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Explorer 4.0 OHV - system too lean banks 1 & 2 Please HELP!!!

Discussion in 'Stock 1995 - 2001 Explorers' started by stikz, December 10, 2010.

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    1. stikz

      stikz New Member

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      ok I have a 1999 Explorer OHV 4.0. I bought it in november of last year. Since i purchased the vehicle the check engine light has been on with various codes.

      for a while it would run ok but occaisionally get a rough idle.
      Then my fuel filler pipe broke. At first due to limited funds i used a washing machine rubber hose duct taped inside the fuel filler hose to fill it with gas- eventually it started to run horrible- and would stall out at idle- whether park, or neutral or at stops- eventually i got a used pipe at a junkyard and installed it- then the filler nozzle on the tank broke off- so i JB welded it back on and now i have no gas leaks-but still running bad- I found some bad plug wires that arc'd thru the insulation and replaced them with older wires in better condition. for about a day it ran perfect.


      Then it started stalling out and would not run unless my foot was on the accelerator. while driving if i took my foot off the gas pedal the RPMs would drop and the truck would stall out- So since i needed to get to work i kept my foot on the brake and gas pedal simultaneously while driving. 2 days after i started it up to see the O/D light flashing. I've heard this is usually related to the torque converter or solenoids on the transmission.

      The next day i put in all new plugs and wires- This brought power back to my acceleration but did nothing for the rough idle/stalling problem.

      Now i just chkd the diagnostics and im getting system lean bank 1 & 2- o2 sensor 2


      and 2 no definition codes- not sure of the numbers

      my truck seems to push and pull in a hesitant manner when down shifting.
      and the RPMS drop slightly at times even when my foot is consistent on the gas pedal.


      when warm sometimes the truck will idle without stalling- and i can let my foot off the pedal without it stalling sometimes as well too but not often


      Since i bought it i replaced

      the DPFE sensor- (July '10)
      both Pre cat O2 sensors
      Plugs and wires TWICE most recent was november '10 a few days ago
      Mass Air sensor (October '10)
      Transfer case (july '10)
      Fuel Filter (October '10)
      Air Filter (May '10)



      I cleaned my IAC
      Sprayed carb cleaner around all of my vacuum lines and the idle stayed the same


      From what i understand the prob could be intake gaskets, fuel pressure (pump or regulator), coolant temp sensor, cam sensor, crank sensor, Vacuum Leak, PCV valve, EGR Valve, Tranny Solenoid Pack, Torque Converter


      so being that my finances are low i was hoping that some experience mechanics or 4.0 ohv drivers could point me in a good direction for low cost/free diy testing/fixes

      or other possible problems


      thnx
       
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    3. swetrid

      swetrid Well-Known Member

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      Probably intake gaskets and possibly bad iac valve on top of that problem.
       
    4. briwayjones

      briwayjones Elite Explorer

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      Most likely culprit is a vacuum leak somewhere. Upper or lower intake gaskets are a big possibility.
       
    5. stikz

      stikz New Member

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      i ran a ohmeter across my IAC and it reads fine......


      seems like a vacuum leak or fuel pump problem.

      Today while sitting idle to warm it up- i was holding my foot on the gas at about 2000 rpms- i noticed the idle shot up t about 4000 while i maintained consistent pressure on the pedal.... I also noticed an extreme power loss while driving home
       
    6. dean1997sport

      dean1997sport Active Member

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      I vote gaskets, I did all the same things you did any the only thing that fixed was the new gaskets!
      You need the codes if they are p0171 & p0174 i'm gonna say do the gaskets and be done with it.
       
    7. Beastb15

      Beastb15 Active Member

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      I had the same problem and code one time and it ended up being the Mass Air Flow sensor. All it took was a can of MAF Cleaner from Autzone, 10 minutes and a heavy dose of the cleaner and everything worked perfectly.
       
    8. JEastonjr

      JEastonjr New Member

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      check the pressure at the fuel rail. just push the valve in.if its not a big spary (lots of pressure like a bike tire) go to the fuel pump. Just did mine and the codes went away.
       
