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When to change ignition coils?

Discussion in 'Stock 1995 - 2001 Explorers' started by sidneyhop, March 13, 2019.

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    1. sidneyhop

      sidneyhop Active Member

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      Im getting lousy city gas mileage lately and considering doing some maintenance to get it back to normal. I used to avg around 17-18 and now its getting 12.5 mpg in the city. Hwy mileage is still the same around 20 ish.
      Are changing the coil packs as a preventative maintenance necessary or do you just wait until they fail?
      Im also encountering a hard start issue where Ill have to turn it over a lot more than normal before it starts. It runs ok once its started though.
      Ive read the 02 sensors going bad are another cause of poor gas mileage.
      The only code is a med fuel vapor leak.
      Thanks!
       
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    3. koda2000

      koda2000 Explorer Addict

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      I've got 265,000+ miles on our '00 Mountaineer 5.0L on the original OE coil packs. It still gets the same fuel economy that it got when it only had 179,000 miles on it. 15-16 around town 21-22 hwy. My '01 Explorer 5.0L has 195,000 on it's original coil packs and gets the same MPG as the Mountaineer.

      Some may argue, but I see no point in changing coil packs unless they're causing misfires. O2 sensors are a different matter. They're only supposed to last 120,000 miles and can have a big effect on fuel economy w/out ever setting the CEL. My test is to stick a finger in my tail pipe. If it comes out black and sooty (same for spark plugs) it's probably time to think about changing at least the upstream O2 sensors. The downstream O2 sensors have no effect on fuel economy. I haven't had a reason to replace the O2 sensors in any of my Explorers or Mountaineers to-date.

      Some other things that can tank your fuel economy is a t-stat that's stuck open or a bad ECT sensor.
       
    4. sidneyhop

      sidneyhop Active Member

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      Ive never heard of the ECT causing poor fuel economy. Thanks for the tip. Ill look into that, hope its easier to change than the 02 sensors.
       
    5. sidneyhop

      sidneyhop Active Member

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      Sure enough, no sooty tailpipe so temporarily ruling out 02 sensor. Ill switch out the thermostat and sensor to see if that does the trick.
       
    6. sidneyhop

      sidneyhop Active Member

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      Inkeds-l1600_LI.jpg

      Is location 1 where the ECT sensor lives or is it 2?
      Thanks
       
    7. koda2000

      koda2000 Explorer Addict

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      I believe on the 5.0L V8's the ECT sensor is the one with 2 wires. The other one is the sender for the temp gauge, which should only have 1 wire on the 5.0L.
       
    8. CDW6212R

      CDW6212R Hauls the mail. Elite Explorer

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      I'd check the fuel pressure also given the hard starting. Yours should be a good 60-65psi at all times.

      Clean the IAC solenoid too, that affects idling the most but it sounds like a few things might do with some extra care. The O2's are good to change as maintenance, 125k would be a good point, so would be 100k, or 150k depending on how the fuel mileage is etc. How old are the plugs and plug wires?

      I did those things with my 98 after I had it for six months, usually I do that kind of thing earlier on. The PCV valve is the only thing I haven't gotten to yet, that monster is hell to just touch, let alone R&R. I bought my truck with 158k, I'm approaching 219K three years later.
       
    9. sidneyhop

      sidneyhop Active Member

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      Wheres a good place to check the fuel PSI? I changed the pump about 8 years ago.
      Its got 175k ish miles currently and never changed the 02 sensors. Plugs and wires around 3 years ago.
      The idle is fine, no problems there. It just takes an extra couple beats to start about half the time. Other times it starts fine.
       
    10. sidneyhop

      sidneyhop Active Member

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      This is for future reference in case anybody is looking for the ECT location. 5.0 v8 location (1) has the 2 wires and is where its at on my vehicle. Its closest to the thermostat.
       
    11. fast_dave

      fast_dave Active Member

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      @sidneyhop,

      Just saying - ever replace the Crankshaft Position Sensor?

      It's extremely easy to get to and replace; (2) bolts and It's located in a high heat, water, road grime, high vibration area (next to your crank pulley)...

