On my 1990 5.8L E40D E/B Bronco (similar to F150) I had the Engine replaced due to Head Gasket failure and wanting a higher torque motor. I got a Ford Motorsports Sportsman block and a Lightning mass air kit. It now has about 75k miles on the engine and sounds abrupt idling at times.

Generally it has much power going up hills. On the last Smog Test it just barely passed the HC emissions test. NOx and CO were way low, since I replaced the EGR valve and the Air Idle device on the TB.

I'm looking to replace the Catalytic Converter (has 199k miles on it) so that it will pass the smog test here in CA. Every time I go there they lower the HC number, thus making it harder to pass.

According to the Ford dealer information, it is suppose to have both the air tube that goes into the exhaust manifold (from the EGR valve) and the CAT Air injection Tube that goes into the CAT (via a tube from a check valve that is connected to the Air Bypass / Air control Valve 9F491)

My problem is that when the engine was replaced, the Air Injection tube #5F235 was not installed.

I would like to put this CAT air injection tube back in when I get the Cat replaced with a #94416 Magnaflow Catalytic converter with tube. It is suppose to help improve the vacuum which is at 13-14 in. now.

Question is how to do this job since the Air Control valve tree is between the firewall and the upper intake manifold right near the PCV valve. It looks like a bitch to get the pre-bent tube in there either from the top or blindly from the bottom. How does the tube connect to the hot CAT? (clamp?)

I had the problem before the engine replacement when the tube was making a screeching noise due to clearance problem with some sheet metal part.

Can I use any kind of high temp rubber tube, like silicon? Or any way of using a flexible metal or copper tube? How do I get to the air valve to connect it. Should it have been blocked off if not used? Can this work w/o an air injection tube and still pass smog?

Any help on this is much appreciated. Ron

 

can't answer all the questions right now, but if you vac is that low, you'll have a problem passing smog. Passing smog is sometimes a hit-and-miss game. Some stations don't look that close, they just check the basics.

I live in CA as well and tried to fool them once by not fixing something correctly (because of cost), I fixed several other things then went to a different smog station and they actually KNEW that the one part was bad from the OTHER STATION!!!

I have a simular setup, I'm in the process of installing a new crate motor and noticed on of the silicon hosed going to the cat was damaged.

I'll look at the connections when the sun comes back out.

Is that #94416 Magnaflow Catalytic converter a smog legal replacement? How much does it cost?
I saw the prev owners papers and he paid about $400 for a stock cat, that seems a bit high.

 

A new catlytic converter will not change vacuum at idle unless the old one was badly plugged or highly restrictive.

A new 3-way catalytic converter might be able to adequately control HC without the assistance of the air tube. This technology has improved considerably since 1990.

You could probably connect to the air tube on the cat with a high-temp flexible hose. If the hose deteriorates on the cat end due to heat, you could piece in a section of hard line to move the flexible hose farther away from the cat itself. The flow of air through the hose will help to cool it; it is the catalytic converter that makes all the heat.

 

They knew because all your results were transmitted to Sacramento, thus any smog station will have access to the same info. That's how you got caught!

The OE part Air Tube is a metal tube that connect betweent CAT and a Check valve that then connects by rubber hose to the Air Control valve. OE is not a rubber or silicon hose

I ordered the Magnaflow 94416 today for ~ $71. from http://www.fle-online.com if that's wrong, look up 'Full Line Exhaust' in Dorham, Alabama. It happens to be a CA legal unit, most are not and get this, Magnaflow is in CA. Go figur!

Ron

$400 means he got it from a Ford$ parts dealer.

