marlon08901

Replacing Air Intake Tube 90-Ls400

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Hello Everyone - I was reading through the forums about installing cold air intakes and someone asked about how to replace the black plactic air intake tubing that comes in our 1st gen. LS400s.....which intrigued me and after finding no responses to this question...I decided to see if it could be done with parts available at the local autozone by my house. Interestingly enough I was able to do the mod and it was not even that hard. I know that we should not mess with our cars because they already have everything they need to run nice and smooth and we love them for it! Nevertheless, I just wanted to have some fun and feel like a teenager playing with my car (have good memories about that)...anyways, here's what I did.

1- Loosen C-Clamps holding the air intake to throtle body and air intake to MAF sensor housing.

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2- Diconect the plug from the MAF sensor (you can try doing it without disconecting the MAF..I had to because I replaced my MAF sensor the same day)

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3- Remove air filter housing and MAF sensor housing (remove 2 10mm bolts attaching unit to car body and theres is also a bolt holding air filter housing to car body on top of headlight)

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4- Remove Air Intake Surge Tank (remove 2 10mm bolts attaching unit to engine)

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Use 45 degree intake elbow attach it to 90 degree elbow intake tube (purchased at autozone)

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Using 2 - 3" red rubber couplers attach end of 90 degree intake tube to throtle body and 45 degree intake tube's end to the metal MAF sensor housing.

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As you will see in the pictures bellow the angles worked out perfectly...the only problem was that there was no attachement on the tubing to connect the vacuum hose from the original intake tube to the Idle Air Control Valve...therefore, I drilled a 3/4" hole on the top of one of the tubes

and using a PCV elbow and a PCV groumet I made a connection on intake tube for the vacuum hose

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NOT FINISH-----WIll FINISH WHEN I GET HOME...MUST LEAVE WORK NOW! -- OK..I am back!

SO...as I was saying I used the above pictured PCV elbow and PCV groumet and both part made a pretty solid, leak proof connection.

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VERY IMPORTANT - as you know, there is a smaller hose attached to the OEM plastic intake body, which goes to the air control valve (ACV) under the Power Steering Pump --

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in my car this valve had been removed due to power steering fluid leaking into the intake --but that's another story....the point is = for this modification you can either repeat the steps above and make smaller connection for smaller hose OR you can disconnect hose and just plug the hole in the ACV valve where the hose used to be. It's up to you!

Ok..so now just put MAF hosing/air filter back together, plug in your MAF sensor...secure all your C-Clamps and you are DONE!

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Ok now a couple of point I will like to make...IF YOU TRY THIS..YOU ARE DOING IT AT YOUR OWN RISK! I DID PURCHASE A COPLE OF INTAKE TUBES AT DIFFERENT ANGLES AND AFTER SOME EXPERIMENTATION THE ONES USED WERE THE ONES THAT BEST MATCHED MY PARTICULAR APPLICATION (I RETURNED THE REST)...ALSO THE TUBING AND COUPLERS I USED ARE 3" IN DIAMETER....THE END OF THE THROTLE BODY AND THE END OF THE MAF HOUSING ARE ABOUT 3 1/4"

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SO YOU NEED TO STRETCH THE COUPLERS A BIT. YOU COULD PROBABLY BUY 3 1/2" OR EVEN 4" IT'S UP TO YOU...I BOUGHT 3" BECAUSE THAT'S WHAT THEY HAD IN STOCK AT THE STORE.

HERE ARE SOME PICS WITH THE 45 DEGREE ANGLE TUBE REVERSED (SO THAT VACUUM HOSE ATTACHES FROM THE BOTTOM) JUST A DIFFERENT OPTION IN CASE YOU WANT A "CLEANER" LOOK. WHAT DO YOU THINK?

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BEFORE

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ALSO - SOME PICTURES USED IN THIS POSTING WERE ORIGINALLY POSTED IN A Article by Curt Oberg (1UZFE Throttle Body Cleaning)which you can find here:

http://www.lextreme.com/tb.htm

AFTER

M07nH

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So you eliminated the Helmholtz resonator box on the right cam cover didn't you? How much power did you lose? Be honest now....

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So you eliminated the Helmholtz resonator box on the right cam cover didn't you? How much power did you lose? Be honest now....

So...that's what it is called?...lol Well, I was not sure what the purpose of it was ... but I was hoping it would not affect performance if taken out....could you tell me about it?

