Coil Pack Question

Joined
Jan 3, 2011
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7
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Seattle, WA
I was wondering how often you can expect coil packs to go out? I purchased a new-to-me 1999 Land Cruiser in late December. Since then I've had to replace 4 coil packs. So with 4 packs replaced in 5 months I'm wondering if this seems unusual. Should I just plan on replacing the remaining 4 right away? The truck has 156,000 miles on it so I expect I have some things to change out but this just seemed a bit odd based on posts I've read on here. I see people with 1 or 2 going out but nothing about them going out frequently. When I changed the 3rd coil pack I went ahead and replaced all of the plugs with new Denso plugs because I didn't know how old the plugs were in there. Guess that didn't work because a few weeks later it threw another code for cylinder #1. Replaced that yesterday and she's running great again.

Thanks to all you who keep this board going. I've found it to be a wealth of information. Pretty much any issue I've run into I have been able to find something related on this board. I know know a lot of other things to look out for and I'm also making my list of future upgrades too. I know as a newbie I need to post some pics. She's still got her skirt on though - haven't been able to buy some sliders because I'm spending all my money on coil packs and plugs :) I can't take the running boards off just yet because i have a vertically challenged wife and a couple of kids that use them on a regular basis.
 
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I've got to think that many is symptomatic of a problem upstream, but I can't think of what it would be. Are you using a strange plug that's hot or made other adjustments to the motor?

And replacing 6 coil packs as PM? That's $500 I'd spend on other stuff.
 
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Are you replacing only the old ones or ones that you have already replaced ?

- Are the ones coming off OEM ? or aftermarket?
- Are you replacing with bad/substandard parts ?
- Do you have an upstream problem ?
- Are you correctly diagnosing the problem ?
 
Joined
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Seattle, WA
So far I have not had to replace any ignition coils that I previously replaced. They've all been for new cylinders. The way I analyzed the issue was by using a code reader I bought. Everytime the CEL light comes on the code is p30# - where # indicates the cylinder. On one occasion it happened on a trip to Oregon and I took it to the Toyota dealer since I didn't have the code reader with me. The dealer hooked it up to their machine and said it was a bad coil pack and replaced it. They didn't indicate any other issues with the truck. I haven't had any other issues with the vehicle aside from coil packs going bad. I just figured it was something that happened now that I was at 150000+ miles. I just wanted to see if anyone else here had run into similar frequency in replacing ignition coils. I have saved the bad coils I replaced. I guess I could always put one back in to see if it throws a code again.
 
Joined
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So far I have not had to replace any ignition coils that I previously replaced. They've all been for new cylinders. The way I analyzed the issue was by using a code reader I bought. Everytime the CEL light comes on the code is p30# - where # indicates the cylinder. On one occasion it happened on a trip to Oregon and I took it to the Toyota dealer since I didn't have the code reader with me. The dealer hooked it up to their machine and said it was a bad coil pack and replaced it. They didn't indicate any other issues with the truck. I haven't had any other issues with the vehicle aside from coil packs going bad. I just figured it was something that happened now that I was at 150000+ miles. I just wanted to see if anyone else here had run into similar frequency in replacing ignition coils. I have saved the bad coils I replaced. I guess I could always put one back in to see if it throws a code again.

My guess is that your truck got a series of coils produced in close sequence with a repeated production error. This happens on assembly lines when the machines get out of adjustment or the tooling gets worn. If the problem is not caught the bad batch gets shipped together and in your case could be placed on the same vehicle. In this case since they went 150k without issue they aren't really bad, just below average.

Are there sequence or production numbers on your coils ?

I wouldn't replace them all at once. Just get one as a spare and carry the tools needed to change it out.
 
Joined
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Seattle, WA
I looked at the coils I took out of the truck. I can't find any markings on them whatsoever. NMuzj100 - Your theory makes sense though. I'll just pick up a spare coil and carry my tools and code reader with me for a while. At least they are easy to change out.
 
Joined
Jun 17, 2005
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Arizona
I just replaced my second coil pack within 2 months and 5K miles. #1 the first time, #5 the second. I had a spare on hand, but will have to pick up another. On a side note, I think this one has been going bad slowly, as I've had a hard-to-diagnose stumble/miss when in D or R while stopped with foot on the break. Just a slight hiccup about the same time that the #1 cylinder coil pack went out two months ago. It never threw a code though, and seemed to be more noticable with an engine load - AC on. Who knows though, I just had to replace the alternator last week as well, so maybe all this electrical voodoo is connected.
 

