New exhaust system for 04 4Runner v8
Hey folks. I've got an 04 4Runner v8 4WD @ 210k miles. I have a cracked manifold (typical cold start ticking), and it's possible a manifold cat is going bad (P0430 code).
I want to get a new exhaust, if not for a bit more power, but to solve any issues that could arise from dying cats or a cracked manifold. After a fair bit of research this is what I came up with for my new exhaust system. I also am putting in a K&N intake 77-9022KP. Edit: I have updated my parts list to be current as of 6/11/20 PARTS LIST HEADERS - Doug Thorley THY-564-SS-C Short Tube Headers UNIVERSAL CATS - QTY 2 - G-Sport #50025 Y-PIPE / REAR CAT - MagnaFlow #93655 CAT-BACK - MagnaFlow #15781 & Vibrant 1141 Resonator AIR/FUEL RATIO SENSOR - QTY 2 - UPSTREAM - Denso 234-4138 OXYGEN SENSOR - DOWNSTREAM LEFT - Denso 234-4261 OXYGEN SENSOR - DOWNSTREAM RIGHT - Denso 234-4260 MANIFOLD GASKET - QTY 2 - OEM 1717350021 HEADER BOLT KIT - Stage 8 (8919) 10mm Header Bolt Kit Questions I have.. 1. I am unsure if those universal cats can be welded onto the DT headers. They do say they're for "rear". Can they be used as manifold cats, though? The DT's are meant to be welded to the factory cats, so I am wondering if this means I would need to buy the full manifold catalytic converters only to cut off the manifold part? Edit: I ended up going with the same cats JONBOY345 used: G-Sport #50025 2. Does my vehicle have (2) cats in the rear or (1)? I am pretty sure I have only (1) cat in the rear, as this isn't/wasn't a California car. I recently read that apparently some 4Runners have (2) cats in the rear. It's confusing because I need the (4) total O2 sensors.. or so that is my understanding. Edit: I have only (1) cat in the rear! See this Walker exhaust diagram that Ed_C posted. 3. Is there any other element of the exhaust system I may be missing? Except for the Y-Pipe, that would still be OEM I assume. I will be taking all the parts to my mechanic who is enlisting the help of his guy who does exhaust. My underbelly has surface rust, as it's been an east coast car it's entire life. Should I provide new nuts/hardware/gaskets? I am really not sure what all is needed because I have limited knowledge when it comes to exhaust systems. Edit: Yes, there is a "front pipe" that connects from the drivers side cat to the Y-Pipe. I also added OEM Manifold Gaskets and a Stage 8 (8919) 10mm Header Bolt Kit to the parts list. I would really appreciate any info or advice for my situation :yo: |
Nice little rabbit hole your about to go down.
First of all, does VA have sniffer or visual tests for emissions? This will dictate if you can use aftermarket CATs and what you can use going forward. Second, do not buy sensors from bargain sites, there have been boot leg part stories for Denso imitations flooding the market. 3rd use this search parameter and multiple threads will pop up. Type in your question, such as -Doug thorley short tube headers CAT install- and put the red text in after your question. site:toyota-4Runner.org/4th-gen-t4rs/ So it would look like this in the search bar: Doug Thorley Short tube headers CAT install site:toyota-4Runner.org/4th-gen-t4rs/ You can use the text in red to learn anything about your T4R. Read till they bleed is my motto. I can't answer all of your questions about CATs as I live where there are no inspections and have LT headers. I do think if the CATs you have listed are for the rear, they won't work on the manifolds. The 2 upstream sensors are actually air/fuel ratio sensors and are technically not o2 sensors, although they look the same and bolt in ahead of the CATs. They read the mixture in real time and send the ECU this information so that it can adjust parameters to the Mass Air Flow sensor so that your engine will have properly mixed fuel and air going into the combustion chamber for ignition. The two down stream sensors are actually the o2 sensors and give the ECU a constant reading of the Catalytic converters state of health and operation. The rear CATs are really only effective for cold start operation as some pollutants get by the upstream CATs for the first few minutes. Once the system warms up the upstream CATs start to work properly. Unless you have a visual inspection, I think these can be eliminated. Also with headers the flow rate changes and you may have to put spacers on the o2 sensors to get them to read the flow properly and eliminate the CELs that other people have had to deal with, myself included. And lastly, Get some Visine or Clear Eyes. Hopefully someone else will chime in with a lot more than my limited knowledge of Short Tubes and Good Luck!! |
Thanks for the info man! I made an edit to my original post, looking at a different universal cat which may work better.
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http://www.dougthorleyheaders.com/im...INST-REV-C.pdf
The headers already have the sensor bungs. If you're having a Y-pipe made you'll need the bungs for the post-cat O2 sensors, they're easily sourced. |
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@Ed_C
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@Az4runnin
Thanks for jumping in! This subject takes a village.
There has been several of us who had fitment issues with the DT Y pipe. Mine didn't match up to the drivers side CAT. I think others echoed the same problem. I could not afford Headers at first, so I had the Y installed to the factory Manifold/Cats, and we had to modify the Y to make it work. Then of course when we installed the LTs a year later, we had to modify the Y again lol. But, if you are having Cats welded to the DT ST headers, the installer might be able to mock it all up and weld the CATs to properly mate up to the Y from the get go. Also of note: The upstream sensors (A/F ratio sensors) DO NOT need spacers, just the o2 sensors downstream if the evil CELs show up. If your worried about moving to a state where you have to go back down the rabbit hole again, this Y pipe might be a better choice because the rear CAT is included, and it's over $100 cheaper than the DT Y. MagnaFlow HM Grade Federal / EPA Compliant Direct-Fit Catalytic Converter |
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-Cats - Magnaflow 59956 (2.5" inlet/outlet). -Blox Spacers - I DID need those to eliminate the check engine light. -With 210k miles on the east coast, definitely recommend AT LEAST the stage 8 bolt kit that you've mentioned - good piece of mind. That is what I got as well. Good luck! It was a bit of a pain sourcing the parts and finding someone to install for me, but well worth it in the end! |
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Just wanted to chime in and say that the GESI cats I have are awesome. I had my mechanic weld on a SS 3 bolt flange to the DT Headers and then to the top of the GESI cats as well. So that if in the future for whatever reason I need to replace the cats, it's a simple process. I did the GESI cats, DT ypipe, and Magnaflow cat back and love it. No check engine lights either... The GESI cats are pricey, but they'll outlast the truck for sure... Keep your factory parts and sell them to RRcats.com for about $350 back (according to market prices about a month ago when I sent mine out). |
GESI cats are nice, designed for higher HP/performance use YouTube
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Thanks everyone for your input! This is helping me tremendously. :happy:
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I don't know what I thought. But this makes so much more sense now. I agree that since I'm trying to not remove any cats I should ditch the DT Y-pipe and use that MagnaFlow. Quote:
I'm really looking at getting the GESI's, not because I like throwing money away, but because they do seem solid. Like you said, buy once, cry once. :crybaby: |
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https://www.toyota-4runner.org/3414058-post28.html |
I believe doof has a '05-on, OP's stock system has a single cat after the Y instead of one each after the manifolds.
Here's the breakdown using Walker exhaust parts... https://i.imgur.com/0WclEtD.png The universal replacement for that Y-pipe converter is a the same ones Walker uses for their 05-on Y, except it uses two. |
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