ULPT Request - How to I pass inspection with no cats?
Posted by Screamo2005@reddit | UnethicalLifeProTips | View on Reddit | 17 comments
So my state doesn’t actually smog but they plug into the car to see if it detects the cats or not. I’ve heard there are ways to fake out the o2 sensors into thinking the cats are still in. But I don’t know them tbh. Please can someone teach me their magik?
ExecutiveCactus@reddit
Since this is the ULPT sub, steal one
Grand_Accountant_159@reddit
This depends greatly on what the vehicle in question is, if it's NY you might not even need them if it's old enough (25+) years and the vehicle is emissions exempt, just needs a basic safety inspection. I have heard that some vehicles like Chevy's the CEL can be tuned out with HP tuners. Older vehicles you could do test pipes with o2 bungs welded in and just run the sensors with a spacer, that's what I did with my Jeep and it worked great for the downstream o2 sensor.
GoodGoodGoody@reddit
Any reason you didn’t mention your state?
Granadafan@reddit
Or couldn’t spell catalytic converter
notcarefully@reddit
Old news my boy. Tech has come a long way and it’s much harder to fool. Any shop will hear your catless exhaust and tell you it ain’t gonna happen
drake90001@reddit
They’ll smell it first. My 1996 Ranger smells baaaad. Catless, and flowmaster 30. It sounds ridiculous for a 2.3l 4cy. It’s fun. 5spd manual as well.
Ghrrum@reddit
The sensor system varies from brand to brand over the years. But essentially you are screwed unless you do a lot of research, do a lot of math, do some basic physics, and then some basic engineering. The sensors can be a resistive sensor, a capacitive sensor, or some other weird thing that I don't know about or wouldn't consider for the application. Then you need to have the output for those sensors lie in an agreeable fashion.
So if you have 5 to 10 years to become conversant unnecessary fields to understand how to do it, you've wasted your time and you be better off getting a job and not having a stupid exhaust on your car.
Screamo2005@reddit (OP)
Truth. But I’m more gears towards forced induction rather than useless noise.
Ghrrum@reddit
The road is not a racetrack, and last time I checked most racetracks do not have emissions standards outside of F1 and NASCAR. Your vehicle is either street legal, or it is not. This is your choice.
If this is something that you can't overcome, either by charisma or knowledge, then you need to either put it back the way it was and pass it normally, or set this vehicle inside of something that's only going to be driven on a track.
If you're going to do modifications like this and either, don't know a guy, or don't know how to make it look like it passes? Don't do it.
East-Psychology7186@reddit
Old trick. Spacers on the o2 sensors
fgtrtdfgtrtdfgtrtd69@reddit
Get a tune that disables the first o2 sensor. My car has passed emissions for the last 8 years with a proper tune with no cats(full turboback exhaust). In my state you can have up to one monitor fail readiness and still pass emmisions. Something worth looking into.
pilgrimboy@reddit
Meow.
Personally, I don't think the cats should live in your car. It gets hot in the summer..I'm glad the state checks for them.
Suicyco71@reddit
O2 sensor spacers are your only hope, if possible at all. You need to add them, delete codes, then drive for a while so they don’t see the codes were recently reset.
weaseltorpedo@reddit
Cars with catless exhaust reek lol it's so incredibly obvious. Even some of the aftermarket high flow cats are still kind of stinky. Those unburned hydrocarbons are gonna make themselves known one way or another
Will2025@reddit
I understand what you're saying, we have a process like you're describing in NY. And I'm sorry but as a licensed inspector I can tell you it's impossible. There are 2 oxygen sensors, one before the catalytic converter, and one after. They measure the amount of oxygen and the computer basically figures out the emissions stuff. Obviously with no sensors, there's no data to feed the computer! Even if you somehow get sensors, the readings will be totally off and it won't work.
TLDR: Install cats for inspection, remove them after.
Round_Dig9686@reddit
You can try installing spark plug spacers on the O2 sensors. It pulls the sensor out of the exhaust stream. Check on YouTube it can explain it better.
ryansteven3104@reddit
Uh.. what?