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Rough idle and "Check Engine Soon" light - FIXED

Discussion in 'Stock 2002 - 2005 Explorers' started by SyberTiger, June 2, 2008.

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    1. SyberTiger

      SyberTiger Active Member

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      ================================
      ================================
      SOLUTION FOUND SOLUTION FOUND
      ================================
      ================================
      UPDATED ON June 22, 2008 - READ BELOW!
      ================================
      ================================

      I have a 2002 Explorer. The Check Engine Soon light stays on. The engine idles rough and sometimes dies as the RPM bounces between 650 - 800 RPM. At normal driving speeds and acceleration I do not seem to notice a problem. Oftentimes, at a red light, I'll put it in neutral and tap the accelerator just a tad to make sure it does not die on me at the intersection. Oddly, if you try to keep it idling at around 1000 RPM you'll see the tach jump up to 2000 RPM then back down to 800 RPM. It is very difficult to give it just enough gas and keep it a constant 1000 RPM when sitting there at a red light. Is there an easy way to read out the ERROR CODE without special tools? Anyone have a good guess as to what the problem is?

      I have the V-8 engine and it has 91K miles on it.

      ================================
      ================================
      SOLUTION FOUND SOLUTION FOUND
      ================================
      ================================
      UPDATED ON June 22, 2008 - READ BELOW!
      ================================
      ================================
       
      Last edited: June 22, 2008
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    3. shadowless127

      shadowless127 Well-Known Member

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      Take it to autozone, they'll read your codes for free.
       
    4. SyberTiger

      SyberTiger Active Member

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      Okay, I went to AutoZone and had the codes read out. I had a total of seven codes. I'm sure some if not most are related. If someone here with some experience on these could point me in the right direction as far as what to do first I would greatly appreciate it. The codes are:

      P0300
      P0171
      P0174
      P1130
      P1131
      P1150
      P1151

      The details of the codes are as follows:

      P0300 - Cylinder misfire detected - Random cylinders - The powertrain control module monitors the crankshaft speed and has detected a misfire condition.

      P0171 - Fuel trim bank one condition - The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.

      P0174 - Fuel trim bank two condition - The ECM has detected a rich or lean air/fuel ratio condition on engine bank two.

      P1130 - No O2 sensor transistion - Fuel trim at its limit - ECM could not adjust fuel trim because of a lean or rich condition.

      P1131 - Lack of bank 1 O2 transistions - Lean - ECM detected bank 1 O2 at its lean limit.

      P1150 - Lack of O2 switches - Bank 1 sensor 1 - ECM could not adjust fuel trim because of a lean or rich condition.

      P1151 - Lack of O2 switches - Bank 2 sensor 1 - ECM could not adjust fuel trim because of a lean or rich condition.
       
    5. shadowless127

      shadowless127 Well-Known Member

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      Deff sounds like you have bad o2 sensors and a misfire. I suggest taking it to the shop ASAP. Running with a possible Misfire is extremely dangerous
       
    6. SyberTiger

      SyberTiger Active Member

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      I'm thinking its the Mass Air Flow sensor that covers most of the issues. The second guess would be a fuel pump or pressure problem. The fuel filter was changed out 5 months ago as I recall. The misfire might just suggest a faulty spark plug or coil. Anyone else have a suggestion other than take it to Ford to have my bank account emptied?
       
    7. crash594

      crash594 Active Member

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      I agree with Tiger. Try unplugging the Mass Air Flow sensor and see if it runs rough. When it is not plugged in it will go into safe mode and run off the other sensors to a point. I was told this by an old Ford tech and it has helped me with strange problems since. It works with most of the sensors. If it runs better it should be that sensor.
       
    8. SyberTiger

      SyberTiger Active Member

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      I just noticed on the AutoZone code printout says: "If bank one and two codes set together suspect fuel pressure or MAF Sensor".

