For a compression test on a 5.4 3v? It's been suggested that I have this done due to ongoing misfire P0305. Truck is going to dealer this Friday so I figured I might have them do it since I don't have the tools.

 

Unless you have had the sparkplugs already changed once it could cost you a lot. Once they start removing the plug its possible it could break increasing the cost considerably and of course if they test all cyls the cost would increase in relation to those that break if any. Depending on your mileage you may want to have them remove all the sparkplugs and install new ones while they have the truck. Get a price including possible breakage. Have you tried changing the COP on that cyl? How many miles on the engine? Has the dealer tried anything else to solve the problem so far? Good luck

 

CT was suggested by jbrew. I just changed the plugs 2 weeks ago so everything will come out no problem. Yes changed #5 cop and plug with no fix. 79k on engine, I'm sending it to dealer on friday and telling them I want crank and cam sensors and VCT solenoids checked. If those are all good they can do the compression check.

 

On an 05 you have to consider an injector may be the cause as well. Have you switched the injector to different cylinders?

 

No, but dealer checked them, they were good. I did the leak test as described here:
https://www.f150online.com/forums/ar...ml#post4213274

and they were good.

 

You can rent/borrow the needed tools from most parts stores.