Exhaust system question....Help!
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Junior User
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From: Bridgeport, WV
Exhaust system question....Help!
I was under my 93 5 liter (106k miles) this morning to replace the O2 sensor, since it appears to be the origninal. While under the truck, I noticed there was a steel tube (about 3/4" dia) that comes off the exhaust just after the cat. This tube was broken, and the exhaust side of this tube was welded closed. What is this tube? The other end looks like it leads to the vacuum / emission system at the back of the engine. Should I get this tube reconnected? Is this adding to my poor fuel economy? Any help would be greatly appreciated.
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From: Belle Mead NJ
The system pumps air into the cat to make it run "cleaner". The repair kit is usually a peice of heater hose and 2 clamps. I have done away with all the air tubes on my truck. Still passes inspection, and get the same milage. So if you want to fix it thats coo, but if its not leaking exhaust out of the tube then leave it alone. lol
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From: Hawkeye Country
Basically the tube is pumping clean air into the pipe between the cats, its suppose to help the second cat work more efficiently.
I don't think theres any kind of performance benefit, basically you'd be pumping even more air through a already corked factory exhaust system.
I left the tube unconnected on my 96 when I replaced the exhaust with headers and duals, leaving it disconnected hasn't affected how the truck runs in anyway.
I don't think theres any kind of performance benefit, basically you'd be pumping even more air through a already corked factory exhaust system.
I left the tube unconnected on my 96 when I replaced the exhaust with headers and duals, leaving it disconnected hasn't affected how the truck runs in anyway.
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From: Hawkeye Country
Originally Posted by shtse
The truck has Flowmaster duals... would this explain having the tube removed?
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The air injection is not to make the cat run cleaner. It's to make it heat up faster when the engine is still cold. After the engine is up to operating temperature, TAB will bypass and vent to atmosphere throught the big muffler mounted on the fender well right next to the starter relay. Assuming I remember what I read, and the document was correct. I've never taken a ride under my hood to find out though.
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From: Gorrie, ON
Originally Posted by Old_Paint
The air injection is not to make the cat run cleaner. It's to make it heat up faster when the engine is still cold. After the engine is up to operating temperature, TAB will bypass and vent to atmosphere throught the big muffler mounted on the fender well right next to the starter relay. Assuming I remember what I read, and the document was correct. I've never taken a ride under my hood to find out though.
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Junior User
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From: Bridgeport, WV
The cat "cleans" the exhaust stream via a chemical reaction with the elements in the cat and the exhaust species. The cat does not operate at peak efficiency until it is up to temperature.