    9. stikz

      stikz New Member

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      I replaced the Mass air sensor already
       
    10. stikz

      stikz New Member

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      where is the fuel rail?
       
    11. stikz

      stikz New Member

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      just found that my passenger side pre cat o2 sensor is bad- how in less than a year tho?.... anywayz i'll try replacing it this week- also going to get a vacuum gauge kit- then fuel line gauge kit after that- i really hope it isnt my torque converter
       
    12. sclausel

      sclausel New Member

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      Intake Gaskets

      Not sure if your OHV is the same as my 4.0 SOHV, but I just replaced my upper and lower intake manifold gaskets yesterday and it got rid of the rough idling. Had a P0147 lean code pulled up at Autozone, the guy tried to sell me an O2 sensor but I declined. Replace the original PCV valve, cleaned the MAF and IAC too. But the ( lower ) gaskets were leaking bad. It purrs now. $24 total. I've got 154,000 miles on it.
       
    13. tlestan

      tlestan New Member

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      Definitely check the fuel pressure first. I just went through this, and luckily I was able to read all the sensors real time, so I didn't throw parts at it. The 99 should be an SOHC, and should have 62 psi on the rail (front left of the motor). The regulator on the 99 is in the tank, just above the tank. Not fun, but instant fix to all my codes and rough idle.
       
    14. iwannabamedic

      iwannabamedic Active Member

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      also check that the intake it self is not leaking, mine did it was like it was comig apart at the seams, jbweld does wonders
       
    15. JEastonjr

      JEastonjr New Member

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      fuel line pressure at 60lbs puts more fuel in then at 25lbs. if you dont have 60lbs orso the computer spits out a lean condition. and you will chase problems all day long.IMHO
       
    16. freddy752

      freddy752 New Member

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      likely a vaccum leak or............>>>

      vacuum leaks are a high possibility,

      my check engine light came on and diagnostic codes P0171 & P0174 lean bank 1, lean bank 2, i was told it could be my oxygen sensors so i replaced all four at $300.00 after two gas refills the check engine light came back with same codes as before, im a do it yourself type of guy, i don't trust mechanics here in new York, anyway i did some research online to find possible cause, which varies as listed below.

      1. faulty or just dirty mass air flow sensor
      2. dirty iac
      3. fuel filter
      4. faulty pcv hose
      5. vaccum leak. coming from faulty manifold gaskets, valve cover gaskets, or throttle body.

      PS: when those two codes P0171 & P0174 are set together it is highly unlikely it is the oxygen sensor, possible but highly unlikely. i feel i wasted $300 replacing mines add it did not solve my problem, but hey live and learn :)

      Everyones possible solution varies. in my case i went to ammoco and they suggested to do a vacum leak test by smoking my engine at a price of $129.99, low and behold i had a faulty throttle body, it had a vaccum leak, i fixed and all is well now, hope this helps someone. by the way you can save yourself money by building your own smoke machine, go to youtube and search for homemade engine smoke machine or you can go to party city or any party store and buy a fog Machine average $30. along with a hose that will fit your manifold, and duct tape, you can find these at home depot. good luck everyone :)

      follow up: its now 3 days after i posted this and the check engine light came back on and same two codes came back P0171 & P0174, i replaced the mass airflow sensor, and so far so good, at dealer it cost $275. bought one at my local autozone for $93. will post back if problem persist. this site has saved me thousands of dollars in repairs just on information alone, I will contribute info as well :)

      its been a few days now and check engine light came back on along with same two codes, this time different mechanic said my manifold gaskets need to be changed, cost $190 for diagnosing and changing the gasket, will post again if problem persist

      WOO HOO!! its 3/14/13 over a month now and all is good, the problem was the manifold gasket causing a vaccum leak.. hope you don't have to go thru all the crap i went thru to finally diagnosing the actual problem,,, good luck to everyone :)
       
      Last edited: March 14, 2013
    17. Keno Biebrich

      Keno Biebrich New Member

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      falla no CE

      afirmativo, cambie mi ETC y todo trabaja muy bien!
       
      Last edited: March 3, 2013
    18. Travis vreim

      Travis vreim New Member

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      Really appreciate the help will get back to let you know what I found.
       
