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Thread: Hard starting, won't idle, won't rev - 2000 Grand Marquis

  1. #1
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    Default Hard starting, won't idle, won't rev - 2000 Grand Marquis

    Hey folks. Trying to help my friend with a 2000 Grand Marquis, but we're both kind of stumped, and neither of us are particularly "bad at cars"...so we're hoping there's someone out there who might have some thoughts.

    History:
    Approx 10L of old stale fuel was recovered from a running vehicle that was having some work done on it.
    That old stale fuel was put in the 2000. The source vehicle ran without issues but the gas was old and smelled bad.

    Later that day, but not immediately, the 2000 began showing mild misfire symptoms while driving. An intermittent flashing CEL began during this time, but it would not consistently flash even when the car was misfiring aggressively.
    Decided to dilute the bad gas, filled tank with premium.
    Drove car from gas station to shop (workplace) with no change in symptoms.
    Car was parked for a few hours.
    When leaving, car started, but had difficulty idling. It was revved a bit to try to warm it up quicker and clear the misfire. All 4 cats were glowing within a couple minutes of this (not surprising given running condition).
    Drove car home, found it was misfiring in extreme ways causing significant reduction in power. Max speed the car would reach was about 60kmh. Violent misfires jerking whole car.

    Car has mostly been parked for a few weeks since then. The battery has run flat and been disconnected multiple times, which has not appeared to cause any change in behaviour.
    Problem has worsened to the point that the engine is very hesitant to start at all. When/if it does, it sounds to me like it has bad ignition AND cam timing (combustion is happening at totally wrong times), and it does not respond to throttle input, including WOT, at all.
    If the MAF is unplugged, the car will start every time, but still hesitantly, and still runs like it is out of time, but will respond to throttle input and will hesitantly rev.
    It usually does not show a CEL (flashing OR solid). It has to be running for a relatively long time before the CEL will give any sort of output, but it will be running terribly the whole time leading up to that.

    Car showed codes for misfires on 2 cylinders, we don't recall which ones at this point, also a MAF code while MAF is unplugged, but no MAF code while MAF is connected.

    Injector spray pattern was unscientifically studied by lifting the fuel rail and injectors with engine running. 2 injectors on right side bank had bad spray pattern but all were cycling open/closed and flowing fuel.
    All coils changed - no change. Cheap Amazon parts used because we figured even if they are garbage parts, they should at least change the issue if we find the problem part.
    Plugs changed - no change. Cheapest copper plug that the part store computer said would fit the car. The plugs that came out looked awful, but we believe that was an "effect", not a "cause" in this situation.
    Drained all fuel and refilled with premium - no change.
    Tested fuel pressure - it makes about 35PSI on first prime and sustains 35-40PSI while engine is running, so we know there is no fuel flow issue.
    Changed all 4 injectors on right side bank which is where 2 of the misfires were - no change. Cheap Amazon parts again, for same reason as coils. Even crappy parts should have changed the symptoms.
    Cleaned the MAF - no change.
    Changed MAF with a technically incompatible one (mostly but not quite) from a different Ford vehicle - no change.

    Pulled the PCM. Found water sealed inside the connector.
    Used MAF cleaner to clean and dry out the connector.
    Opened the PCM. Found these units contain only two electrolytic caps, the others are ceramics. One of the caps, the larger one closer to the connector, does have a bulged top but it is not split open and hasn't leaked.
    No burn damage or any obvious faults besides the one cap.

    We are at a loss at this point. I do not believe it's a fuel system issue anymore despite the fact the symptoms appeared the same day as giving the car questionable gas. It seems to just have been coincidence.

    I have been trying to figure out if there is a way to make it run at "base timing" because I think that will tell us useful information, but it seems the EEC-V cars do not offer that - am I missing something?

    PCM is very suspect and we are trying to borrow one to try (actually trying to pick up a whole second 2000 for parts-swapping adventures). We don't have shop manuals for this car unfortunately, and all of mine are of course for boxes.

    Any thoughts, please?
    Last edited by kishy; 12-13-2020 at 05:12 PM.

