Fan and lean codes

[Kwakazaki2]

We bought our LR4 to haul kids and provide get aways to Maine, Outer banks, etc. LR4 2016 3.0v6 Supercharged, Corris grey. Great truck.

Now retired, I’m more hands-on than ever, love the truck and really trying to look after her.

Have lean fuel codes P2189/7 both banks, and P0483-36 fan frequency modulation failure. Books and forums say the fan failure is from wading, but I think it was actually me pressure washing the underside to better identify where an oil leak was from. Which turned out to be the vacuum pump seal, so seems I fixed one problem and created another! Awesome, tut, tut.

Anyone have any thoughts or good links on testing the fan (electro viscous) and/or fixing it? Anyone taken the electrical bits of the fan apart? Very expensive if I go the parts cannon route.

For the lean codes I already changed the PCV diaphragm and smoke tested all the intake and emissions systems, there were a couple of small leaks which I’ve fixed, but the codes come straight back. Note - codes are for both banks, and reliably return for both banks, so that seems to count out MAF, oxygen sensors, fuel injectors, etc. as both banks would need to fail together, i.e. unlikely. Any thoughts on what to look at next?

I’m clearing these codes with a GAP tool and they come back after 30-40 miles. Starting to get stumped and looking for help… support ha ha!

Regards

 

[jlglr4]

Bad MAF can give lean condition on both banks. There are two intakes/MAFs, but the air is combined at the throttle body, so the MAF readings are used together. If one is bad, it affects both banks. Look at the live values for the MAFs and see if they track each other at a few different RPMs. They won’t be exactly the same, but should be fairly close. Make sure your air filters are clean (or at least equally dirty) so it doesn’t threw off the test.

Also, when you smoke tested, did you have the throttle body open?

Finally, are you getting the lean codes after fixing the vacuum pump? I believe a bad vacuum pump might be able to allow air to be sucked into the intake, depending on how it failed. At least on the older V8, the vacuum system is assisted by both the vacuum pump and the intake vacuum - the lines are joined - so a leaking vacuum pump can turn into a vacuum leak at idle when the intake is at high negative pressure.

Assuming it’s not the MAFs or vacuum pump, and the smoke test was good, another possibility is the fuel canister purge valve. It is a solenoid controlled valve located in a black tube that runs along the drivers side of valve cover (under the foam as I recall). It is normally closed, and should open at higher speeds/rpms as I recall to empty fuel vapors from the charcoal fuel canister. If the solenoid fails, it can cause either a lean or rich condition depending on what it’s pulling from the canister. I think you can disconnect the end from the air intake and blow through it to see if the valve is closed tight.

The lean codes are specific to idle condition, but you can also look at fuel trims to get a little better picture of what’s going on. Look at short term and long term fuel trims, both banks, at idle and holding steady at about 1500 or so RPMs and about 2500 or so RPMs. A classic vacuum leak will show high positive fuel trims at idle that tend towards zero as RPMs increase. If fuel trims trend the other way (get more positive) with increasing RPMs, you probably have a fuel delivery issue.