Low/rough idle has beaten me
03-02-2015, 11:29 AM
#21
Senior Member
If the O2's are original, I would start by replacing them. You would have to replace them with new cats anyway.
You can take the front O2's out and let her idle. If the cat's are clogged, that will relieve back pressure and she should run a little better. You might get a code thrown, but don't worry about it. Also, any exhaust shop can test your cat's.
You can take the front O2's out and let her idle. If the cat's are clogged, that will relieve back pressure and she should run a little better. You might get a code thrown, but don't worry about it. Also, any exhaust shop can test your cat's.
03-03-2015, 12:11 AM
#22
For me and my 04, a misfire melted down my rear and not my front drivers side cat.. Which is weird, but it might have had to do with the fact that the front cats are angled.. So the raw unburnt fuel from a bad cop in my situation caused the fuel to blow passed the front cat and pool in the rear "level" cat.. I had some slight power issues, but the cat rattled when it was hot which was a dead giveaway for me to diagnose. Since you have an 04 you have 4 cats.. The rears can be deleted and replaced with a piece of straight pipe.. Hopefully it's just your rears like in my case, and a delete job on the rears will fix you right up.. But without unbolting the front cats, or at least cutting the coupler between the 2 cats separating the front and rear with a sawzall, we could speculate all day.. If you run the truck with the rears severed or the fronts disconnected you will immediately notice a difference just like jdinner.. If your not getting any ball bearing sound rattling, and you already changed your plugs, and your not feeling a washboard or jerk in the transmission, you very likely have a bad cat with good plugs and cops. If you have t changed the plugs yet, then do so first.. Use a 3/8 impact so they don't break on you with a hot motor.. If you call around your area, you can find an exhaust shop that will weld some new cats in, and replace the exhaust..
03-03-2015, 05:09 AM
#23
Senior Member
My 2006 has only two cats. The rear O2 sensors need to tell the ECM how well the cat is working. The ECM compares values from the front O2 sensors (near the manifold) and the rear (in the cat). Removing them will throw a code.
03-03-2015, 09:29 AM
#24
Senior Member
When I said remove the front O2's, I meant as a test just to see if the cat's are clogged.
Not permanently. You can delete the rear O2's with a tune, but not the fronts.
Not permanently. You can delete the rear O2's with a tune, but not the fronts.
03-03-2015, 10:35 AM
#25
For me and my 04, a misfire melted down my rear and not my front drivers side cat.. Which is weird, but it might have had to do with the fact that the front cats are angled.. So the raw unburnt fuel from a bad cop in my situation caused the fuel to blow passed the front cat and pool in the rear "level" cat.. I had some slight power issues, but the cat rattled when it was hot which was a dead giveaway for me to diagnose.
Since you have an 04 you have 4 cats.. The rears can be deleted and replaced with a piece of straight pipe.. Hopefully it's just your rears like in my case, and a delete job on the rears will fix you right up.. But without unbolting the front cats, or at least cutting the coupler between the 2 cats separating the front and rear with a sawzall, we could speculate all day.. If you run the truck with the rears severed or the fronts disconnected you will immediately notice a difference just like jdinner..
If your not getting any ball bearing sound rattling, and you already changed your plugs, and your not feeling a washboard or jerk in the transmission, you very likely have a bad cat with good plugs and cops.
If you have t changed the plugs yet, then do so first.. Use a 3/8 impact so they don't break on you with a hot motor..
If you call around your area, you can find an exhaust shop that will weld some new cats in, and replace the exhaust..
Since you have an 04 you have 4 cats.. The rears can be deleted and replaced with a piece of straight pipe.. Hopefully it's just your rears like in my case, and a delete job on the rears will fix you right up.. But without unbolting the front cats, or at least cutting the coupler between the 2 cats separating the front and rear with a sawzall, we could speculate all day.. If you run the truck with the rears severed or the fronts disconnected you will immediately notice a difference just like jdinner..
If your not getting any ball bearing sound rattling, and you already changed your plugs, and your not feeling a washboard or jerk in the transmission, you very likely have a bad cat with good plugs and cops.
If you have t changed the plugs yet, then do so first.. Use a 3/8 impact so they don't break on you with a hot motor..
If you call around your area, you can find an exhaust shop that will weld some new cats in, and replace the exhaust..
