When to replace Ignition coils. (1 Viewer)

[CharlieS]

128k miles. Original Denso coil on plugs. Not changing them until they fail. If they need it, replace your plugs - odds are, you'll get the performance return to stock. If it trips your trigger to spend money throwing unnecessary parts at your rig, go for it.

 

[Julian Stead]

I don't think there is any right or wrong on this, if your rig has done say 200k and you put a full set on for preventative maintanence then it is understandable due to there have been known issues. I personally would just change them when they go bad, but I might change the full set when that happens, just depends on how many fault codes pop up. It would also depend on what distances I would be traveling.

You could start a thread on a lot of components that you could put in to this category of preventative maintanence, oxy sensors, maf sensor, exhaust, valve clearances etc. all can affect mpg.

What we used to find, This isn't fact but people that drove with a heavier right foot had smoother more efficient engines, they would be looser, Rev more freely and just drove better. People that drive just hovering the throttle all the time would suffer with more splutters and a tighter engine that would feel less responsive. The old 8 valve VW golf GTI was a prime example, if it was driven from new by a very careful driver to me it just ruined the engine, the car just felt slow. Another exact same car driven by a more aggressive driver would feel a lot more responsive.

 

[Julian Stead]

Ps. One of the most neglected parts that should be changed at a interval to keep the engine efficient is the PCV valve.

 

[2001LC]

I don't think there is any right or wrong on this, if your rig has done say 200k and you put a full set on for preventative maintanence then it is understandable due to there have been known issues. I personally would just change them when they go bad, but I might change the full set when that happens, just depends on how many fault codes pop up. It would also depend on what distances I would be traveling.

You could start a thread on a lot of components that you could put in to this category of preventative maintanence, oxy sensors, maf sensor, exhaust, valve clearances etc. all can affect mpg.

What we used to find, This isn't fact but people that drove with a heavier right foot had smoother more efficient engines, they would be looser, Rev more freely and just drove better. People that drive just hovering the throttle all the time would suffer with more splutters and a tighter engine that would feel less responsive. The old 8 valve VW golf GTI was a prime example, if it was driven from new by a very careful driver to me it just ruined the engine, the car just felt slow. Another exact same car driven by a more aggressive driver would feel a lot more responsive.

Seem to be three camps on the issue of COP.
1) Replace only dead coil(s) when code/CEL dictates.
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 (running rough), 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.

I do enjoy interaction with threads as they develop, just as much anyone else. But I find threads that focus on one issue or parts like wheels, lift, performance enhancements, COP, O2's, PCV, Fuel Injector, T-Body, T-belt, S-belt, MAF or wheel bearings etc. to be very interesting and informative as well. They also become one stop shop for quick information. As I find it much easier than searching through dozens if not 100's of threads of mechanical problems, which is very time consuming. Especially with needing to wait for each page to load up advertisements.

Good point on driving style. Those high RPM engine real don't like a light foot. My understanding is high performance engine are designed to run at high RPM, I know my 240Z was. My modified GTO big block (low RPM) with high lift and long duration cam. Would shake and rumble at idle, loading up the engine with unspent fuel and carbon. It (well I) just couldn't wait to jump on it, smoking the tires and blowing out that unspent fuel and carbon. But the 2UZ-fe is well suited for low power band use. I drive with a light foot as it's not a sport or muscle car. I do get on the HWY as often as I can, recognizing the benefit. Even flooring now and then to blow it out. I also use good fuel & 44K now and then, too aid in keeping gunk & carbon cleared out. But driving style has only a secondary affect on coils at best, which is the subject of this thread.

 

[Bigtex]

My take:

99 LC, currently at 298K miles. I had my first coil go out about 280k, threw the code and was clearly down a cylinder. Second one was two months later, third about 6 months after that. At that point replaced them all with Denso from Amazon. This is our family trip hauler and I didn't feel like swapping any out on the road.

No change in mileage or performance that I can tell, just back to stock. My mileage is lower the last year or so but I suspect that the cause is the Cooper tires compared to the stock Michelin LTX. Dunno for sure, but the timing is suspect. I'll probably go back to the LTX and see what happens, but that may not happen for a while as the Coopers are wearing like iron.

 

[uzj100]

My 100 has 239k miles.

Coil went out after driving through a torrential rain storm. Come to find out the coil had a crack in it. It ran really rough and set off a code. Went to the dealer and $300 later it was done. That was not smart but had to be completed as we were driving back from the beach family truckster style.

Second coil went out about a year ago. Normal driving. Limped over to the Advance auto, checked the code, googled the cylinder numbering scheme, replaced coil in auto parts parking lot and off I went. It was $80 and about 20 minutes all in.

I have no plans to replace unless they fail.

Thank you for the thread.

