[LugNut]

One of my coils has gone bad suddenly -- I plan to replace both. I'm researching parts, and possibly there are two different coil part numbers, one for #1 and #4 cylinders' coil, and another for #2 and #3's coils. Are the two coil packs different from each other? I'm seeing many aftermarket coils that don't make a distinction.

 

[Ken Allistone]

They are both the same, i bought two cheap ones from Rock earlier this year to see if they improved my hesitation, despite being listed as 1&4 and 2&3 they arrived with no marks on them and in fact they look to be from different manufacturers as they differed in colour. I did manage to identify which was supposed to be which from the part numbers but I also switched them around and it made no difference.(I still have hesitation so I put the originals back on)
If I was back there stateside I would sell you mine as I dont need them.
I only have OBD1 on mine, I presume with OBD2 you know which coil it is, if so you could switch your coils just to see the fault code move to the other one and you'd be reassured.

 

[LugNut]

Thanks. OBDII is showing both 1 and 4 cylinders, and there's unburned fuel in the exhaust. So that pack seems to be bad (or the signal going to it ... hopefully not!).

 

[LugNut]

The new coil packs arrive tomorrow, and I had a few minutes, so I removed the old ones. If you have ham-hands, good luck! Getting those four 10 mm coil-to-bracket bolts out (two each coil) is interesting.

They are the original coils; one is marked "1 4" and the other "2 3", but otherwise look the same.

And, unfortunately, both are giving me the same readings on my multimeter for conductivity and resistance. :frown

Hopefully the 1 4 coil is actually bad, or it is back to diagnostics! The FSM said it could also be a bad computer, or jumped timing belt (I replaced it this summer, though), for example, if not the coil pack.

 

[Ken Allistone]

I was going to say to ignore suggestions to remove the IAC bracket etc., as you found out the coils can be removed ok but it's a little fiddly, 1&4 always seems to be the culprit, my multimeter readings were good too but according to everything I read, there's no way to test the output or 'spark' so I bought replacements, in my case it was wasted dollars but I was able to eliminate them.
I also changed my ECU too.
Good luck, let us know if it's cured yours, sure wish I had OBDII

 

[LugNut]

Cured (hopefully), but weirdly!

As part of the original diagnostics, I had pulled the #1 spark plug wire/boot and spark plug. The plug was dry. I didn't pull the wire/boot from any of the other three plugs.

Well, the new coils arrived, and they installed more easily than taking the old ones out. Then it was time to start the engine. And it wouldn't -- cranked but no cylinders firing. Quit trying after about ten seconds. Then tried again and slowly various cylinders started firing, and then enough to let off the starter. Ran poorly, but was obviously clearing out the cylinders.

But it still ran poorly -- better than before, but still putting out the exhaust. Ran like maybe only one instead of two cylinders were not firing. No new error codes.

Figured maybe I had damaged the wire for #1, and remembered that I had an in-line spark tester that had never been used before (!). But it showed #1 was firing fine (ran the same), so checked #2, it was firing correctly too.

But now I got a CEL, and the code was for #4! Pulled its boot and installed the tester, started the engine, and it now ran smoothly! :surprise

I looked closely at the #4 wire/boot, and there is an obvious fresh spark-leak out the side where it attaches to the top of the spark plug. The #1 wire/boot looks fine.

The wire set is a Bosch 09475 with a LTW, but I had mail-ordered it and no one stocks it locally. Ran to the local parts store and got an NGK 8916 set -- hate the blue, but the set fits better than the Bosch. And the engine starts and runs fine.

So ... what do you think? Again, originally I had #1 and #4 no-spark, then after the new coil packs then only #4. So the packs were good, and #4 caused #1 not to fire too? Or I'm guessing the new coil pack(s) produced a hotter spark that blew out a weak spot in the #4 wire? But that still doesn't explain the long cranking to finally get the engine running again (battery was not disconnected; full gas tank).

 

[Ken Allistone]

It does sound like the coil was bad. You had probably the worst wires you could have, plenty has been written on here about how bad Bosch wires are on our rav's as I am sure you know. Denso's would have been the best but NGK's are very good too.
Can't explain why it took so long to start but you were only firing on three, I wouldn't worry just so long as it starts perfectly every time now.

 

[LugNut]

Thanks! I just searched for other threads, and saw one that said his engine bogged with the Bosch. Mine never has had much power, so now I'm eager to see if it accelerates much better! Hopefully I will try in the morning.

 

[LugNut]

Slightly peppier, but I attribute it to the outdoor air temperature being low this morning. But running well, so all's good!