Background: PO said he got a dealer maintenance at 110,000 which included timing belt and plugs. That was maybe 20,000 miles ago. Now the coils are failing, I replaced #2 and 6 last month, now #5 and 4 have conked out. The coils did not say Toyota but they did have a numbering sequence on them (101112, 101113, 101114, etc) , leading me to believe they had actually been replaced with a non-cheapo line, but failed anyway. Anyone know about sequentially numbered coils?
I pulled a plug (pic) and the gap is about .050"/1.25mm. IDK what the gap is supposed to be, thus my question. I am not keen on replacing them though if they are the originals, and 130,000 miles old, I would consider it.
I have two Denso coils in the front # 2 and 6. Today, with the help of posts here on CL, I pulled all three rear coils. My plan is replace those three with Densos and then use one of the still-working coils to replace #4. If (and when) that goes, at least it will be an easy replacement. Anything wrong with my plan?

 

Looks almost brand new to me.

 

I would replace the plugs at or around 110K miles. I did not replace mine and first plug failed at about 130K. I replace them all. Few hundred miles after plugs change coil went out. Please only use OEM plugs and coil packs. Getting 110K out of plugs suits me just fine.

FYI .. iridium plugs should never be gapped [they are prepgapped and bending the electrode weakens it and it can break off.

Salim

 

i wanted to know what the gap was as a clue about if the plugs were new or original. So based on this plug you'd say P.O. was telling the truth and he did get the tune-up?

 

I would defer to the expert (carguy07) on determining age. The beauty of iridium is that they do not get pitted (worn out) as they are used. I would approach it another way ... if the plugs were replaced with quality (there are so many fakes) then they should last another 110k (median fail rate + margin).

When a misfire happens, it is hard to tell if the coil is the problem or the plug. People swap items to narrow down what is the source of the problem.

 

It's not an OEM plug, so it is a replacement. Since you have pulled the coils, buy a set of Denso SK20R11 plugs and replace the plugs in there. A complete set of correct plugs is less $ than one coil.

 

I already bought three Denso coils and replaced the rears and I'm not eager to get back in there. Since the plugs are not OEM I'm feeling better that the PO did get a tune up, though maybe he should have gotten better coils since they seem to be chain-failing. So now I have five Denso coils in there. Instead of buying a sixth Denso coil for #4, which is right in front, I want to use one of the still-working non-Denso coils. I won't though, if it might damage something.