Another LT Headers and CEL for Emissions

[kauffjd3]

I have been doing a lot of reading and searching for information about long tube headers and the CEL. From my research it looks like you can not get around it unless you disable the rear 2 sensors behind the cats with a tune. (congrats to the guys who don't have the cel)

Seems like some are getting a tune and some are just driving it with the CEL. Now comes the question.

I can live with the CEL until I get all my mods on and get it tuned, but the emissions station will fail me in the mean time.

Is it possible to get a code reader and clear the codes right before going into emissions so that the CEL isn't on? Do you think it will stay off long enough to pass?

What is everyone's thoughts on this and experiences?

[R1Ecko]

You can clear the codes but I dont think they would be gone long enough to complete the testing without coming back on. I tried to do a battery disconnect on my old Ranger due to a bad 02 sensor and it came back on pretty quick, quick enough for the inspection guy to give me a "really, guy" look and me to

[zepcom]

The problem here is with "Emissions Readiness Monitors".



If you clear your codes (aka, flash or reset your ECM) just before getting your inspection, you'll still fail.

Emissions readiness monitors were implemented just prior to ODB2 standardization in 1996. It all started due to people simply unplugging the bulb that lit up the CEL light on the dash and passing inspection. Later on, people had found that if you flash the computer just before going in, your CEL would go away, and as long as your inspection station didn't drive your car 100 miles (when the CEL would go back on, still noticing a problem) then you'd still pass.

The readiness monitors are timers that require varied driving styles, speeds, and duty cycles. It's not like "30 miles later, all your readiness monitors will be ready" ... they do a more thorough check of the O2 sensors and other evap and emissions testing during both closed loop and open loop scenarios, over several hundreds of miles. Readiness monitors have 3 modes... "ready", "not ready" and "fail". The fails usually also result in a DTC being set and the CEL light being illuminated.

The only way to get rid of it and legally pass inspection is either:

• remove your headers for the inspection, re-install afterward.
• Tune the car to not look at the rear o2 sensors. This would reset those readiness sensors to "ready" since they would no longer be included in the loop of what the readiness sensor is designed to do.

Sorry to say it, but that's the way it is. Good luck working to resolve this. I just thought I'd save you the headache and expense of resetting the ECM just prior to getting your inspection, only to find you default/failed because none of your readiness monitors were in the ready state yet. Now you have usually 10 days to make it right or they pull your existing inspection sticker and you can't drive the car. At least this is how it is in most states, from what I remember.

Hope this helps...

--zepcom

[caverman]

Originally Posted by zepcom

The problem here is with "Emissions Readiness Monitors".



If you clear your codes (aka, flash or reset your ECM) just before getting your inspection, you'll still fail.

Emissions readiness monitors were implemented just prior to ODB2 standardization in 1996. It all started due to people simply unplugging the bulb that lit up the CEL light on the dash and passing inspection. Later on, people had found that if you flash the computer just before going in, your CEL would go away, and as long as your inspection station didn't drive your car 100 miles (when the CEL would go back on, still noticing a problem) then you'd still pass.

The readiness monitors are timers that require varied driving styles, speeds, and duty cycles. It's not like "30 miles later, all your readiness monitors will be ready" ... they do a more thorough check of the O2 sensors and other evap and emissions testing during both closed loop and open loop scenarios, over several hundreds of miles. Readiness monitors have 3 modes... "ready", "not ready" and "fail". The fails usually also result in a DTC being set and the CEL light being illuminated.

The only way to get rid of it and legally pass inspection is either:

• remove your headers for the inspection, re-install afterward.
• Tune the car to not look at the rear o2 sensors. This would reset those readiness sensors to "ready" since they would no longer be included in the loop of what the readiness sensor is designed to do.

Sorry to say it, but that's the way it is. Good luck working to resolve this. I just thought I'd save you the headache and expense of resetting the ECM just prior to getting your inspection, only to find you default/failed because none of your readiness monitors were in the ready state yet. Now you have usually 10 days to make it right or they pull your existing inspection sticker and you can't drive the car. At least this is how it is in most states, from what I remember.

Hope this helps...

--zepcom

Nice info to know.

I said WTF...and tuned the car with the header install. Only about 3.5k miles on it at the time.

[Riderover40]

Originally Posted by kauffjd3

I have been doing a lot of reading and searching for information about long tube headers and the CEL. From my research it looks like you can not get around it unless you disable the rear 2 sensors behind the cats with a tune. (congrats to the guys who don't have the cel)

Seems like some are getting a tune and some are just driving it with the CEL. Now comes the question.

I can live with the CEL until I get all my mods on and get it tuned, but the emissions station will fail me in the mean time.

Is it possible to get a code reader and clear the codes right before going into emissions so that the CEL isn't on? Do you think it will stay off long enough to pass?

What is everyone's thoughts on this and experiences?

I drove until the CEL's stayed lit permanently then got a tune that fixed. The tune either disabled the rear sensors or the tune changed the timing of the smapling rate or something..... Anyway the tune worked!

[Bee]

Hey kauffjd3..

I was in the same position as you were…where I wanted SLP long tubes but wasn’t ready to have my car tuned…and certainly did not want to have a CEL come on prior to running an emissions test. After doing a little research, I came across a few threads that presented a third, and very viable option.

In my own experience, since installing the long tube headers with the spark plug foulers on the rear O2 sensor, driving over 4000 miles, and going through one PA emission test, I still have not had any CEL’s Check out this thread for more info:

http://www.camaro5.com/forums/showth...rk+plug+fouler

[kauffjd3]

Originally Posted by Bee

Hey kauffjd3..

I was in the same position as you were…where I wanted SLP long tubes but wasn’t ready to have my car tuned…and certainly did not want to have a CEL come on prior to running an emissions test. After doing a little research, I came across a few threads that presented a third, and very viable option.

In my own experience, since installing the long tube headers with the spark plug foulers on the rear O2 sensor, driving over 4000 miles, and going through one PA emission test, I still have not had any CEL’s Check out this thread for more info:

http://www.camaro5.com/forums/showth...rk+plug+fouler

Thanks Bee! I knew someone had to be in the same boat that I'm in. PM sent.

[BowlingSS]

You can program the PCM so the "Emissions Readiness Monitors" show OK at least you can on a 4th gen PCM. You do need EFILive or HP Tuner to do it.

Bill