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    2 decades of DDing Box Panthers, now in a Whale VicCrownVic's Avatar
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    My thoughts were covered by the troubleshooting you described. If the border wasn't closed you could have borrowed my spare, working PCM and '98 Ford Service Manual (not 2000 but better than nothing and mostly the same).

    I agree that the symptoms starting after the questionable gas seems to be coincidence.
    Vic

    ~ 1998 Mercury Grand Marquis LS - new DD
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    ~ 1997 GMC Yukon - wannabe winter DD - returning summer 2020, I finally have an engine
    ~ 1991 Mercury Grand Marquis GS "The Ice Car" - Rotting Retired Winter DD
    ~ 1989 Mercury Grand Marquis GS - Rotting Retired DD
    Gone but not forgotten:
    ~ 1988 Country Squire ~ 1987 Ford Crown Vic

  3. #3

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    Personally, I donít believe in coincidences. My thought is a bad maf and some bad gas. There could be water in it too. Change the fuel filter, run some sort of fuel stabilizer and run the tank down.


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    I'm an air-conditioned gypsy gadget73's Avatar
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    i wouldn't think that 2.5 gallons of stinky fuel that has since been diluted would still be causing this much trouble. I might swap the fuel filter but considering you've changed half the injectors and it made no difference at all I'm thinking its got to be something deeper. if its holding fuel pressure after the engine is shut off the injectors aren't stuck open and flooding the engine either.

    These do run on a crank position sensor for everything. If that is dying or just has water in the connector it can get real stupid. I'd think it would set a code though. I think the crank sensor is down on the passenger side.

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    I absolutely believe we have ruled out the fuel system as the main problem here. The engine is running in a manner that suggests it is getting everything it needs, but the computer is giving it to the engine in the wrong amounts or at the wrong time, or both. Indeed, there is no leakdown after shutting off the engine...we let it sit around a half hour and it didn't come down in that time.

    It is mind boggling to see a throttle plate completely open and the engine not increase in RPM even a little bit. Really a weird thing to see and wrap your head around. It's like the computer instantly pulls fuel so there won't be enough available for that new air. Very weird.

    I hadn't considered the crank sensor. It is worth noting that the day this all went south, it was raining. That was well over a month ago now, but water sometimes stays in places you don't want it. We'll look at the crank sensor.

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    A couple suggestions thrown at me in other channels:

    -Cam sensors. Apparently this failure mode is near identical to what happens to a Taurus SHO when the cam sensor(s) go bad, and they won't throw codes for them.
    Does this car even have them? I see I can buy them for it, so I presume it does.

    -Clogged cats.
    We have actually long suspected restricted cats on this car but it has always worked well enough to not really be a concern.
    The driver side is currently cut apart between the upstream and downstream due to the previously mentioned attempted theft of cats.
    We can see chunks of the upstream sitting in the pipe as it is broken apart, so the driver side is reasonably free-flowing.
    We do not know about the passenger side as it is still attached.

    Our thinking is this:
    Even with a significantly blocked cat a car will typically still start and idle normally for a short time before problems develop.
    I do have a backpressure gauge so we'll see if I can get to the upstream O2s, I'm not sure exactly where they are but I bet they suck to access.

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    I'm thinking clogged cats. My brother had a '93 or '94 waaay back when before I even bought a 99 piece tool kit and was still living with parental unit. Was my first accurate diagnosis ever once I got to the car. I remember starting it up, it idling like shit and stalling out. If you started it, you had it give it throttle to keep it alive and it struggled hard. It didn't take any time at all for it to run like crap either. Car ran great a few days before or whatever my brother said at the time. So it just seemed odd that all of a sudden the car ran like turds. Took it to a shop I knew at the time, they gutted them (chunks made it into the resonators at the rear of the car and stayed for life, rattled something awful under throttle..) but that fixed it up.. But full throttle and basically nothing out of the engine sounds like clogged cats or like you suspect, retarded timing. So I'd clear that passenger side and further establish driver's side is clear as well. You can also drill a hole before the cats and hook a pressure gauge up to it to see if you've got back pressure, rather than tear the exhaust apart. Does it generate a lot of "steam" like exhaust smoke while it's running? I once had the distributor out of Ashley's former '89 Town Car. I ended up putting it back in a tooth off, retarded like. Didn't recognize it at the time and took me a week or so to figure it out. That car started up and idled just fine though. However, it didn't move at all and barely revved up under full throttle, much like your 4.6 is doing... Posted on here about it and the smoking gun was the exhaust smoke- the thing generated tons of it, like steam. Members on here asked me about it and that's how we found it. I dunno, that's all I've got.

