Cold air Intake? - Not a Joke or Noob question

Discussion in 'Gen 2 Prius Accessories & Modifications' started by Daves09prius, Feb 11, 2012.

  1. Daves09prius

    Daves09prius Active Member

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    So I had a headlight bulb burn out on me. I change my bulbs myself and when I change them, I have to take the entire headlight assembly out. I don't have little hands to get back behind the headlights to replace the bulbs, so I remove the entire assembly.

    When I took the passenger headlight out, I looked at and examined the air intake. I followed the tube, there's an small opening for air to be taken in the engine compartment (Looks like a snorkel). If you follow it further the intake tube passes into an opening which leads to a space forward of the front right wheel. (Passenger side for US models.) There is a huge baffle in this space. (Large white box) I removed it to examine it. it's a large box with several chambers in it, and there are 4 or 5 small holes in the bottom (these holes is where the air is drawn through - Extremely restrictive)

    I did a search and found this Priuschat post
    http://priuschat.com/forums/gen-ii-prius-technical-discussion/97156-whats-air-box.html

    Other searches about Cold Air Intakes,showed that the Prius doesn't like CAI's and has resulted in errors in the Prius's electronics, and irregular MAF readings, which doesn't allow the ICE to run. So I wouldn't recommend a true CAI, but removing the baffle might be an option?

    As I was working on the car I was thinking, why not try to drive the Prius without this restrictive baffle instead of a CAI?

    So I removed the baffle last week, and since then I've noticed that hills that the Prius really struggled to drive up before, had to problem going up now. Also the throttle response seems smoother and I've noticed I don't have to mash on the gas as much to get the car going. I've noticed a slight increase in Fuel economy ( like 1 mpg more... but still an improvement.)

    Has anyone else tried this and and any issues, or noticed any improvements?

    Anyone else wanting to remove the baffle the first thing to do is remove the right side / passenger side headlight.

    Here is a link to a video that shows how to remove the headlight assembly:


    (The passenger side requires that you remove the intake snorkel by removing one small push pin/clip that holds it in place, using a flat head screwdriver, gently pop the push pin up, and then remove the clip.)

    Once the headlight assembly is out, remove the air intake pipe, then you will need to remove the bolts that hold the baffle in place (all are 10MM). Two bolts from the top, one nut in the front, and another bolt by the wheel well plastic liner (to remove this bolt you'll need a flashlight to see it, a ratchet, 10mm socket, and extension to reach it and get it out.)

    Anyone who has removed the baffle, or wanting to do this mod please post your questions, results, issues, or successes.
     
  2. qbee42

    qbee42 My other car is a boat

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    That baffle box is an intake resonator. It's tuned for the Prius to reduce noise while creating optimum air flow. Given the finely tuned nature of the Prius engine, removing yours is not a great idea.

    Tom
     
  3. toyotechwv

    toyotechwv Toyota Technician

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    I removed it all on my old car. Just ran the oem airbox most times, even fabbed up a piece of piping and attached it to the side of the box and feed it down through the hole where the original intake piping was. Slap on a cone type filter, remove the oem filter and instant intake. Throttle response was slightly better but nothing to jump up and down about. I would do it again though just to get all that crap out of there.
     
  4. F8L

    F8L Protecting Habitat & AG Lands

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    I've tried removing the entire intake assembly and even the filter while drag racing and I could not pin down any benefits. State of charge seemed to make the biggest difference in ET.

    If you're happy with the mod and no errors pop up then good deal. I'd be a little skeptical of a mpg change without rigorous testing. :)
     
  5. shaneb

    shaneb New Member

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    Be careful when you remove the white resonator box as your ice can ingest water and lock up. Have had it happen here to a gen 2 taxi with 7000km on the clock. Point said you have to live in an area that has water over the road when it belts down with rain.
     
  6. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    Haha - it's been a long time since I've seen someone get warned about water ingestion with a cold air intake. Oh the old days of modded civics and wings west bodykits....
     
  7. LIPriusFreak

    LIPriusFreak Can I haz JDM?

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    for the amount of gain you'll get, the increase level of engine noise from an already noisy engine won't be worth it IMHO
     
  8. toyotechwv

    toyotechwv Toyota Technician

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    I didn't notice a difference in intake noise, of course my exhaust was modified too so...
     
  9. Justdidit

    Justdidit LVNPZEV

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  10. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    (Theoretically) the Prius pushes 1/3 of the fuel/air mixture back upstream into the intake plumbing, if the volume of the plumbing can't hold it, you are letting fuel back into the under hood air and altering your fuel/air ratio.

    As this fuel/air mixture has already been in the hot cylinder, your intake will not be 'cold'
     
  11. Justdidit

    Justdidit LVNPZEV

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    Where is this information available? Is this in all Prius models? Why would Toyota design the system this way? Isn't the MAF supposed to make the appropriate adjustments??

