Tuesday, June 28, 2011

How To: Ford Crown Victoria Tune Up / Check Engine Light (Coil Boots and Spark Plugs)

Yes, it's dirty. It's a police car.

Fast Facts
    Take $10 off $30, $20 off $50 and $30 off $100 orders at AdvanceAutoParts.com with code A123 (exp. 2/29/12) - Link will open in new window! Promo code is valid on "Pick up in store" orders!

      If you use these directions, please comment back with your experience!

      If you've been with me since the beginning of this blog, you might remember my first experience with buying a Police Interceptor. In that post, I mentioned a Check Engine light and a nasty misfire, but I glossed over the actual repair procedure. Well, I recently got another P71, and it too had its Check Engine light (also referred to as a CEL or MIL) illuminated. Due to popular demand, I'm going to explain how I fixed it- and how you can fix yours, too.

      This procedure applies to the most common cause of rough running / check engine light on Crown Vics: misfires caused by bad coil boots. In extreme cases, the light will actually flash, meaning that you will damage your catalytic converters if you continue to drive. Another symptom includes P0300 codes (misfires) like P0301, P0302, P0303, and so on.

      *Even if your check engine light isn't on, this is the procedure to follow when your Crown Vic needs  a "tune up," something that should be done when your car runs rough, or every 70,000 - 100,000 miles.*

      Newer Ford vehicles (all Crown Vics from 1998-on, F-150 trucks, Explorers, etc) don't have spark plug wires. This can throw some people for a loop when they go into the auto parts store and ask for wires, only to find out there aren't any!

      Instead of using a single coil with a distributor and wires, each cylinder has its own coil. There's no distributor, either. It's called Coil on Plug, or COP. The system can seem challenging at first because it's not what most people are used to. But in reality, it's actually easier to repair- once you learn how it works.

      If you have a check engine light on, start by retrieving the codes so that you know what the computer is telling you needs work. If your light isn't on (i.e. you're just ready for a tune-up), you can skip this section.

      You'll need a code reader for this. Code readers are increasingly affordable- or you can borrow one from a gearhead friend. I prefer Innova code readers, but any brand will do the job. Amazon.com has great prices on readers. You can check out mine here. For the price, I like it. It gives freeze frame data like speed, temperature, and RPMs when the code was thrown, and it explains the code on-screen so you don't have to Google each code that pops up. It also has the capability to run Ford KOEO and KOER tests, which I'll touch on in another post.

      OBDII connector on 1998-2010 Crown Victoria.
      The connector should be located right here- to the right of the steering wheel, very close to where your knee would be when driving. Some police departments move this when they install all their electronic gizmos, but it won't be far from this location. I believe civilian Vics have their port here, too.

      Plug your code reader in, following the directions that came with it.

      Waiting for the code(s) to appear.... Mine didn't have any codes because I had already cleared them. Any P030X code is commonly caused by bad coils and/or coil boots. The last number (which I signified with X) in the code is the cylinder number that is misfiring- for example, a misfire on cylinder number 8 would be P0308, cylinder number 7 would be P0307, etc.

      Hey, I never claimed to be a good artist.

      Ford V8 cylinder numbering chart (obviously made by a professional graphic designer, right?)
      Example: P0306 would be a misfire on cylinder six, which is the second from the front on the driver's side. 

      Now that we've figured out where the problem is, let's figure out what's causing the problem- and fix it, of course!

      A worn out coil boot. The voltage can "arc" through the cracks you see in the rubber.

      There are basically three things that can cause a misfire code on a COP system.
      • A bad coil boot (pictured above), allowing the spark to arc out, resulting in a misfire.
      • A bad coil pack that delivers weak or no spark, resulting in a misfire.
      • Extremely worn plugs.
      • An issue with the cylinder itself- low compression from a burnt valve, worn ring, etc. This is the worst case scenario and it's also the least likely- but it does happen.
      To determine which one of the three problems you're having, you'll need to take some stuff apart. Don't worry, it's not that hard. If you're mentally disturbed like me, you think it's fun.

