Author Topic: Stock Exhaust Manifold Pipes (Air Injection?)  (Read 4663 times)

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Weldo

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Stock Exhaust Manifold Pipes (Air Injection?)
« on: Jan 29, 2005, 04:18:37 PM »
I wanna build a header for my 91 pick up, 22re.  My stock manifold has a small pipe running from each exhaust port, I can't really follow them because of the heat sheild, I plan to take a closer look in fairer weather.  I was wondering what are these pipes for, where do they run to, and can I safely block them off and just get rid of 'em.  Thanks!
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FATB0Y

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #1 on: Jan 29, 2005, 04:55:54 PM »
Don't know about yodas' but on my datsun it was 4 the EGR. And I unhooked mine and blocked it off but it makes it SUCK  gas I went from 19mpg w/36" tsl's to 12mpg. Hope this helps

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #2 on: Jan 29, 2005, 07:05:31 PM »
That tube is for the air injection for the cat.  Put more air into the exhaust and the cat gets hotter faster, burns any unburnt fuel more completely.  Therefore less bod stuff out the tailpipe.
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Uncle Jesse

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #3 on: Jan 29, 2005, 11:23:32 PM »
The difference between a blocked off header and a smog hookup header is two holes and two threaded holes.  Well, there may actually be two designs, but my CA 89 22re has just two pipes, thus two holes.  Anyway, you're looking at possibly having to add at most six holes to the header flange, two of them being threaded.  I'd say drill them, so tailpipe emissions don't suffer.  I mean, you're building the header anyway, go the extra mile and do it right.  The air injection doesn't use a pump, and injects air into the exhaust, so its not costing you power.  Check out some of the header manufaturer sites to see what the header flange looks like, in fact, I believe you can get just the flange from LC Engineering.  I think you can find them on ebay too.

Weldo [OP]

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #4 on: Jan 30, 2005, 07:33:05 AM »
Looks like the LC Engineering headers and flanges don't have holes for these pipes.  I looked at Heddman headers too, they also don'y have provisions for the pipes.  I saw a header from Downey that did though.  When you say I may have to tap some holes, does that mean these air injection pipes thread in?  Also, if I do delete the air injecetion pipes, the only thing that will suffer is emissions, right?  Finally, where does the air injection get the air if there's no pump?  thanks a lot!
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79coyotefrg

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #5 on: Jan 30, 2005, 07:43:50 AM »
yea man if you dont need to pass a smog test  just run a good ceramic coated header, 1 1/2 inch diam tube or bigger,   last time i used a 22 exhaust manifold i just filled the holes with jbweld and capped them off,  if you dont have the smog pump on the right side of your engine under the a/c compressor then non of that junk works anyway
AR-TTORA founder 22R bored.060,LCE stage II race cam http://pure-gas.org/    32/36weber, :driving: Marlin 1200 NON ceramic clutch, L52SHD+dualcase #2919, cable-locker, Yukon 5.29 gears, 35's, Allpro ebrake, front springs, and high steer, F150rears    RIP Nitro 9-29-07 :(  I sure miss him :down: MarlinCrawlerInc IS NOT affiliated with TrailGear in any way

79coyotefrg

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #6 on: Jan 30, 2005, 07:45:24 AM »
Downey is on the C.A.R.B  comittee so they HAVE to conform with all those stinkin regs
AR-TTORA founder 22R bored.060,LCE stage II race cam http://pure-gas.org/    32/36weber, :driving: Marlin 1200 NON ceramic clutch, L52SHD+dualcase #2919, cable-locker, Yukon 5.29 gears, 35's, Allpro ebrake, front springs, and high steer, F150rears    RIP Nitro 9-29-07 :(  I sure miss him :down: MarlinCrawlerInc IS NOT affiliated with TrailGear in any way

Weldo [OP]

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #7 on: Jan 30, 2005, 10:14:30 AM »
Well, I don't have an A/C compressor, and the right side of the motor is pretty much empty.  Also, I replaced a muffler a few weeks back and I didn't notice any pipes or anything running to it, or anywhere in the exhaust.  So If the air injection pipes don't run to the cat, and I don't have an air pump, where do the pipes lead too?  Any idea?  Thanks again!
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79coyotefrg

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #8 on: Jan 30, 2005, 01:34:42 PM »
sounds like somebody already ditched most of the crap i would ditch those little pipes as well
AR-TTORA founder 22R bored.060,LCE stage II race cam http://pure-gas.org/    32/36weber, :driving: Marlin 1200 NON ceramic clutch, L52SHD+dualcase #2919, cable-locker, Yukon 5.29 gears, 35's, Allpro ebrake, front springs, and high steer, F150rears    RIP Nitro 9-29-07 :(  I sure miss him :down: MarlinCrawlerInc IS NOT affiliated with TrailGear in any way

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #9 on: Jan 30, 2005, 03:48:20 PM »
sounds like somebody already ditched most of the crap i would ditch those little pipes as well
Me 2 :bud:

Uncle Jesse

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #10 on: Jan 30, 2005, 04:13:00 PM »
late model (as of 85 or 86 I belive) 22re engines changed from a air pump to a pulse air injection setup.  If you follow the small hose from the air box you will see it run into a round accumulator.  From there it goes to a valve, and from there around the back of the head.  Behind the head in the steel pipe is a check valve, from there it goes into the manifold.  The head has pear shaped exhuast ports so that the air goes from the small pipes into the manifold and downstream to the cat.  Its called Pulse Air Injection because the exhaust exiting the head into the manifold causes vacuum and sucks in air from the small pipes on the manifold.  It works on the same principle as exhaust scavenging.  Again, it doesn't use any power to drive, and is injected post combustion.  At that rate, a stock air pump only uses 1-2 horsepower.  It's main downfall on 22r's was the crappy air rail on the manifold that you could never get to stop leaking.

