HELP! Massive Issues After Cleaning Valves w/ Walnut Media

[Phoenix77]

I am the original owner of a 2015 that now has 163k miles on it. No problems, have some upgrades professionally installed (MishiMoto intercooler, 3" catted downpipe, Whoosh! Hybrid turbo, COBB Tuning tune etc.).

Tuesday I got "P0303: Misfire on Cylinder 3" on my way home from work. I pulled the intake manifold today and did the walnut media blast on all the valves, following the procedure outlined here:

https://www.fiestastforum.com/threads/intake-valve-walnut-blasting-my-diy-experience.32544/

And I'm certain I put everything back together correctly.

I started the car - long ignition sequence before firing up, then rough AF. I hooked up the reader and good Lord.

Any insight is greatly appreciated!


Code 0420 is from the tune, but the rest are new.

 

[Mega ST]

1st and foremost, check all plugs to make sure what ever you unplugged is full seated. Pull spark plugs and see how they look. Some crap could also get stuck to the valve seat which can cause a misfire.

 

[Intuit]

A member saw a similar position sensor code with a timing belt slip. It's possible this issue were created by debris left in the intake.

 

[Phoenix77]

Update:

I re-checked and reseated all connections, then let the car idle for a bit and it calmed down. Still have Misfire on Cylinder 3 codes, as well as Camshaft Sensor Bank B. I ordered replacement Camshaft Sensors.

After further research, I've narrowed it down to a bad injector on Cylinder 3. I ordered the part, and should have it tomorrow. Hopefully this solves the misfire issue 🤞

 

[Intuit]

Hall effect sensors rarely have issues short of them or their wiring being physically damaged; more especially multiple sensor failures. Test to make sure that your wire harnesses are fully seating. I had a harness that wouldn't fully seat until I outright removed the seals. (After killing half-an-hour or more trying to figure that out, even looking at another as an example, I simply resided to compensating by cramming copious amounts of dielectric grease around the harness and around the pins. )

It is also unusual to read of a failed injector, even on direct-injection engines. When we do see posts about injectors, it's in regard to cleaning them. High pressures might result with higher failures over leakage. If the cylinder is rich, may be indicated when reading the plug.

 

[scooter123]

My suspicion is the cause is a bit of walnut trapped in one of the plugs that was disconnected to gain access to the front of the engine. Solution is to trace back from the camshaft sensors to identify that particular plug and use a small flashlight to inspect it carefully.

 

[Phoenix77]

I ended up trailering the car to a nearby Ford dealership in the event they needed the Magical Ford Computer to tell my car about the new camshaft sensors and fuel injector.

I told them the codes I was getting: camshaft sensor & Cylinder 3 misfires, and that there was a metallic scratching noise at the top when you rev past 2000 RPM.

The next days the told me there were error codes for camshaft sensors & Cylinder 3 misfires, and there was a metallic scratching noise at the top past 2,000 RPM.... The mechanic heard the noise, looked at the codes and the answer apparently was super simple:

I need a new engine.

Masterful bit of mechanic-ness, for which they charged me $168.

I found a working engine on eBay from a 2017 ST with 16k miles for $3,500 shipped. My [non-Ford-dealer] mechanic will install for $2,500.

This whole situation sucks, but my 162k mile ST will get a 16k mile motor. They'll put my Whoosh! Hybrid Turbo on the new engine etc.

 

[Intuit]

Thanks for the follow up. 😫 Ouch. You seem to be taking this quite well.
I guess they're saying the scratching noises are ??? Piston scrapes ???
If you're keeping the old engine, I'd definitely peep into it.
I guess this begs the question, what performance or running issue lead you to wanting to clean the intake?

 

[Phoenix77]

With the misfires in Cylinder 3, my buddy did independent research and figured it was due to buildup on the valves.

In retrospect, the media blasting likely played no role in the final chapter of the engine. I suspect it was on its way to Valhalla anyway - 162k miles of smiles being flogged daily.

 

[Intuit]

Oh okay. Ooops, you said that from the beginning. Makes sense. Stock these engines don't truly have issues with severe valve build up relative to other engines. Dunno about altered configurations.