Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert! (1 Viewer)

[abuck99]

Throwing a curveball in here- who’s used NGK plugs? Have you experienced the same loosening?

I’ve several bikes and all spec’d NGK- and when Denso equivalents used they ran like crap. I think Denso run a tad cold. Anyway my FJ with the 4.0 V6 had bank 1 with Denso and Bank 2 with NGK from the factory. Just wondering how the NGK might work in the 2UZFE

 

[2001LC]

Follow up on Denso Iridium IK20TT plugs installed 50k ago:

All plugs were still torqued down to 18 ft/lbs using a digital torque wrench. I checked with ambient temps in the low 60's. I don't know how much that would even matter but figured I'd note it just because.


At least from my above example, 50k might be a decent assumption at ~18 ft/lbs. YMMV. I'm going to check again in another 50k, or if I have to be in there for something else, whichever comes first.

What I would like to know(and may be in this thread already but I didn't see it) is how many factory installed plugs(not dealer replacements) are walking out compared to replacements.

Most all I replace, appear (made in Japan) to be factory installed. Most have some loose spark plugs. Mostly the inner (#3, #5, #4 #6) spark plugs.

Throwing a curveball in here- who’s used NGK plugs? Have you experienced the same loosening?

I’ve several bikes and all spec’d NGK- and when Denso equivalents used they ran like crap. I think Denso run a tad cold. Anyway my FJ with the 4.0 V6 had bank 1 with Denso and Bank 2 with NGK from the factory. Just wondering how the NGK might work in the 2UZFE

Interesting. I've NGK in my 07. History is somewhat convoluted, in that Lexus Dealership install Denso ( part # indicates) at 132K. Yet At 162K when I pulled them, to do a compression test. I found NGK.

I was seeing a slightly rich fuel trim, running -3 to -5% negative long term fuel trim (LTFT). After replacing the MAF, FT came closer to zero. But still slightly rich at 0 to -3% LTFT. It's well tuned engine, which includes fuel injectors sent out CLN, rebuilt and tested, new fuel pump, fuel filter, intake and T-body seals & gaskets along with all vacuum hose checked and any weak ones replaced.

But it has after market CATs. Which IDK but suspect, may have effect on fuel trims.

I've been running logs on ECT, IAT, FT, CAT. I'm going to do a compression test, when I've time. At which time I'll toss in a new set of Denso TT. I'll let you know if data like fuel trims change. I can say in running logs on a lot of 4.7L with Denso spark plugs. I always see them run slightly lean.

 

[abuck99]

Most all I replace, appear (made in Japan) to be factory installed. Most have some loose spark plugs. Mostly the inner (#3, #5, #4 #6) spark plugs.

Interesting. I've NGK in my 07. History is somewhat convoluted, it that Lexus Dealership install Denso ( part # indicates) at 132K. Yet At 162K when I pulled them, to do a compression test. I found NGK.

I was seeing a slightly rich fuel trim, running -3 to -5% negative long term fuel trim (LTFT). After replacing the MAF, FT came closer to zero. But still slightly rich at 0 to -3% LTFT. It's well tuned engine, which includes fuel injectors sent out CLN, rebuilt and tested, new fuel pump, fuel filter, intake and T-body seals & gaskets along with all vacuum hose checked and any weak ones replaced.

But it has after market CATs. Which IDK but suspect, may have effect on fuel trims.

I've been running logs on ECT, IAT, FT, CAT. I'm going to do a compression test, when I've time. At which time I'll toss in a new set of Denso TT. I'll let you know if data like fuel trims change. I can say in running logs on a lot of 4.7L with Denso spark plugs. I always see them run slightly lean.

That would be a great comparison with all the data you have pulled already.

 

[94SRUNNER]

Following up on this...it has been about 1 year and 6,000 miles and the plugs are still holding at 17ft-lbs.

 

[abuck99]

Getting ready to make the switch to NGK Laser Iridium - interested to see if there's any noticeable difference.

 

[OwnerCS]

Getting ready to make the switch to NGK Laser Iridium - interested to see if there's any noticeable difference.

I think I may switch to NGK early next year.

 

[04UZJ100]

Getting ready to make the switch to NGK Laser Iridium - interested to see if there's any noticeable difference.

