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Starting problem

Discussion in 'Stock 2002 - 2005 Explorers' started by Firebird68, December 30, 2017.

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    1. Firebird68

      Firebird68 New Member

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      Hi Everyone, I'm new to all this stuff, so bare with me. Here is a problem that is stumping me. Have a 03 Explorer, 4.0 litre. It starts great first thing in the morning. Idles great. After you have driven somewhere and shut it off and let it sit for a bit, when starting it again, it will catch,but only idle at about 300 then die. Turn key off then try starting it again, it fires right up.
      Fuel pump and filter less than year old. If fuel pressure was bleeding off,it would be hard starting first thing not after it's been run. If it's left for a couple of hours, starts first try.
      New IAC put on. Acts the same as with old one. Sometimes it will fire up,idle at 300,sounds like it's ready to die, then it seems the IAC kicks in and then idles fine.
      Tried different ways of starting. Turn key on,wait 4-5 sec for pump to run,no change. Turn key on, let pump run, turn it off, then back on and try, no change.
      This one has me stumped and a friend of mine,who is a mechanic, so any help would be great. Sometimes another set of eyes on a problem can see stuff that we don't.
       
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    3. TechGuru

      TechGuru Well-Known Member

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      I had a totally different vehicle with a similar problem, turned out to be the coolant temp sensor that told the ECU the temp. (It had 3 coolant temp sensors, 1 for ECU, 1 for cooling fan, and one for the gauge).
       
    4. john cris

      john cris Active Member

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      The temp sensor is worth checking as it's inexpensive . You can remove it and bench test it. Use a ohm meter to check it, cold should give a consistent reading as well as hot. If it's never been changed I'd consider just replacing it. Not sure if this is your issue but this might help the troubleshooting process
       
    5. Firebird68

      Firebird68 New Member

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      Thanks for that info. I'll look into that. I've been trying to figure out how temp affects starting.
       
    6. john cris

      john cris Active Member

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      In my experience, those sensors can lead to idle issues as they do report directly to the ECU
       
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    7. imp

      imp Elite Explorer

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      @john cris
      Depending on the failure, an ECT sensor can cause several severe conditions. PCM can "think" the engine is cold, and continually run rich, not allowing closed-loop operation, wasting fuel, or, think the engine is hot when it is not, and stalling will occur when cold due to lean fuel/air mix. imp
       
    8. Firebird68

      Firebird68 New Member

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      Just replaced water temp sensor, still doesn't start right away, but I'm going to give it time,see if something changes.
       
    9. Firebird68

      Firebird68 New Member

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      Just replaced water temp sensor, still doesn't start right away, but I'm going to give it time,see if something changes.
       
    10. john cris

      john cris Active Member

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      Hey.
      Hate to say but, if that were going to fix the problem it would have happened right away.
      Is it showing any codes?
       
    11. Firebird68

      Firebird68 New Member

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      That’s the tough thing with this problem, no codes.
       
    12. john cris

      john cris Active Member

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      Gotta ask,
      Have you done an online search to see what other folks have figured out?
      I would also check for vacuum leaks around the MAF
       
    13. Firebird68

      Firebird68 New Member

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      I don't think it would be a vacuum leak because there's nothing wrong with idle. It's just a issue with actual starting and firing.
       
    14. matt_k

      matt_k New Member

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      I've been a long time lurker, jumped on to say I'm having this exact same issue. The symptoms are very similar. For reference, I've got a 2002 XLT 4.0L 4x4 with 137k miles on her. FYI: no codes thrown at any point.

      Cold start would either stall or run rough, around 300 rpm just like you. If it stalls, the truck will fire right up the second start. Once warm, runs great, no issues.

      I have a question. Does your throttle hesitate just after the rough start? Mine will if I experience either a stall (and start it up on the second), or if it starts and runs rough. The hesitation on the throttle only lasts for 30 seconds or so. This is after the very low idle of 300rpm. So basically, start engine, runs at 300, jumps to 1100, hovers there for 30 seconds, then begins to lower as the engine warms. During that time, where it's running between 850-1100, the throttle hesitates when depressing gas pedal. After that, everything seems to balance out and the truck runs as it should.

