new here
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Veteran
Joined: May 2013
Posts: 256
Likes: 5
Did you ever have an extended period of misfire, or some other engine problem with this van? It's somewhat unusual for a cat to go bad that soon unless raw gas or oil gets into it.
For those of us who DIY, one typical thing is replacing the O2 sensors, which is a relatively inexpensive and easy thing to try. However that's not going to be inexpensive if done by a shop (I would guess $200-300). And because the O2 sensor replacement is probably less than a 50% chance, I wouldn't recommend that if you don't DIY. Some folks have had success running cleaner through with the gas, and lacquer thinner is often mentioned as well. Personally I don't like the idea of that stuff flowing through the fuel pump and other fuel system compoments, but that's just me. A cat replacement by a shop is going to be costly, especially if they will only use an OEM cat.
For those of us who DIY, one typical thing is replacing the O2 sensors, which is a relatively inexpensive and easy thing to try. However that's not going to be inexpensive if done by a shop (I would guess $200-300). And because the O2 sensor replacement is probably less than a 50% chance, I wouldn't recommend that if you don't DIY. Some folks have had success running cleaner through with the gas, and lacquer thinner is often mentioned as well. Personally I don't like the idea of that stuff flowing through the fuel pump and other fuel system compoments, but that's just me. A cat replacement by a shop is going to be costly, especially if they will only use an OEM cat.
Veteran
Joined: Jun 2014
Posts: 299
Likes: 0
From: Mobile Alabama
I have seen cats melt from prolonged idling (aka sitting in a parking lot waiting for someone). Our local muffler shop does cats CHEAP (installed for less than you can buy the aftermarket ones at the parts store). Easy test is disconnect exhaust just before cat (ok not exactly easy since it's old exhaust) and see if it runs better
Veteran
Joined: May 2011
Posts: 394
Likes: 3
cats go bad from cylinder misfire. The misfire is generally caused by neglected ignition issue (bad spark plug, wire or coil) or failed/sticking fuel injector.
Certain commercial vehicle vehicles must idle for 4-8 hours per day for years on end with no cat trouble. Consumer-owned vans never see taxi idling cycles. Some taxi's idle continuously for two shifts per day with A/C on and many of them are grand caravans.
I'm betting on misfire causing the cat to fail.
Some shops have a gadget that will install in the pre-cat o2 sensor hole to measure exhaust back pressure.
Certain commercial vehicle vehicles must idle for 4-8 hours per day for years on end with no cat trouble. Consumer-owned vans never see taxi idling cycles. Some taxi's idle continuously for two shifts per day with A/C on and many of them are grand caravans.
I'm betting on misfire causing the cat to fail.
Some shops have a gadget that will install in the pre-cat o2 sensor hole to measure exhaust back pressure.
Last edited by Lscman; Jun 29, 2014 at 12:46 PM.
