Running rough ... any ideas? | Ford Escort Owners Association (FEOA)

Running rough ... any ideas?

Discussion in 'ZX2 1998-2004 2.0L DOHC' started by steve60tuesday, Apr 15, 2019.

  1. steve60tuesday

    steve60tuesday FEOA Member

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    I've got a bit of a mystery on my hands, I'm looking for suggestions or guesses to get my engine back in tune:

    Symptom: Intermittent surging at low RPMs under partial to full load, with oscillating lack of power every 1-2 seconds. Normal power once I get to ~3+ krpm at full throttle, but returns at partial throttle. Worst when warm. Slight surge at idle. Getting worse every day, now it's difficult to accelerate uphill from a stop light.

    Vehicle: 2001 ZX2 auto, all stock, 102k miles. Plugs changed 1000 miles ago, which didn't seem to affect this problem for the better or worse. Timing belt is super old (possibly original?) but looks OK and the tensioner is still showing at the correct position.

    Diagnostics: There are no codes in the computer and no MIL even after 4 weeks of this nonsense. Code reader app (Torque w/ bluetooth adapter) reports sensible readings for mass air flow, O2, vacuum, temperature, and throttle position sensors, which combined with a lack of error codes, suggests that all these sensors are working. However, the ECU status seems to go back and forth between "closed loop using O2" and "open loop due to component failure" after warm-up, but with no other errors or clues visible to me.

    The engine idles fine (albeit with a slight surge), but if I prop the throttle open slightly in park (e.g., to 2 krpm), the RPMs will slowly drop over the next 10-20 seconds all the way to bogging and stalling the engine. The whole while with reasonable readings from the sensor son the computer. But, if I let my foot off the gas before stalling, it will stumble but recover to a stable idle. So I think IAC and TPS are working fine.

    Next steps, unless someone else has a better idea: I think I'll start replacing sensors like O2 and MAF?

    Thanks!
  2. Swift

    Swift FEOA Donator

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    You did plugs, but did you get wires at same time?
  3. steve60tuesday

    steve60tuesday FEOA Member

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    Nope I didn't... Just ordered a set. Thanks for the suggestion!

    I changed the fuel filter over the weekend, which didn't change anything, but I figured it couldn't hurt.

    Problem continues to worsen and the engine will now sometimes stall out at idle with the A/C on when fully warmed up. Still no fault codes or MIL.

    Does anyone know if a specialty code reader might do a better job of figuring out what's going on? I'm just using a bluetooth adapter with the free Torque app on my phone.
  4. steve60tuesday

    steve60tuesday FEOA Member

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    This car!

    New plug wires, new o2 sensors, continues to get worse.

    Now its leaving the fan on intermittently, as well as either a fuel pump or evap pump I can hear in the trunk. Thus is with ignition off and key removed.

    Battery dead 3 times in 2 days.

    Driving me crazy.
  5. Defunct SR Owner

    Defunct SR Owner FEOA Member

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  6. Texaszx2

    Texaszx2 New Member

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    Have you tried checking for codes while the car is running?
  7. steve60tuesday

    steve60tuesday FEOA Member

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    OK, here's a quick update. I was about ready to scrap the car when things finally started improving!


    The low point: The car would randomly turn on the fuel pump and/or radiator fan, unattended with ignition off, causing a dead battery. Even if I finessed the key out of the ignition just right, and the sun and the stars aligned so that neither of these things remained on when I got out of the car and tiptoed away… a few hours later they'd randomly turn on and drain the battery anyway.


    I got in the habit of disconnecting the battery whenever I parked, and I started daydreaming about buying a newer vehicle. I probably spent a week hemming and hawing over which options I'd choose for my 2019 Ford Raptor, and I also spent a lot of time deciding which Gulfstream model best fits my lifestyle (answer: the G650ER, obviously).


    But as it turned out, neither of these alternatives fit my budget. Meanwhile, the ZX2 ran like crap. Not always, but essentially almost always. Sure, if the battery wasn't dead, it'd fire up and run smooth for a minute but this would give way to surging and stumbling under any conditions other than high-rpm WOT. Idling was iffy, even in neutral (this is an Auto FYI). Every stoplight was a battle of wits between my right foot and this stupid suicidal engine. And whenever I lost, I got pretty good at bumping into neutral and cranking halfway through an intersection without losing too much speed.


    The missing clue: My heater core went out a couple months ago. I drove around with the occasional aroma of coolant form the air ducts for several weeks before I decided to do anything about it, and even then, due to difficulty sourcing a replacement heater core, I drove for several more weeks with the leaky core bypassed but still full of coolant.


    The hypothesis: Coolant from my leaking heater core, although it never even got to my floor mats, dripped down onto an important electrical connector located behind the PCM and directly in the drip path for a leaking heater core.


    Obviously, the failure of a heater core was a freak anomaly that is less likely to occur than winning the lottery while being stuck by lightning in clear weather. Plus, in the late 1990s--when the ZX2 was designed--even the world’s best supercomputers couldn’t have predicted that an invisible force would mysteriously channel this leaking coolant onto the electrical connector located IMMEDIATELY BELOW the air box. (Of course, today, physicists call this force “gravity!”)


    What I can surmise today is that a supernatural reaction occurs between this leaking coolant and a mysterious “electricity” that lurks within wiring connectors of modern automobiles. The result is a curse so terrifying that I am hesitant to name it… the GHOST of ENGINEERING COMPETENCE PAST. Anyway, my car was haunted by this terrifying ghost for several weeks.

    Photos
    img1.png
    Here is a blacklight photo showing the problem area. This makes the coolant light up yellow. As you can see, the whole thing was designed by idiots, so the connector got wet from leaking coolant, even though hardly any coolant actually leaked out. It is really impressive how such a small amount of coolant caused such a big problem, and honestly, it probably took a whole team of incompetent engineers to come up with such a thoroughly terrible design.

    img3.png
    Here is another photo showing how there was coolant in the connector. As you can see, it was not good, and very bad.

    I tried several approaches to dry out the connectors and wires, none of which immediately helped. But, after several days, my car started driving better.

    Now, the car only runs poorly for the first minute or two, and it hardly ever turns on the fan or fuel pump when the ignition is off. I can leave the battery connected all the time. I don't completely trust it, but it is back to being a mediocre commuter car, which is all I need from it.

    I am still hoping that I win the lottery or that the sun explodes, but overall my situation is a lot better.
  8. KirkComer

    KirkComer FEOA Member

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    Holy cow. I'm thinking I should replace my heater core just for safety sake. Maybe you can replace with parts from a junkyard... assuming the jy car didn't have heater core problems either. lol Thanks for sharing!!
  9. steve60tuesday

    steve60tuesday FEOA Member

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    6 month update. Car still works.

    It was the PCM connector being wet.

    That is all.
  10. marclar

    marclar Moderator Staff Member

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    I like the part on the pic where it says "designed by idiots"

    well,... its a ford.. so.... YA
  11. DrZX2

    DrZX2 FEOA Member

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    Ford engineer: So, as you can see here, we’ve strategically placed the heater core directly above the PCM harness to save space in the dash

    Ford quality assurance guy: So if it leaks it’ll go all over the connector and cause problems, right?

    Ford engineer: Oh f#&k yeah...it’ll jack your sh*t up real good

    Ford QA guy: ........Awesome

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