    I agree that this particular intake isn't the 'cold' version considering its drawing air from under the hood near the hot engine and not from the fender or other colder air location... However not sure why/how the engine would allow premixed fuel/air that has previously been inside the combustion chamber back into the intake system...

    Even though this will prob make the engine a little more 'noisy'... I'm more looking to improve throttle response.
     
  12. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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  13. Justdidit

    Justdidit LVNPZEV

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    hmm..Interesting enough.

    But where does it anything mention that the 1/3 of the fuel/air mixture back upstream into the intake plumbing goes beyond the throttle body, far enough past the MAF sensor to cause the cone style air intake system to throw codes??

    From what I can see the MAF doesn't move closer to the throttle body but maybe even further away...
    [​IMG]

    Shouldn't this be more beneficial than detrimental?
     
  14. 69shovlhed

    69shovlhed Surly tree hugger

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    WELL! see my avatar? this very issue is what got me trolled on "priusonline.com". they posted up that pic after the southpark smug prius drivers there had a hissy fit over the idea of improving performance on my prius.
    i made a cold air kit for it and ran it for about 50k. had a cone filter plumbed down in place of the resonator. didn't notice any difference in the '04 except the engine sounded a little better, cause i like a little intake noise-- like a 4 barrel's secondarys opening up. fuel mileage was the same, performance was still weak. i haven't put it on the '05, which by the way seems to have a little better throttle response than the '04. could the ecu software be a little better in '05, maybe?
    i'm real curious about toyotechs exhaust mods. like to see some pix and evaluation.
     
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  15. 69shovlhed

    69shovlhed Surly tree hugger

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    because of the atkinson cycle intake timing, i wouldn't think changing the distance between the maf and throttle would be a good idea, unless perhaps you could get the ecu programmed for it. i didn't remove the filter box, only the tube that went down to the resonator.
     
  16. Daves09prius

    Daves09prius Active Member

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    I didn't remove the entire filter air-box, only the restrictive resonator. The noise isn't any louder, I just think the car accelerates a bit faster. I can't believe the number of people who responded with the prius is a finely tuned vehicle, don't mess with it! "That baffle box is tuned for the Prius to reduce noise while creating optimum air flow. Given the finely tuned nature of the Prius engine, removing yours is not a great idea." How 'bout you try breathing through a straw from McDonalds while running a marathon. -- Now that's a bad idea.
    I would agree trying to squeeze out the last drop of gasoline and obtain the best possible MPG having a heavily restricted air box might be the answer. Slow acceleration with a lean fuel mixture would equal great gas mileage.

    However that's not what I'm trying to achieve. I'm really trying to avoid being rear ended when I have to merge onto the highway and can't accelerate up to speed. MD has some really short acceleration ramps and I was exploring ways to get more power. Removing the resonator box was the answer. No ill effects, no reduction in mpg, no loud intake noise, and I can accelerate quicker up to speed without having to mash the gas pedal to the floor.
     
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  17. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    All modern Atkinson cycle engines have delayed intake valve closing that allows fuel/air back into the intake tract. I may be wrong, but I think the MAF measures air only, it has no idea how much fuel is in it. (if any Atkinson engine had Direct Injection this would not matter, but they do not) Even if it has a 'cold' source, since 1/3 of the mixture has already been in the cylinder once, it is no longer cold, I believe. To improve throttle response, put it in Power mode.

    [​IMG]
     
  18. Justdidit

    Justdidit LVNPZEV

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    ...not aware of any such Power mode in the 2008 Touring or any GenII for that matter. Is this a mod or a hidden feature??
     
  19. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    My bad, no power mode for Gen 2. Just the 1.8 liter engine, not the 1.5 liter in Gen 1, 2, and the c.
     
  20. Daves09prius

    Daves09prius Active Member

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    Here's a picture of my trip log I drove 436.8 miles, still had gas left, but I always fill up at Costco because they have the lowest price of gas in the MD/DC/PA/VA area. [​IMG]
    [​IMG][​IMG]

    Here's a pic from my drive from the Costco Gas station to work Ave MPG = 53.0 over 27 miles.
    [​IMG]
    Here is a picture from work to home, still impressive MPGs.

    [​IMG][​IMG]

    So all of you who are sending me PM's saying that I'm stupid, or that I'm going to destroy my fuel economy... please stop sending me messages. Removing the resonator hasn't destroyed my fuel economy, it hasn't hurt in any way. I just don't have to mash the gas pedal to the floor when I'm driving up a long steep hill, and now I can accelerate quickly to merge on the highway. To all of you whom are open minded and willing to do some research about this issue, Thanks! I find the posts about the modern Atkinson cycle engine extremely informative. Your posts helped me learn something, and I think that's the basic intent of this website. People coming together to share ideas to improve on an already great car!

    Thanks everyone!
     
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