From Denso?

 

[abuck99]

From Denso?

Yes.

 

[urist]

I did this job the other day with almost no problems. When putting the ignition coil back in for #3 cylinder (2nd from front, driver side) I was tightening the bolt and it acted like it was stripping. I only had it hand tight (wrist tight, not using my arm) with a standard 3/8" drive ratchet. I ordered a few replacement bolts for the ignition coils hoping that I'd just monkeyed the bolt threads and not the valve cover. I tried the new bolts today and sadly it still acted stripped.

The boot is still making good contact with the spark plug. No dash lights and no fault codes on my scanner. The bolt still threads down far enough to get flush with the ignition coil, so the coil backs out of the shaft almost none. There is about 1/2 cm of radial/circular play in the coil.

Here is a video pulling on the coil: video
Here is a video twisting the coil: video

Here is the bolt I pulled. No obvious problems that I see:

After the new bolt acted stripped, I pulled it and it had a very similar wear line to this one (most paint gone towards the bottom 1/3 of the bolt). Seems like if the threads in the valve cover are stripped, then maybe I could shorten the bolt? Toss me any ideas. Thanks.

 

[Mike NXP]

I did this job the other day with almost no problems. When putting the ignition coil back in for #3 cylinder (2nd from front, driver side) I was tightening the bolt and it acted like it was stripping. I only had it hand tight (wrist tight, not using my arm) with a standard 3/8" drive ratchet. I ordered a few replacement bolts for the ignition coils hoping that I'd just monkeyed the bolt threads and not the valve cover. I tried the new bolts today and sadly it still acted stripped.

The boot is still making good contact with the spark plug. No dash lights and no fault codes on my scanner. The bolt still threads down far enough to get flush with the ignition coil, so the coil backs out of the shaft almost none. There is about 1/2 cm of radial/circular play in the coil.

Here is a video pulling on the coil: video
Here is a video twisting the coil: video

Here is the bolt I pulled. No obvious problems that I see:
View attachment 3163793

After the new bolt acted stripped, I pulled it and it had a very similar wear line to this one (most paint gone towards the bottom 1/3 of the bolt). Seems like if the threads in the valve cover are stripped, then maybe I could shorten the bolt? Toss me any ideas. Thanks.

So your saying when you go to thread it in, it gets tight and stops at the last few threads ?

You'll probably need to get a bottoming tap and see if you can thread it down to fix things up.. slow and steady , few turns at a time and then back it out...

Suppose you could just use a shorter bolt . At least you didn't strip the spark plug hole...that bolt head looks all rounded out ..hmm

 

[abuck99]

I did this job the other day with almost no problems. When putting the ignition coil back in for #3 cylinder (2nd from front, driver side) I was tightening the bolt and it acted like it was stripping. I only had it hand tight (wrist tight, not using my arm) with a standard 3/8" drive ratchet. I ordered a few replacement bolts for the ignition coils hoping that I'd just monkeyed the bolt threads and not the valve cover. I tried the new bolts today and sadly it still acted stripped.

The boot is still making good contact with the spark plug. No dash lights and no fault codes on my scanner. The bolt still threads down far enough to get flush with the ignition coil, so the coil backs out of the shaft almost none. There is about 1/2 cm of radial/circular play in the coil.

Here is a video pulling on the coil: video
Here is a video twisting the coil: video

Here is the bolt I pulled. No obvious problems that I see:
View attachment 3163793

After the new bolt acted stripped, I pulled it and it had a very similar wear line to this one (most paint gone towards the bottom 1/3 of the bolt). Seems like if the threads in the valve cover are stripped, then maybe I could shorten the bolt? Toss me any ideas. Thanks.

Lower half of threads look rounded and the head on that bolt is mangled- what’s the story?

Chase threads with a tap and use a new bolt, with thread sealant- should hold fine -next option time sert or heli coil.

 

[urist]

So your saying when you go to thread it in, it gets tight and stops at the last few threads ?

It never gets tight, but yes it stops at last few threads. It gets gets flush with the coil, but never tight enough that there isn't a little bit of play in the coil (see video I posted, that's as tight as it goes). The FSM says 66 inch-lbs of torque. I was only able to get it to around 25-30 before the bolt started slipping.