    19. fr4nky

      fr4nky New Member

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      Same issue's

      I have the same damn issue's, my normal mech moved to a smaller shop and he doesn't have the tools to do everything. He changed the MSC that didn't work, he changed the gas filter, that didn't work.... i went to a different shop and they smoked my truck 2 of the tubes had holes i asked if this solved the problem and it didn't, when i started the truck up i felt it was still the same. The check eng came on again, so i went back and the error was P0174, i paid 134 for the smoking and changing the tubes. I am getting about 5miles pre, they told me that doing a tune up will prob solve this... They all want to screw you for money.

      You changed the Intake Gasket and it solved it? Please let me know (fulbldital@hotmail.com)
       
    20. dean1997sport

      dean1997sport Active Member

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      Change the upper intake gaskets and orings!
       
    21. Abbondanza

      Abbondanza Active Member

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    22. dean1997sport

      dean1997sport Active Member

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    23. German Engineer

      German Engineer New Member

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      Hello everyone let me revive this old thread here because I currently also just have this Problem.

      There are some advices posted here already and numerous people keep replacing more or less expensive parts that aren't necessarily the cause, while tracking the issue down.

      Well the best general advice I can give you when you have these lean codes, is by starting with the cheap and less costly things and measures first then passing on to the more expensive ones.

      Lets be frank, these cars are pretty old by now and almost anyone who drives them isn't keen on unnecessarily wasting a lot of money to keep it running.

      So the first and cheapest is definitely by starting to check for Vakuum leaks!
      And when you do that make sure to check ALL of the numerous vacuum hoses.
      This car does have an awful lot of them!
      And they really run all over the engine compartment. Some even go all the way down underneath the battery on the front right, others all the way down underneath the air filter to an Air Conditioning Control device which is really well hidden and you can probably best access from underneath the car by removing the inner plastic covers of the fender. And also don't forget to check if that huge rubber tube from the air filter to the Intake manifold is really installed properly and air tight and doesn't have a visible crack or hole anywhere.

      It's really not uncommon for old vacuum hoses to be broken or even just to have came loose from someone accidentally pulling on it, while doing repairs on the car, or from not being reinstalled properly after repair works in the first place.

      Of course it's a bit of a hassle to thoroughly check all of those vacuum hoses, but its not really any sort of difficult or tricky thing to do and it really has big potential for an incredibly cheap repair of the problem.
      It can certainly save you a lot of money otherwise wasted on unnecessarily replacing sensors or Valves or whatever devices - or even having them replaced by a repair shop one by one!

      As I said, this car really does have an awful lot of vacuum hoses. My Explorer Sport even has a really nice schematic vacuum hose diagram on a sticker right at the front when you open the hood. It tells you a lot about where vacuum hoses all go from and to in this car.
      But somehow even this really nice and very helpful and informative diagram doesn't quite each and every single one of the vacuum hoses on it either. It's just mostly complete not perfectly complete, but it's very helpful to see where to look for vacuum hoses and possibly leaking devices nonetheless.

      The other really cheap and efficient way to check for Vakuum leaks is the
      smoke test with a cigar. Others already mentioned that and there is a video about it posted here already.
      (Even being a nonsmoker myself and having to cough a lot whenever doing a cigar smoke tests by myself, I strongly recommend to do the testing with a cigar and to really just forget the otherwise fairly commonly suggested Carb-cleaner Spray test. The cigar smoke just works MUCH better and its much more efficient and last but not least poses much less of a fire hazard. And if you don't smoke yourself you'll certainly have a friend who does and who might actually enjoy being employed as human smoke machine.)
      This kind of smoke test really does work brilliantly.
      And a very good way to do it on the Explorer, is by detaching the end of the big vacuum hose that goes to the Brake Booster and sticking a smaller transparent hose that's long enough inside it to blow smoke into the engine while moving around looking for leaks. (The Brake Booster is on the driver side all the way back by the windshield, that huge round black Metal - tank or half bubble kinda looking thing where a hose from the intake manifold runs to. If that basic explanation helps increase any possible confusion :) )

      You can get a plastic hose that nicely fits inside the bigger vacuum hose running from the intake manifold to the brake Booster at any reasonably assorted Home Depot. Just stick and push it in a few inches and it will already seal itself up enough to blow cigar smoke inside the engine just by sticking in there half what firmly.

