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Automatic Transmission - 3 Speed

1st Gear: 2.48
2nd Gear: 1.48
3rd Gear: 1.00

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bogus Failed Smog....UPDATED!!! PASSED SMOG!!!
Grand Imperial Pooh-Bah
San Pedro, CA
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Rather surprising, really...

92 Coupe, LT1 (from a 96), new California legal Magnaflow cats, LTCC.

It ran real lean at 25 MPH. The NoX went nuts... went from 300 and something @ 15 MPH to 650 at 25 MPH.

The Lambda calculator indicates lean.

I am thinking:

1. Bad vacuum to the EGR
2. The air pump, being disconnected, isn't helping
3. Loose O2 sensors
Posted on: 2014/10/10 15:59
Edited by bogus on 2014/10/18 22:34:50
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Matatk Re: Failed Smog....
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Posted on: 2014/10/10 18:03
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BrianCunningham Re: Failed Smog....
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for a second I thought they gave you grief about the LTCC
Posted on: 2014/10/10 23:22
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Schrade Re: Failed Smog....
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eastern NC / e-i-e-i-o
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Quote:

bogus wrote:
Rather surprising, really...

92 Coupe, LT1 (from a 96), new California legal Magnaflow cats, LTCC.

It ran real lean at 25 MPH. The NoX went nuts... went from 300 and something @ 15 MPH to 650 at 25 MPH.

The Lambda calculator indicates lean.

I am thinking:

1. Bad vacuum to the EGR
2. The air pump, being disconnected, isn't helping
3. Loose O2 sensors


Lean burn = hot burn; hi NOx's.

Lean burn could be 'rich' (long pulsewidth), with poor atomization from low fuel pressure, and confused O2 readout...
Posted on: 2014/10/11 2:59
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
San Pedro, CA
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Quote:

BrianCunningham wrote:
for a second I thought they gave you grief about the LTCC


They do... but normally, it passes with flying colours...

I think that my assessment is correct.

I am going to check vacuum to the EGR, then check the fuel pressure... It might be low, if so, that would cause this. I was adjusting down to compensate for the different flow rates of the various injectors... but I don't think I need to do that with these newer style matched injectors.

Also, make sure the air pump is up and running ok.
Posted on: 2014/10/11 15:40
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istter1 Re: Failed Smog....
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Like we in California say welcome DMV loves you. make sure the air pump is up and running.

Posted on: 2014/10/11 18:29
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
San Pedro, CA
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no kidding...

Posted on: 2014/10/11 18:40
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
San Pedro, CA
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ok... checked lotsa stuff, still one more thing to check.

However, the various vacuum lines that feed to the EGR were compromised.

The hard line was fitted to a rubber line, and the rubber line was just big enough to not allow a seal to occur. If I was losing vacuum around that connection, well, gee, by all means, I had a problem!

Posted on: 2014/10/11 22:33
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istter1 Re: Failed Smog....
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Quote:

bogus wrote:
ok... checked lotsa stuff, still one more thing to check.

However, the various vacuum lines that feed to the EGR were compromised.

The hard line was fitted to a rubber line, and the rubber line was just big enough to not allow a seal to occur. If I was losing vacuum around that connection, well, gee, by all means, I had a problem!


Good luck at the retest
Posted on: 2014/10/14 4:04
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Schrade Re: Failed Smog....
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Quote:

bogus wrote:
ok... checked lotsa stuff, still one more thing to check.

However, the various vacuum lines that feed to the EGR were compromised.

The hard line was fitted to a rubber line, and the rubber line was just big enough to not allow a seal to occur. If I was losing vacuum around that connection, well, gee, by all means, I had a problem!



Are you sure that EGR vac supply was 'broken'?

Seems to me that ECM looks for vacuum to hold for x seconds (with EGR solenoid valve closed (or open?) ), and if it doesn't hold for x seconds, then you get a 32 DTC SES, or it comes up as H DTC...

Isn't that how it operates?
Posted on: 2014/10/15 12:39
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
San Pedro, CA
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To a degree, but if the bleed off is so slow, it might not notice...

At the same time, I am going to ramp up the fuel pressure. If that's a touch low, then it will cause a lean condition.

Posted on: 2014/10/15 20:03
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NelsonV Re: Failed Smog....
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Sunny Southern CA
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Codes? Or just failed the sniffer/dyno? I have your scanner in my trunk.
Posted on: 2014/10/16 0:03
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
San Pedro, CA
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that scanner won't help my Vette... It helps the suburban... thanks, tho.

no codes, just a rise in NoX and a failed test.

Posted on: 2014/10/16 1:11
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Schrade Re: Failed Smog....
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Quote:

bogus wrote:
To a degree, but if the bleed off is so slow, it might not notice...

At the same time, I am going to ramp up the fuel pressure. If that's a touch low, then it will cause a lean condition.



Maybe before adjusting fuel pressure (you have adjustable FPR?) , note that ANY vac leak will affect stock FPR response to fuel pressure.

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Fuel pressure is critical to get good atomization...
Posted on: 2014/10/16 12:46
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
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That's my next test... and yes, I have an AFPR, with a dedicated gauge on the fuel rail.

Posted on: 2014/10/16 15:58
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BrianCunningham Re: Failed Smog....
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Posted on: 2014/10/16 20:16
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/
383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes
NCCC Governor: http://BayStateCorvetteClub.com
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
San Pedro, CA
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I have "new" magnaflows... under 2 years old, 15k miles, CA OBDII compliant. They better work...
Posted on: 2014/10/16 23:44
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istter1 Re: Failed Smog....
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Bakersfield Ca
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I am curious to see how the new Exhaust system with one less cat works. in California. We have crazy rules/87 has
two pre cats and the third that collects garbage. The California cat tax stamp is a joke. If your smog guy can't pass it just drive up north Andy and see my smog guy
Posted on: 2014/10/17 3:14
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
San Pedro, CA
20856 Posts
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Oh, I will pass... no question about that!

The LT1, LT4 and LT5 have one cat on each bank.

I hate the L98 setup...
Posted on: 2014/10/17 5:47
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Education is the best tool to overcome irrational fear. - me

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Matatk Re: Failed Smog....
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Quote:

bogus wrote:
That's my next test... and yes, I have an AFPR, with a dedicated gauge on the fuel rail.



Double check that gauge. I had one that was 8 psi low and it was driving me nuts trying to troubleshoot the problem when it was the gauge all along.
Posted on: 2014/10/17 11:43
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc.
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bogus Re: Failed Smog....
Grand Imperial Pooh-Bah
San Pedro, CA
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it passed. Very nicely.

I am pretty sure it was the vacuum line, if nothing else, it was introducing more air into th intake.

Posted on: 2014/10/18 20:26
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istter1 Re: Failed Smog....
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Bakersfield Ca
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Quote:

bogus wrote:
it passed. Very nicely.

I am pretty sure it was the vacuum line, if nothing else, it was introducing more air into th intake.



Well done Andy
Posted on: 2014/10/19 1:04
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Carol Burnett
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bogus Re: Failed Smog....UPDATED!!! PASSED SMOG!!!
Grand Imperial Pooh-Bah
San Pedro, CA
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thanks!

Can't over think this stuff, ya know?

Posted on: 2014/10/20 16:31
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