LR4 Rough idle

[MrRodgers]

I have 2016 LR4 V6 & issue with rough idle. I’ve replaced the fuel pressure sensor and no difference.

Research tells me possible fixes are
- injectors and spark plugs
- Fuel pump
- high pressure fuel regulators x2

Which one should I change first to fix this? Or am I missing something

Code are:
P008A-07
Low pressure fuel system - Pressure is too low

P0089-64
Fuel pressure regulator performance

P2189-00
System too lean at idle Bank 2

P2187-00
System too lean at idle Bank 1


Appreciate the help!

 

[jlglr4]

Seems you have a code scanner, so I would check short and long fuel trims and fuel rail pressure (actual and desired) first. Check at idle and at maybe 1500 rpms and 2500 rpms, just holding the throttle steadyin park. Presumably you will see high positive fuel trims. If your rail pressure is normal, the low pressure fuel problem might not be causing the lean condition. In this case, check for a vacuum leak - typically fuel trims will trend towards zero with increasing rpms.

If it looks like a vacuum leak, check the PCV diaphragm. Far easier and cheaper than injectors.

If your fuel rail pressure is low, especially at higher rpms (you can check under load too), then you’ve got a fuel delivery issue and likely the low pressure fuel pump or low pressure sensor since you have codes there.

I bring this up because the low pressure fuel system in these LR4s seems prone to throwing intermittent codes without creating lean conditions. Lean conditions in this car most often seem to be caused by vacuum leaks, specifically the PCV diaphragm. So you might have two unrelated issues.