      These are the repairs I've done over the past year. (In chronological order)
      • Fuel pump and filter: Symptoms: Similar as what is occurring now, however, truck would not start at all. If I let it sit, it would fire up no problem. After reading up on this forum and doing some troubleshooting, (smacking the bottom of the tank). The theory is a flat spot on the motor's arbor (which I read on this forum, forgot where). Which explains why it only happens when starting since the 02-03 has a return type, open loop, fuel delivery. I never opened it up to confirm though.
      • Replaced IAC: No change. It was looking pretty gunked up. For $33 on amazon, got a motorcraft replacement.
      • Cleaned MAF sensor: No change
      • ---- no repairs for 5-7 months at this point, I've just recently started after the gremlin again ----- The following is what I've done in the past couple weeks.
      • Front passenger wheel bearing hub: just mentioning
      • Master Cylinder, Calipers, ABS Module, All new brake calipers, Rotors, Pads, Ebrake shoes + hardware. unrelated, just mentioning. I had a bad front passenger side caliper and pedal was sinking a bit. Thought it was the caliper internally bleeding. Had to fix it anyway. Still sinked a bit. Changed MC, still sunk a bit, decided to change ABS, pedal is much better after that. Stops on a dime now. Everyone needs brakes fully functional, right?
      • Replaced EGR and PCV. The PCV was loose when inspecting, had a bit of a wiggle to it. Probably due to vibration. PCV was gummed up a bit. Not enough to cause failure, but you could feel when shaking that it wasn't as free moving as the new replacement. EGR was fine but swapped it out anyway.
      • Replaced Alternator: Unrelated to issues, it went out, needed a new one. Just worth mentioning.
      • Topped off coolant. I'm stupid. I didn't notice it was low =/ . After sifting through the forums and reading the temp sensor as possible cause I topped it off and got it back to the proper level.
      So at this point, the symptoms have shifted a little bit. They match yours more. For example. Cold starts, and I mean cold (it's been below 0deg F lately). Starts up no problem. But after I get to work, let the truck sit until lunchtime for maybe 3 hours or so, I need to do the two start dance.

      Yesterday I finally got a smoke machine to check for vacuum leaks. I've tested twice. Both tests have come back negative. HOWEVER, after both tests the truck started up perfect. I have read on the forum that intake gaskets could cause a leak when cold, then seal up once warm. Each test was performed when the engine was cold, and warm. I'm not ready to rule manifold gaskets out just yet. I'd like to smoke it out and get a stall condition afterwards. The cold/warm theory doesn't really apply in this case, as it should have leaked when cold.

      What I'm planning in the coming 2 weeks:
      • Valve cover gaskets: Left gasket is leaking a bit (drips every so often). So I'll use this as an opportunity to change out other parts while I've got it ripped apart.
      • Intake Manifold gaskets: If the gaskets are to blame, this should fix the problem.
      • Fuel Injectors: Because, why not =) I'm tearing everything open, should take on as many wear parts as I can.
      • New thermostat housing w/ sensor. I ordered this shortly after topping off the coolant.
      As you can see, I've got my Remington 870 loaded with a buck shot ready to rock and roll. I'm confident that the issue is either coolant sensor, or vacuum leak at the intake manifold. I'm leaning more towards the temp sensor at this point. Mainly due to the symptoms changing after topping off the coolant reservoir. Not sure if that is a coincidence.

      I have recently picked up an Autel Maxisys MS906TS (purchased a family van recently, rolled the cost of the scan tool into it [my rationalization to the wife]). I'm going to take a closer look at live data on both MAF, TPS, and Temp Sensor. After looking through the forums, I have a good idea what the operating voltage range of each sensor should be.

