Cat clogged after 1500 miles.

[ziggysmoov]

My rarely driven E30 started going into a limp mode, no warnings, just lack of power out of no where. Brought to dealership and they found cat was clogged after back pressure test and checking temps of exhaust after it gets hot. Since ownership I have had to change the cat 3 times due to SMOG failures by visual inspection (serial number scrape * low car problems.) Now considering I have barely put any miles and there are no signs of major impact to the cat/resonator/muffler. Is there anythnig in the engine that I should check to ensure I am not contaminating the new custom exhaust set up when I get it fabricated soon?

[MrBurgundy]

You took your e30 to a BMW dealer and they looked at it?

Well, a converter will clog for many reasons, but what it boils down to is- an engine that's not running correctly, or just due to it's age worn internal components are allowing oil to burn and cause carbon buildup.

[ziggysmoov]

Yep, I used to work at a bmw dealership and brought it back to one of the master techs I used to work with.

Over the last 1k miles I did fix a lot of oil leaks.Resealed oil filter housing, valve cover, oil pan. No fuel leaks. No vacuum leaks. Not sure what else to look into that can potentially cause oil/coolant to get into exhaust manifold.

Currently have 134k miles.

only other thing I can think of is the last exhaust shop used a used cat on my car and was already on its way out.

[It's Soda Not Pop]

Running too rich or burning oil. Not an oil leak but oil is either getting past your piston rings or valve seals. If you didn't have inspections I would say get rid of the cat all together.

[ziggysmoov]

Definitely not experiencing any excessive oil consumption. Wouldn’t running too Rich trigger a code? I plan on getting the whole exhaust system replaced anyway. Only thing I worry is causing premature failure of this new cat if I don’t fix the main reason why it made the cat clog to begin with.

[It's Soda Not Pop]

Have you done the stomp test? What codes are showing?

[ziggysmoov]

No codes showing.

[It's Soda Not Pop]

https://www.walkerexhaust.com/support/tech-tips/why-a-catalytic-converter-fails.html

maybe this info can help lead you to a answer

[e30davie]

is the cat removable and can you see through it?

I know cats do callapse and i suppose can in theory get clogged, but its got to be pretty damn rare.

[ziggysmoov]

That’s what I was thinking initially. I did read that walker guide. Which is kind of why I posted this. Not sure if anyones experienced this. I would assume if there was a oil or coolant leaking into the exhaust that would be a bad valve cover/head gasket leak? I did replace all the gaskets maybe less than 500miles ago. Not sure if that was an underlying issue from prior owner that may cause a fairly new cat to fail in 1k miles? I can cut out the cat and inspect internally I suppose. I already took the exhaust off anyway.

- don’t feel misfires. Runs good.
-afm readings seem to be within specification per my friend who is a bmw master tech.
-replaced fuel pump 3k miles ago when it finally took a shit
-haven’t replaced fuel filter so I will plan on getting that replaced.
-only used 91 so definitely not fuel contamination (diesel/e85)
-no visible structural damage.

[ziggysmoov]

Update: had new exhaust setup put together, new cat, resonator, and muffler. Sounded amazing and drove like normal for 20miles on my way home from shop until it started sputtering at steady throttle application. Once i let go of the throttle to coast, vehicle completely died and I had to restart engine while rolling and applying power to the throttle to keep engine on.

aaa wouldn’t tow my car because my registration is out. Luckily It was drivable as long as I didn’t let my foot off the gas, and was able to drop it off at east bay bmw 🥲

Check engine light is on now. Code 1222 on stomp test. Lots of black soot on the tip. Seems like the car is running extremely rich. I hope I didn’t burn through this brand new set up.

[It's Soda Not Pop]

Update: had new exhaust setup put together, new cat, resonator, and muffler. Sounded amazing and drove like normal for 20miles on my way home from shop until it started sputtering at steady throttle application. Once i let go of the throttle to coast, vehicle completely died and I had to restart engine while rolling and applying power to the throttle to keep engine on.

aaa wouldn’t tow my car because my registration is out. Luckily It was drivable as long as I didn’t let my foot off the gas, and was able to drop it off at east bay bmw 🥲

Check engine light is on now. Code 1222 on stomp test. Lots of black soot on the tip. Seems like the car is running extremely rich. I hope I didn’t burn through this brand new set up.

Did you increase the injector size? Maybe your Relay and/or O2 senor is bad.

[ziggysmoov]

Never changed injectors since I bought the car. I’m hoping it’s as simple as an o2 that would be the easiest remedy but I guess we’ll see what the dealership says. I kinda got stuck and couldn’t get AAA to tow my car home due to expired tags. Even though they towed it last Thursday this way.

[It's Soda Not Pop]

Never changed injectors since I bought the car. I’m hoping it’s as simple as an o2 that would be the easiest remedy but I guess we’ll see what the dealership says. I kinda got stuck and couldn’t get AAA to tow my car home due to expired tags. Even though they towed it last Thursday this way.

I didn't realize that you couldn't get a car towed with an expired tag. That's a bit dumb. Check the O2 relay as well. But if your O2 sensor has never been changed then it could be dead.

[ziggysmoov]

I didn't realize that you couldn't get a car towed with an expired tag. That's a bit dumb. Check the O2 relay as well. But if your O2 sensor has never been changed then it could be dead.

Yea I will likely replace that as well for good measure. You never know with these older cars. Pre OBD can be a pain to diagnose