Group buy for Doug Thorley PREMIUM VERSION headers, need 20 people!
- Thread starter Jason B
- Start date
Jason B
Official Vendor
I recommend and sell everyone with long tubes 4 spacers as with long tubes there aren’t any cats. You’ll need 4 regardless of Y pipe or not with the LT. With shorties (2). I have them in stock and you won’t have cels with the ones I’ve been using.
If you are calling to order I’ll go over everything and any other questions you have. Call/text 717-319-2100. Been crazy busy this week but am freeing up for the weekend.
Make sure I’m in :hello:....I’m the guy from WV that was texting
Satori
New member
I was lucky enough to find a local shop that specializes in Toyota Supras and other Japanese sports cars as nobody else was willing to install the LTs because of the cat delete (Toyota said they'd install but once they realized no cats they turned me away). The guys at this shop have been an amazing resource and know their Toyotas... One conversation on the phone with these guys was worth more than 50 calls to the service reps at the Toyota dealership service center.
Last edited:
I'm confused, I thought you said you just needed 4 spacers for the 2 rear o2 spacers and none for the front o2?
2 on up stream and 2 downstream, I have in stock
Satori
New member
The LTs on my v8 right now were purchased through URD and came with "extension harnesses" for FRONT O2 sensors.
URD also mentions on their ad that they recommend using a "Rear O2 simulator" for the rear O2 sensors (on the y-pipe) to prevent the check engine light.
I think Jason B is indicating that something similar is going to be included in his setup to prevent the CELs.
You can read the language on the URD setup here which may clear things up a bit: THY-563Y-LS-C, Doug Thorley LONG TUBE Header, 4Runner, GX470, 2005-2009 4.7L V8 - Underdog Racing Development
I've run through 2.5 tanks of 92 Octane gas since having the LT's installed with front mini cats and no rear O2 sim and haven't had a CEL yet. (I'm not using the rear O2 sim because I'm running UCON-EMS soon which is getting installed this week.) Hope this helps.
Last edited:
JVC8790
New member
For what its worth, when I spoke with Jason on the phone to place my order he asked if I wanted to buy the 02 spacers for the rear sensors for something like $25. I went ahead and ordered them so I wouldn't have to source these later or forget to buy them before I tackle the install.
Ordered a set of these from you last week. Will they be shipping before the headers this thread is about?
Have a set of ST with SS Air Injection Tubes coming before these are manufactured.. Want to make sure the studs will show up in the next couple weeks. Thanks.
[MENTION=117708]blackoutt[/MENTION] Wasn't there an issue with putting spacers in the upstream o2 sensors?
2 on up stream and 2 downstream, I have in stock
blackoutt
New member
To all: Please DO NOT install any sort of spacer, mini cat, or simulator on the UPSTREAM O2 sensors. If you look at your stock manifolds the upstream O2 sensors (circled in red below) are situated BEFORE the manifold catalyst, meaning that when you replace with headers, you don't need to change what those sensors see, they are seeing the same exhaust gases straight out of the heads as they were before. The upstream O2 sensors are actually an air/fuel ratio sensor which is the closed loop feedback for fuel trims. If you make these sensors think you're burning lean the system will add more fuel and kill your fuel economy, log faults, and maybe even damage the engine if ran like this for too long. Harness extensions for the upstream sensors are okay if you need them, some upstream sensors may have physical placement limitations in the headers so that the factory wiring harness connector is not long enough to reach the upstream o2 sensor connector and a simple jumper harness of straight through wires is needed to extend the harness. It should not contain any resistors, crossovers, diodes, black magic, etc. Again DO NOT install any modifications to the UPSTREAM O2 sensors, they are not required nor are they healthy for your engines control system.
The downstream or rear O2 sensors (circled in blue below) are the ones you want to install the spacers on. There are 4 spacers in the kit provided by Jason B because you need to stack them 2 on left bank downstream sensor and 2 on right bank downstream sensor. (I actually needed 3 on each which became quite long so I went to URD sensor sim later on to get rid of the stackup ugliness). You could also install mini cats, or use the URD O2 sensor simulator for the rear O2 sensors. These O2 sensors are located after the stock headers catalysts (which you are removing with long tubes) so it's easy to see that their function is monitoring how effective the header catalysts (primary catalysts) are at cleaning up emissions. With long tubes (again, no header cats) the rear O2 sensors will log P0420 and P0430 left and right bank catalyst inefficiency faults. That is why the spacers or other methods are needed at the DOWNSTREAM O2 sensors ONLY, and ONLY when removing the primary catalyst attached to the header by installing long tubes.
Other notable mentions here. There are no O2 sensors after the ypipe catalysts (secondary catalysts) this is because they aren't there for emissions, they're more for controlling the smell. If only changing the y-pipe to remove secondary catalysts and leaving the factory primary catalysts in place you do not need to add spacers, mini cats, URD sim etc. there is no sensor monitoring downstream of the secondary cats.
