Hello,

Vehicle info:
2008 LR3 - 4.4L
mileage - 88,600

DTC codes: P0172 & P0175 bank 1 and 2 running rich

Hoping for some help on a very tricky one to solve here. Been to both Indy LR mechanics in my hometown and they have not been able to solve the riddle. Fixed all vacuum leaks, tested multiple MAF's, replaced both upstream o2 sensors, replaced ECT sensor, cleaned throttle body, performed injector & fuel system cleaning, replaced o-rings, replaced thermostat and housing, replaced crankcase vent valve, and replaced air filter. Truck idles and runs very well and getting almost 16 MPGs. No loss of power. fuel pressure is steady at 68 psi. Once a while i will experience a hot hard start.... not all the time.

at idle ( warm engine )
LTFT ( bank 1 ) = -23.438
LTFT ( bank 2 ) = -23.438
STFT ( bank 1 ) = 7.812
STFT ( bank 2 ) = 3.125
MAF = 4.18 g/s

Thank you in advance !!

 

How long ago was the last work done in the shop? Your LT trim is negative, ST is positive. Looks to me like your problem may be fixed and the fuel trims are readjusting, this can take some drive cycles because it has to relearn (remap the fuel trims) at various engine RPMs and loads.

 

Unfortunately I don't believe that it is fixed as I have driven several hundred miles since the last shop visit do you think a RE-flash of ECM will help? My local LR dealer won't touch any vehicles older than 2012 🤷‍♂️

 

That’s not uncommon across any dealer network. At some point their techs aren’t familiar with the older vehicles.

Can you elaborate on the original issues you were having and how the various shops approached repair? You currently have rich codes but you also say they repaired vacuum leaks (these cause lean codes) among various other things. It will greatly help to know more.

 

I just recently acquired the truck back in August. I took it to my trusty LR mechanic For a thorough overview and service since I needed to start a maintenance schedule for it. He found a large vacuum leak after smoking it in the intake manifold. He then proceeded to try to track down cause for the rich condition. I do have the AB ILAND diagnostic tool, and can provide more live data. If it would help you…

 

I would have included MAP data. While the MAP sensor is not a common 4.4 issue, it still can be an issue. MAP sensor is located at the back of the intake manifold.

 

Sorry, just realized I didn't answer part of your question. After fixing the vacuum leaks, they then proceeded to try to address the air/ fuel ratio issues by testing the Maf , fuel pressure , and upstream O2 sensors. Also, then did a full injector and fuel rail cleaning and replaced O-rings.

 

Here is the live data from a few minutes ago at idle. That includes the MAP.

 

update here on the Landy.... i have replaced the MAP sensor and have replaced and all spark plugs while i was in there.... still no change . I am planning on replacing the CKP sensor and all 4 O2 sensors very shortly to attempt to solve this running rich / emissions issue. any one have any thoughts..... EGR valve? both mechanics have smoked the system and only a tiny bit of smoke come out of it. Carbon cannister?

thank you in advance for your thoughts.....

 

You need to fix any known vacuum leaks before moving on to anything else. Seemingly small leaks will impact your fuel trims.

If you do anything with the O2 sensors, I would reinstall the old ones you pulled. Those were probably fine.