Spark plug installation problem?

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sprocket

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If you read last post in the diamond anniversary thread, you can see that I am concerned that the new spark plugs are not going in all the way. Here's a recap.

1) Bought Motorcraft plugs and wires.
2) Removed the cheap new plug wire set that the previous owner had installed. This required destroying five of the eight plug wires to get the boot off the plugs.
3) Removed the old spark plugs and replaced them with Motorcraft.

Here's where the problem lies. This engine was overheated by the previous owner and I got the car cheap because of that. When I first got it, it had a cylinder six misfire. I replaced the plug wire and plug and the misfire stopped. Because I had to destroy the plug wire to remove it, I decided to replace them all.

Now here's the part where my friends think I am crazy:
I don't think the plugs are threading in all the way, and I had trouble getting them started. One of my friends had the touch and was getting them started pretty easily. I've never had this problem before. I'm expecting the plugs to thread in all the way to the tapered shoulder, but I'm only counting about five full turns before they get tight. In the case of #6, I don't even think it is going in that far. I am able to turn them by hand almost all the way to tight and they do feel like they are coming to a dead stop. I don't get the feeling that I could make them go further. I tried taking out a plug and putting the original one back in and it goes in the same amount.

So now there is misfiring and due to bad weather I can't get back to the car today with a code reader and a spare set of coils.

Am I imagining things? Or are the plugs not supposed to go in as far as I think they should? I had no trouble getting the old ones out, and they didn't seem to require very many turns to remove either.

The auto parts store had a spark plug thread repair kit that just chases the threads but doesn't cut them. It's $57 though, which is a lot to spend if I am just imagining things. *CORRECTION* I don't need that full kit. I might just need a chaser which is about $7
 
When i did my tune up when i first got mine in November i did the same and it really didnt take much to tighten once i had them in there. Ur misfire maybe to a wire laying wrong or one of the boots set crooked. Just breath and u will get thru it. Dont spend no more $$$ til u check that.
 
the plugs don't have very many threads to begin with. that's why they blow out so easily.
i do not know how many threads they have exactly. but it isn't many.
 
Miksweets said:
When i did my tune up when i first got mine in November i did the same and it really didnt take much to tighten once i had them in there. Ur misfire maybe to a wire laying wrong or one of the boots set crooked. Just breath and u will get thru it. Dont spend no more $$$ til u check that.
Click to expand...

Thanks. I wonder if I could find a link to what the length of each plug wire is supposed to be? The lengths of the aftermarket set didn't exactly match the lengths of the Motorcraft set. Because of that, by the time I got to the last three, I had one that was a little too short and one that was way too long. I tired to swap a couple but I still have one that is stretched and one that is way too long. It should be easy enough to logic out. Actually I have a shop manual, which also forgot to bring along, and I can look at it now to see if it gives the lengths. Also, a couple of the looms broke (big surprise there:rolleyes:) so they are popping out here and there. I'll get some replacements.
 
Motorcraft plugs also have more of a threaded tip than an Autolite 764 has but either way, the plug only threads in so far because of the block not having many threads so, with a Motorcraft plug, it's going to have more threads left and appear that it's not all the way in when it really is.
 
The interesting thing I am seeing in the shop manual is that the numbering of the wires doesn't match the routing that it shows. 1 and 6 for example are reversed, which I guess is ok since they fire together. I would like to lay the wires out exactly like the diagram. There should be 11 wire looms and I think I have 4.

I believe 1,3,and 7 are the shortest and about the same length
#8 would be the next longest
5,6, and 2 should be about the same length and the next longest
#4 is probably the longest

Now I need to get to the car, remove all the wires and measure them. I can't find any specs online for lengths of Motorcraft wires.
 
sprocket said:
The interesting thing I am seeing in the shop manual is that the numbering of the wires doesn't match the routing that it shows. 1 and 6 for example are reversed, which I guess is ok since they fire together. I would like to lay the wires out exactly like the diagram. There should be 11 wire looms and I think I have 4.

I believe 1,3,and 7 are the shortest and about the same length
#8 would be the next longest
5,6, and 2 should be about the same length and the next longest
#4 is probably the longest

Now I need to get to the car, remove all the wires and measure them. I can't find any specs online for lengths of Motorcraft wires.
Click to expand...

This is why you replace them 1 wire at a time, pull the wire off, match length (which isn't always exact) and replace it with a new one that's pretty close to the same
This method also helps prevent getting the firing order mixed up
 
Sapperfire said:
This is why you replace them 1 wire at a time, pull the wire off, match length (which isn't always exact) and replace it with a new one that's pretty close to the same
This method also helps prevent getting the firing order mixed up
Click to expand...


