Help with ca emissions 1999 gc Laredo 4.0 - JeepForum.com
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post #1 of 5 Old 05-23-2020, 01:06 PM Thread Starter
Rowdykev9395
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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.

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post #2 of 5 Old 05-23-2020, 01:56 PM
coldspit47
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Quote:
Originally Posted by Rowdykev9395 View Post
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.
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post #3 of 5 Old 05-24-2020, 03:47 AM
Bigrigr
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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....

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post #4 of 5 Old 05-24-2020, 07:20 AM
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Quote:
Originally Posted by Bigrigr View Post
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.
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post #5 of 5 Old Yesterday, 01:18 AM
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Originally Posted by Waterluvr View Post
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....
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