      Step One. Remove the air intake tube. Simply unplug the two hoses on the back and unscrew the two clamps, then set the tube aside.

      Step Two. Unplug all of the coil packs from their wiring harnesses. If you're in a big hurry (a.k.a. stranded by the side of the freeway), you can just check the one coil pack that is misfiring. But to do this job right, you should check the entire system. Be gentle with the connectors; they can get brittle over time. Just squeeze and pull to disconnect.

      While doing this, take a look at the top of the head in between the valve covers and the intake manifold. Do you see antifreeze? Intake manifold failure is quite common on Crown Vics, and it will cause a misfire on multiple cylinders. To correct this, you'll need to replace the intake manifold. It's not impossible, but it is a full day's work--- not something I'll cover here.

      Step Three: Unbolt and remove all of the coils. Most Crown Vics will use 8mm bolts here, but many that have replacement intake manifolds will use Phillips screws or a different size bolt. Note: Coils aren't cylinder specific, so there's no need to mark them or put them back where they came from. They are all identical.

      Most of the coils will come out with the boot and spring attached. Sometimes, the boots remain stuck in the plug well. No big deal, just pull them out with pliers.

      Don't even think about loosening those spark plugs before you clean the wells! If you don't do this, all the dirt and crap inside the plug wells will go right into your cylinders- not a good idea. An air compressor makes this easy, but your wife/mom/girlfriend/aunt/grandma's vacuum will work, too.

      Step Four. Remove the spark plugs. Again, if you see coolant down in there, you probably need an intake manifold. It's not the end of the world, I promise. If there isn't coolant, continue on. To remove the plugs, use a 5/8" deep socket and an extension on your ratchet.

      As you remove the plugs, watch for oddities like plugs that are blacker than the rest, or whiter/cleaner than the rest. This can be indicative of a problem with the cylinder. Otherwise, just toss them.

      Step Five. Gap the new spark plugs with a gap tool. Improperly gapped spark plugs won't work well. Ford spec is .052-.056. This will be on the emissions sticker near your radiator, too.

      Step Six. Hand tighten - yes, hand tighten - the spark plugs. Once they're hand tightened, tighten them to 14 lb/ft of torque. Don't overtighten or undertighten spark plugs, especially on a Ford 4.6- they are well-known for throwing spark plugs out of the head, causing a very expensive problem. There's no excuse not to have a basic click torque wrench with today's modern cars.

      Step Seven. Pull the old boots and springs off the coils. If desired, spray some electrical cleaner on the coil contact (shown above). Firmly seat the new springs in the coils and put some dielectric grease on them to prevent corrosion. Slide the rubber boots over the springs.

      Reassemble it all. Reverse of removal, of course. Do not overtighten the bolts on the coils- it is easy to strip the threads in the intake manifold. Reinstall the intake tube, and start up the car!

      Drive around and see how it runs! If you get another check engine code, you probably have at least one bad coil. Here's an easy way to determine which coil(s) are bad.

      Let's say you have code P0305 (misfire on cylinder 5). After checking the connections on cylinder 5's COP, just swap #5 with #3, or #2... or any other cylinder that's not throwing a code. Erase your misfire code, then restart the car. If the misfire code moves to the cylinder that you moved the COP to, you have a bad coil. If not, you have an issue with the engine itself. 

      Quick note regarding coil packs: Surprisingly, Amazon.com is one of the cheapest sources for replacement ignition coils, provided you can wait for shipping (3-4 days) you can get a whole set of 8 for under $90, which is just ridiculous. If you're in a bind and can't wait, you can still save some money by using the Advance Auto Parts links at the top of this article.

      If the light stays off, congratulations! Your car probably runs a million times better. You'll get better gas mileage and loads more power, and you saved a ton of money in the process. Assuming that you used Platinum spark plugs (Ford recommends them), you should be good to go for the next 100,000 miles! 