If anyone else continues to give misinformation like this please correct them. I've been asked this question a dozen times in threads and PM's so I've taken the time to explain how it works again. You can also google things like "how an O2 sensor works" and "what is closed loop engine control" to learn more about it. I'm sure URD wouldn't lead anyone astray either as they understand how these things work but I've heard bad info from Doug Thorley and [MENTION=9]Jason B[/MENTION] so please direct them to this post to help inform. It might make a lot less questions for them down the road.
Last edited:
What parts should I purchase?
Hey fellas I've been semi following this thread. Recently on my 2004 4.7 V8 4runner Ive noticed the sulfur smell associated with CATS usually, but ofcourse on our trucks the manifolds are the primary issue.
I have 165k on the dash and recently replaced my upstream bank 1 O2 sensor. The manifolds look rusted and cracked, and I have the engine tick noise associated with a bad manifold.
I figure now is the time to replace the manifold and just go with the Doug Thorley Headers and assembly. I just wanted to know what parts and assembly I should purchase. The only performance mods I have is a K&N cold Air Intake and Gibson Catback. Any help would be greatly appreciated!
Hey fellas I've been semi following this thread. Recently on my 2004 4.7 V8 4runner Ive noticed the sulfur smell associated with CATS usually, but ofcourse on our trucks the manifolds are the primary issue.
I have 165k on the dash and recently replaced my upstream bank 1 O2 sensor. The manifolds look rusted and cracked, and I have the engine tick noise associated with a bad manifold.
I figure now is the time to replace the manifold and just go with the Doug Thorley Headers and assembly. I just wanted to know what parts and assembly I should purchase. The only performance mods I have is a K&N cold Air Intake and Gibson Catback. Any help would be greatly appreciated!
[MENTION=117708]blackoutt[/MENTION]
Thank you very much for the detailed explanation!
Thank you very much for the detailed explanation!
To all: Please DO NOT install any sort of spacer, mini cat, or simulator on the UPSTREAM O2 sensors. If you look at your stock manifolds the upstream O2 sensors (circled in red below) are situated BEFORE the manifold catalyst, meaning that when you replace with headers, you don't need to change what those sensors see, they are seeing the same exhaust gases straight out of the heads as they were before. The upstream O2 sensors are actually an air/fuel ratio sensor which is the closed loop feedback for fuel trims. If you make these sensors think you're burning lean the system will add more fuel and kill your fuel economy, log faults, and maybe even damage the engine if ran like this for too long. Harness extensions for the upstream sensors are okay if you need them, some upstream sensors may have physical placement limitations in the headers so that the factory wiring harness connector is not long enough to reach the upstream o2 sensor connector and a simple jumper harness of straight through wires is needed to extend the harness. It should not contain any resistors, crossovers, diodes, black magic, etc. Again DO NOT install any modifications to the UPSTREAM O2 sensors, they are not required nor are they healthy for your engines control system.
The downstream or rear O2 sensors (circled in blue below) are the ones you want to install the spacers on. There are 4 spacers in the kit provided by Jason B because you need to stack them 2 on left bank downstream sensor and 2 on right bank downstream sensor. (I actually needed 3 on each which became quite long so I went to URD sensor sim later on to get rid of the stackup ugliness). You could also install mini cats, or use the URD O2 sensor simulator for the rear O2 sensors. These O2 sensors are located after the stock headers catalysts (which you are removing with long tubes) so it's easy to see that their function is monitoring how effective the header catalysts (primary catalysts) are at cleaning up emissions. With long tubes (again, no header cats) the rear O2 sensors will log P0420 and P0430 left and right bank catalyst inefficiency faults. That is why the spacers or other methods are needed at the DOWNSTREAM O2 sensors ONLY, and ONLY when removing the primary catalyst attached to the header by installing long tubes.
Other notable mentions here. There are no O2 sensors after the ypipe catalysts (secondary catalysts) this is because they aren't there for emissions, they're more for controlling the smell. If only changing the y-pipe to remove secondary catalysts and leaving the factory primary catalysts in place you do not need to add spacers, mini cats, URD sim etc. there is no sensor monitoring downstream of the secondary cats.
If anyone else continues to give misinformation like this please correct them. I've been asked this question a dozen times in threads and PM's so I've taken the time to explain how it works again. You can also google things like "how an O2 sensor works" and "what is closed loop engine control" to learn more about it. I'm sure URD wouldn't lead anyone astray either as they understand how these things work but I've heard bad info from Doug Thorley and Jason B.
doofenshmirtz
New member
I CANNOT thank you enough for putting everything in one place and breaking it down fully. Up to now, everything I found was half answers (admittedly to specific or tangential questions) or required piecing together info from multiple answers. Or maybe I was too dense until you went full ELI5. Either way, THANK YOU!
4RunnerAquasport
Senior Member
[MENTION=117708]blackoutt[/MENTION] Thanks for stopping by!! Gonna miss your expertise.
Similar threads
