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93 4.0 expo rough idle power loss ((PLEASE HELP))

Discussion in 'Under the Hood' started by toooofast, November 12, 2011.

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    1. toooofast

      toooofast New Member

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      City, State:
      laguna niguel, ca
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      93 expo 4.0l
      Ok ill get right to it my expo has a idle like its miss firing likes to run better it seems when it cold out but it really picks and chooses when it wants to run right. Under load its very sluggish bad gas Mileage and power loss plus it seems to start going and the engine wants to just kick in and run better not always though. When in gear but at a stop light it some times drops down in rpm,s and kinda boggs and idles really rough. Checked the codes and they said EGR, 02 SENSORS but that's it. I can't figure it out. Any help would be very much appreciated.

      Things replaced
      Coil pack
      Plugs and wires
      EGR
      fuel pressure regulator
      fuel filter
      Vac lines
      02's
      Cleaned MAF
       
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    3. Roadrunner777

      Roadrunner777 Well-Known Member

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      94 4x4 Sport 88k
      Can you get a fuel pressure reading when it is running rough? Also, can you give us exact codes please?
       
    4. toooofast

      toooofast New Member

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      Pressure is fine. Codes are.

      KOEO
      335
      10 not sure what this is
      173
      336
      536
       
    5. toooofast

      toooofast New Member

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      Also these codes don't always come up it might be my reader but i can tell when its going to work i can hear the ECM come on and then the codes come up.
       
    6. Roadrunner777

      Roadrunner777 Well-Known Member

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      Ok, I'm going to let someone good with codes take over here, I'm away from my code books right now and sort of fighting another battle. Good luck!
       
    7. Spook

      Spook Member

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      Have you checked for vacuum leaks or loose lines?
       
    8. toooofast

      toooofast New Member

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      Yes i have replaced all vac lines.
       
    9. FLwireman

      FLwireman Member

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      City, State:
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      Innova 3145 Code reader book says:

      335 EGR sensor circuit (ckt) voltage higher or lower than expected.
      10 Not a fault code- it is to signal the operator to perform Wide Open Throttle test.
      173 HEGO (HO2S) sensor fault/lean
      336 EGR sensor ckt voltage higher than expected.
      536 Brake on/off ckt not activated during test.

      This is from the book that came with my code reader. You can find the manual online for free. I read it before I bought the tester. $32 at O'Rielly's, because I ain't swift enough to read the blinks.
       
      Last edited: November 12, 2011
    10. toooofast

      toooofast New Member

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      Yes i have the same tester i replaced the 02 sensors and the EGR. Same problem didn't do a thing. But the wide open throttle does that mean i need a new IAC? Its just not idleing all crazy it goes up to about 1000 rpm's in park sometimes but hardly ever.
       
    11. Roadrunner777

      Roadrunner777 Well-Known Member

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      I wonder if this is a flakey throttle position sensor. Search around, there's a test for the TPS here somewhere.
       
    12. toooofast

      toooofast New Member

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      I thought of that to but its not throwing a code for it. Plus if it was that wouldn't it just go crazy on rpm's all the time. When my expo does jump on rpm's its only in park at idle like it has a choke it never does it when in drive and it hardly ever does that anyways.
       
    13. toooofast

      toooofast New Member

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      Or do you mean that may be why it through that code #10 for wide open throttle. Faulty TPS?
       
    14. toooofast

      toooofast New Member

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      Bump
      Just need help
       
    15. benjammin97624

      benjammin97624 Member

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      fuel pressure can be fine and not volume. fuel pressure test conforms that the fuel pump works it don,t test how well the fuel pump works. you said you have replaced the fuel filter, pressure regulator, and other stuff. have you tried the air filter. if that's a mess it would cause those problems. loss of power and hesitation. when you unplug the vacuum line to the pressure regulator and see in there is vacuum. you don't want to see gas coming out the fuel pressure regulator. you also should notice a rise in rpm once the vacuum line is disconnected. try your gas cap as well. make sure its a vented gas cap. the system gets pulled into vacuum and cause the tank to colaps or suck its self in. also resulting in poor idle and fuel mileage. this requires more surgery but the injectors could be leaking. you can test that by a fuel pressure drop test. that's all i can think off the top of my head. i hope this helps. oh your tps will not throw a code necessarily if there is a dead spot all the PCM (brain) will think that the driver had let off the throttle than floored it. you can check that with a digital volt meter. of coarse connect to a ground with the black lead and the red lead into the signal wire. with no throttle you should get about .3 volts or more. slowly move the throttle and watch your meter. you should see the voltage increase
       
    16. Ageman

      Ageman Elite Explorer

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      After doing a lot of reading on the forum about rough idles I have to ask you to check your intake bolts. According to some forum members some bolts tend to loosen up and cause air to come in and can cause all kinds of code issues.
       
    17. toooofast

      toooofast New Member

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      Thank you all very much for your replays. I did change my air filter to a brand new one when i cleaned my MAF i also sprayed around the intake and changed all vac lines to rule out leaks. I will try the gas i know mine is vented but ill just replace it. Ill have to replace the TPS and the IAC to rule those out. I'm just hoping its not the injectors. Any other help or tips would really be appreciated.
       
