Cylinder 5 Misfire

[gillygong]

Hey all, hoping I can lean on the collective wisdom here to help me figure out a misfire on my 2013 LR4. 147k miles. Apologies in advance for the novel of a post, just wanna get all the evidence in one place

Here's the history up till today..
Last December, got a P0305 and P0316 code together.

Swapped spark plug and ignition coil between cylinders 1 and 5. Misfire stayed on cylinder 5. Tried two bottles of Redline fluid. No change.

Had a mechanic look at it, told me compression looked good, and recommended replacing fuel injectors on Bank 1 (cyl 1,3,5,7). He did this. Misfire stayed on cylinder 5.

Took it back to him, said he found a faulty electrical connector on ignition coil 5 and connector was coming loose. Replaced ignition coil 5. Misfire remained.

Took to Land Rover because I felt I couldn't trust the other mechanic at this point ($2300 in and no solution). LR pulled codes and said there was a misfire on all cylinders. Told me possible head gasket failure. Left it overnight for them to do block test, compression test, and leak down test. Next morning called me and said it wasn't actually misfiring, it passed their test drive, and I could come pick it up- no charge. When they pulled the car around and I got in, engine light was on (lol). It was the same P0305 and P0316 again. Showed the LR service rep, and he said they wouldn't have time till next week to look at it, so I cleared the codes myself and left.

Rented a block tester kit to sniff coolant expansion reservoir for head gasket leak, and it passed. Had a friend revving the engine pretty high for 5 minutes, and fluid stayed as blue as could be. Codes didn't come back for a week. I then drove from LA to Lake Arrowhead to Vegas and back. Including a bunch of off-roading. No engine light the entire time. Vehicle drives great the whole 5 days, no stumbles or anything. Sometimes a slightly rough idle.

A week after return from Vegas, engine light returns. I pull codes and see the following. Only confirmed one is P0305 and P0316. The rest were pending.

• P0301-00 (01) Cylinder 1 misfire detected
• P0302-00 (01) Cylinder 2 misfire detected
• P0303-00 (01) Cylinder 3 misfire detected
• P0304-00 (01) Cylinder 4 misfire detected
• P0305-00 (AF) Cylinder 5 misfire detected
• P0306-00 (01) Cylinder 6 misfire detected
• P0307-00 (01) Cylinder 7 misfire detected
• P0308-00 (01) Cylinder 8 misfire detected
• P0300-00 (01) Random misfire detected
• P0313-00 (01) Misfire detected with low fuel
• P0316-00 (AF) Misfire detected on start-up (first 1000 revolutions)

I decide to do compression test myself.. Results on the right are all dry test. On the left are three attempts at wet test for cylinder 5.

Am I looking at possible piston ring leak on cylinder 5? (wet test markedly improved vs dry..) I had started thinking it was electrical because it's been so intermittent- for sometimes weeks-long periods since December, no codes. When I look at live misfire count, sometimes cylinder 5 is just racking them up constantly, and other times it has showed no misfires at all.

If it were piston ring, or valves, would it be that inconsistent? When the phantom misfire on ALL cylinders happened those two times, I thought maybe ECM grounding issue or something. Now, compression test looks like definitely something up with Cylinder 5.

I suppose my next test will be a leak down test on cylinder 5, does that sound right? Any and all advice appreciated, thank you.

 

[powershift]

That is a problem. It could be leaking through the valve(s). If not I'd pull the head and check the head gasket, cylinder bores, etc.

 

[scapistron]

When the injectors were replaced, are you sure they did the correct bank? On my v6 the dealer said they replaced coils and plugs on 4, 5, and 6. Upon further inspection they replaced 1, 2, and 3. I could tell because they wrote the date on the coils.

 

[gillygong]

Yeah I believe he did the correct bank. It’s a very popular Land Rover indie. Also when he replaced the ignition coil afterwards it was the correct one on passenger side.

 

[greiswig]

That is a problem. It could be leaking through the valve(s). If not I'd pull the head and check the head gasket, cylinder bores, etc.

Curious what you mean by "check the head gasket" here? I've never pulled a cylinder head but what it destroys the head gasket to the point where you're lucky if you can detect forensics that point to a head gasket as the failure point.

