Yesterday driving to work the new to me 05 lr3 4.4 threw a cel p0171. I check for vacuum leaks but didn't find any. I cleaned the maf and then cleared. After 20 min of driving it is back. Ltft b1% is 14.8 and ltft b2% is 13.3. Any help would be appreciated.

 

I may have found the problem. I checked the PCV and air flows through it both ways. I don't think it should be this way.

 

In my experience, cleaning the MAF sensor only helps with about 50% of MAF issues. I replace a few on Rovers and a bunch on BMWs, when cleaning doesn't help.

Never tried blowing through a Vent Valve like that. Faulty valves can usually be spotted by measuring crank case vacuum (in inches/H2O).

 

Anyone heard of this...
http://www.rangerovers.net/forum/9-r...ing-codes.html

I can't seem to find any leaks and don't have pressure tester.

 

I have done a bunch of those reflashes, but it is my understanding that the software update is to correct for diagnostic parameters that are too sensitive, not to actually change how it fuels. That means if the vehicle is actually running lean, it won't fix that.

 

What would you suggest to do? How to tell if it is actually running lean? Does my ltft being different by 1.5 mean that b2 is lean. What is acceptable difference and long term fuel trim? Thank you for you help really appreciate it. Do you think in could be MAF?

 

First, when you cleared the codes, did you also reset the fuel adaptations? Even if you "fix" a problem, fuel trim codes can return due to previous learned values. You would think that fixing the problem would cause the adaptations to migrate back to normal, however this is often not the case.

Second, MAF sensors can be tricky to pinpoint. There are known good voltage readings and g/sec readings and so on, but there are so many variables that can influence them, I don't rely heavily on them. Usually, when everything else checks out fine (fuel pressure is good, smoke testing intake shows no vacuum leaks, no excessive crankcase vacuum, etc...), then I start to suspect MAF sensor. Luckily for me, I usually have another Rover or Jag in the shop that I can borrow a sensor from, to confirm my suspicions.

As for the software update, it would be really good to know if it has already been done or not. The bulletin for lean codes has been out for a bit, so if its been to the dealer previously for lean issues, it may have already been done. Although I don't think it will fix all the lean codes, it does fix some. Usually, if I diagnose a vacuum leak or faulty MAF, I will include the reflash as part of the repair, to prevent comebacks from glitchy software.

Without a receipt, the only way to know if it has been flashed, is to connect to the car and go through the motions of flashing the computer so it can compare what the car has with what is new. Once you are that far into it, actually doing the programming is just one click away, so if you do decide the check on the programming status, plan on paying programming price, whether its already been done or not.

The minor difference between the two banks as far as fuel trim is trivial. Most manufacturers claim that +/- 10% is normal. 13% & 14% indicate that both banks are lean and out of spec.

I have never blown through a crankcase vent valve like you have, so I can't say based on your findings, if its good or not. A normal valve will have a hissing noise while the engine is running. Removing the oil fill cap will change how it sounds. A small amount of vacuum will be felt at the oil fill while the engine running. A bad valve usually causes excessive vacuum. Sometimes its hard to "feel" the difference between good and bad. Sometimes its really obvious, when you can't even remove the oil cap from so much vacuum. You need a Manometer to measure, since the readings are in in/H2O.

 

LR Techniker thanks I will try and clear the fuel trim as well. Have to look into my scanner to figure that one out. Today I replaced the MAF sensor and cleared the codes. I also put on new pcv as cheap insurance. The pcv hose hisses when the LR is running. I will see if these fix the problem if not I will have to take it in to have fuel pressure test and clean/check injectors. Then have the PCM updated alone with any other updates to the computers. Wish you were closer to me I would take the LR to you.

 

So for mine and the group's knowledge, did the new valve flow freely in both directions?

 

Actually the new one flows freely both ways as well. So not sure if I really needed that pcv valve. From my experience with other vehicles it only flows one way but I guess I am either mistaken or LR is just different.