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Rough Idle and Engine Surge Under Load

Discussion in 'Stock 1995 - 2001 Explorers' started by ERUSH97XLT, October 9, 2008.

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    1. ERUSH97XLT

      ERUSH97XLT Active Member

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      Hello!

      My 97 Explorer (4.0L OHV) has a confusing problem:

      1. It has a rough idle only under a cold start. Once the engine warms up (or is started warm), the idle smoothes out.

      2. The engine surges, sputters, and skips under load.

      3. The "Check Engine" light is NOT on. I know it works.

      What can this possibly be?

      Thanks!
       
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    3. MustangP51

      MustangP51 Well-Known Member

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      Clean the Mass Airflow Sensor, the throttle body, and the Idle Air Control and see if the idling problem goes away.

      Welcome to the Forum
       
    4. crazya47374

      crazya47374 New Member

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      can you here a vacum leak under the hood maybe check that the pvc vaulve is still securley in place
       
    5. ERUSH97XLT

      ERUSH97XLT Active Member

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      Thanks for the advice guys!

      I'll check it all out and get back to you :)
       
    6. ERUSH97XLT

      ERUSH97XLT Active Member

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      Ok.... I took the mentioned components off/apart and cleaned them thoroughly with throttle body cleaner (NOT carb cleaner). I also checked for vacuum leaks; none were evident.

      The initial startup seemd fine. No rough idle, sputtering, or other abnormalities.

      A short, normal-condition test drive didn't yield any skips, surges, etc.

      I had similar results trying to resolve this issue when I reset the computer by disconnecting the negative battery cable, but the simptoms returned after a few days. This time, I'll give the engine a few days to reset itself before pursuing any further solutions.

      Thank you so much for your help! I'll reply to this post if the symptoms return.
       
    7. MustangP51

      MustangP51 Well-Known Member

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    8. ERUSH97XLT

      ERUSH97XLT Active Member

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      Oops! forgot to mention that.....

      I had a can of CRC's "MAF Sensor Cleaner" left over from cleaning my old ranger's MAF sensor. Seemed to work just fine.
       
    9. MustangP51

      MustangP51 Well-Known Member

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      Ok good. I was praying that you didn't use throttle body cleaner on it. That wouldn't have ended well.
       
    10. ERUSH97XLT

      ERUSH97XLT Active Member

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      Yeah, I learned that lesson the hard way :p:
       
    11. ERUSH97XLT

      ERUSH97XLT Active Member

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      *sigh*

      The rough idle and sputtering/surging is back! What could this possibly be? Could a sensor be faulty and the "Check Engine" light isn't coming on? I double-checked for vacuum leaks both with a gauge and starting fluid. Any other suggestions?

      Thanks!
       
    12. MustangP51

      MustangP51 Well-Known Member

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      The next thing I would check are the spark plugs and the plug wires. I am having trouble coming up with something else that would only make it run rough when hot.
       
    13. ERUSH97XLT

      ERUSH97XLT Active Member

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      Just to clarify, the engine runs rough only when COLD, not hot.

      I thought something might be wrong with the plugs or wires, too. I already checked the ones on the driver's side (they're the easiest to get to ;) ) , but I'll check the others, too.

      At one point in time, I had similar symptoms (except the rough idle was at all engine temperatures) and a spark plug was broken (yes, I romoved it in pieces). I wonder if that goofed up the whole engine for good.

      I'll check the remainder of the plugs and wires and get back to you.

      Maybe I should squirt some seafoam in the intake and see if that helps? The throttle body and IAC were pretty gunky, so who knows what the rest of the intake its like....

      Thanks!
       
    14. Andreas

      Andreas New Member

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      intake gaskets

      Hi,
      yesterday I have changed the gaskets of my intake system.
      I had rough idle when the engine was cold before, now it runs very smooth.
      The old gaskets especially the lower set where as hard as stone. When i prayed them out of the seats they just break into pieces!
      The new set cost about 40 euro here in germany,
      changing took me about 3 hours, and I'm no professional. I guess I have seen a how to do in this forum.
      Regards Andreas
       
    15. ERUSH97XLT

      ERUSH97XLT Active Member

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      Ok. I checked the spark plugs and wires. Nothing out of the ordinary. I re-gapped the plugs according to my Haynes manual (0.054") just to be sure. I think the "Check Engine" light would come on if there was a major problem here (i.e., misfire, circuit fault, ignition coil circuit fault, etc.)

      No change noticed. Here are some more specific idle and surging characteristics:

      The engine idles at 1000 RPM. Is this high? I mean, my old '93 Ranger (4.0L OHV) used to idle smoothly at about 500 RPM.

      The "surging" and "skipping" occurs around 2000 RPM whenever the engine is under load (i.e., climbing hills, smooth steady acceleration while maintaining 2000 RPM) in any gear and at any temperature.

      I'm "befuddled". The "Check Engine" light is NOT on, and I'm running out of ideas.

      Any more suggesstions?

      Thanks!
       
    16. BubbaFL

      BubbaFL Active Member

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      Sorry if this is obvious, but have you tried filling up with fuel at a different place than usual, or putting in a few gallons of premium along with a gas treatment product?

      I had a similar problem over the weekend - filled the X up Friday, and she got really angry later in the afternoon. No CEL, no vacuum leaks, etc.

      I put in a bottle of Advanced Auto Parts generic gas treatment and it got a little better but still wasn't running right, so I added a bottle of Chevron fuel system cleaner, and a few gallons of premium gas from a different station - fixed the problem.