      With the overall mileage you have on your Ex - it wouldn't hurt to replace it - some of your symptoms sound like it could be either the problem or part of the problem.

      200,000 Miles is about all you can expect to get out of them before they start showing their age.

      Standard Motor Products makes a great aftermarket one that has a super magnet on it, compared to the costly OEM Ford one.

      $18.30 at Rock Auto - PC325 = Pretty reasonably priced for all it does in the hierarchy of ignition parts you might be throwing at your Ex...

      LINK: https://www.rockauto.com/en/catalog...2462,ignition,crankshaft+position+sensor,7196

      [​IMG]


      Good luck and as always, Your Mileage May Vary...

      P.S. How's that gas filter doin'???
       
    12. sidneyhop

      sidneyhop Active Member

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      Thanks for the tip on the cps.
      Gas filter changed about 4 months ago trying to troubleshoot this problem. Didnt seem to have an effect.
       
    13. koda2000

      koda2000 Explorer Addict

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      To check fuel pressure, there is a port on the passenger side fuel rail. It looks like a tire valve and should have a tire valve-style plastic cap on it. You can use a fuel pressure tester or even a tire gauge (the round style gauge work best).

      As far as your crank position sensor - never hurts to clean crud off of stuff, but it the CPS isn't working the engine will not run. Period. It's a Hall-effect style sensor with no moving parts. It has a weather-tight electrical connector so there shouldn't be any water getting in there.
       
    14. fast_dave

      fast_dave Active Member

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      @sidneyhop -

      No problem - just asking the obvious since I saw no mention of the gas filter. Quite often the $15 Gas Filter is left out of the process, more than likely due to it's beer can size that gives the impression "how can that be clogged"?

      So - back in December, out of the blue, my Ex started experiencing some lousy city gas mileage issues - and I take the same route every day. Additionally, just as you are experiencing, my Ex wasn't starting instantly when I cranked the key. Both problems occurred at the same time so I knew something was up.

      Looked at the basics; My situation at the time was that the Ex had a Replacement Motorcraft Coil, Motorcraft Wires, and Double Platinum Champion Plugs and all parts had less than 10,000 miles on them. Also - no issues with the Camshaft Position Sensor making "squeaking" noise (Distributor Type Part located at the back of the engine on the 4.0 OHV). Less than year old brand new TYC fuel pump from Rock Auto and Motorcraft Fuel Filter - both replaced at the same time. Fuel Injectors are cleaned every 6,000 Miles with my pressurized fuel injector cleaner that hooks up to my Ex's fuel rail. IAC Valve & MAF Sensor are cleaned at every 3,000 Mile Full Synthetic Oil Change. That ruled out all of those parts and subsystems. So I was left with the factory original Crankshaft Position Sensor...

      So, I cleaned & inspected the factory original Crankshaft Position Sensor that had over 205,000 miles on it, drove it for two weeks, the two problems that I was experiencing remained the same. Then a third problem cropped up. On two separate days, on the same route I drive everyday to work every day, on a steep grade I take in 3rd gear, my Ex coughed out a single slight misfire (with no check engine light afterwards). That sealed the deal for me...

      Bit the bullet (lol), and handed over $20 to Rock Auto, to replace my factory Crankshaft Position Sensor with the Standard Motor Products offering. First thing I noticed when swapping out the factory original was that the new replacement's magnet was like a "super magnet" compared to the factory original.

      After replacement - and all 3 problems cleared up instantly. Ex is back to starting on 1/2 to 1 revolution, City gas mileage back to normal (16 mpg on winter blend), and no more slight misfire on my daily driven steep grade. Additionally, the engine is slightly smoother at idle...

      Here's a 5% off discount code for Rock Auto if you decide to pull the trigger ;-)

      5% Discount Code: 1191391E850C2F
      Expires: April 23, 2019

      Please enter this code in the ‘How Did You Hear about Us’ box to receive the discount. Please enter ONLY the discount code



      Hope that helps and as always, Your Mileage May Vary! ;-)
       
      Last edited: March 15, 2019

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