      This, in fact, is true. Code P0171 is bank one and Code P0174 is bank two. I've never cleaned the MAF Sensor and I have 91K miles on it. I guess the plan is to unplug it, see if it runs better, if it does then clean it and plug it back in. Reset the codes, see if CEL comes on, then go back to AutoZone to re-read the codes.
       
    9. SyberTiger

      SyberTiger Active Member

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      Well, cleaning the MAF sensor didn't do a thing for the rough idle. I unplugged the MAF and started her up...she still rough idled. Oddly, the CEL never came on. You'd think the computer would be able to detect the MAF being unplugged.


      Guess I need to figure out the next course of action. Anyone know how to check the fuel pump or the fuel pressure?
       
    10. SyberTiger

      SyberTiger Active Member

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      I'm still having this rough idle problem. I'm not sure what the next course of action is. So far I've done the following:

      1. Cleaned MAF sensor twice with MAF cleaner.
      2. New air filter.
      3. Cleaned the IAC with carburator cleaner.

      I went back to AutoZone to get a re-read of the CEL codes. Right now I have codes P0174, P1131, and P1151. I don't necessarily think the other codes have gone away, rather, I haven't given them time to show up.

      I think maybe I need to check the fuel pump pressure at the fuel rail and look for vacuum line leaks.

      Can someone give me some details on the proper way to check fuel pump pressure AND also the best proceedure for checking for vacuum line leaks?
       
    11. rrgone

      rrgone Active Member

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      There's two good threads on checking fuel system pressure in the sticky section of Under The Hood forum. I think one poster even mentions proper pressure range for Gen 3 in the first thread. I was reading over there a few days ago. Good luck.
       
    12. SyberTiger

      SyberTiger Active Member

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      I found the solution to my rough idle problem. I thought I'd give this update in hopes of helping some of the many people who have tinkered with their MAF sensor or IAC without a fix.

      I took the noise insulation cover over the throttle body off again and went back for a second look. As I previously posted, I was going to go back and take a serious look at vaccum line problems. It turns out there was a VERY obvious vacuum hose problem. Specifically, the vacuum tube that runs from the PCV valve on the passenger side valve cover over to the throttle body air intake. The vacuum tube attaches to the throttle body air intake with a rubber elbow fitting. As you can see from the attached photos there is obviously a problem. The rubber is deteriorated at the bend and the significant vacuum causes it to collapse. There is a significant sucking sound coming from this point with the engine running. I never noticed that before because I never started the engine with the insulated decorative engine cover off. With the engine running I put my finger over the gapping hole and, viola, the engine idle returned to normal idle.

      The elbow appears to be a Ford part so I'll go pick one up at the local Ford dealer tommorow. For now, I wrapped some electrical tape around the hole. After the fix I'll drive around a bit and see if any CEL codes are logged but hopefully I'm good to go.

      Hope this helps some of you out. And, as other have said here before, check and re-check those vacuum lines!

      In the photo below I'm pointing to the bad rubber fitting. Note above my finger, the silvery aluminum thing is the IAC on my 2002 4.6L V-8.

      [​IMG]

      [​IMG]

      The next photo is a closeup of the problem.

      [​IMG]

      If your engine/vehicle is configured like mine then the following picture will help you locate the aforementioned rubber elbow fitting. The blue arrow is pointing to it.

      [​IMG]
       
      Last edited: September 11, 2011
    13. SyberTiger

      SyberTiger Active Member

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      I'm closing out this thread with some additional information some of you, specifically with 2002 4.6L V-8 engines, might find interesting.

      I had a hell of a time trying to locate just a replacement rubber elbow. I did a little research on the web concerning rubber elbows used on vaccum systems on Ford products. I discovered this is a very common problem not just in Explorers but all Ford autos using the rubber elbows. I don't know why you can not buy just the rubber elbow from Ford. They make you buy the entire assembly that uses the rubber elbow.

