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Replacing spark plugs

Tiny
QUISTRAT
  • MEMBER
  • 1999 FORD EXPEDITION
Hi, looking for an answer on my 99 Ford Expedition 4.6. 156,000 miles. I've changed 7 of 8 spark plugs and have now changed 7 of 8 plug wires. Since changing the plugs and wires, I''ve been getting misfires on cylinders 2, 4, 6, 8. The check engine light will flash and it won't accelerate as well. The one plug and wire that was not changed was Cylinder #7. I've talked to the local garage and they say the intake shold come off for the plugs to be changed, has anyone heard of that before? What is the proper plug and Gap for that vehicle. And, does anyone know where the A/C Lines run for the rear heat and Air on this vehicle. I'm sure I have a leak, I have the leak detector and UV light, I just want to know where to look before adding the dye in the system. One more thing, will a cold air kit for this vehicle improve gas mileage? Thanks.-Paul
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Monday, May 14th, 2007 AT 11:18 AM

25 Replies

Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
To start, I know its difficult but all plugs and wires need to be done. No, I have never heard of pulling the intake to do a tune up. Are all of the mifiring cylinders on the same coil? , if so then check the plug at the coil, might even need a new coil. The a/c lines run down the underside of the body. Plugs- Motorcraft #SP432 is the only plug I would put in it, calls for a .054 gap. Did you use Motorcraft wires as well? The ignition system is designed around the amount of resistance in that particular wire

this guide will help

https://www.2carpros.com/articles/how-to-change-spark-plugs
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Monday, May 14th, 2007 AT 12:47 PM
Tiny
QUISTRAT
  • MEMBER
  • 2 POSTS
Thanks for the response. I did not use Motorcraft ignition wires, and I'm regretting it. In fact I've thought about replacing just the wires. The misfires are all on the same side of the engine, but different coil packs. I've switched to the recommended plugs and like I said, I've replaced all of those but the #7, which is a real pain to get at. This has only been problematic since I replaced the plugs and wires. Arghh. Deos it sound as if Motrorcraft wires are about the only way to go for this? Thanks.
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Monday, May 14th, 2007 AT 1:00 PM
Tiny
PINPON
  • MEMBER
  • 2 POSTS
Im having a hard time reaching the last 2 plugs in the back any suggestions
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Sunday, October 26th, 2008 AT 8:25 PM
Tiny
FJARAMILLO
  • MEMBER
  • 1 POST
  • 1999 FORD EXPEDITION
  • V8
  • 4WD
  • AUTOMATIC
  • 187,000 MILES
I'm in need of a diagram on how to reach and replace the spark plugs on my 1999 ford expedition
4WD XLT V8 5.4 litre SOHC engine. Specifically what
parts I need to remove to get the spark plugs.
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,117 POSTS
Do you know what the coil packs are? They are below the fuel rail. They are black and have two wires going to each one. Every cylender has one, and to get to the spark plug, you must remove the coil pack. There is only one bolt holding each one in place. I can't remember the size, but they may be 10mm.

Let me know if this helps or if you have other questions.

Joe
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
RJAMAL
  • MEMBER
  • 1 POST
  • 1999 FORD EXPEDITION
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
I bought a 1999 Ford Expedition v8, and one of the spark plugs blew out, Is the engine gone or should I just replace the spark plugs? I know this was a problem with that year model. What should I do?
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,723 POSTS
If the threads peeled out with the plug, there is a repair kit for that but in some applications you have to remove the head to gain access.
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,542 POSTS
  • 1999 FORD EXPEDITION
  • 134,000 MILES
My 99 ford expedition 5.4L is miss firing. I have done my research and understand the process in changing the spark plugs. I don't believe that it is the coil packs because my service engine light has not come on and there are no codes thrown. I have been warned that I can brake the plugs off and would need an extraction tool to remove them, is this true? Or is it that its more problematic to strip the aluminum heads by over tighting them or cross threading them. Thank you for your help.
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,757 POSTS
You do not have the 3 valve engine that breaks off the spark plugs. The only issue yours has with spark plug threads is that they tend to loosen up and blow out after ruining the threads if they are not torqued correctly. You should have any problem getting them out but let me tell you, this job is no picnic on that truck and don't assume your coils are good. You probably have a couple weak ones and you really need to determine which ones they are. They don't always set codes because they are inconsistent. You may be able to see raw misfire counts with a professional scan tool. You definitely should replace the coils on the cylinders that are misfiring once you diagnose them.
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
COPPER571
  • MEMBER
  • 1 POST
  • 1999 FORD EXPEDITION
  • V8
  • 2WD
  • AUTOMATIC
Replace spark plugs and notice water in the plugs and wire of the #4 cyl what causes that
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,757 POSTS
You likely have a coolant leak in the area that is running into the spark plug hole. Pressure test the cooling system to find out where it's coming from.
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,542 POSTS
  • 1999 FORD EXPEDITION
  • 179,000 MILES
How do you change the spark plugs and where are they located at?
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
HOMER1967
  • MECHANIC
  • 875 POSTS
These plugs are very deep in the engine and require very specific tools and methods to remove. They are very prone to breaking off in the engine. You need to take it to a shop and have it done. It can be very costly if you try to do it yourself.
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
PEREZ6268
  • MEMBER
  • 1 POST
  • 1999 FORD EXPEDITION
Engine Performance problem
1999 Ford Expedition V8 Two Wheel Drive Automatic

I have replaced all 8 coils and spark plugs 1 by 1 in a day, #4 piston continues to mis-fire, I replaced that 1 coil and plug again, still got the same mis-fire, now the truck starts and only stays running if I hold down the gas pedal to about .5 - 1.5 rpm, if I let go the engine stalls out. I'm out of ideas, any suggestions?
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check compression and injector for no. 4 cyl and also try cleaning out the idle air control valve and test the throttle position sensor
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
TANDRACROOK
  • MEMBER
  • 1 POST
  • 1998 FORD EXPEDITION
  • 89,000 MILES
I had asked a question on 1/9/13 regarding my truck, I have a mechanic changing my spark plugs and coils. A mechanic before that had changed my spark plugs and coils and for some reason put a pernament clue around the coils to keep them from shortening out. Now we are having problems with the clue and rubber of the coils having melted in the spark plug cylinder. That would be the plug in the back that is the hardest to get to. Can you suggest something we can do in order to remove rubber and clue so that we can grip the plug without making matters worst. Everytime the rubber is pulled on it cracks lower and lower to the cylinder. Please help.
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You will have to break it all out before getting to the plug.

Dont return to that guy

by the way, I assume you mean glue?
Roy
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
PINPON
  • MEMBER
  • 2 POSTS
  • 1998 FORD EXPEDITION
Engine Mechanical problem
1998 Ford Expedition V8 Four Wheel Drive Automatic 200k+ miles

is there an easy way to get to nthe spark plugs changed all but 2 cant reach the last 2 in the back any suggestions
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,117 POSTS
Hi:
There is no easy way to get to them. They are a *&& %. While trying, make sure not to break one of the bolts. I don't even want to tell you what needs to be done to remove the broken studs.
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)
Tiny
GMANZOTARANTINO
  • MEMBER
  • 1 POST
  • 1997 FORD EXPEDITION
  • V8
  • 4WD
  • AUTOMATIC
  • 17,500 MILES
My son replaced the back 4 spark plugs and now the truck idels just below 1 RPMS and the brakes feel like you are stepping on a cement block. If you push on gas pedel and get RPMS up to 2 or 3 the brakes kick back into working mode. What did he do wrong? Help!
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Sunday, January 5th, 2020 AT 1:57 PM (Merged)

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