Emission question

Simpson3344 · Apr 6, 2023

I got a 1996 2dr Tahoe, previous owner put short tube headers and duals with glass packs, got rid of the cats. My question is if I was still able to pass emissions, i only have a check engine light for the back o2 sensors which I’m going to replace but i don’t know if I should run a fouler or just let it go. Thank you

PlayingWithTBI · Apr 6, 2023

Simpson3344 said:
My question is if I was still able to pass emissions, i only have a check engine light for the back o2 sensors which I’m going to replace but i don’t know if I should run a fouler or just let it go.

Don't they do a visual in Illinois when you go in for Emissions testing? It's a Federal law forbiding removal of emission control equipment. If you have an SES light you'll automatically fail too.

Simpson3344 · Apr 6, 2023

Where I live at, no there is no visual inspection.

PlayingWithTBI · Apr 6, 2023

Simpson3344 said:
Where I live at, no there is no visual inspection.

I'm not talking about a safety inspection.

As an example, here in Maricopa County, AZ, they walk around the vehicle with a mirror on a stick to verify the required cat(s) are installed. Then they plug in to the OBDII port to look for any codes. For OBDI vehicles they do the dyno test with the sniffer stuck up your pipe.

Do they do any testing where you are?

Simpson3344 · Apr 6, 2023

where I live at all they do is check for codes from the OBD port.

PlayingWithTBI · Apr 6, 2023

Simpson3344 said:
where I live at all they do is check for codes from the OBD port.

OK, then you need to address your downstream O2 codes.

I'll bet a dollar to a doughnut when they hear you drive up, they'll look at what's making all that noise.

Personally, I wouldn't chance it. Put cat(s) on it which will help cure your codes too.

fancyTBI · Apr 6, 2023

Simpson3344 said:
where I live at all they do is check for codes from the OBD port.

Must be in Cook County or surrounding area?

Simpson3344 · Apr 6, 2023

You are correct sir.

1998_K1500_Sub · Apr 6, 2023

fancyTBI said:
Must be in Cook County or surrounding area?

In IL near StL area they "test" too... just as an FYI for anyone who is taking notes.

IL from my experience just reads the ECU and looks for anomalies, AFAIK.

As noted earlier, an obvious modification (exhaust note) might trigger more scrutiny... YMMV.

Has anyone ever side-stepped these checks via ECU mod/tune, e.g., so no "anomalies" like missing rear cats are reported as such, for 1996 or other later years?

1996-7 can be tuned with JET's DST; later years have additional options.

Supercharged111 · Apr 6, 2023

1998_K1500_Sub said:
In IL near StL area they "test" too... just as an FYI for anyone who is taking notes.

IL from my experience just reads the ECU and looks for anomalies, AFAIK.

As noted earlier, an obvious modification (exhaust note) might trigger more scrutiny... YMMV.

Has anyone ever side-stepped these checks via ECU mod/tune, e.g., so no "anomalies" like missing rear cats are reported as such, for 1996 or other later years?

1996-7 can be tuned with JET's DST; later years have additional options.

If the rear O2s have a test they're supposed to pass with the PCM, then you'll likely fail because that test can't pass.

Emission question

Simpson3344

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PlayingWithTBI

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Simpson3344

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PlayingWithTBI

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