Stutters and backfires - clogged cats?

[RockGlock86]

Update.
So Got the Y pipe and got busy with life. When I removed the bank 1 upstream it had been cross threaded in and hard at that. Tried to remove the Y pipe and snapped the first two bolts on the driver side flange, figured at this rate I might as well take it to the local exhaust shop. Good guys, do good work. On the way there, with 2 broken bolts on the driver side and no upstream sensor it sounded like my harley. The shop owner hears it and runs codes and it has a slew of random codes from cat/o2 sensor/coolant sensor/ coils/misfires/oil sensor and he swears it is a bad ecu.

Back pressure test and no reading from the driver side cat, passenger cat has 7 psi of back pressure, not sure how that reads as a % constriction. Remove the y pipe, which the factory pipe is actually a really nice all stainless unit, and the driver side cat is empty. Completely empty I wouldn't have believed it if I hadn't seen it. The brick in the passenger side has shifted aswell. Replace the Y pipe, all 4 o2 sensors with Denso's and clear codes and it runs fine. No codes, no hiccups, idles smooth and full power. Still a couple little tings of loose metal int he exhaust but other than that its all good.

Now, continuing issues. the cat temps are still 100 degrees cooler on the driver side in town driving. under hard acceleration I saw 1550 on the passenger cat and 1375 on driver side. So still a temp variation, with new plugs and wires, and coils have been mixed between banks, new intake gaskets, pcv valve and line. I can and probably will replace the coils just for GP, I cant think of anything else on why the driver bank would be cooler. Except for injectors. I assume that injectors are originals.

Does anyone know what fuel trims should look like or how can I get a read if the driver bank may have a dead or dieing injector or somehow is fueling less than the passenger bank?

 

[swathdiver]

Update.
So Got the Y pipe and got busy with life. When I removed the bank 1 upstream it had been cross threaded in and hard at that. Tried to remove the Y pipe and snapped the first two bolts on the driver side flange, figured at this rate I might as well take it to the local exhaust shop. Good guys, do good work. On the way there, with 2 broken bolts on the driver side and no upstream sensor it sounded like my harley. The shop owner hears it and runs codes and it has a slew of random codes from cat/o2 sensor/coolant sensor/ coils/misfires/oil sensor and he swears it is a bad ecu.

Back pressure test and no reading from the driver side cat, passenger cat has 7 psi of back pressure, not sure how that reads as a % constriction. Remove the y pipe, which the factory pipe is actually a really nice all stainless unit, and the driver side cat is empty. Completely empty I wouldn't have believed it if I hadn't seen it. The brick in the passenger side has shifted aswell. Replace the Y pipe, all 4 o2 sensors with Denso's and clear codes and it runs fine. No codes, no hiccups, idles smooth and full power. Still a couple little tings of loose metal int he exhaust but other than that its all good.

Now, continuing issues. the cat temps are still 100 degrees cooler on the driver side in town driving. under hard acceleration I saw 1550 on the passenger cat and 1375 on driver side. So still a temp variation, with new plugs and wires, and coils have been mixed between banks, new intake gaskets, pcv valve and line. I can and probably will replace the coils just for GP, I cant think of anything else on why the driver bank would be cooler. Except for injectors. I assume that injectors are originals.

Does anyone know what fuel trims should look like or how can I get a read if the driver bank may have a dead or dieing injector or somehow is fueling less than the passenger bank?

Yeah, fuel trims should be around zero once your running at a constant speed for a bit. At idle they should be near zero too. If there's some kind of vacuum leak, they'll be in the negative and over 10 (-10s).

A Tech-2 or bi-directional scan tool can turn off the injectors and run tests on them and the coils and such.

 

[RockGlock86]

I have a OBD2 reader and the torque pro app right now. so FT 1 and 2 are in constant fluctuation, there is no steady number reading. bank 1 floats in -0.5 to -1.5 at idle and bank 2 is -2.5 to -3.5 at idle but at times they will zero but its for a second and then back and forth, under high idle 1500 rpm they will both be -2.0 to -3.5 and if I rev it to 5k and let off it will give high + numbers, +5.0 to +7.5 on bank 1 and +4.0 to +6.5 on bank 2. These numbers are all in park, no load.

