pumping air directly to cat

[DFXR]

In other words... "you don't have to go up a hog's ass to get a can of grease"

Thank you, Jim-

 

[chelo]

I also have the dreaded smog coming up in Jan. About 2 years ago was when I had issues passing smog. Mechanic rebuilt carb and ran great but could just not get to pass smog. To make a long story short, my mechanic just reversed some hoses around the pump and it passed. He did mention to bring it back in to undue the hose swap. I wonder if something similar to what the op had done.
My mechanic told me it would be hard for a smog tech to notice. Although the first smog tech was a piece of crap. He was giving me bs because my idle was not exactly at 650. I was closer to 700 but that is where my 60 burns extremely clean.

 

[DFXR]

I just re-plumbed to the normal configuration, and before connecting the air hose on the DS fender to the last check valve before the exhaust, tested Jim's tip on the ABV. No surprise... it worked. Disconnect the vac line to the upper chamber of the ABV and air gets pumped right to the exhaust. It certainly is easier than everything I described earlier in the thread.

Just make sure the check valve is flowing before you make this move.

Hopefully future readers skip to the end of this thread before trying anything out in the beginning...

 

[Spike Strip]

OK, question:

I have an A/F analog meter. O2 sensor is installed in the normal place, on the down-pipe, between the inlet for the Air Injection and the CAT.

I tried the above, venting the upper ABV valve port, and got puzzling results on the A/F meter:

With the normal (stock) hook up, cruising at 15 or 25 MPH, vacuum high around 19 Hg, the meter reads (fluctuating) around 12.5.

With the Upper ABV port vented, the A/F meter reads about 10:1. So it's getting richer, or less air.

Normal at 650 idle is slightly lean around 15:1 (prepping for smog test).

Any ideas?

 

[Spike Strip]

Seems reasonable as anything I can think of.

I just verified that indeed, the AIR is directed to the down-pipe when the Upper ABV port is vented. Healthy shot of Air, too.

Lemme see what happens when I plug the inlet tube....

 

[Spike Strip]

Tried the plugged AIR intake and it did change a little.

With AC on and idling around 1300 rpm, it went from around 12.5 to a little over 13, maybe 13.2 or so with inlet plugged / Open.

Did not change enough to notice on an analog gauge at 650 idle.

 

[Spike Strip]

Tried this again last night and it does indeed, make the O2 meter read richer when ABV valve is directed to pump into the exhaust pipe.

From what I've read, I'm guessing the ambient air pumped directly into the exhaust pipe is very slightly cooling the gas or the sensor, because of proximity, which makes the sensor send less voltage, so the gauge reads richer.

 

[Spike Strip]

Failed smog, Bigly.

I is a Gross Polluter.

Time to pull the 1.38 Primary Jet out of it's hiding vault.

 

[DFXR]

Tried this again last night and it does indeed, make the O2 meter read richer when ABV valve is directed to pump into the exhaust pipe.

From what I've read, I'm guessing the ambient air pumped directly into the exhaust pipe is very slightly cooling the gas or the sensor, because of proximity, which makes the sensor send less voltage, so the gauge reads richer.

If I had done before and after tests, my experience would be more helpful. But I just went in once, ready for battle, and it worked.

The placement of the O2 meter does seem like it would have some bearing on the numbers. That air from the smog pump is pretty cool when it hits the inlet and then the meter, but will heat up quite a bit once it enters the cat (esp if you bring it in highway hot), in which case maybe you get a more complete burn of everything that's in there? Even more so with the added oxygen? My residual O2 was zero at 15 and 25mph. Nox and HC were super low, CO was respectable but not exactly low.

 

[DFXR]

Failed smog, Bigly.

I is a Gross Polluter.

Time to pull the 1.38 Primary Jet out of it's hiding vault.

That just sucks...

 

[Spike Strip]

Here's the test.

Nothing changed since last test other than the Upper ABV port vented and a gallon of ethanol that someone may have surreptitiously added to the few gallons of gas....

Everything else stock.

 

[DFXR]

How's your cat? Those look my numbers from a few years ago just before I replaced the cat.

 

[Spike Strip]

Replaced the CAT with new Magnaflow a couple years ago.

And, FWIW, this test was the FIRST time I've ever seen a Tech crawl under the truck and look for the CARB stamp and part number and check that against his list of CARB approved Magnaflow part numbers for Kalif.

I shouldda known it was gonna go South from there.

And just for Pisi-Kaka I hooked the ABV back as normal and the A/F reading jumped up to 18 so I may just take the truck back to another place tomorrow and see what happens.

 

[Spike Strip]

I have it on good authority the alcohol used was 100% EtOH reagent grade stuff. But it was prolly way above 10 percent.

I also had to hover over these couple of techs doing the test as they had no idea even where to look for timing marks and which evap hose went to the tank and couldn't even find the data sticker.

My usual guy said his machine for pre 2000 vehicles is broken and he didn't have the money to fix it...

I hate Los Angeles. I hate Kalifornia. Where can I get a P.O. box in no-smogville ?

 

[Spike Strip]

Well, all I did between yesterday and today was hook the ABV properly and set the timing (a few degrees off) and these are the results:

(Damn Air Injection still can't figure out why it's zero)....

But now it's wait until next year

 

[Spike Strip]

The Nox is because of the fuel.

The tank ran so low I was afraid I was gonna run out of gas on the dyno. Really. I politely asked the guy to hurry because of it and he looked at the gauge and asked why I let it get so low.

I just replied 'you don't want to know'. He looked at me for a long beat, then continued with the test.

I did see him looking at the empty bottle of EtOH someone had left in the cargo hold, but he didn't say anything.

And since he said he was the second guy of two in Los Angeles to vote Trump, I knew he was ok.

 

[DFXR]

Doesn't make any sense to me, but congrats regardless. Here I am thinking the ABV trick is a silver bullet but maybe that's not the case...

 

[FJ40Jim]

Maybe ABV + E85 is the silver bullet?

 

[chelo]

I also just had a smog and failed. Installed new cat in 2014 but tech mentioned it might not be working properly. Numbers are similiar to spike but higher no but still under the gp limit.
I am fouling plugs so I believe carb is running rich. I am also starting to get a small manifold leak.
Is 7 degrees of timing ok or should I move it slightly? I looked and found some of my smog checks from about 10 years ago and timing was at 10 and passed perfectly. Between this smog and my previous smog, I never had any issues.

 

[chelo]

Smog pump is almost toast. Disconnected hose that goes into air cleaner and can barely feel suction. Sounds like marbles in there. I have a new replacement and also have a factory takeoff unit.
I did the carb mixture lean method today. My sparkplugs have been fouling very quickly. Spent a good 4 hours under the rain. Going over everything.