2011 LR4 Misfire/rough idle

[djkaosone]

I agree with @scott schmerge, you need to run live values on fuel pressure to make sure it's somewhere close to the desired fuel pressure. Use the IID Tool and get the live values for Fuel Rail Pressure and Fuel Rail Pressure - Desired. At cold start and idle, pressure is typically under 1000 psi and desired 0 psi and warmed up in the low hundreds (200-300 psi). Under load it could range anywhere between 1400-2200 psi and desired is 1450 psi. If it's too low, then check your fuel delivery.

There's other things that can cause shuttering issues, like injectors (spray pattern, clogged, stuck open, voltage, etc...), maf (dirty, out-of-range resistance ohms, etc...), fuel (91 octane and above on petrol models, bad gas, fuel filter, etc...), spark (new denso or ngk iridium spark plugs, coils, etc... test by taking coil and spark plug out of the cylinder, ground the spark plug with plug facing upwards, and start the truck. Should see sparks), and compression (check each cylinder for proper compression (has to be over 150 psi, 170-190 is great, and 190+ is fantastic). That should cover the basic air, fuel, and spark.

 

[Kevintjones]

Ok. Thank you so much for all of the help. I don't have a lot of history on the vehicle, but I haven't had any issues with it overheating. I will start to work on the suggested ideas and see where it takes me. I'm really suspecting a possible fuel delivery issue.

 

[scott schmerge]

Ok. Thank you so much for all of the help. I don't have a lot of history on the vehicle, but I haven't had any issues with it overheating. I will start to work on the suggested ideas and see where it takes me. I'm really suspecting a possible fuel delivery issue.

If you don’t have a Gap IID tool, highly recommend getting one before blindly throwing parts at it.

edit: I take that back...didn’t mean blindly...but it’s acting on a hunch rather than data. The parts on these aren’t always cheap and it’s best to know before putting parts in it on a hope.

 

[L Crist]

Howdy! I've been following this thread closely and finally signed up to post because I am now 4k bucks in and still no solution!!

Over the past year, my 2011 LR4 (93k miles) misfires like crazy when i drive it right after a cold startup. Once it's warm, it runs beautifully. My LR guy tried a number of different things like reprogramming, running seafoam, and finally swapping out all the injectors, coils and spark plugs. Prior to the inj swap out, it used to rough idle on startup, but no gas smell out the tail pipe.

I always use 91 fuel which is as high as it goes in California. PLEASE HELP!!! I just want my damn truck to work proper.

 

[scott schmerge]

Howdy! I've been following this thread closely and finally signed up to post because I am now 4k bucks in and still no solution!!

Over the past year, my 2011 LR4 (93k miles) misfires like crazy when i drive it right after a cold startup. Once it's warm, it runs beautifully. My LR guy tried a number of different things like reprogramming, running seafoam, and finally swapping out all the injectors, coils and spark plugs. Prior to the inj swap out, it used to rough idle on startup, but no gas smell out the tail pipe.

I always use 91 fuel which is as high as it goes in California. PLEASE HELP!!! I just want my damn truck to work proper.

Codes?

Have you had timing checked? It’s possible your guides are just worn enough to cause a misfire on startup and for it to be slightly out of time. At 93k miles, it is possible that you are at that point.

Sounds like all the other most likely things that would cause ignition issue have been addressed, so that might be where I’d start.

 

[Cthehentz]

Doesn't oil pressure affect the tensioner? Like if the ratcheting has failed but oil pressure is high enough to take up the slack when the engine is warmed up? Or am I totally wrong lol...

 

[scott schmerge]

Doesn't oil pressure affect the tensioner? Like if the ratcheting has failed but oil pressure is high enough to take up the slack when the engine is warmed up? Or am I totally wrong lol...

Oil pressure does affect the tensioner, yes. Not exactly sure why temp would eliminate the misfire though.

It could be as simple as a loose wire connection that as soon as things expand, eliminates the misfire. Did you bring it back to the mechanic who did your ignition system? Sounds like it’s worse after he touched it. Codes would be helpful.

 

[L Crist]

The only codes were multiple misfires on both sides. P0304, P0307, P0305 etc. This is from BEFORE the inj, coil, plug replacements. He ran it so many times (even while driving), to list each code for each time would be a novel's worth. Since I got it back and tried to run it cold, I have not been able to take it in to read the codes. I will report back as soon as i do!!

The main thing that got BETTER post inj swap is that it idles smooth on start up so i can at least get it warmed up in my driveway. So technically it's not worse now. But the mystery remains as to why it misfires when it's cold, which started a year ago. I will ask about the timing. I brought it up months ago and he brushed it off.

 

[scott schmerge]

The only codes were multiple misfires on both sides. P0304, P0307, P0305 etc. This is from BEFORE the inj, coil, plug replacements. He ran it so many times (even while driving), to list each code for each time would be a novel's worth. Since I got it back and tried to run it cold, I have not been able to take it in to read the codes. I will report back as soon as i do!!

The main thing that got BETTER post inj swap is that it idles smooth on start up so i can at least get it warmed up in my driveway. So technically it's not worse now. But the mystery remains as to why it misfires when it's cold, which started a year ago. I will ask about the timing. I brought it up months ago and he brushed it off.

running smoothly as in you can’t feel the misfires and codes pop? Or you can feel misfire until it heats up and then runs smooth? Is it throwing codes when it is hot (if you clear codes do they come right back)?

running down some ideas for you. These are possible but less likely.

PCV valves? Have you smoke tested? Brake cleaner at the pcv valve will also cause the engine to stutter if they’ve failed. Also a vacuum leak on the valve cover if big enough could possibly cause a misfire (but both are more likely to cause a too lean/rich code). As the engine heats, things expand, making the misfire less noticeable.

It could also possibly be a fuel delivery issue. Have you had your hpfp checked? Also low pressure pump at tank. I’m not guessing a failing pump would survive an entire year though.

If it’s running smoothly, would indicate the injectors are firing correctly.

Timing could still be an issue, just spit balling other causes. To check chain tension you can take a screwdriver and stick it in the oil cap where the top of the chain is. You can feel if the chain has play in it. I’m assuming your truck does not have typical timing failure rattle (sounds like a Diesel engine)? I’ve heard of timing tensioners failing without the rattle, but far less typical.

 

[djkaosone]

It doesn't sound like you have an IID Tool. Maybe you should get one to read the codes on your own. It's a big initial investment ($500), but it'll save you time and money from driving it around and allowing you to diagnose it yourself.

If you have one, I'd clear the learned adaptation values. You made a lot of changes where you want to force reset the adaptation values back to factory and allow it to dynamically adjust to your driving style.

This truck is VERY sensitive to vacuum leaks. Leaks will cause it to do weird things, like engine noise, loss of power, random misfires. With the engine running just spray soapy water all around the PCV, valve covers, hoses, and hose connectors on both sides to find any leaks.