When to replace Ignition coils.

[camino70]

Yeah 2001lc, I'm afraid I'm kidding myself, 8 for the price of 1... They at least don't feel like garbage when unpacking, but I'll certainly keep you posted on how they do.
Unfortunately I don't put too many miles on the '98, so my feedback may not be too useful.

 

[2001LC]

Yeah 2001lc, I'm afraid I'm kidding myself, 8 for the price of 1... They at least don't feel like garbage when unpacking, but I'll certainly keep you posted on how they do.
Unfortunately I don't put too many miles on the '98, so my feedback may not be too useful.

Well high price doesn't insure quality either, just take BMW...LOL.. At the price, one could swap out yearly if they effectively enhanced performance.

 

[mmaakk]

I replaced one at 270k miles then another went out at 278K at which point I decided to do all of them and be done, used all Toyota OEM.

 

[Hugga99]

1999 LX470 with 145k. Just had my first go out last week, cylinder 5. Truck was vibrating like crazy, as a result. Had shop replace the one coil, and all new spark plugs while it was there. Car had been idling roughly for a year, and that is gone. Coil must have been failing for some time before throwing the code. RPM at idle are smooth now, and gas mileage seems to be better too.

Now I just need to get over my fear of working on my own car, and do it myself next time.

Sent from my SAMSUNG-SM-G920A

 

[camino70]

1999 LX470 with 145k. Just had my first go out last week, cylinder 5. Truck was vibrating like crazy, as a result. Had shop replace the one coil, and all new spark plugs while it was there. Car had been idling roughly for a year, and that is gone. Coil must have been failing for some time before throwing the code. RPM at idle are smooth now, and gas mileage seems to be better too.

Now I just need to get over my fear of working on my own car, and do it myself next time.

Sent from my SAMSUNG-SM-G920A

I think mine were failing without a code for a bit too, there was a bit of a stumble here and there, then one day it went rough, especially in reverse.

Get over the fear, there are plenty of people here willing to help, take pictures, etc. It took me about 45 minutes to replace all eight plugs and packs, less time than it'd take me to get to a shop. All it took was a 10mm and 16mm socket. I used the same ratchet and extension, fit everything, all 8 plugs/packs, air box, drivers side bracket. The only other thing I used was a rubber spark plug tool. My plug socket didn't fit in the tunnel, so the rubber tool is like a section of vacuum hose with a screw driver handle. It fits over the plug end so you can pull it out and spin a new one in.

 

[Jrod]

99 LX with 225K. Had 2 coils fail within a month of each other and they were all original. I decided after the first 2 failed I would go ahead and replace the remaining 6 just for piece of mind. Replaced all with Bosch coil packs.

 

[lifer]

I think mine were failing without a code for a bit too, there was a bit of a stumble here and there, then one day it went rough, especially in reverse.

Get over the fear, there are plenty of people here willing to help, take pictures, etc. It took me about 45 minutes to replace all eight plugs and packs, less time than it'd take me to get to a shop. All it took was a 10mm and 16mm socket. I used the same ratchet and extension, fit everything, all 8 plugs/packs, air box, drivers side bracket. The only other thing I used was a rubber spark plug tool. My plug socket didn't fit in the tunnel, so the rubber tool is like a section of vacuum hose with a screw driver handle. It fits over the plug end so you can pull it out and spin a new one in.

So true. It makes no sense to do the plugs without the coil packs, since all the same parts must be R&R'ed. (add torque wrench? )

 

[Jrod]

So from before the 2 went bad to after installation of Bosch coils, did you notice anything. Like performance, idle, acceleration, MPG etc...???

Idle seems better when I replaced all of them. I don't track MPG. Acceleration may be better, but hard to tell. I just replaced all of them, so if my wife was driving she wouldn't be stuck on the side of the road with my son in the car needing help.

Just for everyone's info here on the board - at 200k they were all looking really rough and the rubber boots were showing wear. I'd recommend they be replaced every 150-200k as preventative maintenance.

 

[Em cee]

230k mi, #1 went a few months back. #3 went a couple months later. I only drive the LC a couple times a week no more than 50mi or so. she lives a sedentary life, not good for anything mechanical.

Recently had a rough idle when completely warmed up. Would stumble on acceleration from dead stop but would run like a beheaded chicken on all other counts.

R&r commenced between all coils/plugs. Looked for fouling / funky gaps and visible signs of wear around coils to no avail. For giggles, ran a bottle of chevron techron in her along with 11 gallons of 91 octane (don't over fill as you will dilute effectiveness of the fuel system cleaner). Proceeded to wring the big ol beast out and it has seemed to cure her of her ails. Will follow up with another bottle and 2nd round of flogging.

 

[bctlex]

Idle seems better when I replaced all of them. I don't track MPG. Acceleration may be better, but hard to tell. I just replaced all of them, so if my wife was driving she wouldn't be stuck on the side of the road with my son in the car needing help.

Just for everyone's info here on the board - at 200k they were all looking really rough and the rubber boots were showing wear. I'd recommend they be replaced every 150-200k as preventative maintenance.

