O2 Simulator

GrandDragon · February 13, 2004

I was wondering if anyone knew a good place to order and O2 simulater for a 97 Sierra Z71. I want to cut off my Cats but I don't want the annoying service engine light to be on all the time. If anyone has any info I would appreciate it.

JayMan · February 13, 2004

Well, I can't legally recommend defeating your emissions control system. Yuo could get into a LOT of trouble if caught.

I do recall a certain Corvette forum had an "O2 simulator" to take the place of the O2 sensor past the cat convertor. The O2 sensor before the cat isn't affected by removing the cat, but the one after most definitly will tattle on you: Check Engine comes on.

Hypothetically, I do suppose an O2 Simulator might do the trick, in a strictly academic sort of way.

99-2door · February 13, 2004

If you do this your mileage will suffer greatly. Your 97 5.7L has 2 cats already. Just put dual pipes and 2 mufflers after the joint in the exhaust. You will get all the power increase you can feel with that. Everybody that I know that has cut their cats out has ended up having to put them back to get the engine to run right.

Rookie · February 13, 2004

Casper Electronics (WWW.casperselectronics.com) make some O2 simulators. The dont sell directly to the public, but Summit carries them.

JayMan · February 13, 2004

Casper Electronics (WWW.casperselectronics.com) make some O2 simulators. The dont sell directly to the public, but Summit carries them.

I think that's the setup I had encountered. You leave in the O2 sensors BEFORE the cats, with the cats removed they "simulate" an "ideal" O2 condition after the cats. This way there are no driveability problems.

Remember for all OBD 2 vehicles you have an O2 sensor before the cat, and an O2 sensor AFTER the cat: this adjusts the short-term and long-term fuel trims and also maximizes the cat efficiency. If you remove the cat and put in a "test pipe" the MIL immediately comes on with a code for "catalytic convertor malfunction." You would also fail the visual emissions inspection.

Well, there might be very slight gains. That said, you could end up in a LOT of hot water if the fed ever found out. Companies like EG&G Ortec (They have a lot of contract work for DOE and DOD) make roadside portable gas analyzers that can quickly detect a vehicle with abnormal emissions. Makes a lot of money for the local officials.

I think there are legal routes to pursue (CAI, upgraded MAF, upgraded TB, PCM recalibration especially from Westers Garage, wideband O2 sensors, high-flow cats, good cat-back exhaust) that will deliver more power with far less hassle. At least you'd still pass a sniffer test if needed.

GrandDragon · February 16, 2004

I live in the deep south and emissions test are non existent around here. I just want to make my truck louder, I have a friend with no cats and his sounds awesome and it still drives ok and everything, but the dang engine light stays on. I want to get rid of the enginge light, legality dosen't matter!

JayMan · February 16, 2004

If you want "noise" have you considered Megs pipes? You can tune them with rings or inserts to get the right harmonic.

Now you know why my friend in Salt Lake City restored a '69 Chevy C10, but with crate motor LS1 and 4L60E : no problems with the yearly I/M test. If I recall he put in Borla Oval Track bullet mufflers and that thing has a VERY nice tone.