In an earlier post I explained the mix-up. I did match them one at a time but the previous owner had a cheap set installed and the lengths were + or - a couple of inches. By the time I got to the last three it became clear that there was one that would be too long and one that would be too short. I backtracked but couldn't find the right solution. Now that I have the proper diagram that shows exactly how they should route, I can fix it.

Using a routing diagram is the right way to do it. NOT assuming the last guy did it right. That was my mistake.
 
Unfortunately when I went back to the car this evening it wouldn't start and the battery drained quickly. I think part of the problem is that there is some extra wiring to the battery that I think is for an aftermarket HID headlight kit. It looks cobbled to me. This is the first time I have started it after dark and I think the headlights must create quite a draw. I should have turned the auto headlight switch off. The battery terminal ends are junk too from being overtightened. I took the battery with me to charge it and I will replace the terminals and try to make sense of the additional wiring at the battery.

BUT, I did get the trouble codes first, before I disconnected the battery. The only code is for a cylinder 3 misfire. Just one misfire would seem to eliminate a coil as the source of the problem.
 
Just 1 coil can go bad, even if its in a coil pack like the Gen1 has. I wouldn't elimate it until you pull the wire from the coil top and watch the sparks dance around in the basket

I didn't see what year yours was

On a Gen2 just swap a misfire cylinders COP with one that doesn't give a misfire code and rexheck. If the misfire moved, you know you've got a failed coil
 
I'm not sure I quite follow you. My understanding is that there are only two coils in each coil pack. Each individual coil in the coil pack has two towers. The two towers fire spark to two cylinders at the exact same time. Therefore I would think that if one coil in the coil pack goes bad, it would cause misfires on two cylinders.

Unless the tower itself coming off the coil has developed a defect?
 
chris2523 said:
the plugs don't have very many threads to begin with. that's why they blow out so easily.
i do not know how many threads they have exactly. but it isn't many.
Click to expand...

This is the threads of an Autolite Iridium XP that I haven't installed yet. Kinda reminds me of the threads of a Motorcraft plug and not like the Autolite 764 copper plug.

2013-02-11091408_zps35d464af.jpg


2013-02-11091533_zps1a384f1e.jpg
 
Yes, a couple days ago I had the auto parts store show me a few different plugs, including that one and the 764. I kind of wish I would have just went with the 764's and saved some bucks. I also wouldn't have ended up being paranoid about how far in the plugs were threading.

I do appreciate all the responses here. This has turned out to be an informative topic that might help others.
 
sprocket said:
Yes, a couple days ago I had the auto parts store show me a few different plugs, including that one and the 764. I kind of wish I would have just went with the 764's and saved some bucks. I also wouldn't have ended up being paranoid about how far in the plugs were threading.

I do appreciate all the responses here. This has turned out to be an informative topic that might help others.
Click to expand...

I have had 764's in my car since 2010 but not many miles have been put on them. The car idles with exceptional smoothness and if stomped to the floor, it responds just like it should. 764's are really a good plug for our cars but they should be swapped out around 10,000 miles. I have maybe half that on mine since 2010 but the reason I'm going with the Iridium is to see if they will improve gas mileage any. My car isn't modded under the hood besides the air intake tube being shaved. People say they are getting 28-29 mpg on the HWY and I'm getting around 25 mpg and I run only 93, always have. I'm only swapping to Iridium for testing. They can't be any worse on gas mileage than the 764's I have in now. I have never used anti seize on my plugs either and I have never had a problem with removal.

I'm not suggesting to not use it. I'm just saying that I don't use it. I change them when it has sat for a day or two so, I know the engine is as cool as it's going to get. When I tighten them down, I don't use any type of torque wrench.I just get them good and tight but I don't put a whole lot of extra arm into it. I don't want to crack the plug or strip my threads but I do get them in good and tight with no anti seize. Out of three Marks, I haven't ever had a problem loosening all 8 plugs. They come out just like I put them in. I use a long extension and I tape the plug to the end of the socket, just on the edge of the plug to make sure it doesn't just fall off in the hole. I like to know I'm guiding it down and it's maintaining the gap that I have them set at (0.54) and also it's nice knowing that the plug isn't catching any dirt or grime on it's way down. That's just "my way"of changing my plugs. Never had one blow out and never had any misfire.
 
sprocket said:
I'm not sure I quite follow you. My understanding is that there are only two coils in each coil pack. Each individual coil in the coil pack has two towers. The two towers fire spark to two cylinders at the exact same time. Therefore I would think that if one coil in the coil pack goes bad, it would cause misfires on two cylinders.

Unless the tower itself coming off the coil has developed a defect?
Click to expand...

