Expy missing on cylinder 3- cant figure this out

[mdfan]

Ive been chasing this ghost for a year.

04 Expy

Replaced plugs and coils about a year ago.
Started missing on cyl 3.
Ive been all over the internet reading about possible issues- coolant leaking into the plug, vac leak, etc. No evidence of either of them happening.
Ive replaced the new COPs with no improvement.
Last night I replaced the replacement Bosch plugs with Autolite with no improvement.
The #3 plug I removed last night was very fouled- looked like oil. Clearly its not been firing.
I pressure tested the system thinking I may have intake gasket issue- held 17 lbs pressure for hours with no leakage, so Im thinking thats not my issue.

Other possibilities:

The wire to the COP has a broken clip- it feel like its on the COP snugly, but Im going to salvage some good clips at the junkyard today and splice in a new one to see if that helps.

Maybe im not getting spark to the COP? Isnt that tested with a NOID light? I dont have one, will see if Autozone has a loaner.

When I was removing the COPs last night, a couple didnt feel like they were snug on the plug. I tried them on a plug, and some really dont seat well, or at all. So, Im not 100% confident they have a good seat- not sure how to solve that.


Thoughts? This is driving me crazy! Actually, its the wife's truck, so its driving me triple crazy.

 

[Bedrck47]

Report back after you make repairs to the wiring connectors

 

[Ed_Strong]

Why go thru all that trouble getting another connector splicing and rewiring for it to fail the same way?!?
just use nylon zipties to secure the connector(s) to the coils... do the same for the injectors connector(s) as they also fail in the same manner...!

 

[mdfan]

Update

Salvaged some wire clips at junk yard, and replaced the broken ones on my car, plugs 1 and 3 had broken clips. Didnt splice, you can unclip the broken ones and replace.

Replaced all the Bosch plugs with Autolite plugs. The Bosch had about 20k miles on them. One issue- plug 1 seems to be stripped. I cannot get the socket to catch on it at all. Ive blown it out with air, and put a camera in the hole. I have no idea how this could have happened- no air tools were used to install the plug. I dont suspect there is a mechanical issue with the plug, but this is concerning.

Attached is a photo of all the plugs. #3 was generating the misfire code, and was clearly not firing. fouled with oil/antifreeze and/or gas- something. I actually wiped off some of the gunk before the photo, but it was bad.

Plugs 6,7,and 8 on drivers side had a lot of fine dust I blew out of the holes before removing them. COP #6 looked terrible, so I replaced it. That plug also looks different from the others- not sure what this tells me. You can see it in the photo.

The plugs are laid out in order, with #1 missing since I cant remove it. They all look totally different- but all are the same age. Is this telling me I have a intake or head gasket leak? My pressure test didnt show any leakage, but can they be inconclusive?

Car still missing. No noticable improvement.

Thoughts?

 

[docraymund]

Yes, you need to check the cop connector to #3 cylinder with a noid light (there are vids on you tube on how to build that). If there is no pulse, check the wiring from the connector to the pcm for continuity. You need a repair manual for this.

 

[mdfan]

Damn truck is running worst today after all that work.

Now its throwing a p306 code on cylynder 6. Ive swapped out that coil pack with 3 different ones today, with no improvement.

I got these coils on Amazon, and Im wondering if I have some bad ones. They were inexpensive ones, about $50 for the set of 8.

Im thinking about ordering the $200 excel COPs in the hope that will fix my issue. Going to pick up a noid light at advance auto today as well.

Any other thoughts?

 

[stamp11127]

What do you expect for $50? If you buy cheap you get cheap. Best cops out there are the Motorcraft unless you really need a really hot spark.
Stripped plugs usually aren't an issue since they blow out of the head. If you mean it is rounded off that is another story.

 

[mdfan]

Installed MSD blaster coils this am, and I believe Ive solved the issue with the missing.

I still have plug 1 , which seems to be working fine, but the bolt head appears to be rounded off. Its a Bosch with maybe 20k miles on it. I replaced all the other Bosch with Motorcraft plugs, but this one I cant get a socket to grab, so Ill just leave it alone unless I have an issue, although I have no idea how it could be rounded off. I installed it with hand tools.

 

[BerndM]

Have you done an actual compression test?
The 17 pounds you mentioned isn't squat since the cylinders need to hold about 150 to 180 psi with the lowest one NO LOWER than 10% less than the highest reading. Your rings and valves may have no problem holding a measly 17 psi but may be crap at 150-180. That may explain why your #3 is fouling plugs if you have a leaking oil ring.

 

[mdfan]

The pressure test was on the cooling system, to see if there was a head or intake leak.

The car is running perfectly since the MSD coils were installed. Cheap coils were the issue.