      When you do the Cigar smoke test, just make sure you really don't blow any sort of cigar particles or tobacco in there and try not to let all too much saliva get into the manifold either.

      If you see smoke coming out of a little pressure valve on the "Idle Air Control Bypass Valve" which itself is a device mounted on the Intake manifold, don't think that means you have to replace that entire part. But other than that any smoke you see coming out anywhere is pretty certainly a vacuum leak of some kind.
      And if there is a leak anywhere, smoke blown into the intake manifold can come out of the strangest places. Remember all those vacuum hoses are connected to places all over and via the vacuum connection to the engines oil reservoir the smoke - respectively air coming in the other way around through a vacuum leak - can actually even find its way through some pretty surprising passages.

      So please do look carefully and thoroughly to make sure you spot any smoke that might come out of all the various places connected via all those numerous vacuum hoses located pretty much almost anywhere all over the engine compartment.

      You really don't want to miss a vacuum leak in the test and then naturally end up falsely convinced that it must certainly be something else that is causing the problem of the lean codes.

      Another next thing that's cheap and easy to check is, if the Mass Airflow Sensor is dirty. And cleaning that with MAF sensor cleaner spray certainly won't do any harm on an old car either and may very well be helpful or necessary.
      And if you know a tiny little bit about electronics and have a Multimeter at hand, you might possibly also do some basic testing to check if the MAF-sensors electric circuit seems functional.

      To diagnose the Fuel injection System you'll need to get a Fuel Pressure Test Kit. You should be able to get one for 45 Dollars or cheaper.
      I will refrain from posting further detailed instructions on how and what exactly to do to diagnose the fuel Injector system with a pressure tester here, because messing with fuel does have it's fire safety aspects.
      But with a Fuel Pressure Tester you can get further Information that helps find out if any fuel injectors are leaky or the Fuel Pressure Dampener is broken or leaking or if the Fuel Pump or Filter might be clogged or not working properly.

      What you might as well just do without getting a fuel Pressure Tester - since its and older car and could very likely use a new one sooner or later anyways - is simply just replacing the fuel filter.
      The Explorer usually has a metal tank and when that is old it might be rusty inside and a clogged fuel filter can of course also cause low fuel pressure and thus cause lean codes.
      And replacing a fuel filter is still cheaper than buying Fuel Pressure Test Kit after all.
      And the risk of any money being wasted when replacing a Fuel Filter is naturally near 0, unless the car does have a new filter of course.

      Now those things I mentioned here are certainly some really cheap and low cost tests and repairs you may fairly easily be able to do yourself, even without being a car repair genius yourself and you also won't need fancy tools to check those things out.

      And should you happen to find a vacuum leak that way which you aren't capable of repairing yourself, then you at least know where and what exactly it is and then you can have a repair shop repair just specifically that for you and you will much less likely end up with someone replacing parts that don't mandatorily need to be replaced to keep the car running fine and safe for another while.

      I hope this post does help at least one or another of the readers here in avoiding unnecessary costs that occur when randomly replacing parts that may potentially be causing the Lean codes issue.
       
    24. jawknee99

      jawknee99 New Member

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      hey guys

      Heres the deal.
      150,000 miles on my explorer running great until i got the famous po171 po174 codes.
      Had my truck sitting for a good while then finally
      Changed my
      Coil pack, spark plugs wires, spark plugs. Oil, oil filter air filter and of course your intake gasket. Something told me to change the injectors but figured. Hey my car cant be that much in bad shape. Put everything back together what do you know. Worst engine performance ever. No power misfiring, car as red and got. Thinking i had the wrong firing order double checked triple checked. I had it right.
      There i go to change my cats only changed 2 btw...the big ones. Coming back home a little better but still no power. I knew i should've changed my injectors since day 1. New injectors plus new gasket under the fuel rail. Btw all my gaskets were im really good shape so are all of my vacuum and evap hoses.
      So now here i am with a ton of new parts. Got the fuel filter but couldnt get it off . Couldnt wait till the auto store opened so i figured hey what the heck. Turned it on runs like hell again full power. Everythings good till i get those damn codes again.
      Finally changed the fuel filter which was dirty af. Ran it more same codes.
      I smoked out my intake with a homemade machine and no leaks from any places ...im stuck now what... help
       
