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.
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.
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)
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.
Last edited: