Cylinder 4 misfire and events

[ZeroData]

I have a 98 4.6 W series Expedition with 200k miles.

Driving to go visit family on the interstate (70 MPH), the truck began to lose power. Cruise control was on so it floored it to 4500 RPM. I pulled over and the engine died. Checked oil. It was fine. Saw a small leak from the heater hose to the heater cores. Started it back up, it idled rough. CEL said misfire cylinder 4. I fixed the leak over the plug wire. Changed the pall, cleaned the plug wire and it still idles rough and has low power at slow speeds. I also noticed a clack at 1500 RPM.

Is there something else I should check? I tried disconnecting the coil wire for plug 4 and it would not start at all.

Thanks,
Scott

 

[willieo]

Had same problem changed plugs and wires runs like champ now.

Sent from my ZTE-Z990G using Tapatalk 2

 

[ZeroData]

Tomorrow I will be running a spark test on the plug wires and the coil packs. As I stated I changed the specific plug that caused the code with no noticeable benefit. If the plug wires and coil packs pass the spark test then I'll move on to checking the injectors and lastly a compression test to verify the valves and rings.

Thanks,
Scott

 

[ZeroData]

Test

I removed the fuel pump relay and tested the wires using a spark tester. The spark was the same on cylinder 4 wire as on the other cylinder wires. As far as I can tell all tests a pass. However I do not feel the wire clamp onto the plug on cylinder 4 the same way I do on cylinder 1. Yet the wire is all the way down. I guess the next tests are for the injectors then a compression test.

Thanks,
Scott

 

[1997SCEBFEX]

when you say the spark was the "same", was that by visual indication, or did you ohm each one?

Just curious as they have a specific range for operation.

when was the last time ALL the plugs/cops were changed?

PanHandler.

 

[bedrck46]

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[ZeroData]

This was a visual check from a spark tester. Not sure when the last time the plugs were changed. I just got the vehicle. I replaced plug 4 and have plugs for the other 7. My major concern was that I had a ring or valve issue and I didn't want to throw money into wires, coils etc if that was the case. That's why I was looking at the compression test.

Thanks,
Scott

 

[bedrck46]

again suggest you change all plugs and wires Being you have a 4.6 engine which has two ignition coils two plugs fire at the same time if your having a misfire on cyl 4 it could also be effecting the other plug that fires at the same time. Just cleaning the wire is not the same as putting a new wire on. also since you have no idea when plugs and wires were last changed the time you spend doing visual check may be time wasted.

 

[ZeroData]

I did not clean the wires. I did not do anything with the wires other than using a spark tester to validate power was reaching the plug. I have replaced plug 4 with an Autolite double platinum plug. I will replace the other 7 plugs tomorrow and while they are out run a compression test. I plan to run a compression test to make sure I do not needlessly spend $75 on wires if there is a ring or valve issue.

The Torque Pro app is showing continuous misfires on cylinder 4 throughout the throttle band yet it has not thrown a CEL again since I cleared it.

Thanks,
Scott

 

[bedrck46]

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[bedrck46]

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[bedrck46]

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[ZeroData]

I read my original post, when I said "cleaned the plug wire". I should have said removed all the water from the leak. When I said "needlessly spend", I just want to rule out any big issues before I started replacing the electronics.

If the compression test comes out bad, then I'll determine if it's the rings or the valves and repair those before I replace anything else. If I have to tear down the motor I will.

Thanks,
Scott

 

[bedrck46]

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[ZeroData]

Well, considering I will have the plugs out already, a compression test will take no time. Determining if it's the valves or rings can all be done while running the compression test. In other words I will spend no money on the test and only about 30 minutes more than changing the plugs.

Since I bought it used it would be a good thing to know the state of the valves and rings anyway. Since I repaired the front end on my daily driver yesterday, time is not an issue.

Thanks,
Scott

 

[bedrck46]

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[ZeroData]

I didn't see any links. I have already looked at several different sites. I'm not new to engine work, this is however the first Ford I have ever owned.

 

[bedrck46]

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[ZeroData]

I have looked at those sites you linked to. That is why I did the spark test and the coil pack check. Per one of the sites, it suggested a compression test. Due to my doubts of the caliber of work done by the previous owner and the noise that the engine made during and after the misfire condition happened and still continues to make. I wanted to just validate the engine prior to replacing anything else.

I do appreciate the assistance that numerous people have provided and understand that plugs, wires, egr and coil packs are the primary issue with most misfire and rough idle conditions. I just figured a thorough test, if noting else but for my piece of mind, was worth the time required. If I did not believe that the users on the forum were competent in their knowledge of Expeditions I would not have asked for opinions. If I had not seen other scenarios of people with valve or ring issues and similar symptoms I would have just went out and got plug wires and coil packs and started from there.

I have no intentions of selling the vehicle, even if there are valve or ring issues as I have easy access to another W series motor if I wanted to do a complete rebuild. Again I am just trying to be on the cautious side until I feel more comfortable with the state of this vehicle. If I seemed confrontational or unappreciative of the feedback, that was not my intention.

Thanks,
Scott

 

[bedrck46]

I will let you to your work in peace.