I looked at a friends Isuzu Trooper last week with this code. He has a bad intake gasket. So the more likely the culprit is a vacuum leak somewhere. These trucks are getting on in years and like anything else time is starting to come into play.
P0171 with Landtank's MAF
- Thread starter NLXTACY
- Start date
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sleeoffroad
Supporting Vendor
Why not swap your old MAF in and see if the issues are still there. I would really doubt a fuel pump going bad, or a fuel filter that dirty that you would get lean conditions.
Just that if there isn't anything wrong with the connector to the MAF, and there are no air intake leaks introduced anywhere, your sensor itself might be bad or dirty. As Christo already suggested, if tightening the connectors doesn't do it, swap in the old MAF sensor and see if the condition changes. Again this all comes after verifying that there are no air intake leaks. HTH.
fzjconvert
one hand, two ducks
I gave it a try!
Just that if there isn't anything wrong with the connector to the MAF, and there are no air intake leaks introduced anywhere, your sensor itself might be bad or dirty. As Christo already suggested, if tightening the connectors doesn't do it, swap in the old MAF sensor and see if the condition changes. Again this all comes after verifying that there are no air intake leaks. HTH.
OK, back up to Sunday. I went ahead and cleared the code and swapped out the MAF and reconnected the FPR. Before I could get down to the FWY, bloop, lights back on. Not to mention the truck just runs like poop in comparison to how it runs with the Landtank MAF. This tells me that the LT MAF is not the culprit so back on it goes with NO reservations.
Next, I again check and rechecked the various vacuum lines. Short of having a smoke tester I don't think I missed any of them that may be a suspect. I do agree with Rick that our trucks are getting older and the rubber is going to get hard at some point. To that end I have been slowly working my way through the whole truck... The next on the list is the Engine coolant temp sensor. I gave it the once over as per my trusty factory service manual and it checked out OK. All the while I kept hearing my buddy's voice "swap out the fuel filter" Since I had planed on doing that on Sunday. I bit the bullet and replaced the filter. I had been putting it off for some time now. Truth be told, like the PHH it is not as bad as I thought! It took me about thirty minuets which I think is pretty good for me. I know that is slow for some but, good for me with only simple tools!
The fuel filter was filthy dirty! When you held it up to light it was just brown and hard to blow through compared to the new one. I don't think that it has been ever change although it is listed on a invoice from the dealership where the PO took the truck for service. Go figure! Anyway, I cleared the code now three days and about 150 miles later the light has not come back on yet. Knock on wood!
At this point, I think my mechanic buddy was right all a long. The fuel filter seems to be the cause for my PO171 code. I hope this helps Bobby! Sorry for the hijack!
fzjconvert
one hand, two ducks
Now a week since I replaced the fuel filter to remedy my PO171 code and still no light! (knocking on my head)
fzjconvert
one hand, two ducks
Oh gosh! I haven't done the sock yet... That was the next step if changing the filter did not clear the code. Because all of the stuff you have to remove, I would give yourself say 2-2/12 hrs. just to be safe.
Also, I do things somewhat preemptively so while I have the tank open I am going to replace the pump too. I hate doing things twice! Just a something to consider.
Dave
Well. the fuel filter wouldn't have been my first guess but it seems to have taken care of things.
About 1/2 way through a 10 day trip in Navajo Country (last week) I got a PO171 while on the trail. I cleared the code and it and it hasn't come back yet.
The tube from the air filter to intake is about a year old and has no cracks. All vacuum hoses have been changed since I purchased the vehicle just over 2 years ago. Fuel filter changed during HG PM 1 1/2 years ago.
Any idea why I'd get it just one time?
The tube from the air filter to intake is about a year old and has no cracks. All vacuum hoses have been changed since I purchased the vehicle just over 2 years ago. Fuel filter changed during HG PM 1 1/2 years ago.
Any idea why I'd get it just one time?
IMO this code comes from the system or one of it's components not working consistently and predictably. You're likely looking at a problem in the wiring, bad sensor, bad fuel pump, an air leak upstream of the front O2 sensor, almost anything.
In the case of the bad fuel filter, it was likely restrictive enough so that it didn't flow enough fuel to maintain the fuel rail pressure all the time and when it was low it would yield a lean condition that the ECU couldn't foresee and trigger the code.