I am still undecided if I should buy 1 or 2 OEM coil, and keep them with the car, so I can swap it when there is a problem, or just replace all of them with the low cost Amazon/aftermarket coil as preventative measure. The price of these aftermarket coil is just too good to be true, but maybe I am over thinking this haha..

This is my wife (with our 4 yr old) dd so definitely do not want to get them stuck on the side of the road. Ideally I should replace all of them with OEM coil, but that become pricey.

Thanks for the info. I should just pull the coil packs and inspect their condition.
Chris

 

[Jrod]

I am still undecided if I should buy 1 or 2 OEM coil, and keep them with the car, so I can swap it when there is a problem, or just replace all of them with the low cost Amazon/aftermarket coil as preventative measure. The price of these aftermarket coil is just too good to be true, but maybe I am over thinking this haha..

This is my wife (with our 4 yr old) dd so definitely do not want to get them stuck on the side of the road. Ideally I should replace all of them with OEM coil, but that become pricey.

Thanks for the info. I should just pull the coil packs and inspect their condition.
Chris

Chris - I bought Bosch coil packs from Rock Auto. Too good a deal to pass up. Bosch makes the OEM coil packs for Toyota, so I wouldn't worry about buying these directly from Mr. T.

 

[2001LC]

I am still undecided if I should buy 1 or 2 OEM coil, and keep them with the car, so I can swap it when there is a problem, or just replace all of them with the low cost Amazon/aftermarket coil as preventative measure. The price of these aftermarket coil is just too good to be true, but maybe I am over thinking this haha..

This is my wife (with our 4 yr old) dd so definitely do not want to get them stuck on the side of the road. Ideally I should replace all of them with OEM coil, but that become pricey.

Thanks for the info. I should just pull the coil packs and inspect their condition.
Chris

One of the great things about coil on plug (COP) you can have multiple coils fail, and the engine will keep running. Running (rough) with working coils and eventually a CEL will show.
DIY inspection is limited to seals, connections, millimeter test and spark plug condition. To really test coil condition, shop equipment is need to test on engine. I've added some links in OP recently on this.

I replaced one at 270k miles then another went out at 278K at which point I decided to do all of them and be done, used all Toyota OEM.

That is some amazing miles, I'm a big believe in OEM for that reason if no other.

1999 LX470 with 145k. Just had my first go out last week, cylinder 5. Truck was vibrating like crazy, as a result. Had shop replace the one coil, and all new spark plugs while it was there. Car had been idling roughly for a year, and that is gone. Coil must have been failing for some time before throwing the code. RPM at idle are smooth now, and gas mileage seems to be better too.

We do tend to rely a little to much on CEL IMHO. Drop in MPG, roughness, vibration and change in sounds is old school but still telling..

99 LX with 225K. Had 2 coils fail within a month of each other and they were all original. I decided after the first 2 failed I would go ahead and replace the remaining 6 just for piece of mind. Replaced all with Bosch coil packs.

Bosch was a quality name, is that still true?

I used Accel & Bosch stuff on muscle cars in the 70's and loved the performance enhancement. Don't know if that hold true with todays systems, where components are matched so precisely. But quality always matters IMHO.

So true. It makes no sense to do the plugs without the coil packs, since all the same parts must be R&R'ed. (add torque wrench? )

Interesting how a bad spark plug issues like wide gap, can damage coils. I suppose (DK) reveres true?

230k mi, #1 went a few months back. #3 went a couple months later. I only drive the LC a couple times a week no more than 50mi or so. she lives a sedentary life, not good for anything mechanical.

Recently had a rough idle when completely warmed up. Would stumble on acceleration from dead stop but would run like a beheaded chicken on all other counts.

R&r commenced between all coils/plugs. Looked for fouling / funky gaps and visible signs of wear around coils to no avail. For giggles, ran a bottle of chevron techron in her along with 11 gallons of 91 octane (don't over fill as you will dilute effectiveness of the fuel system cleaner). Proceeded to wring the big ol beast out and it has seemed to cure her of her ails. Will follow up with another bottle and 2nd round of flogging.

Bad gas, old gas (moisture) and sitting probable cause a lot needless repairs hunting for issue doesn't it. I've always used 44K. I suppose adding Techron is concentrating the cleaning agent they put in todays quality gas.

**** Bosch makes the OEM coil packs for Toyota, so I wouldn't worry about buying these directly from Mr. T.

Good to know. Do you have a source for that info you can share?

 

[sean2202]

2001lc I am sure there is a way to test the coils with a multimeter. I have been told to replace coils as preventative maint at 200k. I don't put many miles on so I will just run it till I hear an issue. Read on "Bob is the oil guy" one time that chevron techtron is the only cleaner that actually has chemestry. I believe that fuel filter should be changed more frequently as well. Did you change anything else when you saw a drop in gas mileage(ex tires)?

 

[larryt]

Unless Toyota changed it up recently, new OEM coils are made by Denso. With 177k miles on the original coils, I carry a spare but I'm in no rush to change them all out.

