When to replace Ignition coils. (1 Viewer)

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As our 100 series fleet ages we're seeing more ignition coil failures. Is there a certain mileage or age where our 100 series with the 2UZ-FE engine are seeing the need to replace one or more ignition coils?

If you’ve replaced any coils please post any performance differences before & after, along with your millage, years in service and anything that contributing to the reason why you replaced them. Such as age, climate condition, bad spark plugs or improper gap, spark plug tube gasket oil leak, under or over voltage or anything you consider could be a contributing factor.

Sure we need to change coils when we get the P0300 series code suggesting a miss firing coil. Just swap coils to confirm code moves to different cylinder as expected, then replace bad coil. If not confirmed, then work through diagnostic tree.

In some cases we've seen coil replacement correct a poor running engine issue such as rough idle, without the CEL (check engine light) or any code being stored. Can it be that weak coils are robbing us of performance, but have yet to cross the point of giving a code. Would periodic testing with specialize equipment (see: Coil on Plug ignition video below) be a good PM, especially if performance or MPG drops.

Here are some questions to consider:
  • What are some of the reasons for coil failure?
  • Should spark tube gasket, seals & grommet be a PM?
  • Should all coils be replace once one fails?
  • Should we do a complete coil replacement as a PM at some point?
  • Do coils weaken over time reducing engine performance, what the best test to reveal this?
  • Aftermarket or OEM coils?
Edited 3/21/16 Toyota OEM (Denso) or Denso is best, cheap aftermarkets' are failing.
Rough Idle/Sputtering/CEL/Misfire = Coil pack problems
Understanding Multi-Coil Ignition Systems
Coil-On-Plug Diagnostics: Toyota Tundra - Tomorrows Technician

In the Autolite video below, it's recommend one determine cause of failure and correct it or reoccurrence is likely.



Seem to be three camps on the issue of COP.
1) Replace only dead coil(s).
2) Replace hunting for performance issue without CEL.
3) Replace all 8 as a PM.

Certainly replacing only dead coils will give tangible results immediately, for the least $$ at the moment of failure.

What I find most interesting, are the testimonials of performance issues (running rough and/or low MPG) long before code or CEL reveled a bad coil to be cause. Along with notable improving in performance with those that have replaced all 8. The implication here is, coils do weaken and rob engine of performance, before failing.

We've also seen a few reports of a drop in MPG after changing spark plugs. Could we be damaging coils while removing or could there be some issue with matching old with new??

Which camp are you in and why???
 
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2000 470LX second owner
Had one go out in 2014 with 67K miles. Got P0304. Bad coil was original Toyota OEM replaced with Denso 673-1303
3 Weeks later coil #8 went out. Replace with Toyota OEM from dealer.

Since then (2 years) I have had no issues. Acquired replacements when I can find them on sale. OEM or Denso (I think they are equivalent). I plan on swapping them all when i do a tune up this summer at 90K and keep the old ones as spare parts. Now that I know how to deal with the issue I am prepared and not really concerned when it happens.
 
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255 and replaced 2 when they started acting up. Original and replaced with aftermarket
 
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I would replaced as needed. My friends 2UZ is pushing 250k with original coils.
 
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2 failures of number 5. 120k and 140k.
 

kelly saad

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I developed a misfire one day, no light. They checked it and found a code on #4, so I bought a coil and installed it but no luck. I brought it in several months later with a light, finally and they found it on #6, I switched the coil to #6 and problem solved. It was an exciting day!!! I had no light for months though, driving around, sputtering like an old clunker.
 
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Fort Smith, Arkansas
My LX470 has 248,000 miles on it. Last week I was driving around town and the truck started to run rough and the engine light started blinking. I knew one of the cyclenders was not firing. I got home and checked codes. It gave three codes: P0300 Random/Multiple cylinder misfire, P0301 Cylinder 1 misfire, and P0302 Cylinder 2 misfire. I swapped the 1 and 2 coils with positions 3 and 4. Then the error read bad coil number 3. I replace the coil 3 with a Denso coil from a big box automotive store and the truck drove great. A few days later, the truck has skipped and hesitated in the lower RPMs. After a day of this it finally threw a code on coil 1. I replaced it with another Denso. I did notice that the rubber boot had a crack in it. I think that it may have been shorting out threw the crack in the boot. Just a thought.

I am going to keep an extra coil on hand for future failures.
 
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I replaced mine the same week I did the timing belt and related components. I figured at 190k they were due, and I firmly believe in preventative maintenance, not waiting for them to fail and replace them one at a time.
I gained back about 2 mpg on average and the truck does run smoother.
 
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2000 LX470 178k miles, suddenly got P0300, P0301, P0303, P0304 codes and VSC TRAK and VSC OFF lights while driving in neighborhood. Had replaced all plugs with Denso Irridiums 10k prior. Swapped #1 and #7 Coil packs and cleared codes. Restarted engine and only P0304 remained pending. Replaced all coil packs with chinese made. Codes disappeared. Engine now runs better than ever (only owned for 1 1/2 years, since 172k miles). I should have replaced the coil packs at the same time I replaced the plugs. One coil pack #5 was flooded by engine oil by leaking at the valve cover seal but did not cause a code. Seals were hard. Owned and operated in Southern California.
 
