Emission leak turned into engine missfire?

[Huntsman06]

I have an 04 that had the CEL come on about 3 weeks ago. Code pulled, emission leak. My fuel cap light has been coming and going so I figured it had something to do with that. New gas cap and the emission leak code is gone. Now the CEL is on again and it's saying a missfire on cylinder 8. I bought spark plugs and also swapped around the coils to see if the issue would move. No dice. The CEL now is on and blinking almost always when driving (did stop after a while and came back within 100 yards down the road). My next plan of action is to look into injectors and maybe wires too(gonna talk to my father and see what he thinks later today). Suggestions? Are the V8s prone to any specific issues I should be aware of as well?

 

[lincolnshibuya]

when you swap the coils did the misfire move to a different cylinder? don't drive the car for too long when it's misfiring, you're going to end up destroying the catalytic converter and will cost you more.

I replaced all coils when they started to have a misfire.

 

[Huntsman06]

when you swap the coils did the misfire move to a different cylinder? don't drive the car for too long when it's misfiring, you're going to end up destroying the catalytic converter and will cost you more.

I replaced all coils when they started to have a misfire.

I did move the coil from cylinder 7 to cylinder 8 and the issue stayed with cylinder 8. Odd fact, but I went and pulled ou the coil again and returned them the original positions and noticed this.

I'm sure how easily you can tell, but there was certainly liquid on it. It wasn't drenched but it was certainly wet. The car was pretty warm (drove it maybe an hour home from work before taking it out) and it has been raining today and a bit yesterday, but I don't believe water should ever be getting down to the spark plug (assuming its water, didn't taste it but it didn't smell like anything). Do these things usually condensate water? On another note, I cleared the CEL and drove it around the block. Drove very nice, idled good, and no light (maybe a mile driven tops).

 

[lincolnshibuya]

put a lot of dielectric grease on top of the boot and observe. yes water can go into that area since it's near the windshield cowl.

 

[mountaineer2004]

I had number 8 coil go bad, after a rain, because water leaks from the cowl clips, and drips into #4 and #8 coils. Stupid design that I solved with silicone. Another shame on Ford design.

 

[Joe in NY]

the 2002 & 2003 V8 engines have a big plastic cowling with a thick acoustic mat on the underside that actually covers the entire top end of the motor. So 02-03 doesn't have this water issue...

 

[Huntsman06]

the 2002 & 2003 V8 engines have a big plastic cowling with a thick acoustic mat on the underside that actually covers the entire top end of the motor. So 02-03 doesn't have this water issue...

One of these? (not my truck, compliments of google)

Ya know the funny thing is I never knew such a thing existed until about a week ago and was actually curious if the 04 model ever had such a covering available before these issues began. It's running fine now that there is no water getting down into the spark plug and I am going to look into getting it sealed against water better soon, but soon as mid May comes it'll be dry summer until we start getting snow in the winter so, if water stays out, we should be in good shape. I'll check back here if the issues comes back. I am a bit surprised it went all winter with no issues and now a mediocre April shower did it in.

 

[Joe in NY]

Yup that. The engine is actually a good bit quieter with it on when you are standing in front of the car.

 

[Huntsman06]

Yup that. The engine is actually a good bit quieter with it on when you are standing in front of the car.

Oh I assure you my 19 year old brain much prefers the noise

 

[Joe in NY]

lol, well the only noise is the injector ticking and some valve-train noise. I much prefer the exhaust and intake noise for my 21 y/o brain lol. This summer I'll be chopping off this pathetically quiet muffler and going with this awesome beast:

https://www.amazon.com/gp/product/B000VS2AP4/ref=ox_sc_sfl_title_31?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

Should make it have the low deep bass of a proper American V8

 

[mountaineer2004]

My '04, bought new, never had that shield.
So maybe the original design was good, and Ford bean counters ruined it by de-contenting the functional shield !
Saved them money, cost me money :-(

 

[Huntsman06]

I'm not particularly familiar with how the shield attaches, could it perhaps be added to an 04 or did they change too much between model years? Not that finding one would ever be likely--let alone cheap, but it's one of those weird things that may be worth keeping an eye out just in case.

 

[Joe in NY]

4 studs, two on top of the alternator and the other two on top of the throttle body. I bet you could find them from a used auto parts mall or pick n pull yard.

 

[mountaineer2004]

^ Yeah, the attachments are still there, they just removed the shield.