pumping air directly to cat (1 Viewer)

[Southbound]

Hey All,

There was something wrong with the air injection system on my fj60 so I just bypassed it with a hose directly from the air pump to the exhaust. As a result, I passed emissions with unbelievably low numbers. Question is, can I keep the system set up this way? I imagine there is some danger of the cat overheating since I've bypassed the circuit that would turn off air flow if the temperature gets too high. Just don't know how much of a threat there is to that actually happening.

 

[Southbound]

Yup, that's exactly what I did. Wouldn't take long to route everything back to normal, just wondering if it's worth the trouble. And the clean exhaust makes me feel warm and fuzzy. The emissions guy said he'd never seen numbers like that on a cruiser.

 

[micruz60]

Yeah, thanks for the experiment. If one does not have a catalytic convertor, would there be any consequence?

 

[DFXR]

i need to see a picture of this, if you don't mind.

 

[Southbound]

Sorry DFXR, already switched it back. It's a super-easy mod - connect a hose from air pump outlet to exhaust inlet just below the carb fan. Only tricky thing was getting the right diameter hose. I'll measure and post.

 

[Southbound]

All the emissions stuff was still installed. I routed the hose underneath it - you'd have to really know what to look for to notice. I used a 17" length of 5/8" diameter hose, which inserted inside the larger diameter hose coming out of the air pump and the hose leading into the exhaust. Could be a slightly smaller diameter hose would be easier to fit into the others, but 5/8" is what I had on hand and it worked just fine.

 

[DFXR]

Thanks for the explanation. That makes sense. I'll dig this thread up next summer when I'm due again.

 

[DFXR]

Will do. Hopefully it will be a nice short answer like "It worked."

 

[DFXR]

It worked. edit: (BUT SKIP TO POST #25 FOR AN EVEN EASIER SOLUTION)

But I found myself wondering, right about the time I finished buttoning everything up... can you achieve the same effect - pumping air directly to the cat - by running the ABV in "test" mode , where you jump the terminals on the OC thermosensor ( green connector under the console) and get the ABV pumping air into the exhust thru the air bypass hose at all speeds and temps, low or high? Page 3-21 in the Emissions Manual.

Either way, you have to make sure that your check valve at the entry to the exhaust pipe is flowing. Mine needed a good cleaning to flow and I would bet many others out there do, too.

 

[DFXR]

OK, here's where I'm confused - when the ABV is open in (2) and (3) here, with the thermo sensor switched on, it looks like air flow is going through the last check valve before the exhaust pipe. What am I missing in the diagram?

 

[Output Shaft]

When the cat temp sensor plug is shorted, the result is diagram #4.

Unless...

The engine is decelerating, which triggers the vacuum switch to trigger the emissions computer to turn the deceleration fuel cut valve off and flip open the ABV.

Then it'll inject into the exhaust pipe.

The air injection system is triggered by vehicle speed, engine vacuum and cat temperature. If all three of those inputs can be spoofed, then the air injection system can do whatever you want it to do.

 

[DFXR]

OK, thanks.

Then we're back to running a hose directly from the smog pump outlet to the check valve/exhaust pipe just ahead of the cat. Which worked, but might not fly if you have an anal smog tech who looks closely at that side of the bay.

Unfortunately I can't provide a before/after analysis - I didn't test before running the direct hose. I just did it, and did it, and my numbers were good. Very low HC and NO, respectable CO.

But I will take pics if anyone wants them.

 

[jestlurnin]

Yes pics please. I'm 99% sure I'm mentally visualizing what we are talking about but you know what they say about pictures....

 

[Spike Strip]

OK, OS, Challenge time: My head hurts every time I try and study the diagram ( and I've got smog coming up).

As I read it, anytime the ABV is OPEN, Air will be injected to exhaust pipe.

Q1: Is ABV 'open' or 'closed' when manifold vacuum is applied ?

Q2: What's the simplest combination of ABV, ACV, ASV that will route injected air to exhaust pipe?

Q3: Can you think of a simple routing (rerouting) of Vacuum tubes that will constantly force pumped air to the Exhaust Pipe ? .

