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jmc2004 05-04-2012 06:02 PM

Catalytic question
If i were to replace one catalytic converter on my 5.7 with a high flow cat,would it affect anything adversely? I have a code of p0430 and its for catalytic converter efficiency bank 2. So I was going to cut the cat for bank 2 out and replace it. Then I got to thinking if I put a new high flow on one side and not the other,would it run differently? I would guess not but you never now. Thoughts?

Saleen405 05-04-2012 06:18 PM

Re: Catalytic question
If you have less than 80K on your truck, and the cat isn't banged up or visibly damaged, take it to your dealer and they will replace it for you. I had mine replaced about 3-4 months ago for no charge.

jeepgcoman 05-04-2012 08:58 PM

Re: Catalytic question
Also, check and make sure you don't have any other engine and/or O2 Sensor problems, before you replace the cat. They usually last almost forever if everything upstream is properly maintained, or they get bashed. It may not be the cat. at all. As far as putting a "high flow" cat. on one side goes, I can relay what my exhaust guy told me when he built my headers. He said the stock cats. are high flow, wire spun (whatever that means) cats. and I wouldn't gain a thing by putting aftermarket "high flows" on. So, I didn't.....just left them stock.

You know what I find strange????? Both of my Hemi vehicles have had O2 Sensor problems, one just discovered on my last trip. The strange thing is that both problems were on the passenger side bank, and almost all of the problems I've seen on all these forums have also been on the same bank. Is there a pattern here? Anyone have definitive problems with the driver's side O2's/cats.? Just curious.

jmc2004 05-04-2012 11:37 PM

Re: Catalytic question
I guess im not so worried about the flow as i am the price. Frrom what i have read magnaflow makes a cat that is close to the same dimensions as stock and it happens to be high flow. And it is also a fraction of the price of a replacement y pipe. How did you fix your o2 sensor problems? I would love to know because im tired of looking at my MIL light,and from what I understand the MDS also gets disabled when there is a code thrown. Any help is appreciated.

jeepgcoman 05-05-2012 10:28 AM

Re: Catalytic question
You are correct, the MDS becomes inactive with these codes. With the O2 sensors, you just change them, but be aware it is not an easy job with the stock (or near stock) exhaust system. Before you change them though, make sure everything in the engine is top notch, as engine problems can cause O2's and cats. to fail. Here are a few of the things you should look at. Anything that can contaminate the combustion tract can do damage to these components.

--Do you have a catch can?
--When is the last time the PCV Valve has been changed?
--Have you cleaned the back side of the throttle body butterfly? How bad was it?
--On the 05, have you checked the resistance of the ignition wires?
--What is the fuel economy, mixed, highway?
--When was the last tune up, especially spark plugs?
--Any other DTC's lately? Use a code reader to check historicals too.
--If the backside of the TB is real bad and, especially if there is puddling in the plenum, you should probably change the MAP Sensor.
--Any exhaust leaks before the front O2's...i.e. the exhaust manifolds? Will send lean signal to PCM and richen mixture in response.
--Does the engine burn oil? How much?
--Any other items that may affect, primarily, engine oiling, and fuel mixture or engine performance.

jmc2004 05-05-2012 01:11 PM

Re: Catalytic question
I need to do all those things,I just got it a couple weeks ago so i havent had the time to clean the TB or plenum. I was hoping not to have to change o2 sensors as it seems its going to be a hard task. They sure make it hard for people to work on rigs these days lol. As for the PCV,it seems easy and cheap. Dose not burn any oil that I can tell,and the plugs looked pretty new to me,although I only pulled one.A catch can sounds like a good idea,the TB looked pretty caked. My gas mileage definitely isn't very good,It says Im getting 14 in town and 15 hwy. And im pretty sure i have no exhaust leaks,although i haven't thouroughly investigated. How would you check the ignition wires resistance? Are MAP sensors expensive?

jeepgcoman 05-05-2012 01:48 PM

Re: Catalytic question
Jmc, I wouldn't even think of changing O2's or cats. until the engine has been checked out. You'll be doing it again if you don't do that first. I know what you mean, when purchasing a "new to you" used vehicle. The Jeep dealer put the wrong oil in mine and it was ~18000 miles overdue a tune up. How many miles are on yours? If it's over ~75K you should probably do a complete 60K service on it, if you want to get, and stay on top of everything. Do a little at a time as some stuff is fairly spendy. Fluids/oils/filters alone run ~$300, if you purchase them.

The PCV Valve is easy and inexpensive. Just be careful not to break it off in the manifold, as some have done. Don't use excessive force, even though it is fairly difficult to turn. Install the valve with the hole facing the back. This is just my way of doing it, as otherwise (with hole facing front) it will provide a direct path from the valve to intake manifold. The Hemi's have probably the worst crankcase ventilation system of any modern vehicle, and the valve is a real cheapo too. IMO, a catch can is a must. I have one on both of my Hemi vehicles. Cost of the PCV Valve is ~$25.

Your in town mileage is about average, but your highway mileage is way off. There almost has to be something not working as it should. Even mine with the wrong oil and worn plugs got ~18 mpg, highway when I first bought it. Take a look into the intake plenum. Manually open throttle butterfly, look at the backside of it, and shine a light into the plenum to see if it is wet. The backside of the butterfly will probably be real bad, and if the PCV Valve is not doing its job, the plenum will probably be wet.

Again, if you have more than about 75K on it, the ignition wires are probably bad, or very close to being bad. If you have an ohmmeter, check the resistance of each, from end to end. Rule of thumb is no more than ~10000 ohms per foot, but they should be much less.....between ~10000-15000 ohms for a 3 foot long (which most approximately are) wire. If you have to replace them, consider purchasing the Taylor Shorty wires. I've had them on my Hemi LX for at least 6 years now, without issue. It also gets rid of the "rats' nest over the top of the engine.

A new MAP Sensor also runs ~$25 or so. You probably won't be able to find one that looks like the one that's in it now. They've superceded the part number and the new ones have a mounting tab on them. You'll probably have to cut the tab off and also a small part on the intake to get the new one to fit. You can do a search and find out how to do this.

jmc2004 05-05-2012 06:44 PM

Re: Catalytic question
Thanks for the info,I think ill start buying all the parts and fluids and get going on it. You've been very helpful!

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