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a) When they fail (and keep a spare in the glove box), or
b) do them all (with Denso OEM) every 200k miles as preventive maintenance.
 
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I replaced mine the same week I did the timing belt and related components. I figured at 190k they were due, and I firmly believe in preventative maintenance, not waiting for them to fail and replace them one at a time.
I gained back about 2 mpg on average and the truck does run smoother.
Very interesting you've gain ~2 MPG.

After replacing my T-belt, spark plug along with a baseline at ~95K miles my MPG actually decline a bit, and further since. I've been wonder if changing the coils would give me an MPG gain. I've looked into about everything except coils, fuel injectors, compression and valves (leak down test).

I've no reason to believe compression or valves are having any issues, but will check anyway. Additionally I'll recheck my spark plugs for proper gap & condition.

I use high test gas, with loads of cleaning agent infused. I also put a can of 44K in the gas tank annually just before winter tune-ups. Along with driving on HWY as much as possible. So don't have any reason to believe fuel injector are dirty. That said I'm planning on pulling fuel injectors, to send out to be cleaned & tested for spray pattern and flow rate by shop.

Once everything checks out I'll then replace all ignition coils. If I then get an MPG gain, it would be pretty conclusive IMHO.
2000 LX470 178k miles, ***. Replaced all coil packs with chinese made. Codes disappeared. Engine now runs better than before ever. I should have replaced the coil packs at the same time I replaced the plugs. One coil pack #5 was flooded by engine oil by leaking at the valve cover seal but did not cause a code. Seals were hard. Owned and operated in Southern California.
I've noticed over the years, my engine running just a little rougher at idle. "D" vibration developed and getting harder to eliminate each year. I've chocked it up to age, but these 2UZ-FE are so amazing. For example; ponyi said he's seen hash-marks on cylinder walls in an engine with over 300K miles on it and everything was to factory spec. I've not found one post where anyone has ever adjusted valves or felt the need too. So assumption is; age of 2UZ-FE long block has very little bearing on performance. They don't age, well not as much as I have...LOL

Your statement is a testament IMHO, that our coils are weakening with use and are effecting our performance.
 
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I've replaced 6 & 7 when codes came up during Fall season. Carry 1 spare, though I'm worried about #5 as it looks like toughest one to replace in field from a brief look, especially if a cold day.
 
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Replaced all coil packs with chinese made.

Are these the ones from Ebay? I have seen 8 coil packs for $100 or so. I been wondering if these cheap ones are better than my 7 old coil packs (1 was replaced by PO last yr), and maybe would improve my mpg. I am thinking to just keep the old ones for spare. How long have you have these coil packs?

Thanks
Chris
 
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Are these the ones from Ebay? I have seen 8 coil packs for $100 or so. I been wondering if these cheap ones are better than my 7 old coil packs (1 was replaced by PO last yr), and maybe would improve my mpg. I am thinking to just keep the old ones for spare. How long have you have these coil packs?

Thanks
Chris
These are the ones from Amazon for around $76 for the set. I've only had them in for a week - so far so good! Are they better than the 7 old ones? I would say a resounding "YES!" based on my now purring engine.

http://amazon.com/gp/product/B00LAXJPQG?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00
 
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Good to hear, I just recieved these today for my #2 and #5.
Once the engine cover and air intake duct is out of the way, I would say it takes only 5 minutes apiece to replace them. They fit a little more snugly onto the plugs and connectors, but I liked it that way. Make sure you can hear the connector snap lock engage. They are so snug that I thought I had got it all the way on without the snap lock engaging, but on the last few I heard the snap lock-in so I went back and pushed harder and they all snapped in.
 
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Got the same ones from amazon, working good
 
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These are the ones from Amazon for around $76 for the set. I've only had them in for a week - so far so good! Are they better than the 7 old ones? I would say a resounding "YES!" based on my now purring engine.

http://amazon.com/gp/product/B00LAXJPQG?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00

Good to hear, I just recieved these today for my #2 and #5.
Got the same ones from amazon, working good


8 coils for only ~$75 and free shipping, is it to good to be... Please report here, your experience with them over the next few year.

I looked at the reviews on these & other various vehicle's coil sets from the same seller (ECCPP), which are all relatively recent. Found ~10% negative (1 star), and ~75% positive (5 of 5 star) reviews. It could be the 1 stars' didn't install properly (on tight), had something else going on or could be they don't last. Here are three recent negative reviews:
  1. Toyota: "Had two coils fail on me after a month. Price still can't be beat. Ordered a second set of eight to get back on the road again. Now I'll have 6 back up coils in case it happens again"
  2. Ford: "JUNK JUNK JUNK !!! Cheapest garbage I've used I installed them in my truck and drove it for the weekend and started chugging again so I went to the auto parts store and bought ford coils and haven't had a problem yet so I warned you don't buy them"
  3. Ford: "Installed on my 02 4.6 Mountaineer because I was having a misfire on cylinder 4. Truck has 165k miles and never change the plugs or packs. Put these on with new plugs and my truck was misfiring on 6 cylinders. I thought i hooked something up wrong, the next day i reinstalled the old ford coil packs and everything has been fine. I just received a few bad ones which happens all the time. So i give it 2 stars because it did not work for my truck. Factory coils for me only."
 
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