Though it might be simpler to just plumb as DFXR ...

 

[DFXR]

OK, OS, Challenge time: My head hurts every time I try and study the diagram ( and I've got smog coming up).

As I read it, anytime the ABV is OPEN, Air will be injected to exhaust pipe.

Q1: Is ABV 'open' or 'closed' when manifold vacuum is applied ?

Q2: What's the simplest combination of ABV, ACV, ASV that will route injected air to exhaust pipe?

Q3: Can you think of a simple routing (rerouting) of Vacuum tubes that will constantly force pumped air to the Exhaust Pipe ? .

Though it might be simpler to just plumb as DFXR ...

I'll take pics today.

My heads hurts too - I can handle the schematics for the ABV but the conditional table at the bottom of the page stops me cold. I also read "abv open" as "flowing to the pipe" but I also think OS is a lot smarter than me.

Since jumping the terminals on the thermo sensor is easy enough, and you might be re-plumbing in the end anyway, maybe you could try this before going whole hog: pull the hose that goes from the air injection rail to the last check valve, then jump the sensor terminals and see if you get air flow out of that hose at idle, 1500, and 2000 RPMs. Seems to me that if you do, you'll have nice clean air injection for your 15 and 25mph dyno test. Of course make sure the check valve is clear too. If you don't get air flow, then go ahead and re-plumb it.

I would prefer the jumper method over plumbing (if it works), not just b/c it's easy, but because no tech is going to look under the console where the thermo sensor terminal is. With the re-plumbing method, you end up with two hoses to nowhere - one from the ABV that would normally go to the smog pump, and one from the air injection rail that would normally go to the check valve and exhaust pipe. You have to get creative and stuff the open ends down out of sight, and hope the tech doesn't care too much. Mine definitely did not.

Pictures later will help this make sense.

 

[Spike Strip]

Thanks, OS - GL with test. One other thing is IF one were to leave disconnected, the large hose that goes to the VCV on the bottom of the passenger side (LHD) of the Air Cleaner, it significantly leans out the mix.

Just sayin'.

 

[DFXR]

For anyone following at home, here are my pics. It's a hard area to shoot so they may or may not shed light on this get-around. It looks and sounds more complicated than it actually is.

Long story short, like the OP, I plumbed the air pump (aka smog pump) outlet hose - pumping clean, compressed air - directly to the exhaust just ahead of the cat via the check valve. It got me through smog but rather than fixing any actual problem with the emissions system, I think it just dilutes the air at the pipe, and gets your vehicle to pass the sniffer test. Which is sometimes all that matters.

Things to note

- I used one piece of automotive hose with a 1" (25.4mm) ID. Gates makes it but your local parts place might have some off-brand. Get yourself 3 feet of it and you'll have more than enough.
- My smog pump is an aftermarket A1 Cardone reman, bought thru NAPA. That's why you'll see the oddball 45 degree elbow and the blue hose. The stock smog pump outlet doesn't have the elbow or the blue hose but the concept is all the same.
- You'll end up with two open ended hoses that go nowhere. Do what you can to make them look like they go somewhere. After your test, plumb it back to normal.


Passenger side, looking straight down onto the ABV and ASV. New hose running from smog pump outlet (via the elbow):

New hose running down to connect with the exhaust pipe via the check valve (which you can't see in the pic). The new hose is wrapped in the old heat wrap.

 

[FJ40Jim]

As I read it, anytime the ABV is OPEN, Air will be injected to exhaust pipe.

Q1: Is ABV 'open' or 'closed' when manifold vacuum is applied ?

When vent is applied to upper chamber, ABV is bypassing AI to the exh pipe.

Q2: What's the simplest combination of ABV, ACV, ASV that will route injected air to exhaust pipe?

Vent upper chamber of ABV.

Q3: Can you think of a simple routing (rerouting) of Vacuum tubes that will constantly force pumped air to the Exhaust Pipe ? .

Disconnect vac hose to upper chamber of ABV.

Though it might be simpler to just plumb as DFXR ...

 

[Spike Strip]

Cheers, Jim.

 

[doug720]

Smog Sucks! Literaly and figuratively...