      Did you find this guide useful? Please like UpShift's Facebook page! It helps make us look slightly less pathetic.


      1. Hi. What if the coil hold-down bolt threads in easily by hand but then get stuck about halfway in?

        Bolt won't go in much further.

        Can that copper insert be tapped (it doesn't look stripped)?

        I'm having the problem on #8.
        Have changed #1-5 without any issues.


      2. Unfortunately those threads seem to be stripped often. I have also seen the brass/copper insert break free of the plastic manifold, so that it spins along with the screw which prevents it from being tightened or loosened.

        You could try to tap it, but I'd try spraying some PB Blaster or WD-40 in there first, you might be surprised. If it's still stuck, an easier solution might be to get a self-tapping screw and just put that in there. If it makes you feel better, the replacement manifolds use self-tapping screws....

        The good thing is that screw isn't critical. As long as the boot is firmly attached to the spark plug, you'll be fine. There are a lot of cars out there that don't use screws on their coils or wires... think about it, have you ever seen screws on a conventional wire set?

      3. thanks man, i'm surprised to say that in all the posts ive seen on yours was the most straight-forward and accurate one. even on the freaking out part, i couldnt even figure out where the spark plug were until this (ithought the orange things were the plugs and i had bought the wrong ones) and then i was just gona give up cause i couldnt find a chilton with a 1998 crown vic section, so i asked the google gods and their answer was you. now i can change the plugs and not have to pay a mechanic $70 to do it...really appreciate it sir have a good one. btw my vic is much cleaner for a p71 i guess anyway thanks again

      4. Thanks for the kind words!

        In the past, I myself have been frustrated with Haynes/Chilton manuals and their vague directions like "unbolt spark plugs." Duh. I want to know *how* to do that.

        Glad I could be of help; that's the purpose of the site.

        As for the dirty engine compartment, I've had a couple of P71s and this one was the dirtiest by far despite having the lowest mileage. I haven't the slightest idea why.

      5. These pictures are sweet, i was told i needed a tune up and quoted over $300 but i did it myself and my gas mileage went up like 3mpg. so awesome

      6. I just did a tune-up on my '00 P71 w/ 133k and am still having some issues. I used Bosch 4504 spark plugs because I got a good deal on them. Could a so-called "better" plug maybe not be advantageous to my 4.6? I also Seafoam'd the motor (before changing plugs) and changed the fuel filter and cleaned the MAF (after).

        Still feels like it's just not quite all there. Have any suggestions?

        Thanks much!

      7. While I prefer to use Motorcraft or Autolite Platinums in these cars, simply using another brand of plug should not make it run poorly. Those 4504's are very nice plugs and should work well with this ignition system. What are the specific symptoms you are noticing?

        Did you put Seafoam in the fuel, or just run it through the vacuum lines and/or crankcase?

        My immediate thoughts:
        - add a bottle of Techron to your next tank of fuel.
        - Check your air filter. You would be surprised what this can do.
        - Is your check engine light on- do you feel definite "misfires?" You might have some bad coil packs.

        Feel free to comment back with your findings as they will probably help someone else in the future.

      8. I've run Seafoam through several tanks of gas since getting the car (about a month ago) as well as the vacuum line approach once. There was a decent amount of smoke when I did that, so apparently I freed up some crud there.

        Symptoms that I can recall:
        -slight chug at very low speed, under light load (ie - idling up a driveway approach, barely touching the gas)
        -random chugs at highway speeds (~55-60 mph)
        -doesn't have the "snap" to the throttle that it had right when I got it
        -very slight, and random vibration in gas pedal every now and then

        -tranny seems to want to shift into OD too soon, resulting in very low RPM's and I'll either have to turn the OD off or force it to kick back down with the gas pedal quick
        -also, I noticed coolant around the #8 plug well (closest to steering wheel) when I was changing them

        It's hard to tell exactly what's going on as almost all of these symptoms are very sporadic. I had an automotive teacher drive it and he says I'm "looking for something to be wrong" because of course it wouldn't duplicate any of it when he drove it. However, the girlfriend will attest to the chugging for sure. The slight lack of power is just something I notice behind the wheel.

