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Rowdykev9395 05-23-2020 01:06 PM

Help with ca emissions 1999 gc Laredo 4.0
 
need to delete the y pipe on my 1999 grand cherokee Laredo 4.0
My factory exhaust manifold has two flanges that go into a y pipe/downpipe Each flange has what looks to be a pre cat. Each with an 02 sensor. I got a blackhorse racing header I want to install but it only has one flange to downpipe. What's the best way to delete the y pipe and retain both o2 sensors and minus the one cat on bank 2.

coldspit47 05-23-2020 01:56 PM

Quote:

Originally Posted by Rowdykev9395 (Post 40971357)
need to delete the y pipe on my 1999 grand cherokee Laredo 4.0
My factory exhaust manifold has two flanges that go into a y pipe/downpipe Each flange has what looks to be a pre cat. Each with an 02 sensor. I got a blackhorse racing header I want to install but it only has one flange to downpipe. What's the best way to delete the y pipe and retain both o2 sensors and minus the one cat on bank 2.

Technically under Federal law you can't...tampering with any factory installed emission system is a no no. Logistically it does't work either - the O2 has to have different readings up and downstream, so you couldn't keep them without installing some other sort of cat. After a quick Google search, I found Blackhorse has a 6>2 setup though, with O2 bungs, for $5 more than the 6>2>1, it's just currently out of stock. Banks TorqueTube and Thorley's also have setups that work with WJ 4.0, but for significantly more coin. Been eyeing the Thorley's for a while now.

Bigrigr 05-24-2020 03:47 AM

X2 above...


However.....I owned a '99 with a 4.0l engine very briefly here recently, and I noticed while doing the Vari-lok axle swaps, that it had two o2 sensors in the manifold that were unhooked. I am not sure if it was CA emissions or not, and i didnt spend more than 30secs brain power on why they were left dangling, but i know it did NOT have a check engine light on, and it ran perfectly. I'm still curious how though....

Waterluvr 05-24-2020 07:20 AM

Quote:

Originally Posted by Bigrigr (Post 40971833)
X2 above...


However.....I owned a '99 with a 4.0l engine very briefly here recently, and I noticed while doing the Vari-lok axle swaps, that it had two o2 sensors in the manifold that were unhooked. I am not sure if it was CA emissions or not, and i didnt spend more than 30secs brain power on why they were left dangling, but i know it did NOT have a check engine light on, and it ran perfectly. I'm still curious how though....

You make some changes to the electronics and they aren't looking for the extra two O2 sensors any longer and everything under the hood runs right.

I might know a guy that can do that and also makes custom exhaust for the off road guys that like to play on the rocks and in the mud.

Bigrigr 05-27-2020 01:18 AM

Quote:

Originally Posted by Waterluvr (Post 40971943)
You make some changes to the electronics and they aren't looking for the extra two O2 sensors any longer and everything under the hood runs right.

I might know a guy that can do that and also makes custom exhaust for the off road guys that like to play on the rocks and in the mud.


Ha Ha, I bet you do know a guy....

MuloChico 05-28-2020 01:06 PM

Quote:

Originally Posted by Rowdykev9395 (Post 40971357)
need to delete the y pipe on my 1999 grand cherokee Laredo 4.0
My factory exhaust manifold has two flanges that go into a y pipe/downpipe Each flange has what looks to be a pre cat. Each with an 02 sensor. I got a blackhorse racing header I want to install but it only has one flange to downpipe. What's the best way to delete the y pipe and retain both o2 sensors and minus the one cat on bank 2.

To pass CA emissions any aftermarket Intake/Exhaust has to have a CARB #. If it doesn't a reputable shop will not pass it. Some systems are great just the manufacturer didn't go thru the certification process (and $) to make it CA legal. That's why we can't do the Holley carburetor swap on my son's Wrangler, they never got the certification and CARB #.

DJCantonGA 05-28-2020 06:52 PM

Quote:

Originally Posted by MuloChico (Post 40976823)
To pass CA emissions any aftermarket Intake/Exhaust has to have a CARB #. If it doesn't a reputable shop will not pass it. Some systems are great just the manufacturer didn't go thru the certification process (and $) to make it CA legal. That's why we can't do the Holley carburetor swap on my son's Wrangler, they never got the certification and CARB #.

Not to hijack, but I live in GA, and my WJ has CA emissions. If I replace the precats, do I have to buy the CARB compliant ones or can I just get the less expensive Fed/EPA precats? Mine are still good, but I have wondered about it.

coldspit47 05-28-2020 08:08 PM

Quote:

Originally Posted by DJCantonGA (Post 40977101)
Not to hijack, but I live in GA, and my WJ has CA emissions. If I replace the precats, do I have to buy the CARB compliant ones or can I just get the less expensive Fed/EPA precats? Mine are still good, but I have wondered about it.

No need for CARB unless you live in CA/NY/whichever other states have adopted the model. You will need ones which fit a CA model, however. On the 4.0, non-CARB y-pipe to fit a 50 state vehicle runs about $500-600 last I checked.

DJCantonGA 05-28-2020 08:36 PM

Quote:

Originally Posted by coldspit47 (Post 40977147)
No need for CARB unless you live in CA/NY/whichever other states have adopted the model. You will need ones which fit a CA model, however. On the 4.0, non-CARB y-pipe to fit a 50 state vehicle runs about $500-600 last I checked.

Thanks, I appreciate the reply.


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