Hollowed out front cat. you think it will cause an CEL

[EMMETT03]

My girlfriends 96 Camry 4Cyl has been bucking at load and has no power, can't get above 3,000 RPM's. Monroe looked at it and said it was most likely the rear cat and it would cost 620 bucks to replace, the flex pipe was also leaking so either way this pipe needed to be switched. Well I found one on ebay for 100 bucks put it on, fixed the exhaust leak but didnt do anything to fix the power problem, so I thought I would take off the front cat. The cat was all glazed over and not allowing any air to go through, this cat is huge. Well these are big bucks so I decide to hollow it out. Fixed the problem runs great. As to my question, is this going to screw up the 02 sensors, causing a CEL. I guess if it throws an error I will have to buy a new front cat. Thanks for help. Oh where I live we only have OBD II emissions tests and not full tail pipe emissions.

[userlain]

No it won't mess up the sensors. The sensors measure O2 levels and the cat converters don't affect the quantity O2 in the exhaust.

And since you have OBD II emissions, you should be fine.

[Your Uncle Moe]

If it does come back, since you dont have emissions tests, just cover up the light with some dark tape. Problem solved.

[terrastrife]

if theres no 02 sensor after the hollowed out cat.. i dont think itll matter.

[ShawnM]

If its an OBDII system and you gut out the cat. it will cause the check engine light to come on. The purpose of the downstream 02 sensor (the one after the cat) is to monitor the efficiency of the converter. When working properly the converter will use up the oxygen in the exhaust so the downstream 02 sensor will produce a very small voltage compared to the 02 sensor before the converter. With the converter hollowed out, both 02 sensors read exactly the same. The computer will see that and turn on the check engine light. If the check engine light is on, you will fail the OBDII emission test. Hope that all made some sence. Not to mention the huge fine for tampering with emission systems.

[EMMETT03]

Shawn, Thats pretty much what I was thinking just needed confirmation. When the light comes on I will buy a new converter. I only gutted it because it was bad so I said what the hell if it causes problems I will just buy a new one. Just to let you guys know, that front cat right off the exhaust manifold is huge.

[dallison]

the 87 that i had, i knocked out the ceramic insides. it ran a lot quicker, and the lights never came on, and i never had any bad codes from the o2 sensor

[ShawnM]

Just to clarify. Any 96 or newer car has an OBDII system. The OBDII system monitors the catalyst efficiency and will turn the check engine light on if its hollowed out or getting weak. Cars made in 95 or earlier do not monitor the converter (no 02 sensor after the converter). A converter is basically a restriction in the exhaust system so you will get a little better preformance by removing it or gutting it, but you'll never pass the tailpipe emissions test (if they test in your area).

[Tommy]

Originally Posted by dallison

the 87 that i had, i knocked out the ceramic insides. it ran a lot quicker, and the lights never came on, and i never had any bad codes from the o2 sensor

you didnt have any adverse affects from hollowing out your cat? mine is so clogged up it needs to be replaced, but its like $400 to do so.

[userlain]

Originally Posted by Stevethecleric

you didnt have any adverse affects from hollowing out your cat? mine is so clogged up it needs to be replaced, but its like $400 to do so.

Isn't it only california cars that have o2 sensors past the cat?

edit: Nope.

[EMMETT03]

nope, all cars 96 on. Part of the OBDII system is up an dowstream O2 sensors.