PDA

View Full Version : UZJ100 Ignition Coil and Plugs


RicardoJM
03-18-2010, 11:24 AM
Saturday morning my UZJ100 started idleing rough and would not accelerate smoothly. It was very apperant that something was not right and within a couple of miles the MIL (malfunction indicator light or check engine light) was flashing.

When I got home, I plugged in my code reader. My code reader is a very low end model with two aspects that I came to dislike; the cord is too short and it automatically clears codes after displaying them three times. I did not see the code with my reader because in the time it takes me to get down under the dash, it had cleared. Many thanks to Jeff Z.:thumb: who let me borrow his Scanguage II. Using his code reader, I was able to see that the computer was reporting P0305. Some quick research on MUD and I found that my issue was related to cylinder 5; spark plug, ignition coil or fuel injector. The most common issue is ignition coil failure.

I picked up new spark plugs and an ignition coil at Groove. I found the ignition coil in cylinder 5 was not good and after swapping it out and putting in the new ignition coil the idle and power issues from the morning were resolved. The spark plugs for this truck are rated for 100k miles and my truck has 137k miles. I really don't know if my plugs have ever been swapped out; so I did this yesterday afternoon. This truck is very different than my FJ40; each cylinder has its own ignition coil and it must be removed to get access to the spark plugs. In this write up, I will cover what is involved with replacing spark plugs and ignition coil.

There are very few tools required to do this job. The tool kit in the truck has everything you would need if you had to do this job on the road; spark plug tool and 10mm wrench. I was at home, so I used a torque wrench. I also used extensions as they were handy for the plugs at the back of the engine. Here is everything that I used for replacing the spark plugs.

http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_tools.jpg

My truck has a pretty cover plate with a nice V8 logo. To remove this cover, you need to remove two nuts and two bolts. The cover will then lift straight up to reveal the engine.

http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_engine.jpg

There is an air intake tube assembly that must be removed to get access to the spark plugs on the passenger side of the block. To remove this assembly, you need to remove two bolts, two clamps and disconnect 4 hoses. You can then remove this assembly and have easy access to all four plugs.

http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_airassembly1.jpg
http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_passplugs.jpg

Next you disconnect the clip that provides power to the ignition coil. Push on the tab to release the clip and pull up. The shadows make it a bit hard to see, but here is the clip removed.

http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_clipoff.jpg

Next you remove the bolt that holds the ignition coil in place and remove the ignition coil. I didn't snap a photo of the bolt, but you will know which one it is. If you are replacing the ignition coil, here is where you would swap in the new one.

http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_removecoil.jpg
http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_coilout.jpg


The next step is to remove the spark plug. It is about 5" down the tube and here is where the extensions come in handy.

http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_removeplug.jpg

After checking gap is set at the factory, but it is good to check) the gap on your new plug to make sure it is at spec. Install the new plug by hand and use the torque wrench (13 ft lbs) for the final tightening of the plug. Put the ignition coil in, insert the bolt by hand and use the torque wrench (66 in lbs) for final tightening of the bolt. When putting plugs, bolts and nuts back; doing so by hand makes sure you don't cross thread. I found the FSM (two volumes) on e-bay a while back and am really glad to have all the detailed information in them.

http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_fsm.jpg


The last step is to connect the clip that provides power to the ignition coil. You are done with the plug swap. Repeat the process for all plugs on the passenger side of the block. Before going to the driver's side re-install the air intake tube assembly.

Then go over to the drivers side and do the same. Access to the two cylinders at the rear can be made much easier if you remove the wiring harness wire and the bracket it hangs on. Access to rear most cylinder is the tightest. Most people that have posted up indicated that two 3" extensions worked best. I found that approach worked for me as well. When you are all done, replace the engine cover.

http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_coveron.jpg


After replacing my plugs I notice an improvement in power and smoothness. It is not dramatic, but it is noticeable. My old plugs were very clean but also very worn; the gap was right at the edge of acceptable. I took my time as I did this work, checking and double checking as I went along. It took 2.5 hours.

