'07 - Rattle/knock, P3191, simply stumped

2007, 270k miles (more, odometer was dead for a couple years), strict maintenance intervals (plugs, coils, fluids, etc). More on that to follow.

A few days ago my wife drives to work and back home. She reports having no issues with the car. I go to use the car - rattle rattle rattle. Starts out sounding like either a light knock or noisy fuel injectors then starts rattling like it wants to fly out of the bay. It's too violent for me to deem it a knock so rattle it is.

So after I throw a temper tantrum and verbally abuse the vehicle, I start pulling coil connectors, hoping to find an obvious misfire. I start messing with the throttle body and MAF. Nothing. Eventually, after starting it up several times, it throws P3191, red triangle, and shuts off. After that, it turns on, runs smooth for about 10 seconds, then it goes at it again, then dies.

I also had P0102 (Mass or Volume Air Flow Circuit Low Input), P0113 (Intake Air Temperature Circuit Low Input), and P1116 (Coolant Temperature Sensor Circuit Stuck For Coolant Heat Storage System). However, these codes have been here for several months and the car has still been running beautifully outside of noisy injectors and just being old.

Here's one of my hangups though: NO misfire codes. I have gotten them twice and it is ONLY when I pulled the connectors on the coils while running. But they have not nor have they ever shown up by themselves

After some web surfing I start by pulling the throttle body and intake manifold. Clean them thoroughly, and I do mean thoroughly, inside of the manifold is a mirror. Only problem is the cylinder head is REMARKABLY caked with carbon. The valves are clear and shiny, but the surrounding area is pretty bad. I was not about to pull the head for this yet so I left it and put the cleaned parts back on.

After this I replaced spark plugs (NGK) coils (I did use Oreilly's sadly, I've got Densos on order) and fuel injectors (Beck/Arnley). I don't usually fire the parts cannon, but we all make mistakes in the heat of passion, jimbo.

Now, reportedly the wife had replaced her own spark plugs at some point while I was out of town for work. This is about a year ago. Car's running fine and she doesn't put many miles on it, so I think nothing of it. Dawg. These things were fingertight. FINGERTIGHT. Not only that, they were BURNT. CRISPY. TOAST. FRIED. SAUTEED.

So not only do I think, at this point, that she never did them (even if she meant to), but I think either my father in law did them a while ago, or one, or both of them are not at all accurate about the reported maintenance schedule preceding the marriage two years ago. She very well could have been driving with fingertight spark plugs for three or four years, depending on who's telling the truth, idk.

So yeah that one's on me, I shouldn't have taken anyone's word for it. Regardless, I changed them, changed injectors, changed the MAF. Before doing ANYTHING ELSE I pulled the oil pan.

My next hangup: Absolutely no metal in the oil. No piston skirt, no shavings, no chips, no specks, flecks or glimmer. Just some fairly recent, clean dark oil.

I put the oil pan back with a new gasket, 24 hr cure, refill with 3.7 quarts exactly (I measured), let sit for 20 min ish, start the car.

Still bangin baby.

BUT NOW FEATURING: P0301, CYLINDER 1 MISFIRE! *fanfare*

I got P3190 and ignition coil primary circuit codes after I messed with those connectors again. But I reset everything, kept trying, and we're back to P3191 and a death rattle.

ALSO FEATURING: A freeze frame with a 99.6% ST fuel trim under the conditions of the misfire code (turn on, run, stall.) Unsure if that's important. I suspected perhaps if the fuel pump is faulty or dead, the engine is not getting enough fuel so it's just like "GIVE ME ALL OF THE FUEL" but I'm not sure if the STFT is a "real" reading of fuel or a "requested" amount of fuel. Not smart enough for that one.

Open to any tips or wisdom.

My next course of action is to figure out how I'm going to do compression and fuel pressure tests.

My suspicions:

- Fuel pump. I'm aware it's part of the tank and this thing has some miles behind it. never been replaced.
- Head gasket. No coolant loss or typical signs of gasket failure but I haven't ruled it out yet. Compression test will tell me yes or no.
- I'm aware there are several interacting mechanical components between the hybrid and ICE engines - namely the two 'starter' motors and the spring dampener type thing. Only reason this is on my mind is because this almost sounds like something came loose and it making a racket - like a dual mass flywheel.
- EGR; it is my understanding that 2nd gens do not have a serviceable/cleanable EGR so I don't even know what I'd do about it.

My final suspicion, and probably the most likely: She's old, she's tired, and she's run her faithful course.

 

Contender for the head gasket issue, pending comp test:



Cylinder 2 (oily) vs Cylinder 3 (1 and 4 are clean as well). Brand new plugs. Unsure if this is just oil in the spark plug chamber i.e. busted o-ring, or oil IN the cylinder

 

Kinda what I was thinking, it's pretty milky. Oil in the pan looks good though, when I drained it it was normal and the new oil looks good too. So that may be just related to the spark plug well. But I'm unsure if that's related to the engine issue