        I do have a CEL, however it's for a stupid EVAP thing - P0442. I've thoroughly cleaned out the canister solenoid and related hoses, and that solved my fuel fill-up issues, but the light will still come on after a couple of days.

        One other note, when I changed the plugs I cleaned the MAF at the same time. I also sprayed a bunch of carb cleaner into the top of the intake just for the heck of it. When I first fired it back up it choked and sputtered a little bit (flooded I assume) but then ran like a top. I took it out on the highway for a quick pass and it ran like a bat out of hell. However, that slowly faded back to "normal" as if I hadn't done anything.

        I feel like I'm chasing my tail here! My first Panther and it's not going as great as I had hoped.

      9. Don't be discouraged- trust me, you'll get it running and forget all about these problems.

        It sounds to me like you have a leaking intake manifold or intake manifold gasket, for sure. I had similar symptoms when the intake manifold cracked on one of my P71s. The chugging is a good hint, but what gave it away is the "coolant around the #8 plug well."

        What is happening is the coolant leaking out of your intake manifold is shorting out the spark from the coils. When I had a leaky intake manifold, I disengaged OD to speed the car up, just like you said.

        After fixing the leak by replacing the manifold, the car drove like new (even with 225k police miles). I got lucky and only had to replace one coil, but others have reported that they found 3 or 4 permanently shorted coils.

        When you replaced the plugs, did you replace the coil boots, too? If your intake manifold leak is minor, that may solve the problem, but it would only be temporary.

        Amazon.com has the cheapest price I've been able to find on the manifold, they even beat RockAuto. If yours is a 2000, this will work. 2001 and up use a different design.


        It would be interesting to hook up a code reader and do a KOER test, that would probably identify shorting coils that aren't severe enough to trigger a check engine light. Not all code readers can do this, though.

        Oh, and the evap code could be a bad gas cap, but I wouldn't worry about it if that doesn't fix it...

      10. Just realized that you might actually be able to buy that manifold from Advance for the same price as Amazon if you use one of the coupon codes off my "Special Offers" page (see tabs at top of screen).

      11. This comment has been removed by the author.

      12. Tried posting this last night, but there was a weird 404 error going on.

        Well holy exactly-the-guy-I-needed-to-talk-to, Batman. Thanks for the wealth of knowledge you just dumped. I'll have to check into the intake manifold situation. When I pulled the boot off I knew it probably wasn't good. If it was just water, that's somewhat understandable (rain, car wash, etc). But for there to be antifreeze in the spark plug well, it had to come from the engine somewhere.

        Now if it's in the far back plug hole and the coolant crossover is in the front of the intake, would it be the intake that's at fault? Or is there more than one place that the coolant flows across this thing? Sorry, I'm a little new with this whole Panther business.

        So the other day I was doing more inspecting and was testing the coils and the fuel injectors. I checked the coils by pulling off individual connectors - each one works (or at least made the engine stumble when unhooked). Also checked the fuel injectors via screwdriver stethoscope method, and they all were "ticking" rather loudly, so I at least know they're functioning.

        Also, to throw a wrench in the gear, I blasted my MAF again last night and reset the PCM at the same time. When I drove to work it seemed a little better. Never really got on it too hard, but it did seem better. However, when I came home this afternoon the car was driving awesome. Power was there and it seemed really smooth throughout the majority of the powerband. Apparently this thing is moody. I also stopped along the way home and got a big bottle of Techron to feed it. I'm sure it's not gonna hurt it, no matter what the problem ends up being.

        Also, if it's a hassle to reply on here I'm fine with giving you my email address. And I certainly appreciate your sharing of the knowledge.

      13. Sure- shoot me an e-mail. The one on the Contact page is finicky at the moment, so send it to upshiftblog at gmail dot com.