Phrog
03-18-2010, 11:51 AM
Great write-up! Thanks for posting.

-Phrog

1972 FJ40
2003 100

corsair23
03-18-2010, 12:09 PM
Great writeup Ricardo :thumb:

Top notch work as always :)

nakman
03-18-2010, 02:08 PM
Nice work, Ricardo. Only think I'd add that I do differently is I always duct tape the plug socket to the extension- helps to insure I don't leave anything behind when I pull out... also, did you put any anti-seize on the plug threads? :)

RicardoJM
03-18-2010, 04:51 PM
Nice work, Ricardo. Only think I'd add that I do differently is I always duct tape the plug socket to the extension- helps to insure I don't leave anything behind when I pull out... also, did you put any anti-seize on the plug threads? :)

That is some good advice. On every plug, it took a bit of wiggle to get the socket to release from the plug. By the 8th one, I got the routine down. Duct tape would have made it much easier.

No anti-seize on the threads. I had read both sides of this debate. The plugs I pulled did not have it and all of them took some muscle to break free. Once the initial bond was broken, they came out with finger pressure.

DaveInDenver
03-18-2010, 05:07 PM
Nice write up Ricardo. As always.

I always anti-seize my plugs using the copper stuff. Actually I slather anti-seize on everything for that matter. But on the 22R it's not uncommon for the 'breaking loose and finger tight' part to be because you are bring threads from the head with you. I have this fancy NAPA spark plug hole Helicoil kit just for this...

nakman
03-18-2010, 05:30 PM
I always anti sieze mine too.. but didn't realize there was a debate? I'm just paranoid that the "extra muscle" required to break them free will just bust the thing.. then an hour job turned into a weekend job just like that. but hey I'm no mechanic, we all know that! :lmao:

farnhamstj
03-18-2010, 05:48 PM
Nice work, good write up.

rover67
03-18-2010, 06:02 PM
What'd the old plugs look like? just curious...

I always anti seize mine too, didn't realize there was a debate either... Had too many "almost" not come out, or come out with half the threads.

Three Wheel Ben
03-18-2010, 08:25 PM
Ricardo,

You can tell if the plugs are original by a little painted/stamped mark on the very top. Sometimes it is a letter and sometimes it is a shape. Only has it from the factory, replacement plugs don't have them.

Antiseize = good, unless it is a Land Rover, then the plugs won't ground.:eek:

RicardoJM
03-18-2010, 08:32 PM
What'd the old plugs look like? just curious...

I always anti seize mine too, didn't realize there was a debate either... Had too many "almost" not come out, or come out with half the threads.

Here they are:
http://www.risingsun4x4club.org/uploads/ricardojm/470plugs/w_oldplugs.jpg

Wow, it has been a while since you experienced guys have done a MUD search on replacing plugs. There are definitely two schools of thought on the pros/cons; ease of removal, contamination of the plug, affect on torque specs, yada, yada, yada. As these plugs are 100k rated, it will be some time before I get do them on this truck again. Stay tuned for about 8 years or so and I'll let you know how the no anti-seize approach worked.:D

RicardoJM
03-18-2010, 08:44 PM
You can tell if the plugs are original by a little painted/stamped mark on the very top. Sometimes it is a letter and sometimes it is a shape. Only has it from the factory, replacement plugs don't have them.

Antiseize = good, unless it is a Land Rover, then the plugs won't ground.:eek:

Thanks Ben. I just looked and the old plugs don't have this - so they are not the original ones. I bought the truck with 62k on it, so perhaps they were swapped by a previous owner. I've kept up with fluids on a regular basis and the only mechanical issues have been starter and the coil. I'm sure that will change a bit as it gets older, but I have been very pleased with the reliability.