Lower half of threads look rounded and the head on that bolt is mangled- what’s the story?

Chase threads with a tap and use a new bolt, with thread sealant- should hold fine -next option time sert or heli coil.

That picture looks worse than it is. The story was that according to the Lexus dealer, despite 60 pages of history on the vehicle it never had spark plugs done in the 220k miles before I bought it. It was a bit of work to get those bolts out, but I wouldn't have thought it was enough to mangle the head like that. Maybe a non-lexus shop did the plugs previously and weren't as nice with the bolts as I was. I was using a new bolt today to replace the original, but I have a few more spares.

I'm learning as I go, so when you all said to bottom tap it and fix it up, you don't mean up-sizing it with a tap -- just fixing the threads at the bottom that are already there. That way I can still use the OEM bolts that I have on hand and not have to upsize. Sort of like in this video , but fixing the hole that's there and not making a new one.

Thanks

 

[2001LC]

I'd first make sure, that is correct bolt.
Second, I'd try a thread chase as @abuck99 suggested. They're easier to work and will bottom in hole.
If bolt will then hold, your done. If is does not take torque and hold coil firm, pressing boot firm again head cover. I go with one of two choices, I'd can think of at the moment. Either a time sert or replace head cover.

In the end you do need the coil boot to seal against head cover. This keeps, dust/sand out of spark plug tube. It also keeps coil in proper contact with spark plug.

I may have a BK 1 cover, I'd have to check. PM me if you get to the point of wanting one, and I'll check!

O'Rielly's has Chase kit loaner.

 

[J1000]

EZ Loks make quick and easy work of stripped threads like that. Here's M6x1.0, should be that thread: https://amzn.to/3A3oDDQ

 

[urist]

I'd first make sure, that is correct bolt.

Thanks for your notes. I ordered part number 90080-11590 for the bolt. See here at toyota for the diagram of it in the coils. LMK if that was incorrect, but it seemed to be a perfect match.

Thank you for the offer on the cover, hopefully I won't need it : ]

Is there any serious risk to me driving with the play in the coil that could be seen in the videos above? The coil isn't going to rattle out, but making sure I'm not overlooking something critical. Obviously I could lose a cylinder while driving, but the ECU would detect it, disable it, and throw me a dash light. And of course I'm fixing this ASAP.

Second, I'd try a thread chase as @abuck99 suggested. They're easier to work and will bottom in hole.

I'll check O'Reilly for a thread chaser loaner set. Great idea.

EZ Loks make quick and easy work of stripped threads like that. Here's M6x1.0, should be that thread: https://amzn.to/3A3oDDQ

If a thread chaser won't do it I'll try this method. I'm going to avoid drilling out the original until necessary

 

[Mike NXP]

Thanks for your notes. I ordered part number 90080-11590 for the bolt. See here at toyota for the diagram of it in the coils. LMK if that was incorrect, but it seemed to be a perfect match.

Thank you for the offer on the cover, hopefully I won't need it : ]

Is there any serious risk to me driving with the play in the coil that could be seen in the videos above? The coil isn't going to rattle out, but making sure I'm not overlooking something critical. Obviously I could lose a cylinder while driving, but the ECU would detect it, disable it, and throw me a dash light. And of course I'm fixing this ASAP.


I'll check O'Reilly for a thread chaser loaner set. Great idea.


If a thread chaser won't do it I'll try this method. I'm going to avoid drilling out the original until necessary

If you need a temporary fix go to the hardware store and just buy a smaller bolt since it sounds like the top part of the threads are OK.

If you are concerned it is not the right bolt currently installed, remove another one to compare.

 

[2001LC]

Thanks for your notes. I ordered part number 90080-11590 for the bolt. See here at toyota for the diagram of it in the coils. LMK if that was incorrect, but it seemed to be a perfect match.

Thank you for the offer on the cover, hopefully I won't need it : ]

Is there any serious risk to me driving with the play in the coil that could be seen in the videos above? The coil isn't going to rattle out, but making sure I'm not overlooking something critical. Obviously I could lose a cylinder while driving, but the ECU would detect it, disable it, and throw me a dash light. And of course I'm fixing this ASAP.