      I suspect there was some water in the underground tank at the gas station, which caused the ethanol to come out of suspension and when I filled up I got too much ethanol/water and not enough gasoline. :mad: :thumbdwn: 10% ethanol blend :mad: :thumbdwn:!!!
       
    17. ERUSH97XLT

      ERUSH97XLT Active Member

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      Thanks for chiming in, Bubba!

      I usually run Valvoline's "Max Life" fuel system cleaner about every oil change (about every 3000 miles or 3 months), so I know my fuel system is clean (or at least I think it is...). I also use regular, 87 octane gasoline whenever possible. I haven't filled up with ethanol for a VERY long time.

      I'll try premium fuel next time (from a different station), along with another bottle of cleaner and see what happens.

      Thanks! I'll get back to you all!
       
    18. jamester_a

      jamester_a New Member

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      Partially working DPFE or EGR

      Surging under load is sometimes a symptom of a partial problem with the DPFE or EGR. There may be a stored code with a so-so DPFE even though your CEL is not on (ask me how I know - lol). Try to get your codes read. You can also do this simple test - unplug the EGR from the DPFE and and plug the vacuum hoses. You may get a CEL on startup, but ignore it and go for a drive and see if you still get surging under load.

      - James
       
    19. artgod33

      artgod33 Member

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      Wow this sounds like the exact problem I am having with my 96 5.o awd.

      I bought some MAF cleaner but am a noob and am unsure what and where to spray down.

      My cel is on p0446, p0171, p0174 for codes. If I clean the MAF per the p0446 code could that also clear the other two as a dirty maf could cause the engine to run itself richer?

      **BTW- I DO realize that buying a manual would answer most of my questions but I just had a baby 5 weeks ago and money is very tight right now.
       
    20. ERUSH97XLT

      ERUSH97XLT Active Member

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      Thanks A TON for the input, James!

      According to my Haynes manual, my symptoms and driveability issues may due too much EGR flow. I'll tinker around with the DPFE and EGR and get back to you.
       
    21. BubbaFL

      BubbaFL Active Member

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      Make sure the gas treatment you put in "removes water". The problem with mine wasn't a dirty fuel system - it was just bad gasoline. All of the local stations here have 10% ethanol blends now - I can't find non-ethanolated gasoline anywhere anymore.
       
    22. ERUSH97XLT

      ERUSH97XLT Active Member

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      Ok everyone! Sorry for the rather late reply. My explorer is still having issues, although some symptoms have changed:

      1. Rough idle still exists
      2. Driveability issues seem to have gone away after several doses of HEET for the past few months. I guess water got in the system. Thanks for that solution, Bubba!
      3. My CEL is on now. Its the P0171 code: "System Adaptive Fuel too Lean (Bank 1)".

      I've googled around for solutions to these issues. Here's what I've come up with:

      1. Common causes for the P0171 are due to dirty MAF sensors and vacuum leaks. Based on my previous posts, I have no vacuum leaks and my MAF sensor was freshly cleaned.
      2. Another cause I found is a faulty DPFE or EGR. Earlier, James seems to agree. This seems like a likely culprit becuase of my poor idle and previous driveability issues.
      3. A "last resort" cause could be a malfunctioning oxygen sensor that "tricked" the PCM into thinking it was running lean. This seems unlikely (or is it?) because of my driveability issues.

      I think my next course of action will be to replace the DPFE. It seems like the most likely cause of my explorer's problems. It's relatively cheap (~$50) and if its not the cause, I guess that's one less thing to worry about down the road.

      What do you all think? Anything else come to mind? Any input is appreciated!
       
    23. 96eb96

      96eb96 Well-Known Member

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      Rough idle when cold and a lean code is probably trashed intake gaskets. When the engine warms up metal expands and the crappy gasket can make a seal. Not uncommon for our engines at high mileage. There are upper and lower gaskets. I bet its the upper but you should probably do both. There are threads here how to do it. Not a terrible job.

      I would spend money on the gaskets before the DPFE.
       
    24. stang 1989

      stang 1989 New Member

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      i had the same problem with mine i ended up having two cracked plugs (the porcelin)
       
    25. ERUSH97XLT

      ERUSH97XLT Active Member

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      If my intake gaskets are cracked and leaking, wouldn't I have a vacuum leak? I tested for leaks with both a cold and warm engine. The gauge was steady at about 20-in. Hg in both scenarios. Could cracked gaskets cause a leak without any noticeable indication on the vacuum gauge?

      All the sparkplugs were fine, so I'm ruling that out. That was the first thing I checked; I have had broken ones before.

      Thanks for your input! What does anyone else think I should do?
       
    26. 96eb96

      96eb96 Well-Known Member

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      How many miles on your truck?

      Can you read the BARO parameter off you MAF sensor? This will give you a health reading on your MAF. Cleaning isn't always the answer.
      http://www.performanceprobe.com/ind...rmanceprobe.com/misc/tsb.php?article=98-23-10

      What are your fuel trims?

      From what I heard about the gaskets its very subtle and just enough to cause rough idle and codes. A few extra grams of air is hard to see on a vac gauge.

      Maybe try disconnecting the DPFE, or plug the vacuum line to the EGR. Yes you will get a code but that may eliminate the EGR system as a problem. I have a car now with a plugged EGR tube and there are no issues except for a code.

      Also, I would like to know the extended OBD-II info from the lean code. The scanner should report that. What engine temperature did it happen at? What RPM?

      I'm also curious to see the resolution. Keep the suggestions coming!
       

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