To the OP, I'm guessing here so take it with a shaker of salt, but...the wet test, to me, points to more likely the rings sticking or having worn prematurely in that cylinder. I would (again) guess that an inconsistent pattern* points more to sticking, either in the rings or in the valves. And as the valves are likely less affected by oil in the cylinder for a wet test, my primary suspect would be the rings. If they are just sticking, it might be that a good round of some Seafoam in that cylinder, and the rest of it in a low tank, might clean things up enough to unstick things.

*i.e. if the rings were just flat worn to the point of poor compression, it would be a pretty consistent thing to get low compression leading to consistent misfires.

 

[gillygong]

Curious what you mean by "check the head gasket" here? I've never pulled a cylinder head but what it destroys the head gasket to the point where you're lucky if you can detect forensics that point to a head gasket as the failure point.

To the OP, I'm guessing here so take it with a shaker of salt, but...the wet test, to me, points to more likely the rings sticking or having worn prematurely in that cylinder. I would (again) guess that an inconsistent pattern* points more to sticking, either in the rings or in the valves. And as the valves are likely less affected by oil in the cylinder for a wet test, my primary suspect would be the rings. If they are just sticking, it might be that a good round of some Seafoam in that cylinder, and the rest of it in a low tank, might clean things up enough to unstick things.

*i.e. if the rings were just flat worn to the point of poor compression, it would be a pretty consistent thing to get low compression leading to consistent misfires.

This makes sense to me regarding the inconsistency.

Are you saying add some seafoam through the spark plug hole? Which Seafoam product in particular would you recommend using? They have a few.

Thanks very much for your reply

 

[powershift]

Curious what you mean by "check the head gasket" here? I've never pulled a cylinder head but what it destroys the head gasket to the point where you're lucky if you can detect forensics that point to a head gasket as the failure point.

To the OP, I'm guessing here so take it with a shaker of salt, but...the wet test, to me, points to more likely the rings sticking or having worn prematurely in that cylinder. I would (again) guess that an inconsistent pattern* points more to sticking, either in the rings or in the valves. And as the valves are likely less affected by oil in the cylinder for a wet test, my primary suspect would be the rings. If they are just sticking, it might be that a good round of some Seafoam in that cylinder, and the rest of it in a low tank, might clean things up enough to unstick things.

*i.e. if the rings were just flat worn to the point of poor compression, it would be a pretty consistent thing to get low compression leading to consistent misfires.

It could have been overheated and that would break the head gasket. With that low compression I'd want to get to the bottom of it and pulling the head to check for evidence and checking the valve seats is probably the next step or replace the entire engine and be done but I'd at least root cause it if the labor is free.

 

[gillygong]

Welp, I just did a leakdown test! I can hear air hissing in oil filler cap. Nothing from exhaust, and no bubbles in coolant reservoir. To listen for intake valve, would that be thru the throttle body or somewhere else? Was hearing hissing generally from the pass side of the engine (not from the tester gauge). Couldn't pinpoint, but might that be valve cover breather?

This was on a cold engine with all plugs out bc I didn't feel like putting all the plugs back in to warm it up first. Is it worth doing that and re-testing?

I used a borescope to be sure of TDC with valves closed. Grabbed some video if anyone cares to see and comment.. One valve looks a bit more colored than the other three. Seems like a lot of gunk around the top of cylinder too. I did a wet compression test which is probably why there's some excess oil sitting around on top of the piston.

Not holding my breath but hoping Seafoam as suggested above may help (??!). What else can I do?

 

[greiswig]

To @powershift ‘s point, are you aware of whether or not the engine has been overheated substantially?

For the Seafoam experiment, yes, just the regular Seafoam spray ought to work. Spray into the cylinder, leave it for a bit, spray again…I’d do 3-4 treatments of it if you have time, letting it soak for 15 minutes between. It probably won’t be a magic fix, but it’s not invasive and it won’t hurt.

On your video, I thought I saw some kind of deep vertical scores on the cylinder wall? I’ve seen one ring break and the broken end cause scoring like that (in a Ford), but I think that’s very rare.

 

[powershift]

At 20-30 seconds in on the first vid, it looks like pitting on the cylinder walls along with coolant. There is some suspect surface area there. I would re-visit that pitted area to get better video keeping it still on that one area so you can inspect the cylinder wall. If its pitted then the rings wont seal over that surface. It needs to be smooth like everywhere else. A pressurized crankcase can be from blow-by on #5 from pitted cylinder walls. I would think there would be oil burning too. Is there any evidence of circular oil spots on the paint or plastic parts in the rear near the exhaust exits?