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failed smog/ new cat installed 91 n/a

Old 02-28-18, 02:53 PM
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failed smog/ new cat installed 91 n/a

Hey guys i Failed CA smog today. Tech checked first and said looks fine and ran the test but failed. I have a new tps and a new magnaflow cat for CA. I think my ACV is not working properly. How do you shim the ACV to dump air all the time to the cat?

15mph HC
max measure
81------336
25mph HC
max measure
63-----307

15mph CO
max measure
0.52--2.49
25mph CO
max measure
0.43-----2.65


my NO measure are good
max measure
554 48
max measure
511 73

Last edited by Trueno102; 02-28-18 at 03:00 PM.
Old 03-16-18, 04:58 PM
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I'm in the same situation as you: high HC & CO but ok with NO. I think my O% was high as well (don't have test results with me). The FAQ answer is either Rich Air Fuel Mixture or problem with air injection. I've checked everything except for fuel system and ACV. Car idle is not rock solid either. Did you perform tests relating to the ACV?

Noboby is interested in smog problems anymore, I think.
Old 03-17-18, 09:50 AM
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California is the only place in the world that still emission tests a car this old.

the ACV needs to be in "port air" for the test. air should pass through the valve to the round port on the intake
Old 03-17-18, 08:20 PM
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Originally Posted by j9fd3s
California is the only place in the world that still emission tests a car this old.
No, it isn't.
Colorado still etests every car newer than 1975.

Actually, let me amend that...certain parts of CO do this.
The heavily populated front range areas require testing as they run afoul of EPA guidelines.
Heaven forbid they try to regulate the energy extraction industries, who get to throw anything they want into the air and water and you don't want to **** off Envirotest, who have a sweet little testing racket going.
Far better to inconvenience the private citizen, who has no voice or political power.
Old 03-19-18, 03:02 AM
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Do you have an aftermarket fuel pump?
Old 03-19-18, 03:31 PM
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Load it up with alcohol before the next test.
Old 03-20-18, 07:25 PM
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Originally Posted by j9fd3s
California is the only place in the world that still emission tests a car this old.

the ACV needs to be in "port air" for the test. air should pass through the valve to the round port on the intake
I posted these pics on a different thread but no replies so ill post here. I wired this opened.

I have a brand new magnaflow catalytic converter.


Is this correct?

@Jayvee7 I have no check engine codes. I've checked my fuel injectors to make sure their not leaking just to make sure and their not leaking. Also the previous owner had the fuel injectors cleaned. Fuel pump has good psi. I believe car is not getting air properly from the acv. Going to smogg this week.

Last edited by Trueno102; 03-20-18 at 07:31 PM.
Old 03-20-18, 08:31 PM
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... fuel pump... is it stock? You could be doing all of that for nothing. Did you test ACV?
Old 03-20-18, 08:51 PM
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Originally Posted by Rotary Alkymist
... fuel pump... is it stock? You could be doing all of that for nothing. Did you test ACV?
stock fuel pump and I tested the fuel psi. It seems good. Also no leaking injectors. Catalytic is brand new. It seems like the acv is always dumping the air to the floor. My mistake was not checked the solenoids before the smogg but the car is running well. Timing is correct, idel is 800rpms. Tps is brand new and at about 1 volt

Last edited by Trueno102; 03-20-18 at 08:54 PM.
Old 03-20-18, 11:14 PM
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Originally Posted by clokker
No, it isn't.
Colorado still etests every car newer than 1975.

Actually, let me amend that...certain parts of CO do this.
Darn, guess I cant move out that way.
Old 03-21-18, 11:28 AM
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Have you changed your oil? It makes a big difference.

Have you flooded the car on that oil change? More than once? That never helps either.

I have an aftermarket FPR. I turned my pressure down to 35.5 for the test and made sure I had burned my mixed fuel and put straight fuel in. However, my ACV was working properly and the car had good compression and brand new oil and filter. Also the car was taken out for a spirited run for a bit before the test. Make sure your engine is hot hot hot.

Last edited by Rotary Alkymist; 03-21-18 at 11:33 AM.
Old 03-22-18, 01:53 PM
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@Trueno102 I forgot to mention in my reply earlier but mine had a feedback system code 17. Did you take the car on long ride or in cruise mode on the freeway? I'm surprise that you don't have this code.
Old 03-23-18, 04:52 PM
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My comment is not helpful but I can't help myself and you can hate me if you want but socialist states(California, Colorado, New York, etc. etc.) suck *** big time and I would never even want to visit them. Ok I'm done.
Old 03-23-18, 05:25 PM
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Originally Posted by TonyD89
Load it up with alcohol before the next test.
I'm telling ya, do what you plan like wiring open the ACV but, run the tank down, add a bunch of "Water eliminating" products (alcohol, read the ingredients) or E85 if available, and then go for it.