03-03-2015, 10:54 AM
#26
Well, I guess I"ll start with removing the front 02's and see how she idles. I ordered 2 new ones and will replace them anyway, yes I know there are 4. Are'nt the back 2 before the second pair of cats so essentially both sets of 02"s are before cats. This is where Im highly confused. Worse case scenerio I could have 4 bad 02's and 4 bad cats right. Do the first pair of 02's and the second pair of 02's perform the same function. Moniter flow and whatever else. I wish I could just saw zaw everything out and do my own work but I don't weld and don't want to go changing everything around without the knowledge. Basically do what especial did
03-03-2015, 11:00 AM
#27
I realized my comment to Especial may have sounded wrong. I did'nt mean to imply what he did was wrong. I meant to say that I think I like that set up he has with the rears eliminated. Im wondering what a shop will charge me and if they will even do something like that. I hate not being able to do certain work on my truck. I'll stop crying now
03-03-2015, 11:04 AM
#28
If the O2's are original, I would start by replacing them. You would have to replace them with new cats anyway.
You can take the front O2's out and let her idle. If the cat's are clogged, that will relieve back pressure and she should run a little better. You might get a code thrown, but don't worry about it. Also, any exhaust shop can test your cat's.
You can take the front O2's out and let her idle. If the cat's are clogged, that will relieve back pressure and she should run a little better. You might get a code thrown, but don't worry about it. Also, any exhaust shop can test your cat's.
03-04-2015, 07:42 AM
#29
The front 02's are what keep your truck running optimal. They adjust the AFR where the rears just check for catalyst efficiency.
Here's some pics of the delete job..
The rear 02's are visible where the fronts are not.. Changing the front 02's can certainly help the truck run smoother, and tighten up their readings..
This is my new setup..
I've got my aftermarket wideband 02, and stock narrowband 02 up front, and the stock rear 02 I pushed as far back as the wire would reach.. I ran 2 magnaflow 94106 hi flow cats.
You can see in the pics that I cut the rear cat off right behind the rear 02.. The rear 02 on the 04 models only checks the front cat. The rear cat just sits there with no 02 to check it's work.. That's why it's very easy for us 04 guys to delete the rear cats..
Here's some pics of the delete job..
The rear 02's are visible where the fronts are not.. Changing the front 02's can certainly help the truck run smoother, and tighten up their readings..
This is my new setup..
I've got my aftermarket wideband 02, and stock narrowband 02 up front, and the stock rear 02 I pushed as far back as the wire would reach.. I ran 2 magnaflow 94106 hi flow cats.
You can see in the pics that I cut the rear cat off right behind the rear 02.. The rear 02 on the 04 models only checks the front cat. The rear cat just sits there with no 02 to check it's work.. That's why it's very easy for us 04 guys to delete the rear cats..
Last edited by Especial86; 03-04-2015 at 07:49 AM.
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Tommy J (03-04-2015)
03-04-2015, 08:52 AM
#30
The front 02's are what keep your truck running optimal. They adjust the AFR where the rears just check for catalyst efficiency.
Here's some pics of the delete job..
The rear 02's are visible where the fronts are not.. Changing the front 02's can certainly help the truck run smoother, and tighten up their readings..
This is my new setup.. Attachment 371670
I've got my aftermarket wideband 02, and stock narrowband 02 up front, and the stock rear 02 I pushed as far back as the wire would reach.. I ran 2 magnaflow 94106 hi flow cats.
You can see in the pics that I cut the rear cat off right behind the rear 02.. The rear 02 on the 04 models only checks the front cat. The rear cat just sits there with no 02 to check it's work.. That's why it's very easy for us 04 guys to delete the rear cats..
Here's some pics of the delete job..
The rear 02's are visible where the fronts are not.. Changing the front 02's can certainly help the truck run smoother, and tighten up their readings..
This is my new setup.. Attachment 371670
I've got my aftermarket wideband 02, and stock narrowband 02 up front, and the stock rear 02 I pushed as far back as the wire would reach.. I ran 2 magnaflow 94106 hi flow cats.
You can see in the pics that I cut the rear cat off right behind the rear 02.. The rear 02 on the 04 models only checks the front cat. The rear cat just sits there with no 02 to check it's work.. That's why it's very easy for us 04 guys to delete the rear cats..