sebas_nava

OK, here's the story. I've inherited a 1999 Ford Mustang that I have no maintenance records for or anything. The car is very very clean I have no plans on getting rid of it and would like to repair it instead.

The check engine light has been on for a couple of weeks now. The diagnostic result was a 'P0304 Cylinder 4 Four Misfire Detected'. So I did the easy stuff first: replaced spark plugs, still the same; replaced wires, still the same; replaced coil, still the same. I wanted to do some testing before continuing down the list of repairs related to this code.

So I did an oil change and started monitoring the oil levels. After 200-250 miles of mostly highway usage it has lost 1 liter of oil. There are no spills, no leaks, no smearing under the car, nothing. The oil simply disappears. I replenished the lost liter to confirm the loss and checked after another 200 or so miles and indeed it is losing it. Could this oil problem be related to this diagnostic result I'm getting? Am I looking at an engine rebuild here? Or something less problematic like a sensor somewhere? Any help would be appreciated.

Thanks all.

GreyStang

What do the spark plugs look like? Is one of them a lot more sooty than the others? You might have a valve stem leak leaking out the oil into a cylinder. If that's the problem then the fix isn't too much of a nightmare

sebas_nava

One of the plugs was very dirty, but it wasn't the #4 that is indicated in the diags and it was more of a dirty grime rather than oily. The new plugs have been in there for a few weeks so I'll recheck them again to see how they're doing. Another thing I've noticed is that the car doesn't smoke at all. What other signs should I be looking out for?

TripleHmotosports

What size engine? Do you feel the car missing? If it is missing it could be the injector. How many miles are on the car? If you don't feel the engine missing it could just need the PCM reprogrammed as Ford has had issues with misfire codes before?