MoJ

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If a coil pack's job is to transform 12v into thousands of volts for the spark plug than would it make sense to check the alternator/battery if you're having frequent pack failures? Just thinking...if the input voltage is low or irregular would the pack "work harder" to produce the voltage required? I'd be interested to hear from a real mechanic as to whether it works this way or not.
 
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...if the input voltage is low or irregular would the pack "work harder" to produce the voltage required? I'd be interested to hear from a real mechanic as to whether it works this way or not.
I dunno. But I'd rather hear from an electrical engineer who knows the design parameters of a coil pack. No offense to the mechanics...

:meh:
 
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If a coil pack's job is to transform 12v into thousands of volts for the spark plug than would it make sense to check the alternator/battery if you're having frequent pack failures? Just thinking...if the input voltage is low or irregular would the pack "work harder" to produce the voltage required? I'd be interested to hear from a real mechanic as to whether it works this way or not.

That would be the case with an A/C motor, but not the case with a transformer; they (motors) will draw as much current as they need to maintain RPM. With a transformer, it's just straight math. Lower in = Lower out.
 

MoJ

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Interesting. Does that change at all when "electronically controlled" enters the equation?
 
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The 'electronically controlled' is timing not current; it's still just a coil. The output is a function of the ratio of windings between the primary and secondary coils. As such, the ratio can be applied to any input voltage. The output just scales with the variations in input.

I suppose if it was regulated power output you could make an argument that low input may stress the circuit, but then again those type of electronics also will have logic controllers that such them down before they damage themselves.
 
Joined
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Seattle, WA
Well teh Cruiser has been running fine for almost 4 months but this past weekend the truck threw another code indicating a bad coil pack. I've been keeping track of the cylinders where I've been replacing the coil packs and the bad coil was one that i replaced earlier this year. I slapped in the spare I keep on hand and it seemed to fix the issue based on a few trips around town. I took it out on the highway the next day and it started missing again. When I got home I put the computer on it and it had a code indicating multiple misfires - didn't narrow it down to a particular cylinder. I'm throwing in the towel and taking it into the dealer. Something else has to be going on here. The truck went in this morning so I'll update this thread when I hear back from them.
 
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Well teh Cruiser has been running fine for almost 4 months but this past weekend the truck threw another code indicating a bad coil pack. I've been keeping track of the cylinders where I've been replacing the coil packs and the bad coil was one that i replaced earlier this year. I slapped in the spare I keep on hand and it seemed to fix the issue based on a few trips around town. I took it out on the highway the next day and it started missing again. When I got home I put the computer on it and it had a code indicating multiple misfires - didn't narrow it down to a particular cylinder. I'm throwing in the towel and taking it into the dealer. Something else has to be going on here. The truck went in this morning so I'll update this thread when I hear back from them.


Ouch, good luck.
 
Joined
Oct 26, 2009
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Newton, MA
I was also at the Toyota dealership yesterday and here's what they told me:

$2610 for leaking manifolds
$1480 for leaking steering rack
$620 for rear rotors and pads
$320 for seized left emergency brake pivot
$115 for "D" and "P" bulbs out in instrument cluster
$96 to retorque front wheel bearings
-------
$5241 TOTAL

I got out of there with only doing the front wheel bearings, but the leaking manifolds concerns me. Nothing else is critical right now, but I don't like the idea of exhaust fumes potentially leaking into the cabin while driving. Strongly considering the DT headers group buy as an alternative to stock replacement manifolds.
 
Joined
Jan 3, 2011
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Seattle, WA
Well the dealer said it was a bad coil pack in #5. I had a hard time believing it was just a bad coil pack but time will tell I suppose. I explained that I had replaced that pack back in April and when it threw the code again on Saturday I put a brand new one in. He insisted that was the problem and that he ran all the tests he could think of on the truck. I now have an OME pack in there so we'll see if it really fixes the problem. I'll be taking the new one i bought on Saturday back since it has a lifetime warranty. Doesn't hurt to have a spare.

The tech also suggested replacing the other 4 coil packs that I haven't already replaced. Since he didn't find anything wrong with the system he explained that perhaps they all needed to be replaced due to the miles (160k) and the fact that they all seem to be going out. I suppose it couldn't hurt to replace them all but that gets kinda pricey and based on what I've read here it's not common to have to replace coil pack wholesale like this.

lhommec13 - I suppose I should consider myself lucky compared to what you're facing. Best of luck with all of that work you have ahead of you.
 

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