Thanks, I'll take a look at that, but it may have already fried since it shows P304 failure again.

 

Be sure that you inspect the boot between the COP and the plug for cracks. I have actually gotten misfire codes resulting from deterioration of the rubber and cracks allowing the secondary to ground. These boots are $3-4 at the parts store----a lot cheaper than replacing the COP.

 

My engine check light blinks 54 times while driving down the highway, twice today. It's been intermittently running poorly , I.E. rough idle, shakes in drive and terrible mileage. I reset the engine light by disconnecting the battery and it ran great again for a day, but now uugh! I see all your post and find them very informative, what should I check for? 1998 f150 4x4 5.4L

 

Go get your codes read and post them back here.

Probably a misfire, but the fault codes will point you in the right direction.

 

Stop driving it or figure on replacing your catalytic converters. A blinking CEL means there is enough raw fuel being dumped into the exhaust to damage the cats.

 

I have a 1998 Ford Expedition, I was looking for the ac drain plug.

 

If by ac you mean the air conditioner there isn't one.

 

Can anyone help? I have a 99 expedition 5.4L V8 the Truck is nice had engine problems last year while working on the truck a friend dropped a bolt down one of the spark plug holes. screwed the engine. This year I replaced the engine, Now the same driveability problems are back. 1. excessive engine vibration. Was told to do a power balance test, But the pcm corrects the problem before RPM DROP. 2. No misfire codes. Codes are for cat below thershold bank 2. And p1000 system readiness ont complete.
Studing to become a tech, Instructor not a lot of help with outside projects.

 

My first guess would be a vacuum leak or exhaust leak upstream of the fuel control oxygen sensor.


A scan tool with bi-directional control can request that the PCM perform the cylinder balance test and the scan tool will display the results.


Cat below threshold could be separate issue, or it might be a by product of the vacuum/exhaust leak.


So where are you studying?

 

Thanks I'll have to look in to it. But the scan tool the school has states that not and option on the 99.
And I'm currently attending GTC in Wisconsin