Replaced plugs and coils and now misfires when idling.

 

Two thoughts:

One, why did you replace all the coils and did you replace the coils with originals or aftermarket? If the latter the construction and quality is inferior to OEM and many are crap new out of the box.

Also, were any of the original coils (when removed) have any evidence of oil in the spark wells?

If you still have the original coils might at least be worth capturing the code(s) for the offending cylinder(s) where the misfires are occurring and swap back in the original coil.

Sorry, third thought... what plugs did you install? OEM spec or something different?

 

I used Bosch equivalent to NGK OEM plug. I did use aftermarket coils. I was just doing preventive maintenance at 87K miles. I have misfire codes on three cylinders. I have replaced those with original still good coils and idles worse. There are no signs of oil leaks.

 

Are the misfires all on the same side of the engine? If so, check the wiring loom for any breaks and make sure all the connectors are firmly seated.

If the vehicle did not have misfires prior to replacing the spark plugs and coil units, go back over your work to make sure there are no vacuum pipes or connectors that are incorrectly fitted, or cracked.

 

I had the codes rerun since reinstalling the old coils in the three with error codes. Two error were fixed. I now just have a misfire on #8, but I also have p0208 fuel injector open. I think the coil problem is solved and my problem is now with the fuel injector on #8. I checked the wire connection and it seems to be OK. I went for another test drive and it seems much better. I am going to drive it for awhile hoping it will fix itself. I have other error codes p1314,p1316 and p1111. I am hoping they go away as the misfiring goes away.

 

If the MIL is, or has been flashing as the vehicle is being driven, damage to the catalytic converter(s) has occurred.

 

After much to do about the fuel injector p0208 code, I replaced the #8 coil with another of the old good coils. Praise Lord Jesus, It works great now and runs smooth. I can't believe one of the good old coils went bad just moving it around. Jaguars and coils are sure touchy things. I need to recheck the codes and have the CEL turned off. I hope no damage was done to the cat converters. I am also very thankful I didn't have to replace a fuel injector. Thanks Abonano and NBCat for your help.