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Air intake: Extra boxes and hoses, is there a project page to reduce this mess?
1995 4runner, 3vze 3.0l v6
I read about people removing the extra air-boxes that make the precious air take a round-trip around the engine to the 50 brittle hoses and valves that are 25 years old. I am trying to read up on that here on the forum, but there are too many threads, I am overwhelmed. Does anyone have a link to the project page for successful people who have removed this extra stuff ?
Any fracture in vacuum on these 25+ year old hoses that run back and fourth will actually cause this engine to NOT perform. All this does is dilute the exhaust with fresh air, and present a revolving door policy of troubleshooting.
The additional oxygen in that air permits the CAT to burn hydrocarbons that it otherwise couldn't. Maybe you have gutted the CAT too??
All parts are available to maintain this equipment.
As to degraded engine performance, the only cracked, or damaged PAIR hoses that might cause degraded performance are the generic 1/8 inch vacuum hoses that can be got anywhere for cheap.
The additional oxygen in that air permits the CAT to burn hydrocarbons that it otherwise couldn't. Maybe you have gutted the CAT too??
All parts are available to maintain this equipment.
There was no cat-converter on the truck when I bought it. I would have buy one of those, put it on and also buy all the other parts that were partially removed. They already welded shut the EGR port on exhaust. I am simply removing the rest of these tubes and the air boxes that actually do nothing on my engine.
The factory air intake system is well designed and does not include "extra stuff". Toyota gave the 3VZ-E engine a cold air intake right from the factory. How nice of them.
As Millball pointed out, it is a common misconception that the Air Injection or Air Suction system just dilutes the exhaust to fool emissions.
The Air Injection system is just a simple way to introduce oxygen into the exhaust, by way of filtered air, to help the catalytic converter to work efficiently.
On my truck there is no catalytic converter to assist with. A resister is stuck in the temp sensor. I am just removing the rest of the tubes and boxes that only circulate air around my engine.
You can do what you want, but beyond what has already been accurately said by @millball and @old87yota, there are two things that you should know.
1) As @old87yota says, you already have a cold air intake. Beyond that, cold air intakes are something of a fallacy anyway. Your engine doesn't want to breathe cold air, it wants warm air so the fuel will vaporize. That's why the intake plenum is snuggled on top of the engine where it can stay nice and toasty. Engines run poorly on cold air, requiring things like carburetor chokes, cold start injectors, mixture enrichment, etc. to get enough vaporized fuel into the engine so it will start and run at all.
2) The stock air intake on the 3vze has negligible restriction on air flow. If you put a vacuum gauge on the intake plenum at full throttle you'll maybe measure .5" of vacuum. That translates to about 1.5% of power loss vs. if you could get that down to 0" of vacuum, which you can't no matter how you re-plumb the intake. (Power is proportional to absolute plenum pressure. Without a turbo, max pressure is 30" of mercury at sea level. A .5" pressure loss is ~1.5%.) The best you're likely to do is maybe reduce that by half, which nets you .75% horsepower increase, about 1 hp on a 150 hp engine.
With a resistor in place of the air temperature sensor, your ECU is only guessing at the right mixture, which means you are likely either wasting fuel by burning rich, or possibly getting misfires by running lean. You'll get the most bang for your efforts by finding a working air flow meter and getting that properly installed so your engine control system can work.
The engine has started and ran just fine for 2+ years the way it is now. 1/2 a horse won't make or break the engine. The vacuum leaks will actually break the engine.
i would be buying catalytic converter, sensors, pipes, a new exhaust manifold to restore the engine to factory conditions - to AT BEST: gain a half a horsepower. on a rusty 4x4 offroad truck that is 25 years old with 170,000 miles.
You guys drive a hard bargin, it is really tough for me to decide. I really like stuff in the way to break and replace that changes the engine performance on a scale so small, it competes with exhaust leaks or tire pressure. These enormous 35" tires and lift kit also reduce the engine performance - I guess I should remove that too.
I ran my 1995 3vz 4Runner 206 miles today in southern Arizona at altitudes of 4000 to 9000 ft. 70% 65-70mph highway 30% mountain dirt roads.32 inch tires. Carrying wife, kid, dog, and a couple hundred pounds of misc. gear.
It has all factory emissions equipment installed and operating.I burned 10.22 gallons of 10% ethanol 87 0ctane fuel for 20.15 MPG.
These trucks are capable of great things if properly maintained.
Most of the guys who complain that they can barely get 14 or 15 MPG out of them have 'improved them'..
Well, I do understand dealing with the previous owner's removal of the EGR and the catalytic converter. That does get expensive to make that all factory correct again.
But, what is with the resistor stuck in the temperature sensor? Which sensor? There are several Temperature Sensors on the 3VZ-E for various functions.
You don't want the Engine Coolant Temperature sensor or Air Intake Temperature sensor to be bypassed as they give the Engine Computer essential information for proper fuel and timing management.