 

PLEASE HELP!
previous posts relating to the air tubes that run to the catalytic converter
(So, did you connect the little tubes on the cats which go to the engine, creating one? What did you to do that, flexible tubing of some sort or weld some tubing together?

little tubes? are you talking about the air injection ports? Yes, I connectected them to the pollution pump (air pump). Air tube was already in place, just had to add some tubing to make the connection.)



my post trying to get info about what to do with the air tubes, since the truck will not run with them just left open.
(Please explain a little more.
I have a 1991 F250 7.5L 4WD and spent the past week and a half stranded and trying every suggestion I could to fix my truck when it wouldn't start after getting gas.
I am no mechanic so I was at the mercy of everyone who I could ask for their opinion as I bought part after part trying to get rolling again. First was a fuel filter then fuel pump, then a fuel pump relay or eec relay, then MAP sensor, then IAC valve, then finally got pointed to the EGR valve and sensor.. so I took that all apart and cleaned it well. I found these rusted off tubes next to my Cat and one came from the EGR, so I thought I figured it out after tearing apart the EGR and seeing it is spring loaded and fed from the exhaust. My problem was how to reconnect the EGR tube, AIR tube, and O2 sensor to the rusted out cat. A little fabricating and JBweld later and my truck runs great again so I found my problem for sure.
Now I'm interested in just removing the cat, but unsure what to do with the EGR tube and AIR tube and O2 sensor, I don't want to just leave them open or the truck doesn't run for crap.
I saw your post about connecting them to the smog air pump, and thought I would ask for a bit more info. Where is the air pump located? which tube to which nipple in the air pump? can I just connect the AIR tube to the EGR tube? also, can I eliminate the O2 sensor? or where to mount it? Thanks for any suggestions.


well now I have found that the pipe I thought was the EGR pipe on the CAT was not the EGR(the egr pipe goes straight to the exhaust manifold).
when the pipe closest to the rear of the CAT is not connected the truck will not run well, will not idle without feathering the throttle, surges, no power, etc.
the pipe closest to the front of the cat is loose and open but does not seem to affect anything. Evidently they are both AIR Tubes, so I am wondering if I can connect those two pipes together and have a good result.

 

I read somewhere that newer aftermarket cats don't require the air-injection tube to work properly.
I know nothing on the subject.
Just repeating what someone wrote on the Internet. lol
I do know my new Magnafow cat (not yet installed) has no air-injection hookup on it.
I was concerned for about half a second.

 

There are newer cats that do not need the air tube. The air tube was only for the NOx portion of the 3-way catalyst, so would not affect HC or CO readings.

 

Some states require you to have the emissions system as installed, meaning they don't care if a 3-way cat works the same if it doesn't look the same. I would scope out junkyards to find the tube or just fab one from copper pipe and silicone hose. Maybe paint it to make it look less obtrusive.

MIZREE, you need to keep your o2 sensor no matter what or your truck won't run worth a crap. You can chop off cat and plug AIR tube.BUT you must keep EGR tube unless you really want to go into the weeds

 

Yes, there is a visual inspection here in Texas as well, but it is incredibly cursory in many cases. My son's '95 F150 has no cats at all (bought it that way) and they have never noticed it. He has true duals and they stick the probe in one pipe and it passes.

 

Yup. I replaced my dual air-injected cats with a high-pro 3-way and deleted the smog pump cause the 3-ways don't really need em. Safety inspection, mind you not emissions had a problem with it.

Honestly, these carb engines are nasty enough that air injection really helps them function and their longevity.

 

"had no problem with it"?

 

Nope you read that right. Virginia inspector flunked my safety inspection only because a missing smog pump. Truck was exempt from emissions after 25 yr.

 

OK, I thought you were responding to my post above yours where I said they are supposed to inspect it that way but do not, at least where we go. You said "yup" so I thought you were agreeing with me on that point.

 

Thanks for all the replies guys. I did get confirmation that both those tubes running down to the cat were from the air pump, and had no effect on how my truck was running.
I thought I was going crazy because I had symptoms when it was not connected and symptoms nearly gone when the tubes were connected, but turns out that was just coincidence I guess...
now it appears my problem the whole time was the fuel pressure regulator. I may have had a vacuum issue as well, since there is a vacuum line connected to whatever the cylinder thing is on top of valve cover(has three 1 inch air hoses and a vacuum line) the air tubes from the cat were connected to before the air pump. Sorry I don't know what it is called and cannot find it looking online. I removed that piece temporarily while I was chasing down the air tubes and plugged the vacuum line. I am not in a state that does emissions, so if it doesn't keep the truck running it will probably go away.