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So yesterday, I woke up super early for my root canal appointment, when I go to start my car and my engine is bouncing around like nobody's business. I make it to the appointment, and then B-Line it to an Autozone.

They run my codes and I get like P0305 or something like that, which is a basic misfire in cylinder 5. They tell me I need a tune up. Although they're probably right, the only thing I haven't changed in a while would be my plugs.

I left and went to work, and on the way there, my car smelled like it was burning something. Straight nasty smell. At lunch I went to Oreilly Auto for a 2nd scan. Same #5 misfire, told me to check plugs and coil. I know it's possible, but it seems weird that cylinder #5 would completely die. Like it didn't worsen over time. It feels like it's completely dead.

So I popped my hood, and this is what I found, same side as cylinder 5 (see pics below).

Also on my engine cover, there's a new red stain. So I guess the rodent crawled on top of my engine, and our VERY IMPRESSIVE engine/transmission heat baked him to death.

It shredded some firewall insulation, and scrached some wires (but doesn't APPEAR to be chewed through)



TL;DR:
So with the rat's nest and code p0305, I'm thinking it chewed a wire.
1. Does anyone have a diagram of the coil wire layout? Or can you tell me which direction the wires run around the engine?
2. If the wire is chewed, can I simply just splice in another wire?
3. How can I test the pins that plug into the coil to see if the coil is getting a signal?


THANKS!

 

And I ask which direction the wire runs, b/c it's T's off as soon as the coil wires join the thick bundle of wires. One goes towards the front of the engine, the other goes towards the back.

I'm afraid to move the cover... afraid there might be more destruction under there.

 

Pop the cover off and look. Cyl #5 is on passenger side, near firewall, so right in that area where the squirrel nest is. It's possible it yanked a connector loose when it scrambled to leave. I had a squirrel try the same thing when I parked under a large tree for a week, chewed a hole in my under panel and everything. Little bastard.

As far as how the harness is routed, it comes from passenger side firewall - behind the engine, then comes up and around the front of the engine.

 

Thank you SO much! I'll try to inspect the wires as they go back behind the engine and stuff.
My underpanel is off. Stupid, I know. But I was working on a tensioner issue (weeks ago) and didn't put it back on.

I tried pushing the connector back in but it didn't seem to help.

How do coils work? Do they just send the voltage when the ECU tells each one to? Or do they hold a constant source of power? I'm not sure how to test the pins to see if anything is failing to send a spark.

 

If unplug and looking at the end of the connector (terminal side) it goes:
[12V]-[GND]-[SIG]

Should have 12V with ignition on. Ground is ground. Signal comes from ecu to fire. You'll need to look at an FSM for the wiring diagram/pin out if you want to test wires back to ECU, etc.

Unplug it, then push it back on, should clip into place. If won't clip, look for damage. Look for any wire damage in that area. A disconnected injector could also cause a misfire, but given the coil-packs are right were that critter tried to make a nest, ignition seems the most plausible at this point.

 

Okay, during lunch I played with the plug. Took off the engine cover, etc.

There's a little oil leaking on the bottom side of the valve covers, not really much though. I didn't pull the coil, but I plan to after work in the parking garage (so car is cool).

The plug itself appears undamaged. Wiring looks good. The scratched wiring tape/sheath is AFTER the Cyl 5 coil wires split off. So it shouldn't effect that.

I kind of wonder if the rat's nest is just a perfectly timed coincidence lol.

 

Okay, so I swapped the plug, swapped coil cyl 5 with the coil at cyl 1, etc. Cyl 5 still has a misfire.

I'm going to dig up my multimeter and try to test the coil connector pins.
Then I'm going to try and listen to the injectors (with a screw driver or something).

How can I tell if the injector is clogged?
My exhaust doesn't smell rich. It doesn't smell like fuel or anything.

To see if the spark plug actually has a spark, can I pull the coil, plug it up to an extra spark plug, and look for a spark?

 

Wait, so you do have damage to your harness? Any wires cut? Fix that first.

 

Damn this sucks. I was hoping to see a pic of the fried critter but alas, there is none. GL with your fix.

 

I don't see any cut wires yet.
I can't really see much of the harness behind the engine yet. I'm going to get a multimeter and listen to injectors and stuff today.

Gunna need all the luck I can get!

 

So.. My injectors are under the plenum. Impossible to test w/ the engine on. If I take the plenum off, engine basically won't run, can't test injectors for noise.

I don't want to take it to a mechanic, but I might have to...
This sucks so bad.

 

Take off the plenum and inspect all the wiring, and re-splice any wires that are damaged to the same color wires. if you dont have any damaged wires then you may have a more serious issue. Take the injector plug off and apply 12v to the pins on the injector and listen for the click like that. you could also buy a set of injector lights and hook them on to the connector to test it that way

 

Found it.

I can't figure out what that blue/white wire is, unless a #5 injector changes from grey to blue/white.
I've been following this manual. It's down in EC-678 area.
http://www.nicoclub.com/manuals/G35/...5_Sedan/ec.pdf

Basically says that...
5 is G (Grey or green?)
3 is R/Y (red/yellow?)
1 is R/B (red/blue)
6 is P (Purple?? what else does P stand for)
4 is R/L (Red and ??? Light Blue?).
2 is R/W (red / white?)

I don't know, I'm probably wrong at reading that.
Anyway, that blue wire looks like it has a white stripe, it's definitely cut in 2.
I can't see the grey wire.

I'm so mad. I'm going to poison the entire tree line by my car.

 

Never mind, I think L/W is Light Blue/White right?
Check this diagram below. Inj#5 goes from...
ECU > G colored wire > plug F33 connects to F221 > L/W colored wire > Injector.

It actually flows in the opposite direction b/c it's ground, but you get the picture.
Does L= Light blue?

 

Im not sure on the letter and color things but I would say you need to open up that wiring harness loom and take a more detailed look at all the wires.
As a mechanic I dont consult wiring diagrams like that unless i have 2 or more wires with the same colors. Unwrap that whole section of harness and find the other end of the chewed wires, match the colored wires together and thats all it takes, no need to look at all the wiring diagrams and testing things with a DMM. I deal with rats in car wiring quite often and have had to fix more than one Fisker Karma with chewed up wiring.