      I'm sure a lot of people will read this and say that I'm not properly diagnosing and just aimlessly throwing parts at it. Yes. You would be correct. I'm not a mechanic/technician by trade. I'm a software engineer. Having a family with two kids (both under 2 years old) my time is scarce and out weighs the cost of parts. I have to use what little time I have to my advantage and be smart with it. For me, the time I spend troubleshooting a part is about the same amount of time it would take me to replace (at least the ones mentioned [PCV, EGR, IAC]). So while some of you may think it's wasted money, for me, it's more time with the family. And I get the added benefit of not worrying about those parts failing in the near future. I'm already getting complaints from the wife about how much time I spend fixing the truck.

      I'll keep you posted on what transpires after I rip into the engine. It's supposed to warm up by me next weekend, I plan to use that time to do the repairs.

      Matt
       
      Last edited: January 6, 2018
    15. matt_k

      matt_k New Member

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      Quick update:

      I was able to get out of the house and run some diagnostics. No luck reproducing my stall/hard start issue. I hooked up the maxisys and grabbed live data for MAF, TPS, ETC. All of them looked good.

      I did three tests throughout the day to try to replicate what I've experienced. Which is:
      • Morning:
        Hooked up scan tool. Pulled live data for engine temp. Readout was +/- 10deg of ambient air temp. Did the 'wiggle sensor' test, subtle change (+1deg) in readout. On start, engine temp was 17deg F. No issues starting. Prior to coolant top off, this was also a stall condition. *seafoam treatment performed*
      • Noon: engine temp 85deg. No issues starting. Typically this is a stall condition
      • Night: engine temp 40deg. No issues starting. Allso a normal stall condition.
      Worth mentioning that it takes me a solid 2 minutes to pull up the live data prior to start. Which does not replicate typical behavior. Perhaps the time allows the sensor to send the correct voltage. I did notice a small leak in my thermostat housing. I have the replacement part, did not originally buy it due to leak (only just discovered it), I purchased it since it was cheaper to buy the entire housing with sensor and therm than buying them separate. Bonus.

      Along with the diagnostics, I performed a seafoam treatment in the morning. Allowed engine to get to operating temp. Slowly poured into brake booster vacuum hose. Added so a small amount to oil. Let sit for 10mins. Aggressive driving afterwards.

      I have not smoked it since Thursday. Evidence suggests this is a temp sensor issue (ECT). All of my issues have become less frequent since topping off the coolant.

      So far, no issues with timing chains. When I rip into the valve cover I'll do some inspections. I only have 500 miles on my last oil change. Next time I'll drop the oil pan and check for plastic. As of today, it sounds great. I've read on the forum that starting 2002 they updated the guides. I've also ready that a lot of people with 3rd gen will go have the guides blow out around 150k. I'm fast approaching.

      Tomorrow I plan to run the same test, but include smoke prior to start.

      It seems like my starting issues are evading me every time I've got the microscope out. Guess this wasn't a quick update =) . I'll keep at it and report back.
       
      Last edited: January 7, 2018
    16. matt_k

      matt_k New Member

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      Still unable to recreate my stall issue/rough idle issue. I've concluded that it's a bad ECT sensor.
       
    17. john cris

      john cris Active Member

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      Seems like dropping the pan and inspecting for plastic in the oil pump pick up may be worthwhile. At the same time I intend to pull the valve covers and maybe the front timing cover to inspect the timing chain guides. I also need to double check for codes.
       
    18. matt_k

      matt_k New Member

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      Yeah.. Good call. I'll be sure to do that too.

      I'm thinking that my primary jackshaft or balancer guide has gone. For the past couple years when rpms are above 2500, I hear some noise. It's not really a rattling sound. It almost sounds like air pressure releasing intermittently at a high rate (correlates to rpm). When I first heard it I didn't think much of it. And to be honest, I don't really recall when it started.

      After reading on the forums last night, I stumbled on someone talking about the 2500rpm+ rattle.

      I've got 137k on mine, so it's in ready for failure. Trying to delay it as much as possible. Will get a closer look at it over the weekend. I'm hoping that it's the balancer.

      Also truck has been running fine today. So I definitely think that it's the ECT now.
       

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