If it was a hot day you might consider the fuel pump itself as they can run sporadic when old in that type of environment.
In the case of the bad fuel filter, it was likely restrictive enough so that it didn't flow enough fuel to maintain the fuel rail pressure all the time and when it was low it would yield a lean condition that the ECU couldn't foresee and trigger the code.
If it was a hot day you might consider the fuel pump itself as they can run sporadic when old in that type of environment.
NLXTACY
Wits' End
- Thread starter
- #31
Ok quickie half-ass update:
I've been out of town ALOT and now I'm on my way to the World Cup in South Africa. (Just wanted to brag
)
I swapped out the MAF and switched the wires back. Pretty painless. Wife was driving around and after about 70 miles the P0171 came back on. So I'm pretty sure that takes the MAF out of the equation. I also inspected the intake hose again and its still soft~ish with no cracks.
Now while I was gone my wife said that the truck just didn't feel peppy any more and it lost all its power off the line. I chalked it up to her being a needy woman who just wants to complain about every little thing. Well I drove it today and sure enough. It doesn't bog down when you step on the gas, it just doesn't go anywhere fast. Its like I am cruising and not giving it gas at all. On the freeway at speed its totally fine.
So my next step is to do the fuel sock finally and change the fuel filter as well. Even though I just changed it six months ago. Just in case.
I've been out of town ALOT and now I'm on my way to the World Cup in South Africa. (Just wanted to brag
)I swapped out the MAF and switched the wires back. Pretty painless. Wife was driving around and after about 70 miles the P0171 came back on. So I'm pretty sure that takes the MAF out of the equation. I also inspected the intake hose again and its still soft~ish with no cracks.
Now while I was gone my wife said that the truck just didn't feel peppy any more and it lost all its power off the line. I chalked it up to her being a needy woman who just wants to complain about every little thing. Well I drove it today and sure enough. It doesn't bog down when you step on the gas, it just doesn't go anywhere fast. Its like I am cruising and not giving it gas at all. On the freeway at speed its totally fine.
So my next step is to do the fuel sock finally and change the fuel filter as well. Even though I just changed it six months ago. Just in case.
Thanks for the update and taking the time to swap in the stock MAF. I realize it's pretty easy to suspect an associated MOD with any kind of problem that might crop up.
It's probably going to be a step by step swapping of parts that finally reveals the problem.
Good luck
It's probably going to be a step by step swapping of parts that finally reveals the problem.
Good luck
fzjconvert
one hand, two ducks
It has now been almost four months since I changed the fuel filter and the code has not come back since!
Ok quickie half-ass update:
I've been out of town ALOT and now I'm on my way to the World Cup in South Africa. (Just wanted to brag
I swapped out the MAF and switched the wires back. Pretty painless. Wife was driving around and after about 70 miles the P0171 came back on. So I'm pretty sure that takes the MAF out of the equation. I also inspected the intake hose again and its still soft~ish with no cracks.
Now while I was gone my wife said that the truck just didn't feel peppy any more and it lost all its power off the line. I chalked it up to her being a needy woman who just wants to complain about every little thing. Well I drove it today and sure enough. It doesn't bog down when you step on the gas, it just doesn't go anywhere fast. Its like I am cruising and not giving it gas at all. On the freeway at speed its totally fine.
So my next step is to do the fuel sock finally and change the fuel filter as well. Even though I just changed it six months ago. Just in case.
Try the filter first it solved the problem for me. I have yet to do the sock...
I too was glad to disprove that your MAF was the culprit! Also, since I installed your sleeve my truck hasn't run better! Thanks Rick!
fzjconvert
one hand, two ducks
NLXTACY
Wits' End
- Thread starter
- #36
Ok so finally tracked down the issues and solve it all and PASS SMOG AND CLEAR THE CEL!!!!
I plainly don't have time to do anything anymore as my job sends literally all over the world. I just got back from South Africa for shooting the World Cup in 3D and now I'm preparing for Amsterdam and Munich. Needless to say my post count is going no where fast
So I am actually having Richard over at K&H Imports do all my dirty work now on the LX. I like him because he's knowledgeable BUT is very receptive to new ideas and "other" methods.
I had him change the fuel filter. CEL still there.
