New Y-pipe and cat for the old girl

[OlSmokie]

My 1990 C1500 got really loud, fairly quickly, and it was running like crap. Stalling and stumbling. The Y-pipe was blown out right by the O2 sensor and the Cat, the 33 year old one, was pooched.
Living in Ontario, Canada, I wasn't looking forward to the job, but I bought a stud puller, and to my complete amazement, it rattled the studs out of the manifolds. I thought I would be taking them off and drilling them out for sure.
I got a new Y-pipe from a local source, along with new studs and I ordered a new cat on line.
Again, by a stoke of luck, the new cat had 2 1/2" inside diameter so it slid right on the new Y-pipe. The new cat is shorter, so I went to the local muffler shop and bought a 19" piece of 2 1/2" pipe and it slipped right into the cat, and with a little persuasion, into the stock intermediate pipe, which is not that old. It's nice and quiet now and running a whole lot better.

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[Schurkey]

Kinda surprised you have the O2 sensor just ahead of the cat, instead of in the left exhaust manifold.

 

[OlSmokie]

Kinda surprised you have the O2 sensor just ahead of the cat, instead of in the left exhaust manifold.

That hole in the Y-pipe just took a plug. It probably fits many applications. My truck does have the O2 in the drivers manifold. That's where the Y-pipe blew out and I think it was throwing the sensor off.

 

[PlayingWithTBI]

It probably fits many applications. My truck does have the O2 in the drivers manifold. That's where the Y-pipe blew out and I think it was throwing the sensor off.

My JBA mandrel bent "Y" pipe has the same ********* in it. I have my WBO2 in it and my NBO2 in the left side shorty header.

Edit: B-U-N-G H-O-L-E is snsored, ha ha.
Here it is with my high flow 3" Cat.

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I think later years TBI (maybe 95) had the O2 in the "Y" collector.

 

[Boots97]

That hole in the Y-pipe just took a plug. It probably fits many applications. My truck does have the O2 in the drivers manifold. That's where the Y-pipe blew out and I think it was throwing the sensor off.

Pretty sure 96+ Trucks/SUVs needed those O2 sensor holes. My 97 needs 4 O2 sensors and came with plugs for all the holes when I bought my Y pipe and cat.

 

[PlayingWithTBI]

Pretty sure 96+ Trucks/SUVs needed those O2 sensor holes. My 97 needs 4 O2 sensors and came with plugs for all the holes when I bought my Y pipe and cat.

These Y pipes are for TBI trucks 88 - 95, not for Vortecs.

 

[PlayingWithTBI]

This is crazy! When I bought that "Y" pipe (maybe 4 years ago), it was $188.99, now it's $309.99 - 164% more!

 

[Casey916]

Pretty sure 96+ Trucks/SUVs needed those O2 sensor holes. My 97 needs 4 O2 sensors and came with plugs for all the holes when I bought my Y pipe and cat.

yours has 4 o2 sensors my 98 Chevy 4.3 only has 3..how many should they have

 

[99xcss4]

yours has 4 o2 sensors my 98 Chevy 4.3 only has 3..how many should they have

you have the right amount 4.3 v6 305 vortec have one converter and 3 o2 sensors 350 and 454 vortec have 2 converters and 4 o2 sensors

 

[L31MaxExpress]

you have the right amount 4.3 v6 305 vortec have one converter and 3 o2 sensors 350 and 454 vortec have 2 converters and 4 o2 sensors

4.3L and 305s have 4 x 02 sensors. One behind each manifold outlet, one after the Y-pipe ahead of the cat and one after the cat. If you are only seeing 3, you are likely missing one of the two RH sides ones that are nearly on top of each other.

L35/L31 vs L31 setups

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