2011 LR4 Misfire/rough idle

[Pfunk951]

I has this issue, and threw the misfire codes.. It turned out to be my injectors; the dealership replaced all of them.. I think that the computer just reports the banks, not the individual injector failures, so they usually replace all instead of bench testing all of them..

My warranty company actually sent an inspector to the dealership to verify this, and the dealer showed them that bench testing would cost more in labor than a new set would cost, so the guy conceded..

Mike

 

[TheDave]

@Pfunk951 Did you only throw codes on one entire bank? I’m going to replace the oxygen sensor tomorrow morning (suggested at 100k miles, so needs to be done anyway I suppose) and see if that helps. It just seems strange that all 4 injectors on one bank went bad at the same time, but I can’t say I know much about these specific motors.

 

[Pfunk951]

AFAIK the codes read only "right bank" or "left bank" so you can only narrow down failures to the respective side. It would be nice to have them say "cylinder 6" but I think it correlates data from the O2 sensors, which are only left and right. I had codes on both sides- the dealership said that means I had at least 1 injector on each side failing. Finding out which one takes bench testing of the individual injectors, and the dealership's stance was screw that nonsense and replace 'em all..

Let us know if the O2s make a difference..!

Mike

 

[djkaosone]

Anyone have any experience changing out the oxygen sensor? It’s not so much the sensor that’s hard to get to as much as it is the plug behind the heat shield. It’s the driver side sensor.

Its a PITA, but you can access it easier by removing the plastic covers between the wheel and motor. It'll give you access from the side while under the rig. You don't have to remove the wheel to do this, but you can and access it from the side as well.

 

[TheDave]

Changed the o2 sensors and no fix. I ended up ordering new injectors and currently working on those. I got everything broke down to the fuel rail attached to the injectors. Does anyone have any advice for separating the two? The retainer rings, to me, look to keep the fuel rail from being pressed on too far. Is that correct? Or do they need to be removed to separate the rail and injectors?

Edit: I’ve also been taking a lot of pictures throughout this process. Hoping to help contribute to anyone that runs into this in the future with a simple write up.

Edit 2: ended up calling Gareth at the parts store and he advised me to break the clips on the injectors. Hah, it ended up working, but sucks that's what I had to resort to.

 

[Azoo]

Have you tested the fuel pressure ? if you're having multiple/random misfires , fuel delivery might be you issue. I believe the fuel pressure should be btw 55 to 65 psi. O2 sensors just monitor the fuel ratio and will not cause a misfire. Several injectors cannot go bad at the same time so i wouldn't even check the injectors since the codes say multiple misfire. My best guess is your fuel pump or fuel filter.

 

[TheDave]

Have you tested the fuel pressure ? if you're having multiple/random misfires , fuel delivery might be you issue. I believe the fuel pressure should be btw 55 to 65 psi. O2 sensors just monitor the fuel ratio and will not cause a misfire. Several injectors cannot go bad at the same time so i wouldn't even check the injectors since the codes say multiple misfire. My best guess is your fuel pump or fuel filter.

@Azoo I would have thought the same thing in regards to the injectors. As a side note, I wasn’t sold on the o2 sensors causing the issue, but found that they needed to be swapped anyway due to mileage. I felt it best to spend money on regular maintenance items that needed replacement before throwing money at injectors just on the off chance it helped.

I just finished the injector install and the truck runs perfectly fine now. It’s been a long, arduous task trying to sort this out, but glad it’s back to working. There was a lot of ups and downs that I plan on detailing in a write-up. One thing I’ll recommend getting is a cheap code reader. That made a big difference when looking into sensors, vacuum, etc.

 

[jpjp]

@TheDave So I too have the same symptoms as you did, unfortunately it was up in Asheville NC driving from Raleigh to Pisgah National Forest. Currently waiting for a flat bed to arrive in the next 30 min down here in Miami Mechanic up there called Autologic, the company that supplies the computers to read the codes, and they recommended changing all 8 injectors. Obviously only 1 is bad and the driver's side bank is showing misfires. I'm thinking while the mechanic down here is in there they should just do all 8. How hard was the work, 3-4 days of a few hours labor or?

Did you change the fuel filter as well while you were in there?
We only use premium and I ran a can of BG44 before I changed the oil about 5,000 miles ago. I have an '11 with 104K miles.

 

[Pfunk951]

Hmm.. I might be spotting a trend here.. Here's a hypothesis: Could infrequent intake cleaning cause this? I know that the injectors aren't having intake debris forced through them, but a) cleaning the intake and b) injectors going bad seem to be happening in tandem for some of us.

When I bought my truck, I had no history of any intake cleaning.. I had a shop do the BG intake cleaner at 45k on the odometer, and threw left and right bank codes 2 days later. I took it to the dealership, they cleared the codes and re-performed the BG cleaning, and it ran fine for a week and threw the codes again. The result was 8 new injectors.

Some folks like Umberto stay on top of an intake cleaning schedule, I think he does his every 15k or so.. My question is what happens when one of us buys a truck with 70k and runs the BG intake cleaning for the first time?

I have seen pics of the inside of the intake/ top of the valves on some LR4s, and it looked pretty nasty- is releasing all this into the combustion chamber clogging our injectors?

Just a thought..

Mike

 

[scott schmerge]

Hmm.. I might be spotting a trend here.. Here's a hypothesis: Could infrequent intake cleaning cause this? I know that the injectors aren't having intake debris forced through them, but a) cleaning the intake and b) injectors going bad seem to be happening in tandem for some of us.

When I bought my truck, I had no history of any intake cleaning.. I had a shop do the BG intake cleaner at 45k on the odometer, and threw left and right bank codes 2 days later. I took it to the dealership, they cleared the codes and re-performed the BG cleaning, and it ran fine for a week and threw the codes again. The result was 8 new injectors.

Some folks like Umberto stay on top of an intake cleaning schedule, I think he does his every 15k or so.. My question is what happens when one of us buys a truck with 70k and runs the BG intake cleaning for the first time?

I have seen pics of the inside of the intake/ top of the valves on some LR4s, and it looked pretty nasty- is releasing all this into the combustion chamber clogging our injectors?

Just a thought..

Mike

I got mine with 115k on the clock. My intakes are very nasty. Not sure all that crud would be good to go through the engine, so leaving it alone for now. I did turn my manifold on it’s end the last time I had it off, and it was crazy the amount of oil that drained.

I’ve considered a walnut blasting of intakes but have not done enough homework to weigh the pros/cons.