Any idea what the issue could be?

[fieSTeban710]

Not too sure what happened this evening with the Fiesta? As I was shifting through the gears I hear a kind of popping noise, then some metal like sound as if something came off the car. Now the car sounds like it doesn’t have a CAT. Maybe the DP came off? And of course the day I need to use my jack it doesn’t work 🥲 Plus I’m not mechanically savvy unfortunately. (Why did I mod the car? I know 🥴)

car still turns on and drives but feels as if my engine is hitting the firewall like if my RMM is loose or broken.
Any of you experience something like this?

I couldn’t get good videos of the sound but I’ll post what I have to see if it helps. Any ideas are appreciated!

 

[dhminer]

RMM issues are common, especially if you’re still on the stock one. Push on the engine with your hand, trying to rotate it forwards and backwards. It should hardly move. If it does, your RMM is probably shot. It’s possible it went out in a dramatic enough fashion to loosen up (or hopefully not shear) some downpipe or exhaust bolts.

All speculation though.. gotta get in there and take a look

 

[Intuit]

His sig says "Woosh RMM".

PO420 is a catalytic converter code.
Other than the exhaust leak and phone moving around I didn't notice any unusual sounds.

I'm thinking your exhaust may have come loose, pre-cat.
If that's the case DO NOT RUN the engine as the hot exhaust may damage surrounding components.
Other than that possibility, check your flex-piping.


The ECU analyzes the catalytic converter by comparing the readings to oxygen sensors, before and after the catalytic converter.
A pre-cat exhaust leak would also result with incorrect information being fed to the ECU.
Whether or not that could trigger a cat code, depends on whether the cat was still getting enough of what it needs (heat, oxygen) to adequately perform its function; and with a severe leak it might not.
Tuning is also based on there being a certain amount of back-pressure from the exhaust piping; "changing" the exhaust, potentially necessitates, changes in tuning.

Wonder whether it's possible that it could be on reduced performance, purely as a method of controlling emissions?
There are multiple ways to explain a drop in performance, with a (major) exhaust leak.
Mainly depends on where it's at and the severity.