94T/A5.7LT1

iTrader: (1)

Anyone else have to replace one from failed smog test? The guy said it was either the valve my cat. Just wondering what would be more likely the cause since neither of them is a cheap fix. Thanks

RamAir95TA

iTrader: (2)

Depends on what portion of the emissions test you failed. A faulty (or lack of) EGR system causes elevated levels of NOx.

djjab57

iTrader: (17)

EGR valve is $52 at AZ

94T/A5.7LT1

iTrader: (1)

The NO2 part is then one that failed, past the rest with no problem.

djjab57

iTrader: (17)

Have you ever Seafoamed the car ? It will clean up the vacuum lines ad EGR system

Transamthunder

Maybe stuck, pull the egr valve off the back of your intake, it is 2 thirteen mm bolts, and stick in a small screwdriver, maybe some passagesw are blocked withb soot, then take the tube off right next to it as it comes up the exhaust manifold to the back of the intake, and check your passages on the back of the intake too for any carbon. It sounds like it is closed if your nx levelsb are to high, also check the seliniod to make sure the vaccum action is working, I am pretty sure it is run off the computer. I had the same prob too about 3 years ago too so I had to go through all the same stuff. Short hopes don't get everything burned off like a good long everyday drive does.

94T/A5.7LT1

iTrader: (1)

I just replaced it. I know when I shook the old one it sounded like dirt was in the diaphragm area where the vacuum line hooks too

letsrun97z

iTrader: (7)

Hopefully it's just that. I need a passenger cat and the direct replacement is 456 and the weld in is 300. I hate Cali smog for the price of two cats I could have a real nice SS longtube set up

94T/A5.7LT1

iTrader: (1)

Got the car smoged today with the new egr valve. According to the smog tech it was better but it still failed the 15mph test but passed the 25mph test. Looking at previous smog checks in 2006 & 2008 my car roughly put out the same amount of NO (PPM) amounts that it did today.

in 2008 (Bone stock)

15mph Max 689 Ave 150 Meas 576 pass
25mph Max 706 Ave 136 Meas 530 pass

In 2010 (See sig, ls1 lid replaced with factory+ New EGR valve)

15mph Max 483 Ave 268 Meas 589 Fail
25mph Max 494 Ave 250 Meas 471 Pass

Because California Lowered their emissions it seems that my car would never pass smog bone stock or not and spent 100 bucks for a new valve that wasnt the problem.

djjab57

iTrader: (17)

I haven't tried it but have friends that have, But the parts store sells the stuff you put in your tank that lowers the emissions. Might try that seeing that it is real close, I just cant remember the name of it right now

94T/A5.7LT1

iTrader: (1)

I did the EGR test where if you open the valve the car bogs down. Now I just need to check if A) the silinoid isn't opening the valve B) I'm not getting enough vacuum to control the silinoid or C) it's actually my cat that isn't doing it's job.

flame

iTrader: (13)

The standards here in Ontario are tighter than that on Nox my limit is 420. I see a pcmforless tune in your sig. If they raised the timing that will increase Nox.

94T/A5.7LT1

iTrader: (1)

I didn't think it could be that since I wouldn't have passed anyways when I was stock from the readings I posted. But it's a possibility, thanks

Transamthunder

I wasn't able to see the sig since I am on a mobile app. That might open another can of worms.

94T/A5.7LT1

iTrader: (1)

okay yesterday the guy told me to come back since his technician (if you want to call him that, I wouldnt) would be there. puts it on the dyno again to test it, fail yet again but this time it seems its getting worst. to make this better the so called tech said that he doesnt know why its doing it but to take it to a place to get fixed then bring it back. Now since it could be my tuned computer can a company like pcmforless or someone tune a car computer so it will pass emissions with flying colors?

94T/A5.7LT1

iTrader: (1)

Another not with the tune was the rad fans kick on sooner so even with the 180* thermostat the car will go no higher then 175* no matter what.

94T/A5.7LT1

iTrader: (1)

I tested my old egr and the new. The old one was bad as the vacuum pump couldn't open it. So question is what could the egr valve mess up from not working properly?

Low N Slow

iTrader: (4)

I would try getting it up to temp somehow and retest it. I think the main reason the stock program didn't turn the fans on until 225* was to pass emissions.

flame

iTrader: (13)

Nox will go up with higher temps

Spartan7

iTrader: (7)

I doubt it's the tune. I just passed smog easily with a PCMforless tune, and my car runs at 175* all day (engine is stock).