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Thread: Hard to Start 2000 MGM Only When Cold

  1. #1
    Goal was 'giving back', done by 2020.
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    Default Hard to Start 2000 MGM Only When Cold

    My 2000 MGM used to start super-fast even when cold, but by last winter, it hasnít wanted to start easily while cold, though it still does when warm. After fuel injector cleaner didnít magically work, I found the #8 plug was fouled in a way that the online charts indicate is from fuel additives or burning oil (lots of ash on the vertical part of the ground electrode), though the others looked fine. The plugs were well on their way to .056" at one-third of their lives, so I gapped them to .052". I then put in a new set of COPs, plus a new battery since a cell happened to crap out. (For those who strip the plastic holes for the COP screws on aftermarket intake manifolds, I managed to drill through the holes for cylinders 1 and 2 using a hand drill and resorted to zip ties.)

    The hard start when cold problem was still there, though it was obvious that the electrical side was working at or near its peak, so the car gods were happy with that. Multiple primes of the fuel pump havenít helped, so Iíve been figuring fuel injectors. I think at least part of the problem has been not driving much and not occasionally driving the much longer distances that I used to. I also hadnít used fuel injector cleaner in years since I never saw it on sale. Iím currently relying on fuel injector cleaner and driving with OD off, which might be doing some good. If things donít improve further, my next step would be to check the injectors using the Ď9V battery and carb cleanerí trick. I suppose I should make an effort to do compression testing too if it comes to that, though I donít foresee myself trying to fix a compression problem.

    I saw the same type of hard start issue raised in various other places where all kinds of other stuff was mentioned, but nothing else struck me as probably applicable. Unfortunately, I never saw anyone reveal what their problem ended up being.

    If someone happens to know of a flowchart or something somewhere outlining the sequence of things that should be happening in the startup process, or doesnít mind coming up with something like that, it would be very much appreciated, as would any other useful insights/suggestions. Dunno if I will ever figure out the problem, but I will certainly post a definitive fix if I find one.

    2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
    mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

  2. #2
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    Do you have any way of datalogging? It might tell you if a sensor is acting up.


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    When was the last time you replaced the fuel filter? If you've been dumping cleaners into the tank it may have dislodged some junk that found its way into the filter. Hopefully not the injectors.

    I'd replace the filter and take it on a good hard run and see what you get.
    These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.

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    Check fuel pressure (can use a tire gauge, but you will destroy it as the gas will eat the rubber in the gauge - they will last long enough to troubleshoot the fuel pressure at the fuel rail). If you have good prime and pressure through the start process, it's not fuel supply related... if not, replace the filter first since that's typically the cheap option.

    When I had hard starts dealing with temps, it was the ECT being stupid. Didn't fail open or short so the ECM didn't throw a code. It failed static resistance. You can check to see if it's in the ballpark when cold with a multimeter on OHMS (resistance) settings.
    Should also check the ACT as well as either of those being in that failure mode will do stupid stuff like this.

    ECT: http://www.grandmarq.net/oldfuelinjection/page28.html
    ACT: http://www.grandmarq.net/oldfuelinjection/page29.html

    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
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    I'm thinking sensor(s) as well, but I don't know the 4.6 well enough yet. ECT and ACT came to mind but I'm used to the 5.0 and wasn't sure if the 4.6 has ACT sensor and. It experienced enough to know if temps affect MAF sensor.
    Vic

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    ~ 1991 Mercury Grand Marquis GS "The Ice Car" - Rotting Retired Winter DD
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  6. #6
    I'm an air-conditioned gypsy gadget73's Avatar
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    Its got an air temp sensor but not sure if its part of the MAF or in the air cleaner lid. At some point it moved from the lid to being part of the MAF but I don't know when exactly. Pretty easy to tell, if there is not an electrical doo-dad plugged into the air filter box right next to where the air pipe bolts up, its in the MAF.

    Possibly just cleaning the mass air sensor will sort it if the signal from it is flukey. Same with the air temp sensor itself. They don't go bad that often but if they get gak on them for whatever reason it can screw with the readings.

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    2000 it's still on the air filter box. That didn't combine with the MAF until 03 IIRC. It's pin 1 and 6 in the combined one and still uses the basic resistance same curve from what I can tell.

    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.
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    Overhead, some poor bastards are flying in airplanes.

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    I have an Autel AL439, which has more than paid for itself by localizing misfires to particular cylinders when COPs crapped out without triggering a code. I had a look at the live data with engine running at one point and didnít see anything out of sorts, but it hadnít occurred to me to get readings before starting the engine despite knowing the temp sensors were a possibility (duh). When I checked, the IAT was correctly reading 1C while the ECT was reading 27C. Iíll verify with a meter eventually and let yíall know how it goes.

