I've searched the misfire codes on the forum and can't find the fix. I'm a new owner to an 03 Disco and I got my SES light on the second day. It came and went twice before it stuck. Codes read were misfires in cyl 3 and 7 and another 1300 small evap code. It's not sputtering, nor does it feel like it is missing. No smoke or coolant leak detected.... yet. I'm still looking. My truck has 82K mi and has STI blue wires and had Champion PYP B4 plugs. Well, I changed the plugs out to start with. All of the old plugs seem OK. 3 of them did have a slightly larger gap but they all looked good and relatively the same. 3 and 7 were no different from the others. SO - as I've read here on the forum... the next step is wires, coil packs and then it may be head gasket or a dropped sleeve. Here's the deal... My engine does have a distinctly different sound coming from the right side of the engine. It's a little noisy, especially during the fast idle, and with my limited knowledge, seems like exhaust leak but not sure at all, really.

What's my next step here? Should I post a video for you guys to hear my engine sound? I'd hate to replace good wires and coils for nothing. Plus, that's what my dealer would do anyway...

Engine is clean, and wit no lights and only 82k mi, I thought I was getting a great deal... and maybe I did... if I don't have to tear this engine down or buy a rebuilt one.

I'm new - any help is appreciated. Thank you.

 

For the exhaust leak you can try this little trick to help locate it. If you crawl under the car while it's running and have someone hold a towel over the exhaust pipe it will force exhaust gas out of any leak and make it easier to find. When I installed my new Magnaflow y-pipe I had a to do this to find and fix a leak I had. When my wife held the towel over the exhaust I was able to feel air rushing out where it bolts to the manifold. I would tighten up the nuts a little and have her hold it over the exhaust again to check for leaks. I kept tightening a little at a time until no more air was leaking out. The truck runs much or quite.

Have the person covering the pipe wear gloves and a use thick towel so they don't get burned. Only hold the towel over the exhaust for 10 seconds at a time.

As for the misfires:
Make sure the wires were installed the correct way first. People can cross wires if not paying attention. Probably not your issue but it should be your first step.

New wires can still have cracks in them causing arcing. This is probably your issue.
It is easier to detect arcing in pitch black. Try watching the engine while it is running at night and as dark as possible. Check closely around the boots and you can pull off the rubber hood seal along the top of the firewall so you can see the coils better and watch for arcing.

 

Oil in the oxygen sensor plugs. Will miss for a small window when switching to closed loop, then go open loop and run like a dream.

 

not saying this is your problem but i had set of those STI blue wires lasted about a year and a half. I found one had broken inside the 90 degree molded bend at the plug. Never would have found it without ohming the wires out.

 

Thanks a lot for the tip. I'll check for arcing tonight and exhaust leak this weekend. Thanks for being so thorough and helpful.

 

Well... Those are the exact same wires that are on mine! I'm starting to get hopeful now, that is possibly where my problem lies. I'm going to check for arcing tonight. Did you replace the sti with magnacore wires? How would I check the ohms of my wires? Thanks for mentioning that.

 

In this video the guy shows you how to test the wires with a Multimeter.

 

Thanks for sharing that video. Honestly, if I have to take them off, I'll just replace them with new magnacores. I'd still test them, and keep them on hand if they're good. I already have a multimeter, so that's a plus.

 

Well, they are indeed a bit greasy back there near the firewall. What would I use to clean those up and how? Are you talking about the orange connectors?

 

Unplug the battery. Unplug the O2's. Spray parts cleaner on the inside and outside of the connectors until all the oil and dirt is gone. Dry out the plugs really good with the air compressor. Snap the plugs back together. Plug the battery back in.