I'll check O'Reilly for a thread chaser loaner set. Great idea.


If a thread chaser won't do it I'll try this method. I'm going to avoid drilling out the original until necessary

You can just pull one of the other coil bolts, to verify it's correct bolt.

The only issues driving with coil unsecured. Is getting dirt in tube as mentioned above. We're concerned about the dust/sand getting into to cylinder, next time spark plug removed if sand in tube. It's one reason we replace boot and top seal, with spark plug change. If coil contact with plug, gets to far away. The spark jumps a greater and greater distance. This is not a big concern! But I suppose it could weaken (age) coil if allowed to go on for to long. If spark to weak to spark plug, you may get a misfire DTC. But no big deal, as not going to damage the cylinder.

 

[urist]

If you need a temporary fix go to the hardware store and just buy a smaller bolt since it sounds like the top part of the threads are OK.

If you are concerned it is not the right bolt currently installed, remove another one to compare.

I tried some slightly shorter bolts from AutoZone today but no luck. So I got a tap wrench set from them that included the M6x1. Here is what they advised me to use: https://www.autozone.com/test-scan-...ebilt-metric-tap-wrench-set-6-piece/66272_0_0

A couple sanity checks:

1. That tap set does mentioned above does not say bottom tap. Based on this guide, I believe these are bottom taps though. Do I need to return this and get one that specifically says bottom tap? Photo is below.
   1. 
2. Do I need to take the valve cover off to prevent metal shavings from falling below the valve cover when fixing the threads? Looking at this photo of the underside of the valve cover, I think it is capped on the bottom.
   1. 

Thanks

 

[Mike NXP]

I tried some slightly shorter bolts from AutoZone today but no luck. So I got a tap wrench set from them that included the M6x1. Here is what they advised me to use: https://www.autozone.com/test-scan-...ebilt-metric-tap-wrench-set-6-piece/66272_0_0

A couple sanity checks:

1. That tap set does mentioned above does not say bottom tap. Based on this guide, I believe these are bottom taps though. Do I need to return this and get one that specifically says bottom tap? Photo is below.
   1. View attachment 3167203
2. Do I need to take the valve cover off to prevent metal shavings from falling below the valve cover when fixing the threads? Looking at this photo of the underside of the valve cover, I think it is capped on the bottom.
   1. View attachment 3167201

Thanks

Definetly don't use a drill when using the tap. You should have a tool that grabs the tap or sometimes a 12 point socket will do. Slow and steady with some some pb blaster sprayed on the tap to help grab any metal shavings. Thread a few turns in, then back it all the way out and wipe clean. Repeat until your through. I don't think you need to remove the cover since your not cutting new threads.

I don't get why the shorter bolt wouldn't work.

If you need to clean up the threads all the way to the bottom you may need a bottoming tap.

I'm not sure of bolt size and thread type. Make sure you compare the tap and a bolt that threads in to compare the threads.

 

[urist]

Definetly don't use a drill when using the tap. You should have a tool that grabs the tap or sometimes a 12 point socket will do.

It's not a drill -- picture is a photo of the end of the tool that came with the taps. Shouldn't have cropped it. Won't use a drill : )

Slow and steady with some some pb blaster sprayed on the tap to help grab any metal shavings. Thread a few turns in, then back it all the way out and wipe clean. Repeat until your through. I don't think you need to remove the cover since your not cutting new threads.

Noted. Thanks

I don't get why the shorter bolt wouldn't work.

The problem here was that only the bottom ~1/3 of the bolt actually goes into the threads in the valve cover. I hadn't realized it when I posted this photo previously. The plastic top of the coil is thick enough such that only the bottom 1/3 of the bolt threads in. Getting a slightly shorter bolt (closest I could get was a M6-1.00x20mm while still being shorter) produced the same issue as before...it would thread in a bit, then reach the stripped exterior threads and wouldn't tighten. Any shorter than 20mm length (closest they had was 15mm) and it wouldn't reach the bolt hole / exterior threads at all due to the thickness of the top of the coil.

If you need to clean up the threads all the way to the bottom you may need a bottoming tap.

Noted.

Thanks Mike