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Discussion Starter · #1 ·
My car is 2005 with 64k miles.

A few weeks after I bought the car (39k miles) I gutted the precats. Shortly after that I switched to the PPE header/catless DP setup, with the single o2 sensor splice.

Smog Test time: switched back to stock Gutted manifold, stock cat & stock exhaust. With car still running off the single o2 splice.

Ended up failing the HC portion on the Emissions test by just a little.

Meanwhile the car still has AEM CAI ( I have paperwork with C.A.R.B legal #)

MY QUESTION- do I need to re-wire so the car runs off both O2sensors or do I need to put the stock air box back on?? Or both??

Feedback much appreciated... THANKS
 

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My main cat was not strong enough, had to have the precat on but mine was a 2001. Oxygen sensors shouldn't change the hc but i can't confirm that.
 

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I also didn't pass when I tried with a gutted manifold, and yes the car was hot. Maybe when these cars/main cats were newer you could get away with that. You can pry my precat manifold during smog time from my cold dead hands.
 

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Discussion Starter · #5 ·
was your cat HOT? from what I hear you gotta take the car for a drive, make sure its smogged when the cat is nice and hot, dont let it sit for too long, ect.
The car was hot. Then it sat on the rollers Ideling for a good ten min before we tested it, so I'm sure the cat was good & heated up
 

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switched back to stock Gutted manifold, stock cat & stock exhaust. With car still running off the single o2 splice.
How many Cylinders is the Single O2 Sniffing?..

If it's only Two, and the Fuel Injectors are dirty at all, then this could be your problem..

Cap
 

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Discussion Starter · #9 ·
How many Cylinders is the Single O2 Sniffing?..

If it's only Two, and the Fuel Injectors are dirty at all, then this could be your problem..

Cap
Sniffing 2 cylinders. Still running on the wiring I made (per your recommendation) to run on the PPE testpipe setup.

Do I need to wire it to use both sensors??

Sending out injectors for cleaning at 64k miles, would that also be a good idea for the near future?
 

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Sniffing 2 cylinders.
Need four Cylinders Sniffed..

You can pull the 'Passive Side' plug ( the one that uses the Resistor for the Heater load ), and just screw in a Normal Sensor for that side.. leave the 'Split Sensor Wires' only feeding one side..

Clean injectors are always a plus..

Cap
 

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How did you get on? I was about to remove my precats, but this is a bit unnerving, given I have a 2001 and want to retain the stock manifold. My next smog test is not until 2013, so I'm guessing the new computer-based smog testing will be in place by then - I wonder how that would change things, compared to the existing tailpipe reading?
 

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How did you get on? I was about to remove my precats, but this is a bit unnerving, given I have a 2001 and want to retain the stock manifold. My next smog test is not until 2013, so I'm guessing the new computer-based smog testing will be in place by then - I wonder how that would change things, compared to the existing tailpipe reading?
I think it is more unnerving that at anytime your engine could go out due to precat failure.
 

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Discussion Starter · #16 ·
The time has come for me to smog the car, again. The car failed, AGAIN.

For the past two years I've run AEM intake with PPE header, catless mid pipe & Magnaflow muffler. All the while rigged to run off one o2 sensor. 2 years car runs great, not a single code thrown.

Yesterday: switched back to stock (gutted) manifold, stock cat & stock muffler. Rewired o2 sensors to get them both working. Still on aem intake. (FYI this is the same exact setup I passed with 2 years ago)

Today when I failed the guy said "the cars computer is not reading right."

When I switched back to stock exhaust I disconnected the battery to reset computer.

My QUESTION, after switching back to stock exhaust does the car need to be run for a while to get the ECU happy again?? Like 100 miles or a day or two??...

Your thoughts appreciated..
 

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The time has come for me to smog the car, again. The car failed, AGAIN.

For the past two years I've run AEM intake with PPE header, catless mid pipe & Magnaflow muffler. All the while rigged to run off one o2 sensor. 2 years car runs great, not a single code thrown.

Yesterday: switched back to stock (gutted) manifold, stock cat & stock muffler. Rewired o2 sensors to get them both working. Still on aem intake. (FYI this is the same exact setup I passed with 2 years ago)

Today when I failed the guy said "the cars computer is not reading right."

When I switched back to stock exhaust I disconnected the battery to reset computer.

My QUESTION, after switching back to stock exhaust does the car need to be run for a while to get the ECU happy again?? Like 100 miles or a day or two??...

Your thoughts appreciated..
Yes. You need to drive it. I drove mine to wildomar and back to get the sensors ready. 100 miles should do it.
 
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