Magnaflow 452843 Exhaust Manifold & Catalytic Convertor... - Lexus IS Forum
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post #1 of 7 (permalink) Old 11-15-2017, 06:57 PM Thread Starter
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Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...

Magnaflow 452843- Direct Fit Exhaust Manifold & Catalytic Convertor System

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-fullsizerender-2.jpg

*I apologize, I had a lot more step by step photos of what I worked on but the attachment manager only allows me to upload 10 photos, total.*

___ !!! DISCLAIMER: DISCLAIMER: DISCLAIMER: !!! ___

I AM JUST SHARING MY EXPERIENCE WITH THOSE OF YOU WHO ARE POSSIBLY INTRIGUED BY WHAT I ACHIEVED. DO NOT IMITATE, THINK OF IMITATING OR DREAM OF IMITATING WHAT I DID BECAUSE YOU MIGHT BREAK SOMETHING, INJURE YOURSELF AND/OR SOMEONE AND I CAN'T TAKE RESPONSIBILITY FOR THAT, SO DON'T DO IT!


With that said, I recently forked out the funds for the Magnaflow system to address the darn P0420 & P0430 CELs. The bank #2 catalytic convertor went out last year so I had it replaced it to pass (CA) smog. During this past summer bank #1 went out. I wasn't so impressed with the way bank #2 was welded together and the Magnaflow setup looked so clean, so I decided to make the move and purchase the whole assembly. THMotorsports had the best price so I purchased the Magnaflow system through them. Thanks for the great deal, Justin!

This system is thankfully CA legal, not many replacement systems are. It came with the exhaust manifold gaskets and the exhaust pipe gaskets. Unfortunately, the finish isn't as pretty as it shows on Magnaflow's website but the welding looks good. It was a VERY tight fit to squeeze her in from the top side but it bolted up nicely.

I also replaced all 4 of her O2 sensors. Here are the Denso P/N's I used...

Upstream Cylinder 1,2,3: 2344626
Downstream Cylinder 1,2,3: 2344015

Upstream Cylinder 4,5,6: 2344630
Downstream Cylinder 4,5,6: 2344517

First, I unsecured the negative battery cable to disable the electrical system since I was going to be messing with electrical connections.

Then I lifted my girl up on her passenger side so I could access the 3 exhaust-pipe nuts and bolts plus the Downstream Bank #2 O2 sensor beneath the passenger seat area. The bolts are all 14mm in size. The bolt on the very bottom and the outermost bolt screw into a "C" shaped bracket. The innermost bolt is a standard setup, I used another 14mm wrench to hold onto one of them while I loosened the opposing one. After I removed all 3 exhaust-pipe nuts and bolts, I rested the exhaust pipe on a short stack of 2X4's. The Downstream Bank #2 O2 sensor was VERY snug so I sprayed WD40 a few times and allowed it soak in while I shifted my focus to the topside tasks.

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5070.jpg

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5084.jpg

I slid off the exhaust side valve cover vent hose by unclamping the hose at the elbow fitting above said valve cover. I loosened the 2 intake hose-clamps to remove the intake hose assembly.

This was also a good time to unplug the throttle body servo motor-wire connector and remove the 4 nuts securing the bracket directly beneath the throttle body. I slid the bracket off, with the wiring harness attached, and carefully negotiated it around the throttle body orifice and rested it on top of the throttle body to keep it out of the way. I needed that extra wiggle room (when I installed the Magnaflow) where the wiring harness runs next to the exhaust side valve cover. Like I said, it was a VERY tight fit.

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5144.jpg

It was also a good time to snap off the 2 zip-tie anchors (82711-16830) securing the O2 sensor wiring for Upstream Bank #1 & Downstream Bank #1 . There is an anchor for the negative/ground cable (82711-16830) the drainage hose clip (90959-01505) next to it, which I also snapped off.

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5082.jpg

I also undid the bracket securing the negative/ground cable to the engine block, I forgot what size that bolt was.

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5092.jpg

I unplugged then removed the Upstream Bank #1 & Downstream Bank #1 O2 sensors. Luckily I noticed the white marking on the Upstream Bank #1 male and female sides of the connectors. The Upstream Bank #1 connectors are marked white so you plug the correct male connectors into the correct female connectors, it can be accidentally swapped because they're the same type of plugs next to each other. I used a yellow paint marker to mark the new and correct O2 sensor male plug and yellow-marked over the existing white mark on the correct female plug.

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5088.jpg

I used a medium size Crescent wrench to unscrew the O2 sensors because I didn't feel like buying the special O2 sensor tool. Again, I needed the extra wiggle room so I didn't want those sensors protruding while I was extracting the OEM exhaust system. The Upstream Bank #2 O2 sensor is sort of tucked in so I didn't bother removing that one but I obviously unplugged it. It's connector is located beneath the heater hoses coming out from the engine-bay wall.

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5089.jpg

After all of that was sorted out, I unscrewed the 8 exhaust manifold nuts. They're all 14mm in size and I had to use a deep socket on a most of them. Once all of the nuts were off, I slowly wiggled out the OEM exhaust system out of her engine bay and removed the old exhaust manifold gaskets.