 

[larryt]

This is anecdotal at best, but my wife's Cadillac CTS uses Bosch ignition coils as OEM and I've replaced 4 of 6 well before 90k. Granted, it's a filthy direct injection engine and a total POS so there may not be a quality correlation.

 

[Jrod]

One of the great things about coil on plug (COP) you can have multiple coils fail, and the engine will keep running. Running (rough) with working coils and eventually a CEL will show.
DIY inspection is limited to seals, connections, millimeter test and spark plug condition. To really test coil condition, shop equipment is need to test on engine. I've added some links in OP recently on this.

That is some amazing miles, I'm a big believe in OEM for that reason if no other.

We do tend to rely a little to much on CEL IMHO. Drop in MPG, roughness, vibration and change in sounds is old school but still telling..
Bosch was a quality name, is that still true?

I used Accel & Bosch stuff on muscle cars in the 70's and loved the performance enhancement. Don't know if that hold true with todays systems, where components are matched so precisely. But quality always matters IMHO.

Interesting how a bad spark plug issues like wide gap, can damage coils. I suppose (DK) reveres true?

Bad gas, old gas (moisture) and sitting probable cause a lot needless repairs hunting for issue doesn't it. I've always used 44K. I suppose adding Techron is concentrating the cleaning agent they put in todays quality gas.
Good to know. Do you have a source for that info you can share?

I apologize - they are Denso, not Bosch.

 

[hankinid]

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?
• After market or OEM coils?

> The same reasons any coil will fail...primary reasons look to me to be engine heat, temperature changes, and vibration.

> I'd not replace gaskets, seals or grommets until / unless I saw weeping or leakage...same way I'd look at valve cover gaskets. Anecdotally, with ~180K miles on the '01 LX, she remains dry as a bone.

> I see no logic in replacing all coils if one goes bad. I would check the resistance on the remaining 7 and replace any that test out of the FSM spec range. That said, I do carry a spare.

> No...failures are random enough that periodic resistance checks may catch impending failures.

> Imo, OEM.

 

[Em cee]

Somewhat off topic but opportune time to snug and validate torque of valve cover bolts. I had 8 or so that werent even hand tight. Leaks fixed.

 

[2001LC]

I'd like to do a before and after test of coil "health". Would be nice to find someone with high end shop testing equipment that shares my curiosity.

2001lc I am sure there is a way to test the coils with a multimeter. I have been told to replace coils as preventative maint at 200k. I don't put many miles on so I will just run it till I hear an issue. Read on "Bob is the oil guy" one time that chevron techtron is the only cleaner that actually has chemestry. I believe that fuel filter should be changed more frequently as well. Did you change anything else when you saw a drop in gas mileage(ex tires)?

So far in this thread it does seem that ~200K is the average we start seeing failures. I hope we get many more testimonials here to draw from.

I added some links to OP. One shows millimeter the another more specialize on engine coil testing. Both have merit, but I'd think the on engine would be the most reveling. Be interesting to do on engine coil test of high millage, then replace with new OEM and retest, coupled with MPG data don't you think?

I'll take a look (Bob***) on Chevron Techtron, thanks for the heads up. I've just been sold on BG product like 44K forever, may be time for a change.

I did a ~95K baseline; both belts (no W-pump) along with all idler & tensioner pulleys, spark plus and all filters, fluids and lubes. After this time I first documented a drop in MPG. I've since changed out front O2's (no code) and fuel filter (a second time) with no change in MPG or performance. I've logged differences with/in/of tires, air conditioning use, cabin fan use along with experimenting on fluids, lubes & grease to see viscosity variance over the years in MPG.

My LC runs very well but MPG is on a declining curve. MPG is actually good, but it has room for improvement IMHO. MPG is a reflection of performance of "parts" of these very integrated systems.

Which parts is the question. IMHO the combustion chamber is key and some post here defiantly point to weak (not failed) coils as a large suspect contributor to reduced performance.

This is anecdotal at best, but my wife's Cadillac CTS uses Bosch ignition coils as OEM and I've replaced 4 of 6 well before 90k. Granted, it's a filthy direct injection engine and a total POS so there may not be a quality correlation.

So many companies that start out offering a great produce, drop the ball when accounts pull the cost strings.

> The same reasons any coil will fail...primary reasons look to me to be engine heat, temperature changes, and vibration.

> I'd not replace gaskets, seals or grommets until / unless I saw weeping or leakage...same way I'd look at valve cover gaskets. Anecdotally, with ~180K miles on the '01 LX, she remains dry as a bone.

> I see no logic in replacing all coils if one goes bad. I would check the resistance on the remaining 7 and replace any that test out of the FSM spec range. That said, I do carry a spare.

> No...failures are random enough that periodic resistance checks may catch impending failures.

> Imo, OEM.

All very good points. Starting with heat this is for sure IMHO the number one cause of failure. Rubber grommets & boot ageing (shrinkage & brittleness) would certainly accentuate vibration, brought on by age, heat & climate.

I'd add over or under voltage to coils, short along with fouled or improper spark plug gap contributing to coil failures.

 

[RootMeanSqr]

I've had 2 (or 3?) fail since 70k miles on my 2000 LC. At 98k now.