coils. Was definitely worth it as 6 out of 8 were in very sorry state.

 

[2001LC]

Factory coils can last a very long time. The 1 million mile 4.7L 2UZ, had no record of coils being replaced.

So why do we have coils failing. "Excessive Heat"
Two main reason for excessive heat:

• Spark plugs walking out. Hot blow-by combustion gasses, cooking the coils.
• Excessive spark plug gap.

One other reason I see coils fail, aftermarket or bootleg.

Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!

TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...

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