      I went to my local Ford dealer's parts department thinking that if I have to buy the whole assembly then I'll just do it and consider myself lucky since I was able to self diagnose and repair my rough idle problem so easily. The parts department punched in on their computer parts inventory system the year, model, engine type and even the VIN number to pull up a diagram of my engine's emission control system with parts diagram. It looks like this:

      [​IMG]

      They ordered the assembly labelled 6C324 insisting that this was what I needed and pointed out that the drawing even shows the rubber elbow plugging into the throttle body. When the part arrived it was ridiculously obvious that that assemble was not correct. Thinking it must be the other assembly in the picture labelled 6A664 they ordered that one. When the second assembly arrived it was also obvious that it would not fit my engine. They were baffled and said they didn't have a clue as to why neither assembly would fit. In the end they suggested I go to a junk yard and retreive a rubber elbow off a junked Explorer.

      I called a couple of junk yards but no one had a 4.6L V-8. I then went to NAPA and Carquest in search of a rubber elbow. Neither place had them and neither place had a clue as to where to get one expect to insist that my local Ford dealer was the only place with such replacement parts.

      I ended up going to a different Ford dealer to see if they were a little more on top of their game. I ended up going throught the same "riga-ma-roll" as I did with the first Ford dealership. Both dealerships were just baffled and at a loss as to an explanation as to why they could not find the right replacement parts. Finally, a fella at the second dealership got the idea of trying to locate an engineering number off of the original assembly. Thankfully, with a little digging around in my engine compartment he was able to cut off a tag on the original assembly with an engineering ID.

      [​IMG]

      Confident he was easily going to figure out this mystery he plugged in the engineering ID into his computer only to find that this number doesn't exist for a 2002 Explorer. In fact, for some reason he was unable to locate the actual part number for this assembly. A crossed referenced part number to the engineering ID would have allowed him to get a list from the computer of all the cars that use the assembly. In the end, on a whim, he walked back to the parts bins that contained a hodge-podge collection of emission control vacuum assemblies and started looking for one that matched my original. By some stroke of luck he actually found an assembly matching that of the one on my engine.

      [​IMG]

      [​IMG]

      [​IMG]

      [​IMG]

      Finally, not only did we have what I needed but we also had the part number of the assembly. The parts guy punched the identified part number in the computer to find out what cars used this assembly. To our amazement this is what was displayed:

      Mustang - years 2002, 2003, 2004
      Explorer/Mountaineer - years 2003, 2004

      The only thing I can think of is that my vehicle is a March 2002 build and therefore has a 2003 engine configuration. I've heard of mid-year production changes but this was ridiculous because the drawings on the Ford computer systems didn't reflect this change nor were there any notes. What is really disappointing is that the Ford dealership pulled up the emission control engineering drawing for a 2003 Explorer and it looked identical to a 2002. Anyone with at least a 2002 or 2003 V-8 that uses the pictured PCV vacuum tube assembly is going to have the same problem I had locating a replacement.

      If any of you have a 2002, 2003, or 2004 Explorer or Mountaineer with a 4.6L V-8 and are having the same issue with replacing the PCV vacuum tube assembly and it looks like mine you'll want to have your dealer to order:

      Part Number 2L2Z 6A664 BA
      Motorcraft KCV-129
      Engineering ID Number 2L2E 6K817-BC

      In the end I'm glad I replaced the entire assembly. The rubber fitting that plugs onto the PCV value on the other side of the tube was starting to deteriorate too. Because of my troubles, the parts guy at the second Ford dealership sold me the vacuum tube assembly for $16.17 instead of charging me the normal $28.76 price. He also sold me a Motocraft PCV valve for $9.05 instead of charging me the normal $16.09 price. I figured that with 91K miles I might as well change the PCV valve while changing out the vacuum tube assembly.

      Lastly, the X is running normal...no rough idle problems and no Check Engine light. Who would have thought that that hole in the rubber elbow on that vacuum line could cause those 7 Check Engine codes?
       
