Range Rovers Forum banner

1 - 16 of 16 Posts

·
Registered
2006-2009 Range Rover Sport
Joined
·
623 Posts
Discussion Starter · #1 ·
I have had this code and I have no idea how to fix it. All O2 sensors are new and operating as intended.
I cleaned the oil separator.
I replaced the MAF with another unit and the code is still there.
I replaced the Air filter.
I searched and searched the internet and found no info for this code being solved on a P38 or Disco 2.
My nanocom died while updating the firmware but I can read live data with Bluetooth adapter if needed.
Any help would be great.
 

·
Registered
2006-2009 Range Rover Sport
Joined
·
623 Posts
Discussion Starter · #3 ·
Thanks for your response. I will check tonight when I am heading home.
 

·
Registered
Joined
·
271 Posts
And when you say, "The code is still there," do you mean you cleared the check engine light, and the check engine light came back on after a couple days? or what?

What part do you mean by oil separator? I wasn't aware there was an oil separator on the Range Rover.

Brett
 

·
Registered
2006-2009 Range Rover Sport
Joined
·
623 Posts
Discussion Starter · #5 ·
I mean I cleared the code and it comes back. 3 to 4 restarts of motor for the code to return. One day I had P1171 also but it has not come back since.

Right hand valve cover has an oil separator in the hose. It gets clogged.
 

·
Registered
Joined
·
271 Posts
Thanks, I should have just googled it. I didn't realize there was this tiny set of baffles in the right side valve cover.

Back to your original problem, assuming that Land Rover's P117x codes all track with the generic P0170, 1, 2, 3, 4, and 5 codes, these are all fuel trim related codes. Your long term fuel trims should tell you which trim is out of whack and in what direction. Hopefully, with that knowledge, we can come to a logical course of action to solve the problem.

Brett
 

·
Registered
2006-2009 Range Rover Sport
Joined
·
623 Posts
Discussion Starter · #7 ·
You just want long term fuel trims at idle right? I am not very knowledgeable with this engine management stuff.

Just pulled the info.
Long term trim Bank 1 = 9.4
Long term trim bank 2 = 9.4
 

·
Registered
Joined
·
271 Posts
One last question. When you say your o2 sensors are "operating as intended," do you mean that you have observed the real-time output from the pre-cat sensors, and they are oscillating between 0.1 and 0.9 V? Just want to be sure of what is going on.

The positive long term trims means the ECU is adding fuel because it is detecting a lean running condition. Question is, is it a real lean condition or a false lean condition? Causes of a real lean condition include low fuel pressure, poorly flowing injectors, intake vacuum leaks. Causes of a false lean condition include exhaust leak, bad MAF sensor.

Some things are easier to rule out than others. An exhaust leak you can probably hear. If it sounds like a tractor huffing under the hood, one or both of your exhaust manifolds probably has split open at the accordion section. Very common failure. I replaced both of mine during my ownership. Injectors are not easy to test. There are shops that provide this service, but the injectors aren't easy to pull on the Range Rover since they're buried under the top half of the intake.

You can perform some DIY diagnostic tests such as testing fuel pressure and smoke checking the intake. You'll need to buy or borrow some equipment (fuel pressure gauge kit for pressure test and odds and ends to make a smoke generator for the smoke test).

But, your experience is eerily similar to mine documented in my post from 3 weeks ago.

http://www.rangerovers.net/forum/7-range-rover-mark-ii-p38/300298-p1172-p1175-issue.html

You say you replaced your MAF with another unit. What was this other unit? If it wasn't a new Bosch unit, I'd probably not consider the results meaningful. Unfortunately, it's an expensive shot in the dark to buy a new one, but I don't have confidence that you can detect an issue with your current MAF by testing the outputs. I tested the voltage output of my original MAF sensor, and it looked pretty normal. I then tested the new Bosch MAF, and I found the voltage outputs to be within 0.01 V of the original MAF at all rpm's except idle (original, 1.54 V; new, 1.48-1.51V). Whether that idle number difference is responsible for the fuel trim issue, I don't have the experience to say. Maybe one can look at those numbers and say, yep, the MAF is bad. I just don't know. But, I do know a new MAF sensor returned my long term fuel trims to zero on both banks after a couple days of driving. I just drove about 130 miles over 2 days then decided to check the trims, and they were back to normal.

You kind of have to rule everything else out and then finally come to the conclusion that it is likely the MAF causing the problem after everything else checks out OK. For what it's worth, the very experienced indy Land Rover mechanic that I spoke with about my problem said that these Range Rovers are "stupid" sensitive to the MAF sensor.

