By February 5, 20070 Comments Read More →

1999 Ford Expedition

Reader Question: Hi Austin,

First of all, thank you for providing this service to us DIY that have been ripped off too many times by the so called “certified professionals”.

My dilemma is this:

I have a 1999 Ford Expedition (4.6L Triton) with 136k miles, which I have treasured for the past five years. I have had no major complaints up to this time. I do most of my own work on my vehicles and have done so since the late 1960s.

Just recently, it was time to replace my spark plugs, wires and coils and after doing so, my truck has never ran this smooth & peppy & super quick response during acceleration. I was very pleased with the knuckler breaker job since I saved myself approximately $800. I could not wait to see the difference in my miles per gallon usage.

Now, bear in mind, my truck ran beautifully like this for approximately 3 weeks and all of a sudden, my wife says to me – I hate to tell you this but your truck is starting to run rough again and she was right. The engine actually shuddered so badly that it occasionally made a popping noise [combustion problems].

My “Service Engine Soon” light came on and stayed on. I wasn’t about to take it to the Ford garage, so I finally broke down and bought an OBD II Pocket Scanner to read the problem codes which were being sent to the trucks computer. The problem codes had to do with misfiring at #3 & #5 cylinders. When I pulled #3 & #5 plugs, I found that they really were misfiring and so now, I am now replacing all of them with Bosch Premium +4’s.

The spark plugs, which I put in 3 weeks ago, were just standard Autolites. I have since been sorry for that stupid decision.

My question is this:

When I pull out #4 spark plug, I found it fouled with wet oil and this cylinder did not even come up on my obd scanner? What I would like to know is – where did the oil come from. Is it possible that the oil is from one of my oil changes (ie. oil spillage on top of the intake manifold area)? When I send a small rubber hose down into #4 cylinder – I find some wet oil still remaining.

How should I remove the oil residue without contaminating the top of the head, etc? Do I need to remove the oil or will it burn out over time?

Please give me some ideas how to treat this situation.



Hey Rick,

I am assuming that you have resolved the engine misfire and the engine runs good again and the service engine soon light is OFF. The oil on top of the cylinders should burn off with time, although if oil is seeping into the cylinder from somewhere like a valve stem seal, that leak will have to be replaced to stop the leak.

I think if there is no engine misfire and the service light is out…I would just drive this vehicle awhile and monitor the situation. I hope that things will cure themselves with no intervention from you.

If you want to, you can buy an over the counter intake cleaner that you can spray inside the throttle body or suck up in liquid form via the PCV hose. This will help clean the intake system and the tops of the pistons. It will not hurt anything and might improve idle performance anyway.

Austin Davis

Posted in: Reader Questions

Got Something to Say?