    The fuel filter was replaced some time ago and is not due yet. I had checked the air filter box to make sure it wasnít clogged and that the temp sensor was clean, and Iíll check that sensor with a meter too for the helluvit. A mechanic said he cleaned the MAF when he changed the plugs ~35,000 miles ago, and Iím always careful with the filter seal since the boxes tend to warp, so cleaning the MAF wasnít high up on my list without a can of proper MAF cleaner on hand.

    The fuel injectors could still be implicated if the fuel pressure is good, no? Iíve read that the spray pattern might be off enough to prevent ignition in a cold engine but not a warm one, but Iím no expert. Iím not going to bother cleaning the injectors if the coolant sensor is the problem, though the Ď9V battery and carb cleanerí trick is something I would do if I ever do the PI intake swap. Hereís a quick video to show how easy it is:


    2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
    mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

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    Just when I thought I was going to get a break, the new coolant sensor from Ford is behaving the same as the old one. When the IAT was reading ~12C, the ECT was reading ~44C with a resistance of ~6kohms. When the IAT was reading ~2C, the ECT was reading ~33C with a resistance of ~8kohms, and the engine was still hard to start. This suggests to me that the new sensor is bad, which would be rather bizarre. Are the chart values in the links for the sensors standard for all makes of those sensors? If so, then I guess I have a clear case for a return based on the meter readings, which Iím guessing Iíll have to demonstrate conclusively since they donít allow returns for electrical parts.

    Curiously, there was nothing I could do to get a resistance reading from the IAT sensor, but the scanner shows it working properly. Does anyone happen to know what kind of witchcraft might be at play there?

    2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
    mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

  10. #10
    I'm an air-conditioned gypsy gadget73's Avatar
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    The links are specifically about the 80s and early 90s units, I have no idea if they changed resistance but it wouldn't surprise me if they did not.

    try measuring resistance directly on the sensor if you can and see how that compares to what the scanner has to say. If you have some wiring gremlins it might be throwing the readings off through the harness.

    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

  11. #11
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    Which sensor did you test? I donít know when Ford changed it but the early whales had a coolant temp sensor in the crossover and a cylinder head temp sensor under the intake.


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    Keep it easy on yourself re the sensors. Monitor the IAT and ECT temp via live data and drive it. Does it make sense for the length of drive you made? Keep in mind IAT will read higher than ambient depending on where the sensor is and as engine bay temperatures build up.
    And those temperatures you cited, those from live data on a stone cold engine thats sat over night before starting it? ECT wont take long to show on the sensor once the car is started if you had the engine running and got 32C reading.

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    Somewhat randomn, but where do you buy your gasoline from? More ethanol = harder start.
    Shell 89 might be upto 5% (stations that mix regular and premium) and Shell 91 is zero ethanol. Depending on geographical location shell regular might also have no ethanol.
    If you fuel up and any of the classic co-op style places (Co-op, farm supplier stations, Pioneer, expect ethanol in everything (that includes petro smell (worst offender in my opinion, they ruined sunoco 94 with ethanol when they bought them), and crappy tire)). And if you are in the habit of buying fuel at any hole in the wall place because its cheap, I'd be suspicious of water contamination.

  14. #14
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    The temperature readings are from the scanner, and that was dead cold before starting the engine. The 12C was upon installation, and the 2C was after waiting a few hours. Both coolant sensors top out at 94C, which Iím guessing is normal.

    The resistance readings are from a meter at the sensors. Silly me, I have service manuals on a disk but had not looked to them sooner. It looks like the graph and chart are still valid, as seen in this screen shot from the 2000 manual:

    Click image for larger version. 

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    Iíll call the Ford parts counter to see what they have to say about the seemingly abnormal resistance readings. Another step would be to check the voltage available to the sensors when unplugged and what the voltage drop is across the sensors when plugged in.

    Iím pretty sure my car has the cylinder head temp sensor, though my guess would be that it is limited to detecting overheating and not involved in the start process.

    I generally get gas at Costco. I had suspicions about water initially, but nothing is really suggesting a fuel quality issue. Itís the kind of hard start where lots more cranking is required before the engine even tries to fire off. Iím inclined to think that injector, compression, or fuel quality issues would involve sputtering along the way, but Iím no expert.

    2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
    mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

  15. #15
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    I tried another meter on the IAT sensor and got ~63kohms. I was able to replicate that with the first meter, so my problem was obviously something other than witchcraft. When I saw that, I had no doubt that the new coolant sensor was bad. The mechanics were already gone by the time I showed up at the parts counter with a meter, so I have to wait until tomorrow for them to verify the defect and order a replacement.

    2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
    mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

  16. #16
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    Bah. And humbug.

    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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