I have an 03 Ford explorer and when I take the key out the truck is still on and won't cut off what could it be

Asked by Jul 30, 2015 at 12:08 AM about the 2003 Ford Explorer XLT V6 4WD

Question type: Maintenance & Repair

3 Answers

4,025

This is a common problem that can be caused by a couple of things. Some people call this "dieseling" or "run-on". What is happening is; when you shut the ignition off, something, somehow is causing a couple of the cylinders to keep igniting, which in turn keeps the engine running, although "sputtering" pretty badly. This can be caused by excessive carbon build-up in the combustion chambers or on the piston tops which when hot, acts like little glow plugs. This is common on engines that run way too rich or have oil burning problems. Dieseling is a common problem with high compression / high performance engines, especially in warm weather or when the engine is hot. In this case, it is usually caused by running "cheap" gas with inadequate octane. In this case it can usually be remedied by switching to a higher octane fuel.

4,025

big cause for engine run-on is having the idle set too high, or the carb is misadjusted which requires the idle speed screw to be screwed-in too far to allow the engine to idle. When the idle screw is screwed-in too far, it opens the throttle plates too wide and actually pulls fuel through the main jets a little, so when you shut the engine off, the inertia of the spinning engine still pulls air (and some fuel) through the carb and into the cylinders and the heat built-up inside the combustion chambers is enough to light a few of the cylinders at random to keep the engine spinning and sputtering. Again, this is especially true with fuel that isn't high enough in octane. The more the octane, the less volatile the fuel. Even though the key is off, the engine won't stop sputtering because the throttle plates are opened up enough to still pass a little fuel and air. This is why more modern cars with carburetors (mostly 80's and early 90's cars) had idle stop solenoids that completely close the throttle plates off when the key is switched- off which completely shuts the fuel and air off, thus preventing run-on from happening. With an idle stop solenoid, when you turn your key on, it clicks into position which pushes the throttle linkage to the normal "idle" position, but when switched-off, it allows the throttle to completely close-off. Fuel injected cars don't have any Dieseling or run-on problems because the fuel is electronically pushed to the injectors via an electric fuel pump, and the injectors electronically fire, so with the key off, the fuel delivery completely stops. Carburetors aren't electric, so even when you shut off the ignition, the inertia of the engine still rotating is still sucking-in a little air and fuel, and as long as it is still rotating, the fuel and air is still flowing just enough through that carb to feed a couple of the cylinders. Even though the ignition is off, hot carbon in the cylinders can continue to ignite that fuel. There is another way to remedy this other than installing an idle stop solenoid, which involves the vacuum advance and the ignition timing. Even though the timing has nothing to do with engine run-on, (because the key is turned off and "ignition timing" is no longer in play), timing DOES affect the engine's idle when it's running. You can experience this when setting your timing at an idle. If you advance the timing - the idle goes up. If you retard the timing - the idle drops. You can manipulate the idle speed by using the vacuum advance by hooking it uo to manifold vacuum which will pull more timing (advance) at an idle, thus causing the idle to go up a couple of hundred RPM. Once this happens, you can back down the idle speed screw a bit which will drop the idle back down to a normal RPM. Because you just closed- off the throttle plates more than they were before hooking-up the vacuum advance to manifold vacuum, when you turn the key off now, the plates are closed enough to no longer pass enough fuel and air to allow the engine to run-on and sputter. Some will say this will add too much overall timing to the engine when running around and driving, but this isn't so true because when you are on the throttle, the vacuum signal drops and puts you back to normal "mechanical" timing. if you romp the throttle hard, your vacuum signal drops to zero, so now the vacuum advance and additional timing isn't in play at all. It's a remedy, but like all remedies, it may not be a perfect solution. It works most of the time for most people, but to find-out, it only takes about 3 minutes, a piece of 50 cent vacuum line, and a screwdriver to see if it works for you or not. If you don't want to mess with any of that, then there is still an easy option. In cars equipped with automatic transmissions, you can simply shut the engine off while still in "Drive" and the load from the tranny will cause the engine to shut right off. Manual transmission cars can be shut off while in gear (with the clutch pedal down) and then letting the pedal back up slowly when the key is turned off to load the engine a little, thus not allowing it to run-on. Really though, the two best ways are either to install an idle stop solenoid, or use your vacuum advance hooked-up to manifold vacuum and then re-adjust your idle speed so it idles back down to a normal RPM. WILL SENT YOU A LINK

21,080

Is the engine running normally when you remove the key? If it is dieseling you would be able to tell. It would be running extremely rough as if has a bad miss. If running normally and continues to run there could be a problem with the ignition module located inside the steering column or the ignition lock switch itself.

Your Answer

Explorer

Looking for a Used Explorer in your area?

CarGurus has 68,759 nationwide Explorer listings starting at $750.

ZIP:

Ford Explorer Experts

  • #1
    OJ
    Reputation
    11,300
  • #2
    Tom Demyan
    Reputation
    4,450
  • #3
    tennisshoes
    Reputation
    2,600
View All

Related Models For Sale

Used Jeep Grand Cherokee
1,032 Great Deals out of 71,542 listings starting at $1,195
Used Ford Expedition
365 Great Deals out of 17,102 listings starting at $1,500
Used Ford F-150
3,111 Great Deals out of 218,905 listings starting at $1,200
Used Chevrolet Tahoe
798 Great Deals out of 41,559 listings starting at $1,987
Used Dodge Durango
337 Great Deals out of 24,088 listings starting at $1,500
Used Toyota Highlander
582 Great Deals out of 35,915 listings starting at $2,500
Used Ford Escape
1,209 Great Deals out of 102,870 listings starting at $1,200
Used Toyota 4Runner
337 Great Deals out of 26,120 listings starting at $1,800
Used Honda Pilot
653 Great Deals out of 40,571 listings starting at $998
Used GMC Yukon
580 Great Deals out of 20,677 listings starting at $2,695
Used Nissan Pathfinder
472 Great Deals out of 25,098 listings starting at $2,388
Used Ford Explorer Sport Trac
52 Great Deals out of 1,805 listings starting at $3,000

Used Cars For Sale

2018 Ford Explorer For Sale
14,042 listings starting at $28,092
2017 Ford Explorer For Sale
158 Great Deals out of 27,588 listings starting at $18,303
2016 Ford Explorer For Sale
163 Great Deals out of 4,130 listings starting at $15,999
2015 Ford Explorer For Sale
385 Great Deals out of 7,585 listings starting at $8,900
2014 Ford Explorer For Sale
215 Great Deals out of 4,541 listings starting at $8,500

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.