How to Pass Smog

[Yota4life]

ok i hooked the gauge up to the little vacuum line going from the modulator to the EGR and i was only getting about 1 in. of vacuum at 2500 rpm and once i hit 3000rpm it shot up to 5 in. The pressure coming from the bigger tube on the egr was like nothing. Iv never done this before but i think i was doing it right lol

[emsvitil]

You're tapping into the exhaust, so you want pressure not a vacuum.

You need to see at least a 1/2 PSI.      With 2 PSI you'll definitely have EGR working.

[Yota4life]

You're tapping into the exhaust, so you want pressure not a vacuum.

You need to see at least a 1/2 PSI.      With 2 PSI you'll definitely have EGR working.

Ok ill check it right now. But is 1 inch of vacuum enough to engage the egr? might mean the modulator isnt working properly

[emsvitil]

Don't think 1" is enough for the little hoses.

But if backpressure isn't pushing the diaphragm up,  the vacuum is vented to atomsphere.

Article 61
http://www.autoshop101.com/

[Yota4life]

Ok i just took the truck around the block and when i was cruising at 25mph (2500rpm) there was zero backpressure. If i really got on it once i hit 3000 rpm it was like 1psi then 4000rpm was almost 3psi. But if i wasent hard on the throttle i was hardly getting any pressure not even 0.5psi. The egr must not of even been working when the smog test was ran. And same goes for the modulator not enough vacuum

Im running a tri-y header to 2.25" exhaust all the way with a plate at the collector. must need a smaller hole in the plate and move it behind the cat.

[emsvitil]

Here's my plate:

[Yota4life]

Thanks for all the help by the way. What size holes are those? I have an iron worker at work so i can make one of those quick

[emsvitil]

Thanks for all the help by the way. What size holes are those? I have an iron worker at work so i can make one of those quick

1/4" from a sheet-metal punch

[Yota4life]

If i did the math right that will be more restrictive then the 1.25" hole i put in mine.

[emsvitil]

If i did the math right that will be more restrictive then the 1.25" hole i put in mine.

Just a bit.......

Multiple smaller holes may cause more backpressure than 1 of equivalent area....

[Yota4life]

True. 19 1/4" holes is equal to 15/16 square inches and a 1.25 hole is equal to 1.22 square inches. Should i flip my cat around also? or i can spend 100bucks on a CA legal cat. i couldnt find any info on the internet about the cat i have being Directional.

Edit: maybe i need to check the cylinder compression. It should be really good but it could also be part of the problem

[emsvitil]

I'd flip the cat.

I'd also see about putting the restriction after the cat.   (that's what's working for me)

[emsvitil]

Thinking about this, I think having the restriction after the cat may be the key............

The restriction would keep more exhaust gas inside the cat.      Having more exhaust gas may enable it to work better (and stay hotter too).     

If the exhaust gas is stuck inside for a longer period of time, the catalyst may get a chance to work for the NOX

[Yota4life]

Thinking about this, I think having the restriction after the cat may be the key............

The restriction would keep more exhaust gas inside the cat.      Having more exhaust gas may enable it to work better (and stay hotter too).     

If the exhaust gas is stuck inside for a longer period of time, the catalyst may get a chance to work for the NOX

I was thinking that also. Im going to flip my cat and put the restrictor behind it. I was also thinking about how if i had 35" tires instead of 37s the rpms would be higher at 25mph so the egr would engage... or i can just find a better smog guy that will run it in a different gear

[emsvitil]

My last test was at

1649 and 2579 rpm for 15 and 25mph.    So the rpms sound right.

What was the HC?

[emsvitil]

And the 25mph test is lighter load than 15   (25% vs 50% load)

[Yota4life]

The HC was 38 (at 15mph) and 19 (25mph) So pretty low considering the max is over 100

[Yota4life]

Also i was looking at the vehicles the cat i have is made for and they are all 5-6 liter engines. Way bigger and also its usually a secondary cat on the exhaust so i just need to buy the correct one an im sure it will pass then..  Im just gonna go for it im tired of screwin around with this an i have a lot of snow wheelin to do

[emsvitil]

Other than being in backwards possibly doing something, I don't think the converter is the problem.

Mine's basically the same:

http://www.jegs.com/i/Dynomax/289/15032/10002/-1#

[Yota4life]

We will see after the next test, i will report back

[Yota4life]

So i emailed Magnaflow, and they checked the drawings on the specific cat i have on right now and its non directional.  i can now eliminate that one... Its just not enouph for my motor. Because iv read people getting sky high nox readings then putting the correct cat on and getting a nox reading of around a 100 after

[emsvitil]

I'd hate to see you get a new converter and get the same results.

I really think having the restriction after the converter is the key............

I had been squeaking by on the NOX at 25 before the last test  (about the same as your last test, but mines an 86 so I was allowed more).     
HC and CO always passed.



Unfortunately I don't know if it was the restriction or a new converter on my last test (previous one broke up inside).       


Test results  (max/measured)

2005, 15;      HC 146/86           CO 1.04/0.04       NOX  1136/892
         25;           118/57                 1.32/0.05                 1222/744

2007, 15;            146/119              1.04/0.07               1136/769
          25;            118/87                1.32/0.09               1222/1176

2009, 15;             146/19               1.04/0.00               1136/325
          25;            118/14                1.32/0.00               1222/88

[Yota4life]

im going to have it set up correctly, hopefully i get a low nox like you did.

[Yota4life]

So i got my new cat today and heres the difference. New CA legal cat on the right.

[Yota4life]

Got the new cat nice and hot and had it smogged for the 3rd time today. It ran 0 nox at 15mph and 698 at 25mph. I passed!!! Im stoked

[emsvitil]

Now take it off and save it for next time..........


Did you put a restricter gasket behind it?

[Yota4life]

Yeah i did and after checking the egr modulator i dont think it was even working correctly but i still got by....

[z 12]

hey guy worry about smog i got the connection it cost you more but you will pass for sure

[Yota4life]

hey guy worry about smog i got the connection it cost you more but you will pass for sure

Wheres this? I managed to pass it already.... But my buddy cant get his too pass

[kneedownnate]

Nevermind, not worth commenting on