The dreaded y pipe. Mocha sho

[cali+Mocasho+]

so I bought a 91 sho with 125k for cheap. Runs great after all I've done to it. Spark plugs,wires,egr valve,egr electronic controller, hoses, fuel filter,valve cover,thermostat, thermostat temperature sender and sensor. I have a ways to go before I can say I'm half way done. Suspension,bushings.ect.
Anyways to the point! I'm at a point where I can not pass smog for the life of me,effing Cali emission regulations. So I've done everything but the cats and I have an idea the driver side cat isn't functioning properly. figured that because of how hot the rear of the cat was. So where can I buy a new y pipe? And witch would be best? Opinions and questions are welcomed

 

[SHOdded]

Isn't CA a visual check state? Hopefully they will let aftermarket cats pass, since OEM would be RARE if not impossible. You can get Y pipes new here:
http://www.shosource.com/catalog/product_info.php?products_id=52 (pick CA option)
http://rcmautomotive.com/id12.html (pick CA option)

Or put up an ad in the Wanted to Buy section to get a good used Y Pipe.

Use new gaskets & bolts wherever possible.

As to WHY the cat got killed in the first place ... Did you pull any codes? Prior to the work you did, did the car have a hard time starting? Any odor of fuel out the exhaust? Could be simple age also.

Putting in new O2s would also be a good idea with the Y pipe. You can check the existing ones (see youtube videos) with a blowtorch, but if you are taking them out anyway ...

 

[cali+Mocasho+]

Isn't CA a visual check state? Hopefully they will let aftermarket cats pass, since OEM would be RARE if not impossible. You can get Y pipes new here:
http://www.shosource.com/catalog/product_info.php?products_id=52 (pick CA option)
http://rcmautomotive.com/id12.html (pick CA option)

Or put up an ad in the Wanted to Buy section to get a good used Y Pipe.

Use new gaskets & bolts wherever possible.

As to WHY the cat got killed in the first place ... Did you pull any codes? Prior to the work you did, did the car have a hard time starting? Any odor of fuel out the exhaust? Could be simple age also.

Putting in new O2s would also be a good idea with the Y pipe. You can check the existing ones (see youtube videos) with a blowtorch, but if you are taking them out anyway ...

I've done both 02s already. Also the car ran really good for how long it was sitting. I suspect it was the thermostat geting stuck in the open position witch caused the car to run rich and **** the cat. Not to mention when I was doing the tune up it still had stock Motos in the back and some autolights in the front. This baby runs great after what I've done .just need to do that y pipe I'm good. Can't wait to get to suspension .

 

[cali+Mocasho+]

Isn't CA a visual check state? Hopefully they will let aftermarket cats pass, since OEM would be RARE if not impossible. You can get Y pipes new here:
http://www.shosource.com/catalog/product_info.php?products_id=52 (pick CA option)
http://rcmautomotive.com/id12.html (pick CA option)

Or put up an ad in the Wanted to Buy section to get a good used Y Pipe.

Use new gaskets & bolts wherever possible.

As to WHY the cat got killed in the first place ... Did you pull any codes? Prior to the work you did, did the car have a hard time starting? Any odor of fuel out the exhaust? Could be simple age also.

Putting in new O2s would also be a good idea with the Y pipe. You can check the existing ones (see youtube videos) with a blowtorch, but if you are taking them out anyway ...

Thanks I appreciate it.

 

[sdpatt]

Which emissions component is causing the test to fail? If it is HC, then you have to correct the problem that is causing incomplete combustion of the fuel. If it is the NOx being too high, which I suspect is the problem, that is the job of the EGR system, which you stated in your original post that you fixed.

Another way to lower the NOx number is to pull the rectangular, gray SPOUT plug near the CID sensor. This limits spark advance to the base 10° BTDC, reducing the combustion temperatures that create the NOx molecules.

This will severely limit the power, but may allow the 80's vintage engine and emissions control systems to meet modern emissions limits. Reinstall the SPOUT plug after driving away from the test location to once again enjoy the SHO.

My 25-year old 1991 is now considered a classic automobile in Texas and no longer has to run the dyno portion of the test.

If you do find that one (or both) cat is bad, just have a good exhaust system shop replace the cat. Find one that does MIG or TIG welding for a cleaner weld seam. I have had several cats replaced over the years for much less expense and effort than swapping Y-pipes. They have installed the "Mustang" versions with 2" i.d. piping for less flow restriction.

 

[sperold]

A well priced cat system is $250.00, Eastern Catalytic Converters from RockAuto, if you are not testing in NY or CA.

I have the California approved system, and following is a description of what one looks like.

In the very center of each converter, in 1/8" high letters stamped into the metal (not the heat shield) is the following:
CA/CE 53005
12/06 57782
These are Magnaflow converters and the 11/06 is the date of manufacture (month/year) (I think) and mine have different dates on each converter, but close in time.
The 53005 and the 67782 numbers are fainter and look more professional; while the CA/CE and the date 12/06 (month/year) are heavier stamped, but still quite neatly done. The box that the converter came in had 53005 CA on the end, so I think that the 53005 is the distinguishing number that makes it compliant.

Hope that helps you identify one if buying used.

When my area had the dynomometer testing, it was difficult to get a pass. Mine passed with the Eastern Catalytic Converters.
We now use a "2 speed Idle Tailpipe Emission" test with no dynomometer, and it is never a worry if it will pass now. I don't even change the air filter.

 

[1993MTXSHO]

A well priced cat system is $250.00, Eastern Catalytic Converters from RockAuto, if you are not testing in NY or CA.

I have the California approved system, and following is a description of what one looks like.

In the very center of each converter, in 1/8" high letters stamped into the metal (not the heat shield) is the following:
CA/CE 53005
12/06 57782
These are Magnaflow converters and the 11/06 is the date of manufacture (month/year) (I think) and mine have different dates on each converter, but close in time.
The 53005 and the 67782 numbers are fainter and look more professional; while the CA/CE and the date 12/06 (month/year) are heavier stamped, but still quite neatly done. The box that the converter came in had 53005 CA on the end, so I think that the 53005 is the distinguishing number that makes it compliant.

Hope that helps you identify one if buying used.

When my area had the dynomometer testing, it was difficult to get a pass. Mine passed with the Eastern Catalytic Converters.
We now use a "2 speed Idle Tailpipe Emission" test with no dynomometer, and it is never a worry if it will pass now. I don't even change the air filter.

As long as the car's stock. My 93 failed the crap out of that 2 speed idle test with stage 2 cams.

 

[LOUDSHO92]

We do offer a CA version of the SHO Source y-pipe: http://www.shosource.com/catalog/product_info.php?cPath=61_43_54_86&products_id=167

 

[cali+Mocasho+]

i appreciate all this knowledge thanks guys. ill update as soon.