I eliminated the resonator box attached to the black intake tubing going into the throtle body and honestly, I don't feel that I have lost any power at all....was I supposed to? In the couple of days since this mod I have used the car mostly for in town driving and just took in on the highway a couple of times and all I can say is that so far I have not felt any difference...the car still drives like a beast! I did not think this mod would make much difference anyway, except maybe for looks...and it was not expensive at all...I only spend about $45...it was just to see if the mod could be done inexpensively and with easy to find parts and now we all know it can be done. I am going to fill her up tomorrow morning and measure to see if there are any changes in fuel consuption....just to see if anything changed but I doubt it. I guess next I will do a short air intake to let more air come in and maybe then I will gain some horsepower like some members claim....however, I will be keeping any stock parts I take out so I can put them back again if I'm not happy with the changes.

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The resonators are complex in theory, so just google it and you'll find out. My understanding is that it reduces intake noise and improves mid-range. Many cars use them these days, of various shapes and sizes.

If you haven't lost enough to notice, no big deal. The mod looks good anyways!

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Suspence laugh.gif

Suspence is over! lol cool.gif

Thanks, It was killing me................cheers.gif

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The resonators are complex in theory, so just google it and you'll find out. My understanding is that it reduces intake noise and improves mid-range. Many cars use them these days, of various shapes and sizes.

If you haven't lost enough to notice, no big deal. The mod looks good anyways!

Well, yes...the noise reduction part was what I first thought of when I saw the resonator but I was not aware of any potential power lost. I did some quick research (funny enough when I googled ls400 Helmholtz resonator...this was the first link they showed)anyways, what I read made sense. Basically, air is pulled in from outside then pushed into the resonator which will incrase the pressure of this air before it exits the resonator and gets sucked into the throtle body "When air is forced into a cavity, the pressure inside increases. When the external force pushing the air into the cavity is removed, the higher-pressure air inside will flow out." therefore, giving more power..in the low to medium range. Sounds reasonable, however, as you mentioned, I have not experienced enough power lost to notice...hopefully, if I did lose any power it will be compensated by the cold-air-intake mod coming up. We shall see!

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What's the CAI mod ? From the outside to your current mod or something else ?biggrin.gif

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What's the CAI mod ? From the outside to your current mod or something else ?biggrin.gif

Honestly, I am not sure as to what kind of CAI [Cold Air Induction] mod I'm going to do because I did not think about doing one until a I finished the intake tubing mod. There are a few options I have seen for DIY mods and short ram intakes....taking out the front cover of the air filter housing and keeping the stock filter..using a K&N filter instead of the stock filter (without front filter housing)...cuting holes in the front of the air filter housing to allow more air in...and removing the filter housing and using a adapter to install one of those cone shaped filters. Here are some pics of what I found..and their respective websites with more info.

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http://www.clublexus.com/forums/ls400/215535-air-intake-mod-ect-reprogram-power.html

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http://www.clublexus.com/forums/ls400/56619-my-cold-air-intake-more-pictures-2.html

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http://www.clublexus.com/forums/ls400/56619-my-cold-air-intake-more-pictures.html

I think I will try using the adapter and the aftermarket filter and building some kind of heat shield...although, I did see an INJEN HEAT SHIELD on ebay but I don't think I wanna pay $60 when it does not even include the filter. Anyhow, for anyone interested here's a picture and the link:

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http://cgi.ebay.com/ebaymotors/Injen-AIR-FILTER-HEAT-SHIELD-lexus-LS400-LS-400-90-2000-_W0QQcmdZViewItemQQhashZitem563d6be4c8QQitemZ370397668552QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

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Removing the resonator does not affect power output at all. The primary purpose is to reduce intake noise, 99% of cars have them and it's simply to slow down airflow and give it somewhere to reduce turbulence, on some cars it's not even part of the intake tract, it sits off to the side before the airflow sensor.

As for the piping, you haven't gained any power either since you haven't changed the diameter or the length, which affects the tuning. Plus the stock airbox is still the restriction here, so while it looks different, there's no gain. I made the same type of thing out of high temp rubber piping like VW uses for intercooler pipe, but fitted a high flow filter to the MAF and cut out the area below the filter, as well as cutting a vent in the front bumper, to allow forced air in from the front of the car. Sounds the same, feels the same, I just didn't like the resonator in the way of the plugs and I had broken one of the plastic nipples off the OE plastic pipe, so it was easier to replace it this way than to hunt down a used pipe.

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thank you marlon08901, your post inspired me to do mine. materials are a bit different tho. it seems i cant attach image here. this is the pix

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Why? Waste of money for one, waste of time and waste of good LS parts that get ruined. Nothing gained, especially for a driver around town car. Ls is not a race car as far as I know, its a 4 door luxury type car fancy cars do not get raced. Look inside a Nascar some time and see the lack of fancy comforts.

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Because I just don't like to see these cars messed up. Just makes them more difficult to find when everyone turns them in to junk yard queens.

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