There is a heat sensor on the EGR. Since my EGR does not exist, a 10k resistor was installed to the socket where that normally would go. Without the resistor a "check engine" light comes on. The pair valve also does not exist. It appears to me they did the procedure, except for removing a large array of tubes and replacing them with caps.
Everyone is right as far as just keep it simple and stock! But I removed all of it EGR and PAIR all hard lines all of the intake which is great from factory but some unnecessary parts! The bottom box is there just to reduce sound and the others is a air cleaner! But I think it’s not bout getting cold air in but just getting more air in in general! I live in Idaho so no emission testing at all so I can get away with removing all that stuff and can honestly say my 91’ 4Runner SR5 premium runs way better and has more power and picked up 1 to 2 miles per gallon! If you saw the pile of hoses and parts that came out and to have it run better and cooler it’s crazy! So I’m my opinion yes there is stuff you don’t need but if you start to remove things it’s all or nothing cause the way it came from the factory is just fine! Do know from experience EGR systems are engine killers!
Thanks for the information. I managed to figure out the EGR part of the system, seems like there is 1 tube into the air-box, and 2 vacuum lines out of the throttle body - with about 6 more vacuum lines in and out of a solenoid on the passenger side.
Now I still have ANOTHER air-tube that goes into another empty box that connects to a 2 1/4" t-pipe into the air intake, after the air cleaner. My pair-valve is removed, so I am just trying to clean up and out the rest of whatever else was connected to that.
Black are lines to remove, green is stay but suggest replace all you can Some I’ve seen bring the fuel return around behind the intake, I went around front Red valve is all you will need This shows where the egr was and where to now plug your vacuum hoses back Hard to see all of it but this is mine done!
Ok sounds like you are past what most everyone’s is saying about the stock setup is fine and dandy but there are a lot of unnecessary hoses, valves and parts! So if you get rid of the PIAR also you can also abandon the green and blue valves that sit behind the diagnostics port and just use the red. Which will let you eliminate the vacuums to the top of the throttle body! But from here to make things less confusing you really should remove the phlemal and remove the hard lines running under it! There may be some pics of the same area but I really had to do a lot of what I did from these vacuum diagrams and coolant diagrams! I will get some better pictures of exactly how I did mine! You can continue to use the stock intake setup minus the 2 box shape parts that stick down under the distributor! I think I saw something bout the 10ohm resistor for the EGR heat sensor which must have and also start running premium fuel! But if you search EGR/PAIR delete you can find some info but I just put a lot of it here for you! Again All or nothing! Sorry if it is confusing but I’m just going off of memory on the fly here cause it took me 2 months to complete this project because it was hard to find info and also it can be done a few different ways!
Thanks for the information. Nice work. Your engine is nice and tidy. I still have the metal pipework left, and I think I have to remove the upper-intake in order to get that out. Probably do not want to disturb that until I actually need to.
Do you have a manual transmission? I have 3 cables into my throttle body; cable for the gas-peddle, cable for cruise control, and ANOTHER cable runs next to it into the transmission (which is all jammed up and I have to fix since the stupid cable part is like $80 or $130 ridiculous dollars).
I still do not see on your diagrams, the LOWER air-box that my truck has. I think it's an "Air resonator box". Goes under the air box, into a t-pipe on the air intake. There is a 1/2" air hose that goes INTO this box, connected to the metal pipework. I can't figure out where that air is coming from (or should be vacuuming from) - what is the other side is a mystery to me. I looked all over the FSM manual I found online, either I am blindly not seeing the pages (which also it seems to be excluded from every printed diagram) which not make sense, there must be different versions of FSM. Extra air intake box that goes who-knows-where.
Last edited by Erich Stein; 04-21-2019 at 06:16 AM.
Reason: Add pictures, better explain unknown undocumented 3rd air box.
Yeah I’m pretty sure if it’s the lowest of the boxes it’s just there to cut down on intake noise! I’m fairly certain that’s where I started on my adventure! Cause I had a 96’ Tacoma 3.4 with K&N cold air and it was a monster and my 91’ runner well is not lol so I just started tearing things off and reading and watching videos online and I’m stoked with the outcome, and yes blown away from how much stuff was just there waiting to break moving AIR! I boxed all the stock intake up but I know I started out taking the bottom box off and putting a pvc pipe threaded end cap in the hole of the above piece with a hose clamp! But for 35$ on EBAY you can get a cold air kit that has a bunch of parts and the part for the MAFS to hook into so I did that and picked up a full gear on uphill climbs! You can cut the silicone around the top of the MAFS and pull the cap and inside is a bunch of electrical connections and a round gear type thing that controls the fuel relay in the passenger side kick board that makes the pump turn on and off! That’s how you can test it! BTW maybe something is stuck in there!
03-20-2019, 05:18 PM