Or does California know if you're running E85? Are they flunking you for ECU codes?

After you pass, fill up on your favorite fuel.

Oh yeah, I'm with Red95FD, wholeheartedly.
Old 03-24-18, 08:47 AM
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Tap a "T" fitting into the air pump output hose and run it to the split air of the Catalytic.
Use like a 1/2 inch line..tuck it in there and nobody is none the wiser.the steel pipe on the cat can be either modified with a compression fitting to attach the hose from the engine(easy swappability) the cat OR just place a good quality "won't go up in smoke" hose on it!
I went from TWO's to "Holy Crap what did yo do to this car..it's not even reading!"
I left my setup on the car as I was lazy to take it off and it didn't harm anything anyways.

*the attachment for the stock split air can be plugged up...On an s4 you need to keep a aux port feed on it but the S5 uses Electrical Aux port activation so it doesn't apply...You'll find a sparkplug fits nicely to plug up that hose.

* by the way the Cat was new when I did the test and failed,so I did the hose trick and Voila!..car on road!
Old 03-24-18, 10:20 AM
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Originally Posted by Trueno102
Is this correct?
blow through it, if air goes from the air pump inlet to the round port you're good
Old 03-28-18, 04:49 PM
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Trueno102, did your car pass smog? When you took out the ACV, did you see the check valve at the hole in the intake manifold?

I took out my ACV to inspect over the weekend. The switch air diaphragm is toast: it's all hardened up by the exhaust gas back pressure because my engine was missing the check valve at the hole on the intake manifold where this port air hole mate to. My S4 part car still has this check valve and the diaphragm on its ACV is still soft. I'm going to switch that diaphragm over and check if the ACV will work. Crossing my fingers that not having the check valve for that long didn't damage my air pump.
Old 03-30-18, 04:15 PM
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Originally Posted by Red95FD
My comment is not helpful but I can't help myself and you can hate me if you want but socialist states(California, Colorado, New York, etc. etc.) suck *** big time and I would never even want to visit them. Ok I'm done.
Actually, your post is quite helpful.
We now know that you don't understand what "socialist" means and don't mind advertising the fact.
Old 03-31-18, 02:47 PM
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Originally Posted by Red95FD
My comment is not helpful but I can't help myself and you can hate me if you want but socialist states(California, Colorado, New York, etc. etc.) suck *** big time and I would never even want to visit them. Ok I'm done.
Originally Posted by clokker
Actually, your post is quite helpful.
We now know that you don't understand what "socialist" means and don't mind advertising the fact.
Also the fact you're a bigot.
Old 04-24-18, 11:07 PM
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I want to give an update. I passed smogg by doing the alcohol trick. I think my acv was not working well so I wired it open to constantly put air in the exhaust instead of dumping it to the atmosphere. Also I have a new magnaflow cat which helped. This all helped me pass.
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Old 04-25-18, 06:37 PM
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Had an emissions issue with my '85 GS about two years ago. Turns out the acv's diaphragm was hard as a rock and not doing it's job. Replaced the acv with a used one having a flexible diaphragm, that solved the issue and was able to pass CA emissions. Forward to now where the car failed due to high oxygen output at the tailpipe aka a "sample dilution failure". The tech stated there must be a leak in the exhaust system or improper engine adjustments, something I'll be investigating including the acv, air pump its connections and hoses. And yes, CA is a pita regarding emission testing!
Old 04-26-18, 07:26 PM
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I think all the diaphragms in the ACV can be rebuilt if you are mechanically inclined.

For the AAV, the crimped top/hat looks intimidating but it can be removed and put back like this:
. Once opened, I think it will be easy to put in a new diaphragm. I think I got a leaking AAV diaphragm and I'll try to replace the torn diaphragm on one of the spare s4 ACVs laying around.

For the Relief and Switching valves, a new rubber diaphragm can be cut and glued on using contact cement but I think it should be shaped/moulded first like this:
. I've actually tried the unshaped/unmoulded diaphragm for the Switching valve but it required too much vacuum to stretch the rubber and to overcome the spring at the same time. I'm using the spare diaphragm for now but will try to mold the rubber and see if it will work.
Old 05-09-18, 07:24 PM
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Drill a small hole prior to the converter and re-test it. The small hole will pull in some air which should help burn off excess HC and CO without bringing up the O2 readings too much
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