- Location
- West Bountiful, UT
I think my misfire issue killed one of the precats. With about 75 miles since first startup on the head R&R, getting two fault codes. One is a P0431. Which could indicate a failed catalytic converter. This motor has two precats, one for cylinders 1-3 and another for 4-6. Got this same P0431 code shortly before tear down. It's for precat bank two where my misfire was. Misfire dumping fuel being one of the most likely causes of a cat going bad.
It could possibly be a bad 02 sensor. Or an exhaust leak. But I'm pretty sure there isn't an exhaust leak and I just replaced all four 02 sensors while I had it all apart and they were so easy to get to (and, like I said, got that code just before tear down, so...). I'll check all the manifold and flange bolts on the exhaust later today, just on GP, but I really don't think there is a leak.
I don't have anything to monitor 02 sensor activity to diagnose further. And even reaching the inlet on the precats to check temperature looks just about impossible. I'll check the temp of the two precats to see if the bank two cat is hotter, maybe that will tell me something. But I think I'm just going to have to get it into a muffler shop with a scan tool that will do some actual diagnostics on it to verify suspicions before throwing parts in. I think 02 sensor activity will show it. But, I think the misfire probably did kill the cat
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The other code is unrelated, and potentially much more troubling, a P0016 crank-cam correlation fault. The OPDA is about a year old. Very strange for this code to happen a year after install. And the timing, immediately following a major tear down, well, I don't believe in coincidence in this situation. Most likely suspects are either the OPDA moved, or perhaps gear wear. I pulled the OPDA - the teeth haven't even got shiny yet, gear wear eliminated as a possiblilty... It was not lined up quite as perfectly as it could be. I was stepping on it while climbing around in the engine bay setting the head back on, so maybe I moved it just a tiny bit. But the spec is it has to be lined up within +/- 3.5 degrees. Which is a pretty big window. I don't think it was more than 1 degree from perfect, certainly not more than 2 degrees. Made the tiny adjustment to line it up as perfectly as I could, cleared the code, and crossed my fingers. Timing set wear is the next most likely, but that really doesn't seem probable. I saw very, very little wear on anything while in the motor doing the head. Can anyone think of anything related to a head R&R that could create this issue? Other than possibly moving the OPDA, I can't think of anything. Didn't touch anything to do with timing. If this code comes back, I'm going to have to get the Jeep to someone with much stronger diagnostic skills and the right scan tool.
Ah, well, it all is what it is. It's discouraging, but, just keep working through the issues one at a time and it will all be back to good sooner or later. Hopefully sooner! And, should mention, despite these two codes, it's running great. I'd never suspect there is anything wrong if it weren't throwing the codes.
- DAA
It could possibly be a bad 02 sensor. Or an exhaust leak. But I'm pretty sure there isn't an exhaust leak and I just replaced all four 02 sensors while I had it all apart and they were so easy to get to (and, like I said, got that code just before tear down, so...). I'll check all the manifold and flange bolts on the exhaust later today, just on GP, but I really don't think there is a leak.
I don't have anything to monitor 02 sensor activity to diagnose further. And even reaching the inlet on the precats to check temperature looks just about impossible. I'll check the temp of the two precats to see if the bank two cat is hotter, maybe that will tell me something. But I think I'm just going to have to get it into a muffler shop with a scan tool that will do some actual diagnostics on it to verify suspicions before throwing parts in. I think 02 sensor activity will show it. But, I think the misfire probably did kill the cat
.The other code is unrelated, and potentially much more troubling, a P0016 crank-cam correlation fault. The OPDA is about a year old. Very strange for this code to happen a year after install. And the timing, immediately following a major tear down, well, I don't believe in coincidence in this situation. Most likely suspects are either the OPDA moved, or perhaps gear wear. I pulled the OPDA - the teeth haven't even got shiny yet, gear wear eliminated as a possiblilty... It was not lined up quite as perfectly as it could be. I was stepping on it while climbing around in the engine bay setting the head back on, so maybe I moved it just a tiny bit. But the spec is it has to be lined up within +/- 3.5 degrees. Which is a pretty big window. I don't think it was more than 1 degree from perfect, certainly not more than 2 degrees. Made the tiny adjustment to line it up as perfectly as I could, cleared the code, and crossed my fingers. Timing set wear is the next most likely, but that really doesn't seem probable. I saw very, very little wear on anything while in the motor doing the head. Can anyone think of anything related to a head R&R that could create this issue? Other than possibly moving the OPDA, I can't think of anything. Didn't touch anything to do with timing. If this code comes back, I'm going to have to get the Jeep to someone with much stronger diagnostic skills and the right scan tool.
Ah, well, it all is what it is. It's discouraging, but, just keep working through the issues one at a time and it will all be back to good sooner or later. Hopefully sooner! And, should mention, despite these two codes, it's running great. I'd never suspect there is anything wrong if it weren't throwing the codes.
- DAA