    18. toooofast

      toooofast New Member

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      Still have the problem. Any more suggestions?
       
    19. SwaintaN

      SwaintaN Well-Known Member

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      maybe i missed it did you do a test yet on your fuel rail to see what your gas pressure is?

      when you say power loss as in electrical or hg/torque

      sorry if i missed it, long night.... i had the same problem, where the idle would drop way to low and didnt feel like it could pull its own weight, turned out to the the FPR, while changing it you might as well do fuel injectors... i can give you a link from the guy i got mine where you get all 6 for 100.00 w/ warranty

      VERY RANDOM.. have you checked your Negative to your battery?
      OR
      After replacing everything did you clear the codes?!?

      edit: what was your fuel pressure test readings??
      edit 2: what plugs and wires did you use? did you gap them right?
       
    20. arcblue

      arcblue New Member

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      This sounds very similar to what mine is doing; I've just lived with it because I haven't found the problem and neither has anyone else I've taken the car to.

      On mine, most of the time the idle is randomly rough in drive or neutral/park, with a slight miss noted. Sometimes I can detect a miss under acceleration too. Power seems to be slightly down and mileage too, though I also had removed the octane shorting block years ago to fix pinging.

      After coming to a stop, while in drive, the idle will be about 800 rpm (or over 1000 if in neutral), then after 15-30 seconds, the idle will suddenly drop to 500 and then return to normal (625-650 in drive), but lumpy.

      However, sometimes it will idle almost perfectly smoothly.

      I suspect on mine, the FPR is going bad but haven't replaced it yet (I sometimes smell fuel, and sometimes I get a really rough idle after a hot start - but even these symptoms are intermittant). I've replaced the IAC, plugs, wires, battery, cleaned MAF (maybe I should replace it entirely?), checked vacuum lines, etc. with no change. No CEL and no codes.

      I'll see if my problem continues after a new FPR but I suspect in both our cases, it could be the PCM. It seems to be the only thing left if you've checked everything else, and could account for the symptom being random. I have also read about several people replacing that and curing idle problems (although there have been many other causes too).
       
    21. SwaintaN

      SwaintaN Well-Known Member

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      i know this is random but umm check your voltage supply etc... wiring can cause some messed up issues.
       
    22. Leith

      Leith New Member

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      Replace your MAF

      I had the same problem you have and I did everything that you have done so far too. Today I replaced the MAF ( about the only part left to replace ha ha )
      It fixed it completely!!!!
      Got it at Autozone for $76.00 there is a $60.00 core charge so take your old one with you to avoid that.
       
    23. Playtyme94

      Playtyme94 New Member

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      im sorta having the same issue but with no codes... runs fine when driving but when im at a complete stop, seems to misfire.... anyone have any ideas??
       
    24. RALLIART15

      RALLIART15 New Member

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      So need some help guys, sorry to bring up a dead thread but saves me typing as I have the same issue but add maf to the replaced list.
      Current codes
      KOER
      411 412 538
      KOEO
      157 172 173 176 177 181 189 332

      Only had the truck a week now decided I missed my last one. Been playing with this a bit now and it's driving me nuts. Ran seafoam thru it with no change.
      I'm stumped..
       
    25. SwaintaN

      SwaintaN Well-Known Member

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      Is this what your looking for?... Clean your Maf with denatured alcohol and replace your o2s, ive always replaced o2s after a seafoam.

      411
      (R)
      Idle speed system not controlling idle properly (generally idle too high) - ISC
      412
      (R)
      Idle speed system not controlling idle properly (generally idle too low) - ISC
      538
      (R)
      System did not receive "goose" test - TESTS

      157
      (R,M)
      Mass Air Flow signal is/was low or grounded - MAF
      172
      (R,M)
      Oxygen sensor not switching - system is or was lean - Single, Right or Rear HO2S - Fuel control
      173
      (R,M)
      Oxygen sensor not switching - system is or was rich - Single, Right or Rear HO2S - Fuel control
      176
      (M)
      Oxygen sensor not switching - system is or was lean Left or Front HO2S - Fuel control
      177
      (M)
      Oxygen sensor not switching - system was rich Left or Front HO2S - Fuel control
      181
      (M)
      Fuel system was lean at part throttle Single, Right or Rear HO2S - Fuel control
      189
      (M)
      Fuel system was lean at part throttle - Left or Front HO2S - Fuel control
      332
      (R,M)
      EGR did not open/respond during test or if memory code, did not open intermittently - EVR or PFE
       
    26. RALLIART15

      RALLIART15 New Member

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      Appreciate that but I already had the print out of the codes.
      MAF is new, O2's are less then two months old as are plugs, cable, coil pack..
      I emptied out the cats.. Not to be an illegal driver but pulled the exhuast due to rattling and half the cat fell out so I jammed it all out with a pipe and that helped with the sluggish quite a bit so it was blocked and had back pressure but it is still stupid rich.. the whole reason for a V6 ranger was MPG's over a full size Dodge but this thing is only getting 10mpg
       

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