OP, can you take a picture of that piston (3rd pic you posted) further down its bore? Would like to see the whole top (or as much as you can capture with the scope) and not so close. That just looks like carbon to me.

 

Correct, the pics are showing cylinders 1-4. I'll scope 5-8 but don't expect those will be visually different. I'm 99 percent sure it's pinging, based on what I know and the opinion of a couple of mechanics. It's a rattling sound, like the ball in a spray paint can, that only presents under hard throttle once the motor is warm. The second I let off the pedal, it'll go away. I've never been able to recreate at half throttle for example.

I have installed a new PCV. I'll try the MMO and a couple of the other ideas. I'm hopeful the Delo recommendation might help too.

I'm using Motorcraft plugs that are properly gapped, but have read switching to colder plugs could be a potential solution. I love this mid-90's generation and don't want to give up on my first F-150! lol

 

Definitely. Here's a fresh set, hopefully a little better quality as well. I've marked accordingly.


Cylinder 1

Cylinder 2

Cylinder 2

Cylinder 3

Cylinder 3

Cylinder 4

Cylinder 4

 

The two return passages look good to me. I don't see anything visually that looks clogged or out of the ordinary.

 

Thanks yeah those look pretty good for 150k miles from what I can tell. Not so sure I'd pull the heads off for it. Did you try running it with the o2 sensor disconnected?

 

Appreciate the opinion! Haven't had an opportunity yet but I plan to. I get injectors back mid-week and then I'll work of putting everything back together.

I haven't touched the inside of a motor since high school 15 years ago, so this has all been a good learning experience if nothing else! Haha

 

did you get a chance to check timing

 

How long have you had the truck and how many miles have you put on it? Valve seals are not that hard to put on with the heads on the truck.

 

Purchased from original owner in late-2018. I've put about 750 miles on the truck. Would like to get to point where I can rely on it as a daily driver. Putting on the valve seals seems pretty straight forward.

 

You haven't driven it enough to burn the crud off the pistons. Did you drain ALL the old gas out, or just mix? The reason I ask, I bought a '97 Crown Vic that had been sitting for two years. I had never hears the kind of spark knock that engine had. It sounded like marbles rattling in the engine. I ended up putting a new fuel pump and draining the tank before it ran like new again.

Also, Check your fuel pressure. The pump could be going out, and change all fuel filters. Your problem could be that simple.

 

Fuel pressure is good after putting a new regulator in and I've installed new filters. I mixed when I took ownership. I was told the truck was driven often but who knows if that was the truth. New fuel pump is a new option I haven't heard before. What prompted you to focus on the fuel pump in your Crown Vic? Any idea what the correlation between the pump, draining tank and elimination of spark knock?

 

Do you know what the PSI readings were when you tested the pressure? I’m curious to know the reading at WOT and if it increased/decreased or maintained pressure compared with part throttle at cruising speeds.

 

I had to put in a new fuel pump after I tried to start the car with an almost dead battery. Then engine kicked back, and caused two lash adjusters to pop off the lifters. I parked the car for a few months after I figured out why it had a dead cylinder, and it was too cold for me to work on it. By the time I was ready to fix the lash adjusters, the fuel pump was stuck from me trying to run the car with the old, varnished up gas.

A Crown Vic fuel pump is pretty easy to change, and while it was out I siphoned all the gas out of the tank. OMG what a smell the dead gas had.Changing the pump was much easier than getting the valve cover off the passenger side of the engine. After new gas, new pump, lash adjusters back in place, and a new battery, the car ran perfect. It was a low mileage school superintendent's car that had been replaced and sat at the county garage.

I had my dealers license, and sold the car to a couple 10 years ago. They still own and drive the car. I met them in town just this weekend. The way it rattled when I first got it I thought I had messed up, but it was bad gas and probably a weak fuel pump.

 

Checking in as I’m curious if the cleaned injectors solved your pinging issue?

 

I got them back today and swapped out the valve gaskets. Covers are back on now, so should find out tomorrow after I get plenum back on and check timing. Flow chart showed injectors for cylinders 1 and 8 were pretty crudded up. Fingers crossed ...