2001 LS - CEL, Rough Idle, Misfiring

Hey there everybody. New here to the forums.

I'll get straight to the point. My dad has an '01 LS V8, Sport pkg. He bought it over the summer, 70K miles on the clock. He has put 5K miles on and so far has done a tranny rebuild, his passenger front window regulator go out and now he has a CEL, indicating misfire in cylinder #4. With that, he has very rough idle. Took it to our trusty mechanic, said it was neither the coil nor the plug. He said it was more in depth electrical. FYI, previous owner had head gasket changed, not sure if it was one side or both.

Now its sitting at the Ford dealer. Their mechanics couldn't figure the problem, so they called Ford hotline. Hotline told them to throw on a new cat converter. They did so, but that did not fix the problem. They said it helped, but its still rough. You guys have any ideas as to what it could be? Dealer said they have to call back Ford in the morning for the next step.

My dad loves the car, its just really an inconvenience at this point since the car has been in the shop for a week.

Just another bit of info, my trusty mechanic said something about the voltage on the cylinders on the side of cylinder #4 being low, and the other side being normal. I thought it may have been irrelevant, not too sure though.

Any input would be greatly appreciated. Thank you all in advance.

Have they checked the wetness of the spark plug in cylinder #4 after the car's been running? If the plug is dry, there may be a fuel injector that is failing.

One thing to try would be to swap the coil, spark plug, and fuel injector to another cylinder, clear the codes, and see if the misfire follows the itmes or stays with the cylinder. Check the cylinder compression as well.

If all that checks out, you'll want to have the wiring diagrams and check for voltages to the coil primaries, fuel injector, and some of the sensors.

-Rod

Thanks Rod.. I appreciate the advice. I forgot to mention they already went ahead and changed the injector on cylinder #4. They said it was going bad anyway. We picked up the car today though.

Dealer called back Ford hotline this morning, and now they want to do a leak down test on the cylinders. They suspect a hole in one of the cylinders. Anybody ever seen something like this?

I also talked to the service manager and she said something about if its worth actually working on the engine or just having it swapped out. That made me think twice. Looks like expensive stuff now.

We decided to take the car out and have our trusty mechanic see if there was anything he could do about it. I'm now just wondering how a hole develops in the cylinder or if it can just happen suddenly?

I normally don't work on gas engines beside my hobby cars, but that sounds shady to me. I may be wrong but the compression on a cylinder is eather bad or good. I never herd of a leaking hole in the cylinder. :headshake
A bad head gasket would give you bad compression but you would also have coolant in your oil (grey oil), there may be leaks along the side of your engine block and many other symptoms that are associated with that problem. Your best bet is to go with Rod's advice. That is the fast, easy, and inexpencive way to find the problem. Sounds like that dealer is trying to take you to the cleaners.

Sorry to bump this thread, but is anybody on this forum out in southern california?

I'm looking for a specialist in these cars. Anybody know of one? Basically what happened was our mechanic took in the car to repair after we took it to the dealer and has had it for about a month. He did some serious work on the car but took so long because he had no knowledge nor experience on these engines. My dad and I want to find a specialist so that next time we won't have such a hassle. We want a mechanic that knows these engines fairly well. We plan on calling some Jag specialists because I can't seem to find any Lincoln specialists in the phonebook.
If we can't find someone trusty, were going to end up giving away the car. Not sure how this car could be so problematic, but I guess it really depended on how the previous owner maintained the car.

Still love the car though.