You are correct in that the pack has 2 coils in it, and each coil inside will fire 2 spark towers. This is known as a Waste Spark Ignition System, meaning 1 of the towers spark is wasted because its cylinder isn't on the combustion stroke and the other is. One of the towers could be loose from its coil. So dont rule it out until after you've checked the wires and plugs
 
Sapperfire said:
You are correct in that the pack has 2 coils in it, and each coil inside will fire 2 spark towers. This is known as a Waste Spark Ignition System, meaning 1 of the towers spark is wasted because its cylinder isn't on the combustion stroke and the other is. One of the towers could be loose from its coil. So dont rule it out until after you've checked the wires and plugs
Click to expand...

Thanks, perhaps this could explain how it is possible to have no misfire or at least not one that occurs often enough to trip a code and then change the plug wires and suddenly have a misfire. Maybe the tower was on the edge of failing and the act of changing the plug wire was enough to cause it to fail.
 
Or you didnt snap the wire on the plug all the way
Or an improper gap on the plug?

.054
 
I'm either going up today (car is at friend's shop) or tomorrow to redo the plug wiring. Here is something very interesting:

I have the shop service manual for the '96 Mark VIII, and it has a very nice picture showing exactly how the plug wires should be routed. It would not be hard to make it look spot on identical to the picture, and that is what I intend to do. There should be a total of 11 wire separators. I think I have four.

Anyway, the interesting things is that the picture shows wires 1 and 6 reversed and 2 and 8 reversed. They are numbered one way but are actually run the other way. I know 1 and 6 fire together and 2 and 8 fire together.

The big question: DOES IT MAKE A DIFFERENCE???

Should I follow the numbering or follow the diagram??
 
The right way

In the manual, is it an actual picture of a running engine, or a drawing.. a drawing is just a rendition
 
Sapperfire said:
The right way

In the manual, is it an actual picture of a running engine, or a drawing.. a drawing is just a rendition
Click to expand...

OK, here is how it is: On one page there is a drawing of the coil packs. The coil packs are numbered like this looking from the front of the car:

passenger side: . . driver side:

6 3 . . . . . . . . . . . . 7 2

1 5 . . . . . . . . . . . . 4 8

The wiring diagram looks exactly the same as the one in this link with the exception that the NUMBERING of the wires at the coils is reversed in the following way: 1 and 6 are reversed and 8 and 2 are reversed.
http://mark8.org/users/driller/pics/plugwires.jpg

HOWEVER the actual routing of the wires is IDENTICAL to the picture in the above link.

I believe there was a change made in '96 to the positions of the wires at the coils, which was noted in the numbering in the '96 shop manual, but they did not update the picture of the routing to reflect that.
 
sprocket said:
OK, here is how it is: On one page there is a drawing of the coil packs. The coil packs are numbered like this looking from the front of the car:

passenger side: . . driver side:

6 3 . . . . . . . . . . . . 7 2

1 5 . . . . . . . . . . . . 4 8

The wiring diagram looks exactly the same as the one in this link with the exception that the NUMBERING of the wires at the coils is reversed in the following way: 1 and 6 are reversed and 8 and 2 are reversed.
http://mark8.org/users/driller/pics/plugwires.jpg

HOWEVER the actual routing of the wires is IDENTICAL to the picture in the above link.

I believe there was a change made in '96 to the positions of the wires at the coils, which was noted in the numbering in the '96 shop manual, but they did not update the picture of the routing to reflect that.
Click to expand...

That link is identical to my 93 manual.
 
I changed the plugs today to Autolite 764's gapped at .048. I also pulled all the plug wires and routed them again from scratch. I really think I have an extra 36" wire that should be 32", but I made it work and look neat. BUT...

I still had a cylinder 3 misfire bad enough to flash the CEL. So I put in a different coil. It still had the misfire. I pulled the wire off the plug and attached an old plug to it. It sparked fine. Just for grins I switched the plug wire to a Motorcraft junkyard wire. It still had the misfire, but I started to notice something. After clearing the code it was taking longer and longer to trip it again. I started to think it was a sticky tappet, bad gas, a bad fuel filter or some combination of those things. My friend said I probably need to just get it out on the highway and hammer on it a little, because it has sat in very cold weather and mostly has just been idled and the outside temp has been all over the place, from 40 above to 10 below zero.

It appears that he was right. Once I actually took it for a drive and got in on the highway the misfire never came back. I should say, it never misfired enough to trip a code. I still think it is occasionally missing a little. The fuel level was low so it now has new gas, but I think I will change the fuel filter next.

Anyway, I DID GET IT HOME to my house. I reset the economy and it says it got 27.5 mpg on the way home. The engine temp never went above 160. It currently has a thermostat with the center cut out. I will change that soon too.
 
Add some seafoam to the fresh tank of fuel, but not the next, and then add to the one after an untreated tank has gone thru... then report back :)

And yeah, cheap and easy...change the filter
 
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