Anyway, the air injected to the cat is an attempt to maintain a 14.7:1 Air fuel ratio at the cat.  It does its best work at that ratio.  When cold the engine is running rich and the cat cannot reduce emmissions.  So you inject air to get back to stoichiometric ratio, the cat works better, and it warms up faster, thus working even better.  Once the vehicle is warmed up the valve under the intake will block flow of the pulse air.  Air isn't needed once the engine is warmed up, unless you decelerate, when the throttle is closed, and the engine isn't in fuel cut yet.  This time the engine is rich again, so they inject air to keep the cat happy and working.  And to keep it from melting down from an overly rich ratio.

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #11 on: Jan 30, 2005, 04:16:08 PM »
:o

79coyotefrg

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #12 on: Jan 30, 2005, 04:48:39 PM »
:dunno: sounds good to me :dunno:  Unclejesse,  do you work for toyota or a california smog shop?????????
AR-TTORA founder 22R bored.060,LCE stage II race cam http://pure-gas.org/    32/36weber, :driving: Marlin 1200 NON ceramic clutch, L52SHD+dualcase #2919, cable-locker, Yukon 5.29 gears, 35's, Allpro ebrake, front springs, and high steer, F150rears    RIP Nitro 9-29-07 :(  I sure miss him :down: MarlinCrawlerInc IS NOT affiliated with TrailGear in any way

Weldo [OP]

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #13 on: Jan 30, 2005, 06:10:42 PM »
I can't see any pipes running to my cat, so should I assume that my air injection system doesn't work anyway?  I have all the other stuff you mentioned, the round accumulator and pipes and what not, jus nothing going to the cat.  So what can I expect if I get rid of all this stuff, from the round accumulator to the actual pipes on the manifold?  It sounds like my emissions may be a little higher when the motor is cold, but will return somewhat to normal when the motor is warm.  Is that right?  Or will I burn up my cat without air injection?
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Uncle Jesse

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #14 on: Jan 30, 2005, 09:37:57 PM »
There will be no pipes going to the cat.  The air enters at the manifold through those pipes you see.  They go into the manifold not out.  If you remove the Pulse Air system, remember to block off the open hole in the air cleaner where the hose is attached.  There is also a vacuum switching valve on the valve cover that controls the air injection.  Some lines will run from there to the throttle body and to the valve under the intake.  There is a possibility of catalyst damage if you remove the system, but then again, if you are going that far you might as well remove the cat.  Of course, if you have a cat monitor (O2 sensor behind the cat), then your check engine light will eventually come on.  My 89 manual does not show a code available for a failure in the pulse air system.

From my manual - "To reduce HC and CO emissions, this system draws in air into exhaust ports to accelerate oxidation, using vacuum generated by the exhaust pulsation in the exhaust manifold"  Oxidation is what the cat does when it adds O2 to the HC and CO to make H2O and CO2.

Once again, I have to point out that this an afterthought system, just like the cat itself.  What I mean is that it doesn't affect combustion directly.  Unlike EGR which releases exhaust back into the engine, this system releases air into the exhaust.

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #15 on: Jan 30, 2005, 11:19:55 PM »
your jus full of info  :working: Uncle Jesse

Weldo [OP]

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #16 on: Jan 31, 2005, 03:24:12 PM »
OHHHH, I see, the air is injected into the manifold.  What kind of damage can be done to the cat?  Will it become clogged up or what?  Also, is there any hope of passing emissions without it, or is it completely hopeless without the air injection?  Sounds like emissions would still be good when the motor is warm?
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Uncle Jesse

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #17 on: Jan 31, 2005, 04:55:22 PM »
An overly rich mixture can cause the cat to overheat and melt down.  You may be able to pass tailpipe emissions, if the machine doesn't measure decel emissions.  I can't remember if it does or not.  You will fail a visual inspection due to the lack of the pulse air equipment.  You might also fail due to the header itself.

Also, remember that egr comes into the head from the manifold, so unless you make ports for that, the egr will not function, and you will fail a five gas emissions test.  But before that, the check engine light should come on from the lack of egr flow.  That is assuming your truck is a california truck or has the same equipment as california.  You will notice a two wire sensor on the pipe the feeds egr into the intake manifold, back by the firewall.

According to my manual, air injection is on below 3,600 rpm when the engine is below 86 F.  Above 104 F, it operates at above 1,000 rpm with the throttle closed and below 2 mph.  Above 2 mph with the throttle closed and above 104, it operates all the time.  So basically when cold it runs at idle to pump air to the cat because of the cold rich mixture, then once it warms up it pumps air because of the decelleration event.

So if it is a two speed idle test, the air will turn on when the engine is revved to the 2,500 rpm test.  If its a dyno loaded mode test, then the throttle is open so the air should (the book doesn't say) only come on during deceleration.

Weldo [OP]

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #18 on: Feb 01, 2005, 01:26:53 PM »
Last year I was emissions exempt.  I had under 5000 miles for the year (I live in Pennsylvania, by the way).  Last time I did get an emission test the truck passed OK.  They just did the 2 speed idle test.  The guy who had the truck before me said the truck never had a problem passing emissions anyway.  Could I fail a visual inspection if they don't see the air injection stuff, even if I'm exempt?  Or would they not even look under the hood? 
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FATB0Y

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Re: Stock Exhaust Manifold Pipes (Air Injection?)
« Reply #19 on: Feb 02, 2005, 02:46:34 AM »
NC passed a new emissions law 95 and under don't have to take the test good thing mine is a 94  :yupyup:

 
 
 
 
 

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