Besides being a federal felony, $2,500 fine, it will throw fault codes and mess up the mixture, since it will see the same A/F ratio at the upstream and downstream sensors. It will increase emissions of HC and NOx by 5x to 10x. It will change backpressure and hurt engine performance.
No, you can't do it without both computer and performance problems.
Also, at least in MA and probably a number of other states, if you ever sell it, you must pay to replace it for the buyer.
So why would you want all that grief?

 

I don't want all that grief. That's why I asked about it.

 

What leads you to believe the cat is beginning to fail? Drivability issues? Diagnostic codes? What symptoms/issues are being encountered?

 

Thank you Gerry. I'm going to forget the whole idea.

 

Federal felony??? Ok forget it.

 

As a converter ages, it may throw a P0420/P0430 fault code.

https://www.kbb.com/obd-ii/p0420/#:~:text=the%20p0420%20code%20signals%20a,sometimes%20be%20tricky%20to%20diagnose

.

If the converter is beginning to plug, a back-pressure test can be performed.

 

Very frustrated. The car started smoking a little white smoke when I started it up right after I did an oil change. 5W30 full synthetic high mileage. The oil filter is the correct one. It's not thrown any codes. When in park sitting in the driveway I rev it up and it will start crapping out just under 3000rpms. The smell is like rotting something stinks. I'm not loosing coolant, the oil is clean and clear, it's not overheating, also new air filter. I took it out for a drive and it accelerated good? Doesn't blow ANY smoke at all. Just at idle. Transmission oil is clear and pink.
The heater DOES NOT work? The smell of the exhaust is what got me on the catalytic converter trail from experience with other cars. Put a new battery in it too. Spark plugs are next. When I went to pull the throttle body intake off one of the 5 bolts was stripped and obviously thread locked down or... but I wasn't able to pull it out, it's stripped and stuck. So I stopped there to cuss and think about it. The car started doing this right after the oil change. The oil level is right on 5qts. It was a quart low and very used oil when I got it. I've been going through all the neglected maintenance stuff except PCV valve's.The suspension system needs attention front and rear.
I don't think the smoke is a blown head gasket. The heater not working does bother me though. The AC blows very cold. Also, the air box does not close properly. It's going to need a new one. It's not a tight seal. Thanks IC

 

I'd try flushing AND back flushing the heater core if that was mine. As for the crapping out around 3,000 rpms while in park or neutral, that's normal. There's a rev limiter to keep you from doing that and blowing the engine by slinging a rod. DON'T DO THAT. You really need to keep an eye on your coolant and oil to see if there's the chocolate milkshake look to them. If so, it's time for a head gasket. If not, keep driving it until you know for sure. I'm thinking the problem is your cat con, but I'm NOT a mechanic. Change the PCV valve. It's cheap and easy to do. As for that stripped bolt, is there anyway you can get a flat blade screwdriver under it and pry up while turning it to back it out? I don't think that's got anything to do with the white smoke, but you really need to get that out and fix it. The throttle body does need to be snug so as not to leak.

 

👍Yeah, I can get that bolt out. I have the stuff to back flush the heater out. It worries me that someone may have poured some magic potion to seal a bad head gasket and plugged up the heater core so I am keeping my eye on it. Thanks for your time. It's just weird that this started immediately after a oil change. I'm just going to drive it and see what happens. It runs fine. I have no experience with car computers. I'm a old guy who could work on the old stuff with carboraters, points, plugs, and distributer caps. We didn't need code readers to fix our cars but looking back our cars were junk compared to what we have now. Highly sophisticated to say the least. Thanks!

 

White smoke doesn't have to be coolant or oil. In cold weather, it can be the normal water vapor. For every 8 gallons of gas burned, 1 gallon of water is produced.

If the odor is like sulphur or rotten eggs, it may be running rich? If the spark plug tips are carbon-fouled, either clean them or replace them. The correct plug is Champion RE16MC or NGK LZTR4A-11 Copper-Nickels.

 

I have spark plug NGK LZTR5AGP Platinum alloy. O' Reilly sold me the wrong plugs didn't they?

 

Yes sir about to get to the plugs, had a little trouble getting to them but hopefully it will be today. Let you know. Thank you,

 

I prefer the OEM spark plugs. Some cars can tolerate platinum plugs better than others.
Coppers offer a better burn but should be replaced every 30K miles (50K km).
The '5's are listed for a turbocharged 2.4L.

 

👍

 

My one PT has intermittently had a check engine light with a P0420, low catalytic converter efficiency. The first couple of times I took it out on the highway and gave it a good run, that held it for a while. It's become a little more persistent. I have put a can of Cataclean in it twice now, again it works for a while. Just my experience, not anxious to replace the cat.

