My daughter's Expedition, 150K miles, is blowing white smoke, and has been running a little rough lately. She doesn't live close to me so I had her check for codes. Came up with cyl 5 misfiring and running rich. She says that the exhaust smells like fuel. At first I figured a head gasket, but after some reading online, I think it could be #5 injector stuck open or a head gasket.

Coolant looks normal, oil is not milky or light colored.

Thought about pressurizing the cooling system to see if it holds pressure. Thought is that if the head gasket is leaking it might not hold pressure (unless both valves on the effected cylinder are closed.

If its the injector, I've read that it can hydro lock and then the engine is done.

I don't want to do further damage, but how do I diagnose the problem if I shouldn't start it.

I can have the Expedition towed to my house, but then what.
Was thinking a NOID test to see if the system is telling the injector to stay open, but that requires at least turning it over right?

I mean it could be just a bad COP (coil).

Any suggestions?

Thanks for any advise in advance!

Paul

 

Compression test of #5 should tell you something. White smoke usually means water so a head gasket leak would be suspected. Of course they all put out white smoke until the exhaust pipes warm up a bit in cold weather since water is a product of combustion.

You could also switch injectors and see if the misfire follows the #5 injector.

 

With a hydro lock wouldn't a compression test be bad? I think I'm going to pull the plug, so no compression. Then do a NOID test to see if the signal is telling the injector to stay on.

Thanks for the reply!

 

If the injector is leaking or stuck open, it's more likely the injector itself.

A compression test/leakdown test can help you find a leaking head gasket. Another thing you may want to do is a hydrocarbon test on the coolant.

Only hassle with a compression test is you should do all 8 cylinders for comparative readings, and with a 5.4 3V this may result in broken spark plugs.

 

NOID test should be easy enough to rule out electronics.
I hate to pull the fuel rail just to swap injectors. I think if I go that route I'll just put a new one in.
What about a bad coil? I've replaced several on Fords (and BMWs) over the years. Would that throw the same codes?
Looks like I'll be driving to my daughter's house tomorrow to see if I can figure it out. I just don't want to get the blame for a Hydro Lock.

Thanks again

 

Coils and plugs can do that, but the white smoke and fuel smell concerns me.