Clean engine - dirty misfires!
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Clean engine - dirty misfires!
After changing my oil recently, I decided to use a little engine degreaser on the engine to clean it up a little. BAD IDEA! After letting it sit overnight, the next day I had a terrible misfire. I took it to have the codes read and it turns out that cylinders 3 and 6 showed misfires. This is a 5.4 in a '97 Expedition with 190,000 miles. The plugs were changed recently (less than 20,000 miles ago), along with the wires/boots. A couple of the COP's have also been changed over the past few years.
I have a few questions:
1. Should I replace the two plugs that are on the cylinders showing misfires?
2. How can I tell if it's the plugs/boots/arcing, or the COP that is the problem?
3. What's the best way to dry out these components? Air hose, hair dryer, etc?
4. I plan to put dielectric grease on the boots, etc. Is that OK to do?
I have a few questions:
1. Should I replace the two plugs that are on the cylinders showing misfires?
2. How can I tell if it's the plugs/boots/arcing, or the COP that is the problem?
3. What's the best way to dry out these components? Air hose, hair dryer, etc?
4. I plan to put dielectric grease on the boots, etc. Is that OK to do?
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I did run it for about 20 - 30 miles to get to a place to read the codes, etc. I guess I won't know until I try it.
How about testing the coils? Any easy way to see if one is good or not? I read about switching them from one cylinder to another, but without a code reader, I'm afraid a miss on one cylinder will feel like a miss on another. I do have a thermal instrument that I can read exhaust temperatures that could tell if a cylinder is dead or not.
How about testing the coils? Any easy way to see if one is good or not? I read about switching them from one cylinder to another, but without a code reader, I'm afraid a miss on one cylinder will feel like a miss on another. I do have a thermal instrument that I can read exhaust temperatures that could tell if a cylinder is dead or not.
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Joined: May 2003
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From: E.Lincoln County, NC
These engines DO NOT like to be washed! Pull the COP's & blow everything off with compressed air. A good spray of brake clean and another blow for good measure might be a good idea too. I think you'll find it's just wet.
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I'm going to give the "blow-and-go" method a shot. Hopefully that will work. This engine has been really picky with these misfires. I've replaced two coils and 11 plugs since last October trying to cure it's ills!
Postmaster
Joined: May 2003
Posts: 3,310
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From: E.Lincoln County, NC
Boots seem to be a big problem area too. My '98 F150 has wires but my '98 Crown Vic had COP's. My uncle had a '01 Screw and now has a '03 reg, both of which gave problems after he cleaned the engines.
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Well, I did some swapping around of coils, etc. and isolated it to the two coils. I replaced them one at a time, and it was fixed. I guess they were so old that the water just finally did them in.
thanks for the forum help!
thanks for the forum help!