        These manifolds have coolant passageways in the front and the rear. You can see them in this picture: http://1.bp.blogspot.com/_KyM4bhWqvHo/TQRM7sEiXTI/AAAAAAAAAAw/c7GjbmJlKBM/s400/work3.JPG

        Usually, they leak in the front, but a leak at the rear isn't unheard of. The manifolds with plastic crossovers in the front are almost 100 percent likely to fail at some point; all the replacements have metal crossovers in the front.

        As for pulling the connectors off the coils to test them, that works if you're trying to find a completely dead coil, but it won't show you a coil that's simply weak. Even if it only misfires on 1/500 revolutions, you'll still experience symptoms, but it won't trigger a CEL or be detectable by disconnecting the connectors.

        Keep me posted!

      14. Ahh! I see now. I've been blasting myself with everything I can possibly read on these things, and I'm more than overwhelmed to say the least. However, I've heard a ton about the intakes with the plastic crossovers and that they are pretty much junk. However, I've apparently gotten lucky because somebody must've replaced it already as mine has the aluminum crossover in the front. So maybe it's just a bad gasket job?

        I also remember seeing a small pool of liquid underneath the intake in that little open area on top of the motor. Perhaps the gasket is leaking on both sides and is eventually pooling up.

        What is a better way of checking the coils? Or would it better to just replace all of them?

        As far as replacing the coils, I've recently read that you can replace just the coil or just the boot, and obviously buy them as a whole and replace the whole thing. I'm guessing at this point it would be more effective to replace them as a whole? I found an 8 pack of Accel coils on Amazon for about $170 or so. Have heard good and bad things about them, but I'm assuming they're better than 11 year old factory ones...

      15. I've read feedback that's 50/50 on those Accel coils, too. Overall, they seem worth a try- they do have a warranty, after all.

        As for checking your coils, the only sure way I know how is to do a KOER (key on engine running) test with a more advanced OBD-II reader, or waiting for it to get bad enough to pop a code.

      16. Manifold issues shure as hell create alot of problems via cop issues as well! Thanx for the acccurate problem solving!

      17. Well, dangit. I just bought a 98 model P73 Crown Vic (old man car)that has had a barely-noticeable miss since I got it (which still didn't keep me from getting 25 mpg on a 350 mile trip)-- and now it's got a check engine light. This all sounds like some pretty useful info, though.

      18. Hello. I have a 1989 crown vic that I had to put new head gaskets on. When I re-started it, it ran rough. I used a code reader on it and it said that I had an open spout. I got a new ccu (I think) that mounts on the distributor. Did not fix it. Ran really rough and was getting a lower voltage reading to the distributor, around 9 or 10 volts. Now, it won't start at all. Any ideas? Thanks, DM

      19. DM- As much as I love the "box" Crown Vics, I've never owned one, let alone worked on one. Running rough for up to a few minutes after replacing head gaskets seems fairly normal, because of all the crap that's in the engine and the fact that there's air in the fuel lines and all that. But I unfortunately can't give you any advice because of my limited knowledge with those motors. Try CrownVic.net.

      20. Hello, I have an 05 Ford Crown Vic P71 SAP CVPI w/88K mi.
        Having an issue with tapping the brakes in reverse, i.e. backing outof a parking stall. The brakes pulsate and grab, sometimes throbbing. I've had the brakes checked 2-3 times...everything checks ok. One mechanic did locate what appeared to be a very slight cut in the R/R tire abs module line after removing the sleeve. Do you think that might be the problem or do you have any other ideas based on my symptoms? Thank you, Jerry.

      21. I recently paid this mechanic to fix my spark plugs and discovered I had a broken coil I then had the coil replaced 2 days the later the car did the same thing a little smoke and sound like some putn I then discovered that the coil bolt was missing could this be the problem because the coil is mounted down

      22. Just wanted to say thanks! Well written & great pics! ☺


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