 

Ma

I haven't heard of Cataclean, how is it applied? In the fuel supply?

 

Thanks 👍

 

I've heard that lacquer thinner also can be added to the fuel tank. It may damage rubber components.
I'd rather fix this the right way. Walker Direct-fit cats aren't that expensive.

 

Me too. I got the right plugs last night . Going to put them in today. Anxious to see what the old ones look like, forgot the pcv valve but I'll get that too. I found a a cat con for $150 too. Not that bad. I'm not crazy about dumping chemicals in a car. I believe in a few injection cleaners can help but i don't know about some of these things I hear. What do you think about Seafoam in the gas tank ?

 

In the past 40 years, the only aftermarket fuel additive for gasoline engines mentioned by Chrysler in a TSB has been Techron for cleaning, decarbonizing fuel systems & combustion chambers.
Engineering couldn't possibly evaluate all the 'miracle mechanic-in-a-can' band-aid chemicals out there. Most of it is just marketing-fluff anyways.

Basically all of additives/blends that you need should be already in the approved fluids, including fuels. Follow the material standards (MS) for the recommended fluids like coolant, oil, sealers, etc.

The closest equivalent to Seafoam might be the Combustion Chamber Cleaner. As higher tier fuels are refined to remove the sulphur, they should produce less soot.

"On top of that, the U.S.'s Tier 3 regulations require gasoline to contain less sulfur, but the process of making low-sulfer gasoline reduces octane, making high-octane premium fuel more expensive to produce". Mar 20, 2023

 

I can't get the throttle body manifold off because of a stripped bolt. 2nd one from the left backside between the ports. Will not come free even with all the bolts out and wedging pressure up and pulling on the plastic housing. I can't get to rough with it or I'll mess this plastic up. The nut insert on the bottom is just spinning in the plastic housing. It was like this from the beginning. Acts like it's also warped because it rocks the entire plastic housing in a circular motion whith all the bolts pulled.

 

If I can get a pencil grinder in there and grind the bolt head off I might be able to get the bottom piece drilled out then go through with a different bolt and put a regular nut on the bottom. Would that suffice or not a good idea?

 

What is it about this car that I love...

 

This stripping blind nut issue has happened to members here before.
No resolution posted back. He may respond to a PM? Last logged in 2022.
Steel bolt into a brass nut=bad idea.

https://www.allpar.com/threads/08-pt-cruiser-stripped-intake-manifold-bolt.171109/#post-1084950881

 

Yep. Good info on the Stanley stuff. I'm going to go by a friend's house and see what he thinks too. He's got a pretty good shop and a pencil grinder. Thanks a lot brother your dang sure a great friend to have here. I'm impressed 👍 I'll keep you posted.

 

Yeah. Steel bolts on brass nuts, that are melted in hard plastics needs to have, at the least, an Anti-Seize compound applied to the bolts and properly torxed. Dissimilar metals oxidized.

 

I dunno if it's worth mentioning this, but I had a couple of instances, when I was in my late teens and early 20s, where I owned a couple of vehicles and this happened.
NOT straight after an oil changes though - that may be just one of those weird coincidence things?
Anyway, heaps of white smoke on start-up, which smelled nauseating. It would go away while driving under acceleration, but down hills with my foot off the gas, back it came, and at idle.
Turned out it was a pinhole in the brake booster diaphragm, and at high vacuum, the engine was hauling brake fluid in through the intake manifold and burning it. Unbelievable smell.
Second time it happened, on a different car, that was the first place I looked, and it was actually making a faint "whistling" sound.
Last up, and only slightly related, (no smoke), my next door neighbour was having seemingly incurable idling problems on a 5.0 litre Holden V8. It would stall at the lights and if he drove VERY slowly, it would die.
Full throttle pretty good, but a bit hairy around town at a steady low speed.
He fitted a new carb kit, then a complete new Holley, glugs, leads, distributor cap and rotor, drained and replaced the fuel, then did the PCV, (not necessarily in that order...).
Still ran like before.
Guess what?
Yup, booster diaphragm was split -it had gone all dried out and hardened.
Diagnosed by pulling the vacuum hose of it, and blocking it with my thumb. idled just fine, thanks. Reconnect to the boster, nope. Ran like a bag pf rocks.
So, a rebuilt booster, and it now runs like a Swiss watch.
The super-stinky smoke on my own cars it what gave it away, and it was thick, white smoke, not blue and smelling like burning oil.
Maybe???
Seems weird about the heater going out at the same time, unless a vacuum leak in the booster somehow affects it's operation? There are vacuum hoses all over the place on some vehicle heaters...