My rear O2's are missing/capped shut
11-14-2014, 11:27 PM
#1
Intermediate
Thread Starter
My rear O2's are missing/capped shut
Sorry, just bought this 2008 C6 with AR long tubes and appears to be catted X pipe. I crawled underneath and the front O2's are installed. But where the rear O2's should be there are just bolts filling each hole. I have NO check engine light on. Would this mean the car has a tune installed?
Thanks,
Kyle.
Thanks,
Kyle.
11-15-2014, 12:59 AM
#2
Yes, the rear cats are tuned out since they just cause problems with LT header and high flow cats.
Its a two part problem,
since the placement of the cats are now farther away from the engine, so the are not as effective as the OEM, and this can cause problems with not enough reading difference between the Pre and post O2 sensor to throw a code, and at the same time, the rear O2 will foul out quickly as well.
As for the extent of the tune, who knows, since the tune may be a canned tune to just turn off the the rear O2' and a quick adjustment for the header, Or the car may have been dyno tuned to try to get everything possible out of the motor instead.
Its a two part problem,
since the placement of the cats are now farther away from the engine, so the are not as effective as the OEM, and this can cause problems with not enough reading difference between the Pre and post O2 sensor to throw a code, and at the same time, the rear O2 will foul out quickly as well.
As for the extent of the tune, who knows, since the tune may be a canned tune to just turn off the the rear O2' and a quick adjustment for the header, Or the car may have been dyno tuned to try to get everything possible out of the motor instead.
11-20-2014, 11:12 PM
#3
Intermediate
Thread Starter
Yes, the rear cats are tuned out since they just cause problems with LT header and high flow cats.
Its a two part problem,
since the placement of the cats are now farther away from the engine, so the are not as effective as the OEM, and this can cause problems with not enough reading difference between the Pre and post O2 sensor to throw a code, and at the same time, the rear O2 will foul out quickly as well.
As for the extent of the tune, who knows, since the tune may be a canned tune to just turn off the the rear O2' and a quick adjustment for the header, Or the car may have been dyno tuned to try to get everything possible out of the motor instead.
Its a two part problem,
since the placement of the cats are now farther away from the engine, so the are not as effective as the OEM, and this can cause problems with not enough reading difference between the Pre and post O2 sensor to throw a code, and at the same time, the rear O2 will foul out quickly as well.
As for the extent of the tune, who knows, since the tune may be a canned tune to just turn off the the rear O2' and a quick adjustment for the header, Or the car may have been dyno tuned to try to get everything possible out of the motor instead.
So with the rear O2's capped, no check engine light and the possibility that the car I bought has a tune.....does this mean I can replace the cats with straight pipe and not have an issue or check engine light?
11-21-2014, 12:24 AM
#4
Yes, no, maybe.
Pulling the cars will end up with more stink from unburnt fuel that the cats are burning off now. The cats are high flow, so you not going to loose much back pressure from removing them. What you do lose, may have to have the car re-tuned to get the AFR correct.
If you have to run through car through a smog test, without the cats (and if the car will pass a sniff test now), going to fail the test.
Really, what few HP gains you may pick up by pulling the cats, will not be worth the unburnt fuel smell of the catless system for a street driven car.
Pulling the cars will end up with more stink from unburnt fuel that the cats are burning off now. The cats are high flow, so you not going to loose much back pressure from removing them. What you do lose, may have to have the car re-tuned to get the AFR correct.
If you have to run through car through a smog test, without the cats (and if the car will pass a sniff test now), going to fail the test.
Really, what few HP gains you may pick up by pulling the cats, will not be worth the unburnt fuel smell of the catless system for a street driven car.