    25. German Engineer

      German Engineer New Member

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      Well, with all those parts you threw at it already I suggest You try thoroughly figuring out what the issue is before throwing anymore random parts at it.

      The things that come to my mind which it seems you haven't tried yet, are the following things:
      A bad or dirty Mass Airflow Sensor.
      A problem with the EGR System EGR Valve.
      Or a problem with the fuel delivery.
      Faulty O2 sensors (but probably rather unlikely, because there is one for each bank)

      I suggest You get or loan an OBD2 scanner and look at the live data and freeze frame data. From looking at the live data on a good OBD scanner You can get an idea if the MAF is giving reasonable values. And from looking at the freeze frame data you might be able to get an idea if its a lean condition under load or under idle. It might take more than one freeze frame data to get some certainty if the lean condition is predominantly under idle conditions (where the vacuum is maximum) or under load (with the fuel injectors open and a dropping fuel pressure). ((With needing more than one set of freeze frame data, I mean clearing the error codes and checking and comparing all the freeze frame data whenever the codes come up again and again to get an idea of the operating conditions of the vehicle when the codes come up. You might also try resetting the PCM now and then, during the process of diagnosing the lean codes from the freeze frame data, by detatching the battery for a while to make the car relearn the driving parameters.) You should be able to get a pretty good idea if the lean codes tend to come on rather when the engine is at idle or also when it is under load fairly soon, when collecting and comparing freeze frame data.)

      You can also get an idea if the O2 sensors appear to be working properly from interpreting the livedata.
      And the Explorer also runs some on board tests of the EGR system. You can see the results of those in the IM readiness tests when they are completed as well as in some of the Information provided in the manufacturer specific test section under Mode $6.

      To diagnose the fuel pressure you can loan or buy a fuel pressure test kit. Those do not have to be very expensive.
      Should the fuel pressure be low you might possibly have a bad fuel pump. (Or an electric problem with the fuel pumps power supply or ground).

      Your really badly clogged up fuel filter might be an serious indication to a problem with rust inside your gas tank and that could of course make your fuel pump go bad as well.

      Below is a really good and video You might want to watch regarding the diagnosis of the MAF sensor, and the freeze frame data to determine the type of lean condition, as well as diagnosing a fuel pump. Even though the guy in this video has professional equipment you probably won't get a hold of yourself, most of the information he used can also be gained with regular OBD2 scanners of the kind those major auto pars shops offer as service for their customers to use for free.
      Going along that route of further diagnosing the issue is my suggestion of a "battle plan".

      Here's the YouTube video from ScannerDanner:

      www.youtube.com/watch?v=nYN-RoFVwAA

      Good luck!
       
      Last edited: February 25, 2016
    26. Macgiobuin

      Macgiobuin Active Member

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      Forward Catalytic converter (one of them) broke down and got blown down to the common downstream catalytic converter. After it stalls and then cools, the powdered ceramic material falls down and suddenly you can run again. Separate the input pipe that goes into the downstream (common) converter, and if the common converter is full of cat junk, that's your problem. But which one upstream failed? And why did it fail? Possibly a bad fuel injector, either stuck open (causing a rich condition, which the computer tries to fix by starving all 3 cylinders on that bank of fuel), or stuck closed, (causing the computer to fix by richening up all 3 cylinders, which leaves 2 cylinders running real rich, causing the cat on that side to burn up and disintegrate.) Nevertheless, check the downstream converter for being clogged. I pulled mine off and turned it input side down and a pile of junk came down like an avalanche. So if you replace it with a new one, now will it happen again? Here's where you gotta check for bad fuel injectors, bad fuel pressure regulator/housing....
       

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