While driving they are generally the same but on the lower end of the ranges listed above. Also does new cats have a new cat smell? it doesnt smell like standard exhaust, I can't put my finger on it but its just off. Also idling in the drive way I get these random wisps of exhaust every 45 seconds to a minute. Visible exhaust as if it were a cold morning. I have driven a total of about 30 miles so far on the new cats and o2 sensors.

 

[Rocket Man]

Not sure about the fuel trims, James knows more about that but that smell and a bit of smoke is normal for the first few hundred miles.

 

[RockGlock86]

Not sure about the fuel trims, James knows more about that but that smell and a bit of smoke is normal for the first few hundred miles.

That's good, I was immediately concerned I either got bad cats or something else was wrong

 

[RockGlock86]

So its back at it. I get in the truck this afternoon and it doesn't start, it didn't do anything. I turned the key to on at first and let it go through the cycle, just a force of habit is all, and then I turn to start and everything goes off. No clicking, just all off. I turn the key back off and then back to accessory and it cycles through fine, and then to run and it looses power again but i held the key there and after 2-3 seconds, it powers up and starts. Everything seems normal, except for the oil minder is reset to 100 and the engine hours is reset to 0.

I drive normally about 2 miles and then I loose power almost like a limp mode, slight backfireish sounds but very quiet, like a **** or a bump noise. I pull over, turn the truck off and then restart and it cranks a little longer than normal, but not overly long, and fires up still in this limp mode. I do not know if it is an actual "limp mode" I just do not have full engine power. Roll the 2 miles back home as its mostly down hill anyways, pull codes, I have a 303/351/353/357. So not even sure where to go from here. Obviously the cats were toast, but that may have been an effect and not a cause.

Through all of this its always on the driver side bank, the cat temp issues, the coil codes and the misfires. I think its almost electronic maybe and not some sort of mechanical issue. I have switched the coil packs previously as a set from bank to bank and it still only threw the codes on driver side.

 

[Rocket Man]

I’m wondering if you have a cracked intake manifold. I know in your first post you said you broke the plastic on the intake manifold GASKET. Explain this, and also what did you torque the manifold to? You wouldn’t have been the first to torque to ft/lbs instead of in/lbs if that happened. If all your misfires are on one side and the cats weren’t the cause but instead a symptom, it seems like it’s more likely an issue with something that happened on that side of the motor when you were doing the AFM delete.

 

[RockGlock86]

I did torque to in-lbs, and followed the torque specs and pattern shown on the jegs website.

I did break the plastic gasket, both of them actually, but I very well could have broken the manifold too. It could be cracked near the driver side cathedrals and be the reason why it's only affecting that bank? I'm not sure what else intake manifold related could have caused all this, but it definitely started after I had the intake off the last time. I had a couple hundred miles on the AFM delete and non such issues and then pulled the intake to replace the gaskets and it started 2 miles later. I guess from here I can pull the intake again and really clean and inspect it and see what I come up with.

 

[Rocket Man]

I did torque to in-lbs, and followed the torque specs and pattern shown on the jegs website.

I did break the plastic gasket, both of them actually, but I very well could have broken the manifold too. It could be cracked near the driver side cathedrals and be the reason why it's only affecting that bank? I'm not sure what else intake manifold related could have caused all this, but it definitely started after I had the intake off the last time. I had a couple hundred miles on the AFM delete and non such issues and then pulled the intake to replace the gaskets and it started 2 miles later. I guess from here I can pull the intake again and really clean and inspect it and see what I come up with.

I have heard cracks in them can be hard to see. Might be worthwhile to just replace it, idk.

 

[RockGlock86]

I have heard cracks in them can be hard to see. Might be worthwhile to just replace it, idk.

Real world is this something that can be yarded or is it best bought new? Should I get other new stuff with it or just the plastic manifold and switch everything over with it?