Here is a very informative 2-part youtube video on diagnosing fuel mixture issues using the long term fuel trims:

https://www.youtube.com/watch?v=5WnM_NsOtd8

The problem with my issue and I suspect with what you're seeing too, is that the long term trims didn't change much from around +10%. In this video, he talks about observing the long term trims going up and down pretty rapidly with rpms, and I watched other videos where the long term trims change rapidly. These trim changes tell you something, but I never saw significant variation in my trims with rpm, so I wasn't learning anything about what the fault could be like the video explains. The trims just seemed pegged around +10% all the time. New MAF was my fix. Your mileage may vary...

Brett
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
455 Posts
Were you able to get Nanocom working buy using backup software?
 

·
Registered
2006-2009 Range Rover Sport
Joined
·
623 Posts
Discussion Starter · #10 ·
Were you able to get Nanocom working buy using backup software?
What backup software do you speak of? I get nothing but a blank screen on the unit with loud beeps. I was not able to revive the nanocom and I have to send it back to Cyprus. I might try again before I send it.
 

·
Registered
2006-2009 Range Rover Sport
Joined
·
623 Posts
Discussion Starter · #11 ·
One last question. When you say your o2 sensors are "operating as intended," do you mean that you have observed the real-time output from the pre-cat sensors, and they are oscillating between 0.1 and 0.9 V? Just want to be sure of what is going on..............

Brett
Thanks for your detailed response. The O2 sensors are operating as designed and I have seen the info on my nanocom before it died. The OBD2 scanner does not respond quick enough on Bluetooth to see as clearly but the numbers are going up/down. The lean condition makes sense with the lack of power right now.
Less than a year ago I hads both the manifolds welded and tested but they could be cracked again in different location. Both accordion sections were 100% sealed back then. I replaced all injector O-rings at that time also but the injectors leaking gas internally should show on a fuel pressure test.
I have 3 used Mass Air Flow units that I swap out if I get a code. I figure they will not all fail in the same way. I could be wrong. Codes never change or get solved by the swaps. I hate throwing $200 at the truck for nothing.
I am in the process of building a smoke tester as I think you are correct about the intake leak. I could swear I heard one on the weekend. It will be a couple of days before I can test the truck due to the -30C temps outside.
Thanks again!
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
520 Posts
if you think you have an air leak then spray it with water from a spray bottle, it will whistle if its leaking
 

·
Registered
Joined
·
271 Posts
I hate throwing $200 at the truck for nothing.
Me too. But, I was at my wits end trying to solve the problem, and nothing else seemed amiss. Not even the MAF sensor seemed to be faulty. Ultimately, I was swayed by the mechanics comments. But, it is a $200 hail mary, if you can't find anything else.

If you're experiencing detectable running issues, that is different from my experience. My engine was running beautifully (as it had for the 12 years of my ownership). Never any power or misfire issues. Those P1172/P1175 codes just kept popping up right when I wanted to sell it. I think I'd worry more about the loss of power. You might consider a compression test. A slight fuel correction of just +10% shouldn't cause any power issues. In fact, it shouldn't cause any check engine light issues either. The threshold for throwing the P017x generic codes is something like +/-25% for the long term fuel trims. I think this is the root of the hypersensitivity of the Thor/Bosch P38 to the MAF sensor that the mechanic noted. It seems Land Rover programmed the ECU to be more sensitive and throw proprietary codes earlier.

For the smoke test, hopefully, you can get in a darkened garage. Much easier to see smoke in the dark with a flashlight (and without wind). I removed my MAF sensor fearing it could get gunked up by smoke residue and stretched and secured a nitrile rubber glove over the intake tube. To introduce smoke into the intake, I removed the big vacuum port plug from the intake manifold (the port that is used for brake booster vacuum supply in discos) and jammed a tight fitting hose into that opening. You push in the red collet and pull the plug out just like the suspension air lines. It's possible that plug is a vacuum leak source, too, so I replaced the O-ring in mine. It's the same size O-ring as the larger air hoses for the suspension valve block. Fortunately, I had one lying around from valve block rebuilds. I was concerned about getting good positive smoke flow into the intake, so I poked a small hole in the glove which was inflated like a balloon, so that positive flow through the intake could occur. You get smoke pouring out there, but hopefully it isn't so much that you can't discern smoke coming from somewhere else.

good luck,
Brett
 

·
Registered
Joined
·
271 Posts
And, I hope you will stick around and finish out this thread. I faced the same problem you mentioned in your original post. There were plenty of people reporting the same codes that I was getting, but there was not a single thread concluding with a resolution. Not one! So frickin' annoying.

Brett
 

·
Registered
2006-2009 Range Rover Sport
Joined
·
623 Posts
Discussion Starter · #15 ·
I will report back if I solve this. It is -35C with the wind chill here right now so I am putting up with resetting the code every third drive.
 

·
Registered
Joined
·
271 Posts
There's really no reason to reset the check engine light. If there aren't any running issues, just drive it. Maybe check the codes every once in a while to see if there's something else popping up. And, continue to watch the long term trims.
Brett
 
1 - 16 of 16 Posts
Top