    Also, I've heard of crap parts straight outta the box. I'm not as technically savvy at all but I'd have swapped coils before buying them. That way I'd at least see the problem move. Hopefully the coils you bought are actually just peachy.
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    It makes sense that there would be a cam sensor since there is no distributor.
    óJohn

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  9. #9

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    They do use cam sensors but even with a messed up one the ecu runs in waste spark. I guess if the signal is erratic just enough to cause issues but not enough to throw a code it is possible thatís the issue. The connector I believe is on the drivers side timing cover near the power steering pump. Unplug it and see how it behaves.


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    I'm an air-conditioned gypsy gadget73's Avatar
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    cam sensor should be on the driver's side timing cover if I remember right. I also seem to remember its not all that important. Apparently they will run with it unplugged. I don't know exactly how much it affects things, possibly just used to confirm there isn't excessive slop in the timing chain or something. Spark and injector events are driven from the crank sensor so far as I know. If unplugging the cam sensor makes no difference, I'll vote for it not being it.

    I did have similar symptoms on my car when the MAF took a dump, but unplugging it made it run normal enough to get home. Since you've already done that and it didn't change anything I think its safe to say that ain't it.

    thats one cool thing about a lot of the sensors. If they are unplugged, the ECM will ignore them and just stick in some failsafe value. Diagnosis by unplugging things may not be the most hi-tech method but its cheap and effective.

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    Yes, driver's side timing cover.
    A few diagrams from my '98 FSM. #53 in the first diagram.




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    Vic

    ~ 1998 Mercury Grand Marquis LS - new DD
    ~ 1991 Mercury Grand Marquis LS "The Scab" - plenty of rot, summer DD
    ~ 1997 GMC Yukon - wannabe winter DD - returning summer 2020, I finally have an engine
    ~ 1991 Mercury Grand Marquis GS "The Ice Car" - Rotting Retired Winter DD
    ~ 1989 Mercury Grand Marquis GS - Rotting Retired DD
    Gone but not forgotten:
    ~ 1988 Country Squire ~ 1987 Ford Crown Vic

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    No mention of fuel pump yet
    Do you know what the fuel pressure is?
    ..

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    check the intake bolts for proper tension. My wife's car (2000 cv) did this BS and the intake manifold was loose. Noticed the issue because there was a slight leak of coolant at the thermostat housing. Tightened up all the bolts and no more issues.

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    Thanks all.
    Fuel pressure was mentioned in OP, we have no confidence issues in the fuel system at this time.

    Friend has confirmed cats are not the issue. The driver side upstream was definitely a bit melted and broke apart, but is able to breath freely currently, and he's saying after cutting the downstream off that the upstream on the passenger side can also flow freely. I haven't seen it to know exactly what he's done, but I trust his assessment.

    Having him investigate intake related concerns, he says if it has any vacuum leaks they are minor only - so no massive gaps at the heads. It's a junkyard-scavenged aftermarket intake with aluminum crossover and I recall he had to work some magic to make the water passages mate properly. The car has worked properly with this intake before.

    Because of how significant the change is when the MAF is unplugged, this does seem like an engine control issue rather than a mechanical issue, but since the computer doesn't seem to understand anything is wrong, it's difficult to narrow down.
    Last edited by kishy; 12-15-2020 at 03:22 PM.

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    There were no codes with my wife's car either. It just ran like crap. Very small leaks between the intake and head. I think it was consuming most of the leaking coolant in #5 at the time which is why we never really saw any puddles under the car.

    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
    Quote Originally Posted by gadget73
    ... and it should all work like magic and unicorns and stuff.
    Quote Originally Posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

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    I'd be changing the fuel filter. You might have the pressure but not the volume. Who knows what that old fuel sludged up in the existing filter, or even if the existing filter was on the verge of causing problems even with good fuel. Not to mention any foreign debris that may have been introduced by the transfer vessels.