 

[BMWSTOY]

*Only replaced when they failed. They do seem to give a little notice prior to complete failure from my experience. Both very slight sputter and very slight performance lag, or lack of total power. The first time it went much faster. The second time, I was able to drive several hundred miles before replacing. I experienced an intermittent sputter along with several codes. One thing for sure, the dash lights up like a christmas tree telling the operator extreme danger ahead - but with the huge V8, there is still enough power to get by.
#2 coil out at aprox 120 and then again at 160K. At first I thought it was strange but if you reference the firing order, #2 is first. hence from my lack of knowledge ont them, it has more use. Or theory 2, its the only one under all the air flow attachments and perhaps gets hotter than the others?
I sure do miss my Landcruiser... I will be back someday

 

[dnp]

Green 2000 100 - I replaced one at about 180K. Went back with Denso brand. No cause for failure, and no perceptible performance increase/decline.

White 20001 100 - Bought at 292k miles, now at 306k miles. Previous owner told me engine and transmission are totally untouched. If this is true, all coil packs are original (from inspecting a couple of them, I'm inclined to believe him) I always keep some coil packs on-hand, and I even bought a complete set of aftermarket coils from AM Auto, because they have a 10-YEAR warranty!

 

[uzj100]

I drive with a heavy right foot. ;<)

Engine is smooth as silk.

 

[BamaHeel]

Buddy with a shop sent me this today:

2002 with just under 200k

 

[FJCowboy]

1999 LC with 175K miles.
I've replaced 2 or 3 over the last 25K miles/5 years. Each time they failed, engine ran extremely rough and engine light came on. Initially they were replaced with aftermarket brands, I don't recall what brand. All of the aftermarket ones failed again and very quickly after installation. Those were replaced with OEM/Denso brand, no issues with those. I have an extra one on hand for the next time. Nothing noticable regarding performance or mpgs.

 

[Marshmallow]

Recently replaced the #5 coil pack on our 2001 with 178k. Third owner, bought it at 135k 3 years ago, I think it is an original coil pack (denso). Replaced with a jobber from the local parts store for $100, dealer wanted $170 for the denso.

Symptoms - really rough idle as my wife would throttle to and from a stop, she thought it was transmission (I feared it was the transfer case or differential based on her description), so she parked it at home. Was rough at takeoff and stopping, smoothed out at speed with intermittent jerking at neighbourhood speeds. I drove it around our cul-d-sac flipping the dif lock on and off, into and out of 4-lo trying to isolate, but it disappeared completely after my second loop around the block. Stopped for supper and came back out for a longer drive - idled fine on startup (high idle above 1000 rpm), but noticed the instant idle drop below 500 as soon as I put it in reverse, disappeared when I flipped it out of reverse and completely disappeared by the time I reached the drug store 5 minutes away.

Drove it to work the next day with intermittent symptoms when it finally dropped a CEL. Definitely felt like a misfire (diagnosed the same thing on our 4 cylinder turbo Passat while climbing a mountain pass back in 2012). Bought a coil pack on the way home and installed it as soon as I had the cylinder figured out. It took longer to get the wifi code reader I own working than it did to replace the coil pack.

At $100 each locally, I'll probably just replace them one at a a time.

John

 

[Kofoed]

I've had bad luck replacing Toyota ignition and other sensitive electrical components with generic Auto-Zone type parts. So I pony-up the money to get genuine T parts.

As for the coil packs in particular, changing out a failed one IF it has a bunch of miles on it and then addressing the same-aged packs as needed is not for me. Who knows what the coil's performance is at operating temp and high engine load, even if resistance tests out ok when cold, at-rest. I will change out all 8 in the next year. I would rather do it in my garage, than on the side of the road.....

 

[2001LC]

Always a good idea to check the corresponding spark plug of a failed coil.

 

[camino70]

When two of my original coil packs failed, I replaced all 8 with the $80 pack on amazon. One of them failed already, within two months and under 1000 miles.

Now I get to see how to return stuff to amazon.

Glad I kept the originals

 

[CharlieS]

Denso is OEM, but if you like to spend more for the same part, feel free to buy Toyota parts from the dealer.

 

[CharlieS]

Amazon.com: Denso 673-1303 Ignition Coil: Automotive

 

[sean2202]

Interesting thing happened to me the other day, very slight skip (which I could here better with the small pinhole I put in the exhaust under the truck from a rock) slight miss at around 40mph hardly noticeable. No CEL or pending codes. Have plugs and coil to try. Makes me wonder how many rigs are firing within the CEL range and losing performance as mentioned. 155k on original coils.

 

[2001LC]

This is what I'm wondering. I'd like to find a shop with testing equipment.

 

[Dwight S]

That's kinda what mine did. Just a slight miss off idle. Thought it was bad gas or a slight slip of transmission. No CEL. After a month, got a CEL. Cylinder 1 misfire. Replaced the coil and runs great.