So this thread has convinced me to give anti-seize a go on the next round. With my FJ40, that won't be too long from now.:hill:

DaveInDenver
03-18-2010, 09:35 PM
contamination of the plug, affect on torque specs, yada, yada, yada.
Valid points, particularly torque. That is always true, though. Any torque spec in the FSM or otherwise is given assuming unaltered bolts. IOW, just as they are delivered to you by Jerry. Sometimes they will have thread sealant or anti-seize from the factory, but mostly they are given to you dry. If you choose to add Loctite or anti-seize then you have to adjust accordingly. I generally take the lowest setting of the range Toyota gives and reduce by 10%. I've never done an elongation check to see if this is appropriate, so I dunno if that matches the recommended adjustment by Permatex. I think that is something like 25% reduction from the recommended bolt pre-load, e.g. 80 ft-lbs becomes 60 ft-lbs to achieve the same clamping force.

Anti-seize is nothing but a lubricant with a soft metal suspended in it. If the fastener gets hot enough, as would spark plugs, the base burns off and just leaves the metal. In the case of copper anti-seize that leaves you a pretty good conductor filling the voids between the threads. Regular anti-seize I think is nickel, which is also a conductor. The grease or lube is not what's doing the anti-seizing, it's that the interface between the iron atoms in the threads is discontinuous with the suspended metal as it forms in the thread voids. This then prevents cold welding of the parts, which is what happens when iron atoms are put in tight contact under pressure, they start sharing electrons and literally start welding. The anti-oxidation and anti-galling is only a side benefit but not the main mode of keeping the bolts from freezing in place. This is why anti-seize works even after extreme heat like on engine or exhaust parts or being pounded by road salt. It doesn't matter if the lubricant gets flushed or burned off as long as the soft non-ferrous metal remains in place on the threads the joint cannot self-weld.

Now galvanic corrosion, hmmm. You are adding another metal to the equation, be it aluminum, copper, nickel. I think aluminum is fairly active, but nickel is fairly inactive. I'd have to put down this beer, stand up and get a book to check the galvanic series. Yeah, not worth it. My guess is there is probably a reason that spark plugs stick into heads, though. Maybe it's the galling and so it's not the anti-welding. I dunno.

RicardoJM
02-24-2011, 08:39 PM
The #3 cylinder coil pack went bad today, that makes 2 only 6 more to replace. :D

Air Randy
02-25-2011, 10:04 AM
The #3 cylinder coil pack went bad today, that makes 2 only 6 more to replace. :D

I would do the rest of them now, all at once and get it over with.

subzali
02-25-2011, 10:20 AM
Hopefully mine don't start going out soon, I'm at 120K miles :eek:

cbmontgo
02-25-2011, 11:47 AM
My first coil pack failed about 3 months ago. # 6 cylinder if I remember correctly. Great writeup by the way...never noticed this before.

RicardoJM
02-25-2011, 12:23 PM
I would do the rest of them now, all at once and get it over with.

Hopefully mine don't start going out soon, I'm at 120K miles :eek:

:eek: This modern technology is way different (expensive) when compared to the FJ40. A coil pack runs about $80 and there is one for each cylinder. I suppose I could drop another $480 in preventive maintenance and be good for another 150k miles - but that would cut into my FJ40 budget. However, it would probably be a good thing to pick the next one up and toss it in the glove box.

subzali
02-25-2011, 12:26 PM
I was just going to ask if they are interchangeable. If they are I should probably have a spare one all ready to go so I can get to work if one of mine dies.

RicardoJM
02-25-2011, 03:55 PM
I was just going to ask if they are interchangeable. If they are I should probably have a spare one all ready to go so I can get to work if one of mine dies.

In my V8 they are all the same part number. My brother had one go out in an ES300, as it happens my father has a Solara with the same engine - but the ES300 had variable valve timing so the ignition coil was not interchangeable between the two cars. That said, there were not different part numbers for any cylinder differences.

I am pretty sure that if you picked one up, it would be the same part number and work in any cylinder. :thumb:

subzali
02-25-2011, 06:34 PM
Cool, since you and I have basically the same engine then I'm sure that's the case :thumb:

farnhamstj
02-25-2011, 07:55 PM
I have replaced 1 (#4) in 208,000 miles. I carry a spare, they are all the same.