rusted exhaust bolt removal?

[yonyon]

Your trims at idle are normal enough. Unfortunately that suggests to me that you probably are going to be doing a cat replacement.

The large negative trims don't look too good. I think that's worth investigation. It doesn't make a lot of sense replacing a cat if there's still a running problem. Your PCM is having to take away quite a bit of fuel when you get the engine turning.

Normally, on a Dodge I'd first check the fuel pressure. I expect you won't have a guage on-hand but you can probably borrow one from an auto parts store. If the fuel pressure checks out, make sure the charcoal canister purge solenoid isn't stuck open (if you can blow through it while it's unplugged it's stuck open) or installed upside down. It should be labeled with TOP on the top.

I have no idea what impact the "wrong" (as far as the PCM calibration is concerned) temperature thermostat is going to have on things with this truck. It might be a good idea to ask the other guys with that engine running cold what they get as normal trims. If they're all seeing the -10 to -12 also and not eating cats then you can dismiss it.

 

[Jimmy9190]

Thanks YonYon for the help. Actually I do have a fuel pressure test gauge kit and a vacuum test gauge kit. I bought them both at HF back when I needed to check the vacuum when I was working on the ping problem. Fuel pump is just a few years old, only has about 25,000 miles on it. It is an Airtex pump, I have read those are not very good but I have had no trouble with mine. I bought it at AAP with a good discount code. I can check the fuel pressure but I don't think anything is wrong there, truck starts right up with just a blip of the key and I hate to sound like a broken record but the truck does run very well, no driveability or fuel delivery problems at all.

The fact you mention the charcoal canister made me wonder about something. Before I slid under my truck last Saturday to get a look at at my cats and exhaust pipes, I thought I noticed a faint smell of gas. When I was under the truck I found there were faint gas fumes coming from the charcoal canister. It is mounted under the truck, just forward of the gas tank. I went outside just now and sniffed around the canister again and did not notice any fuel smell at all. I have no idea if that could be part of this cat problem. I have not noticed any fuel smell at all before or since last Saturday.

A lot guys on the Dodge Forum run the 180 thermostat. Some did it because they feel it gives a litle more power on the butt-dyno, some others did it because of the ping problem. No one I know of on the forum is having cat problems. Come to think of it, I have been on the Dodge Forum for 8 years now and can't really recall very many of us posting with cat problems.

I use MMO in my fuel. I have not mentioned it until now because I do not want to start any kind of MMO flame war here. It may or may not be relevant but I have been adding 4 ounces to each 10 gallons at every fuel fill for about 3 years now. I started on it for the UCL properties, mild fuel injector cleaning and to help increase my gas mileage. MMO is also reported to help with the negative effects of ethanol. I have read that MMO is harmless to cats, but now I have to wonder if that is really true. And if so, then why did the MMO not ruin my other cat too? I did not add any MMO to the gas I bought this past Monday and my truck is still running fine. After this is all over and I solve the cat problem I may stop using MMO and either switch to TCW3 or just a dose of Techron/Regane every 3,000 miles.

I have no other codes stored besides P0432. I have no pending codes either. The guy at the local AAP is a tech at the Chevy dealer in town and he works part time at AAP. He is pretty knowledgeable but not a know-it-all. He told me today that if the only code I have is the low efficiency cat code, then the cat most likely is bad. He also told me they have an ethanol tester at his shop, they have tested the ethanol content in some Police cars and are finding upwards of 12% ethanol in the fuel. The Police cars get filled up at our local gas stations, and maybe I got some ethanol heavy fuel myself which may have contributed to this cat problem. I have no way to know for sure.

As far as I know from reading the Dodge Forums the only negative effect of the 180 tstat is the truck will run just a bit on the rich side. I don't know if the thermostat is causing this cat problem.

One last thing, is a universal cat OK? I may just take the truck to the exhaust shop and have them weld in a new cat. It is not in my nature to fix one cat but not the other but I guess I could worry about the Bank 1 cat if and/or when it throws a low effeciency code.

Thanks again for your help on this.

 

[Jimmy9190]

I talked to the exhaust shop guy again today, now the cost of the universal cat has mysteriously gone up to $150.00 and he said I may be looking at $150.00 to upwards of $200.00 in labor depending on how hard it is to weld in a new cat. For that price I will just replace the cat/exhaust assembly myself. Other than getting the rusted bolts loose the job is pretty straightforward, and I am confident I can do the work myself.

I checked some pics of the exhaust manifold in my Dodge Service Manual, it does not show bolts cast into the donut flange end, it only shows holes for bolts to go through. I am thinking if a bolt does break off I can push it through the other side and replace it. I will use new bolts and nuts anyway. I will get with Rock Auto and order the new part later today.

Everything I have learned here and online points to the cat being bad. I don't think MMO had anything to do with the cat failure, if anything it was because the truck ran a little rich for 7 years because of the 180 degree thermostat. I may swap out the t-stat for a 195 and see how it goes.

I appreciate all the help here. I am sure I will be back with more questions once I start on swapping out the cat/exhaust assembly.

 

[Jimmy9190]

Well I ordered my new cat/exhaust pipe assembly this past Sunday, Fed Ex delivered it to me on Wednesday. I took a good look at the exhaust again earlier this week and figured I could do the job. I had to buy $80.00 worth of new tools from Harbor Freight - sawzall, blades, long wobble drive extensions, and a few others I thought might come in handy for the job. I had every intention of doing the work this weekend but I took a few hours off work this morning and took my truck to a good local independent garage near my house just to see what they might charge. His verbal estimate was "somewhere between $100.00 to $200.00, but no more than $200.00." He also said my new parts from Eastern Catalytic looked good, were very well made and good quality. I thought about it and had the shop do the job for me. They charged me $191.00 and had it done in about 2 hours. Turns out it was money very well spent.

I watched the guy doing the work, he is an old timer named Dave, he has been turning wrenches for 30 years and he does a good job with the same level of care as I would take. While I watched him work I realized there would have been no way I could have done that job myself, flat on my back with only a foot or so of room to work. It took Dave and another guy 15 minutes working with a torch and 4 pound sledge just to get the end of the pipe from my old cat removed from the exhaust extension pipe. He had to use the torch in a few other places too and he welded all the seams where the new pipes joined. I could not have done that at home no matter how bad I might have wanted to. The exhaust flange nuts did come off pretty easy though.

Dave cleared the code for me and I drove about 18 miles to work, so far the CEL has not come back on yet. The other night when I replaced the downstream O2's the CEL was back on again within just a few miles of driving. I sure hope I got this cat problem solved now...

If anyone here needs replacement cats, the Eastern Catalytic brand they sell at Rock Auto is what I bought. They are made here in the USA and great quality, the cat/exhaust assembly fit my truck perfectly and Dave said the welds and construction were very good. You can tell by looking at the parts they are welded by hand. It's hard to find that kind of quality nowadays.

A buddy of mine here at work knows a junk man/metal scrap guy. My buddy called the junk man for me, he came by the office a while ago and I sold my old cats to him for $40.00. That brought today's labor cost down to only $151.00 and I can return the tools I bought at HF.

Sometimes there are jobs where it just makes better sense to pay a shop. I sure hope I am done for a while though.

 

[cjcride]

Nice story with a Happy ending.

 

[Jimmy9190]

Yep, so far so good with the new cats and CEL. I drove 20 miles home from work tonight, stopped at the barber shop for a hair cut, came on home and after dinner I drove about a 5 mile round trip to Target with my wife, so far the CEL is still off. I would think if there was a problem the CEL would have lit back up by now. I am still keeping my eye on it though...