I gave him all new vacuum hoses and the fuel tank sock kit, but he never installed it cuz the PO401 came on too again. This time I had him replace the VSV under the intake manifold. PO401 hasn't come back since. That one annoyed me forever. He said he doubts highly that the fuel sock is the issue. So he put it aside for the time being. We do some more digging and the BRAND NEW O2 sensor that I just got from CDAN decides it wants to be well outta spec. So a new front O2 sensor goes in. He inspects the Y-pipe again to make sure there isn't a crack or hole there. Nothing. Totally clean and rust free.
Finally he takes off the air filter canister cover and removes the air duct. Everything is cool. No issues. He does notice that there is what looks like a very thin coating of black soot on the throttle body so he cleans that out. Then he takes a look at the sensor of the MAF. Its coated with the same black soot. He sprays it down and re-installs everything, does nothing else. CEL is gone.
Take it down to get smogged, passes with flying colors. In fact it does very very well. Now with this there are three things that I immediately noticed happened as a result of finding this issue:
• My truck is now running MUCH cooler. It happened immediately. It always ran either at the center or just above center to "hmm, that looks kinda warm". BTW I have the LANDTANK/RAVENTAI coolant gauge mod. Now the truck has yet to pass the half way mark.
•*My truck no longer does a weird studder thing when I am accelerating from a stop, going uphill. It always kinda felt like a dog and would ping a little.
•*The "pinging" or what I thought was rod knock is now completely gone. I would always here it at highway speeds when I was accelerating to get to speed. Its completely gone now. And yes I am running regular gas.
Needless to say I am pretty damn happy right now and so is the
I plainly don't have time to do anything anymore as my job sends literally all over the world. I just got back from South Africa for shooting the World Cup in 3D and now I'm preparing for Amsterdam and Munich. Needless to say my post count is going no where fast
So I am actually having Richard over at K&H Imports do all my dirty work now on the LX. I like him because he's knowledgeable BUT is very receptive to new ideas and "other" methods.
I had him change the fuel filter. CEL still there.
I gave him all new vacuum hoses and the fuel tank sock kit, but he never installed it cuz the PO401 came on too again. This time I had him replace the VSV under the intake manifold. PO401 hasn't come back since. That one annoyed me forever. He said he doubts highly that the fuel sock is the issue. So he put it aside for the time being. We do some more digging and the BRAND NEW O2 sensor that I just got from CDAN decides it wants to be well outta spec. So a new front O2 sensor goes in. He inspects the Y-pipe again to make sure there isn't a crack or hole there. Nothing. Totally clean and rust free.
Finally he takes off the air filter canister cover and removes the air duct. Everything is cool. No issues. He does notice that there is what looks like a very thin coating of black soot on the throttle body so he cleans that out. Then he takes a look at the sensor of the MAF. Its coated with the same black soot. He sprays it down and re-installs everything, does nothing else. CEL is gone.
Take it down to get smogged, passes with flying colors. In fact it does very very well. Now with this there are three things that I immediately noticed happened as a result of finding this issue:
• My truck is now running MUCH cooler. It happened immediately. It always ran either at the center or just above center to "hmm, that looks kinda warm". BTW I have the LANDTANK/RAVENTAI coolant gauge mod. Now the truck has yet to pass the half way mark.
•*My truck no longer does a weird studder thing when I am accelerating from a stop, going uphill. It always kinda felt like a dog and would ping a little.
•*The "pinging" or what I thought was rod knock is now completely gone. I would always here it at highway speeds when I was accelerating to get to speed. Its completely gone now. And yes I am running regular gas.
Needless to say I am pretty damn happy right now and so is the
I would do the sleeve for sure. It does seem to improve things some.
If there is one draw back with my MAF mod it is that the newer style sensor is a little more sensitive to contamination. Doing a search for MAF codes on the Toyota models that come stock with it and you will see that cleaning it regularly eliminates the issue.
If you watch two roads to Baja, the FJ died because of this sensor. Of course they didn't clean it, they just swapped in a new one which unfortunately had a different pinout on the connector which gave them the same symptoms and took them 4 hours to figure out.
94SRUNNER
GOLD Star
So Landtank, is this something we should all be doing on a regular basis (at least those who have your MAF)? Cleaning the sensor that is?
I would. I'd put it on the same schedule as your air filter. Clean them both at the same time. But that would assume that you are using a stock element that is cleanable and not an oil type like K&N. With an oil type I'd clean it much more often.