  17. #17

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    Having worked at a gas station in my youth, "there's nothing as expensive as free gas".
    Even diluted, if it's sludge and varnish then it's not going to burn as well. The stuff in the tank is exposed to air; the stuff in the lines is not. So the donor car will run well on startup, but maybe not much longer. Once the gas is mixed from running the pump/return line, 20 years of condensation and sediment is stirred up in there.
    Drain it out and use it for a bonfire. On a carb'ed car with no return line, might be able to run a few miles before it conks out.

    On OP's car: Drain as much as you can. You've added gas to it and the gunk is on the bottom, so not sure of the best way to get it out without getting a lot of the gas you just added. Water and sediment sink to the bottom (fuel pump/pump sock) but if the sock is gunked up running it out with the pump means you'll be dropping the tank next.

    If it was my car, I'd drop the tank, empty it, scrub it with a rag, new fuel pump sock, new fuel filter. A can of injector cleaner and 4 gallons of fresh gas (4 gallons in a 5 gallon can so there's room to pull it all out if I need to drop the tank again: never top off the tank when dealing with fuel issues, or at least know you have a big enough container to put it all in before you start!). Then get back to basics on diagnosing the start and run.

    A long way back, as a dumb kid at the aforementioned gas station, I was doing an oil change. A kid came in with his grandad's Oldsmobile diesel. A Cutlass, I think, but it was a looooong time ago. He puts in 10 bucks, which was probably about 10 gallons back in those days. Then realizes: this "diesel" has been replaced with a gasoline engine, the only diesel part left on it is the lettering on the trunk lid.

    So we siphon out the tank and get him filled back up with gasoline. There's about 12 gallons of mostly diesel in jugs in the shop. We've got a waste oil burner and it's been cold so we're almost out of oil, I know we can burn diesel in it. I dump it into the basically empty waste oil tank and fire it up. About 10 minutes later there's a series of bangs but everything seems okay. More smoke than usual from the chimney pipe but it's running so after a few minutes I figure everything is okay.

    Next time we go to run the WO burner, it won't light. Apparently there wasn't enough gas to do serious damage, but when it fired up it damaged the igniters in the furnace. Heater tech told us it could have done serious damage if there was much more gas in there. Got a reaming from the boss (but learned a lot about setting up oil burners).

    Plenty of cars and motorcycles came to us with fuel systems gummed up from free gas. "I sold the boat with a 2 stroke, realized I had a couple gallons left, so I just dumped it in the truck..." "It's been in the garage for a decade so I figured I should just use it up..." "We were having that old junker towed out of the back yard, and thought I could save the gas from it..." "It fired right up, but as soon as I got halfway around the block it stopped dead..."

    So, yeah. Nothing so expensive as free gas. Maybe in a mower or weed whacker where you can turn it upside down and shake it out, but not in a truck. Heck, I got a load of bad gas from a gas station in 2004 in my F150 and I couldn't use the rear tank for years. Clogged the pump and tank selector valve and stupid me kept trying to burn it in batches after separating out the water. Spent a lot more in filters than I saved in gas. Should have just capped it off, or dropped everything and worked the system over from back to front, but I'm not that great at taking my own advice (it ran great on the front tank, so if I just use the rear tank a few minutes at a time to use that gas up...right??)
    Last edited by bgreywolf; 12-16-2020 at 03:38 AM.

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    Sorry I missed the part about fuel pressure in the OP.
    Does the the fuel pressure rise with RPM?
    ..

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    I just re-read my post and I apologize if I was a bit cranky. Free gas (and multiple other instances of "completely change the design to save 5 bucks because someone gave me a 3 buck part") is one of my pet peeves; usually because I have to help people fix it, and because I warned them before they did it, then they object to putting things back to the way they were when they worked, and then they do it again as soon as I'm gone.

    OP, I hope that it's not going to require dropping the tank. My most recent go-round was a friend who used the in-tank pump from his parts van instead of a $30 new one...and then immediately put over 25 gallons in, only to have the old pump seize up that afternoon because it had been sitting in a tank full of old gunky gas for over a decade. Again, sorry for the rough reply above.

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    I'm an air-conditioned gypsy gadget73's Avatar
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    you can always tell who has dealt with things too many times by their reply

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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