Now the fun part... The slow wiggle wiggle. After cleaning her engine's exhaust port faces, I slid on the exhaust manifold gaskets making sure they were facing and situated the correct way. I applied the supplied anti-seize on all of the Magnaflow O2 sensor hole threads then I installed the new Upstream Bank #2 O2 sensor before I installed the Magnaflow system. It's position looked to be in a PITA spot to get to if I tried to install it after I secured the Magnaflow system.

I lowered the Magnaflow system into the space and slowly wiggled it in while making sure I wasn't damaging any wires or anything in the process. The Magnaflow system is slightly beefier than the OEM system so every millimeter of space mattered. During the first attempts the exhaust pipe flange kept getting caught on the edge of her transmission and her suspension brace. But after some slow wiggle wiggle and praying, the Magnaflow system slid in. I tightened the nuts to about 36 ft.lbs. I used a ft.lb torque wrench to tighten nuts I could access with the bulky torque wrench. The ones I couldn't access with the torque wrench, I tightened using the comparable feel of the 36 ft.lb torque tightened nuts. After the Magnaflow system was secured, I proceeded with the following:

- Reattached the wiring harness bracket beneath the throttle body
- Plugged in the throttle body servo motor wire-connector
- Routed, connected and zip-tied the Upstream Bank #2 O2 sensor
- Installed, routed, connected and zip-tied Downstream Bank #1 O2 sensor
- Installed, routed, connected and zip-tied Upstream Bank #1 (remember the markings) sensor
- Reattached the negative/ground cable bracket to the engine block
- Reattached and secured the air intake hose
- Reattached and secured the valve cover vent hose

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5145.jpg

Magnaflow 452843 Exhaust Manifold & Catalytic Convertor...-img_5097.jpg

Sorry, my cellular phone battery died so I wasn't able to capture photos of the seat removal/reinstallation and the Downstream Bank #2 plug location beneath the carpet. For this part of the project, l needed to temporarily attach the negative battery cable so I could move the seat forward and backwards to access the mounting bolts. I began by removing the 2 rear bolts of the front passenger seat then I moved the seat backwards to access the front 2 bolts. After I removed the last 2 bolts I disconnected the negative battery cable again. I then tilted the seat backwards and noticed the lower air vent for the right rear passenger. It's designed to snap on and off so I just pulled it off. Afterwards, I felt beneath the carpet through the vent passage. I found the Downstream Bank #2 O2 sensor plug just to the left of the vent passage.

After I unplugged the Downstream Bank #2 O2 sensor plug, I crept beneath the passenger seat area of my girl to undo the cover protecting the Downstream Bank #2 O2 sensor wire leading to the grommet attached to the floor. To do this I removed the large plastic nut near the O2 sensor and a 10mm nut towards the center of the cover. I didn't have to completely remove the cover. After locating it, I popped off the grommet and removed the old Downstream Bank #2 O2 sensor. Thankfully I allowed the WD40 to soak into the threads because it was pretty snug in there. After I installed the new Downstream Bank #2 O2 sensor, I reversed the de-installation process I wasn’t able to photograph.

I installed the new exhaust pipe gaskets, reattached the 3 bolts, lowered her down, attached the negative battery cable and took her for a 2 a.m. drive.

She sounds a little bit throatier with the Magnaflow system.


JPB

Steps are calculated risks. Leaps are tests of fate.

Last edited by SilverIsMy300; 11-27-2017 at 11:46 PM.
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post #2 of 7 (permalink) Old 11-15-2017, 07:44 PM
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Was it that much cheaper than the Dezod green header?
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post #3 of 7 (permalink) Old 11-15-2017, 11:37 PM Thread Starter
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I just looked on Dezod's website. Yes, it's considerably cheaper. It's unfortunate Dezod's is300 headers aren't California C A R B Compliant because they're good lookin' headers!

JPB

Steps are calculated risks. Leaps are tests of fate.
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post #4 of 7 (permalink) Old 11-18-2017, 11:40 AM
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There seems to be 3 versions of this. MagnaFlow 50603, 49283, 452843

You had to go with the CARB version so not much choice.
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post #5 of 7 (permalink) Old 11-19-2017, 08:51 PM Thread Starter
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Yup, I had no choice here in California. I didn't even realize there were 2 other versions, LOL.

I don't know if it's just a placebo effect but she feels like she's gained a little bit more power since the install. She does sound a bit meatier though.

JPB

Steps are calculated risks. Leaps are tests of fate.
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post #6 of 7 (permalink) Old 11-26-2018, 10:24 PM
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Take one for the team and get those dyno numbers for all us law abiding cali owners plis 😅
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post #7 of 7 (permalink) Old 12-08-2018, 09:33 AM Thread Starter
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I'll pass, LOL! It'd be cool to know but I have a mortgage and home improvement projects to pay for, sorry. I'm trying to get her to a 'Million Miles' so I'm not doing any mods that will wear her engine out prematurely, so it really wouldn't be worth doing any mods that would justify a dyno run.

My current mileage is 310,635 and she's thankfully still running VERY nicely.

JPB

Steps are calculated risks. Leaps are tests of fate.

Last edited by SilverIsMy300; 12-08-2018 at 09:42 AM.
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