      Last edited: September 11, 2011
    14. DavidS

      DavidS Member

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      When mine did this, I went to Autozone and bought a small 1/2" rubber 90° elbow for $5.99 and trimmed it to fit.
       
    15. rrgone

      rrgone Active Member

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      Nice post Syber. Mine's also a March 2002 build w/4.6L engine. Otherwise I'd take a look to see if it's different than yours.
       
    16. not8taxi

      not8taxi Active Member

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      ive been having a hard idle problem now for a while in my 02 ex 4.0 v6...never really looked at it because of no time but the rpms did drop a few times this week when i was stopping... good write up too bad i got the 4.0 lol
       
    17. killermobile

      killermobile New Member

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      SyberTiger, you're a lifesaver man! Thanks a ton for taking the time to put up this post, plus the photos!

      I had the exact same issues as you, and what do you know! Exact same puncture in the elbow fitting. This is the second time this forum has saved my ass and a load of cash.

      Now the only trouble is finding the part - I'm way down on the coast of Oaxaca, and there's no way I can get the part down here before I scheduled to drive back north.

      Cheers and many thanks!

      Josh
       
    18. Explorerer

      Explorerer New Member

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      Awesome post Tiger and filled with good information. Thanks.

      I'm tucking this one away in case my 03 4.6 does the same thing.

      Steve
       
    19. uefear

      uefear Member

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      My engine was throwing P0171 P0174 P1130 P1131 and P1150. Exact same puncture in the elbow like yours. I have an 02 Explorer Sport and I fixed mine using 5/8 Heatercore Hose with an elbow in between so the hose won't kink. Worked for 30 minutes. Now I have P14000 and P0130 codes.
       
      Last edited: August 10, 2008
    20. scarletgem

      scarletgem New Member

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      could it be kinked? did you use an elbow?
       
    21. Beausdad

      Beausdad Member

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      You are the man...

      I had the same exact problem. I pulled that shroud off and located the elbow and sure as all there it was. All deteriorated and cracked.

      Saturday afternoon and of course all dealership parts depts. close at noon. I went to NAPA and asked the sales person for 1 foot of 5/8 inch fuel line thinking I could make it work. Then just out of curiosity I asked if they had any random elbows. SHE SAID YES! I almost wet myself. I cut off 2 pieces of hose approx. 1.5 inches, attached them to each end of the elbow. Then attached my new elbow to the appropriate ends and what do you know it worked.

      Mine was all brittle like it had gotten hot and dry rotted. I would recommend that all of you just go ahead and replace it now if you haven't done so. You are going to have to do it eventually I promise you. If you are remotely close to 87K miles be proactive and do it now.

      That being said - does anyone know howto shut off the Service Engine Soon light manually or does on eof the stores do it for free?
       
    22. scarletgem

      scarletgem New Member

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      Try disconnecting the battery for a while...good time to clean it up and then reconnecting it....I seem to remember it turned my light off. Sort of a reset.
       
    23. scarletgem

      scarletgem New Member

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      Has anyone ever had this problem with a 5.0 V8?
       
    24. Beausdad

      Beausdad Member

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      Usually that works, bur Ford has truly dropped the ball on the 3rd gen X's. No tranny dipstick, 4 wheel independent suspension, push button woman's 4 WD.

      Remember the good ole' days when you could work on your own trucks with a simple set of standard sockets and combo wrenches. I tell you what. Next vehicle I buy is going to be at least 20 years old. I need me a 1973 Ford Ranger Custom XLT Shortbed 4x4. Oh I long for manual locking hubs and solid front and rear axles and the ability to put a suspension lift on this piece of crap.
       
    25. scarletgem

      scarletgem New Member

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      No kidding..I don't even have the push button...AWD
       
    26. shibbz

      shibbz New Member

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      I think this is what I'll end up doing. I don't care if it's pretty, don't want to wait for a dealer part!
       

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