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The o2 Spacer Thread

launchd

Drag Racing Champion
Location
New York
Car(s)
2018 GTI, 2021 A7
yeah but the medium on the J spacer works for cars with no cat or the location pre-cat. since you already have a cat that seems beefy too, you're already getting a cleaner reading without a spacer than others.

This is not accurate... I use the Vibrant J spacer with the smallest insert installed on my APR downpipe (location post-cat). I'm running APR's stage 2 non-test pipe file (does not block/code out CEL for cat efficiency below threshold - P0430) and I have had no issues/passed NY state emissions with all monitors Ready (they're all still showing Ready)/been running my car this way since June 2020.
 

launchd

Drag Racing Champion
Location
New York
Car(s)
2018 GTI, 2021 A7
Dang...ok. I'll have to take the spacer out. In the meantime...will the o2 not getting a reading affect anything? I'm not getting a CEL at the moment.

If your car is truly not able to receive the data it expects to receive from the O2 sensor, I'm fairly certain you'd have a CEL immediately. You can prove this by installing a damaged O2 sensor and/or wiring harness. The fact that you do not have a CEL and the monitors are simply not showing "Ready" make me think Jake is right, the drive cycle is still happening. Unless your JB4 is impacting any of this in any way... I doubt it is though...
 

El_bigote_AJ

Autocross Champion
Location
Las Vegas
Car(s)
2019 GTI bunny
This is not accurate... I use the Vibrant J spacer with the smallest insert installed on my APR downpipe (location post-cat). I'm running APR's stage 2 non-test pipe file (does not block/code out CEL for cat efficiency below threshold - P0430) and I have had no issues/passed NY state emissions with all monitors Ready (they're all still showing Ready)/been running my car this way since June 2020.
At what point was your specific setup and situation referenced here?

His cat is in a much more efficient location that the APR as the Catalyst can get much hotter and do it’s actual job as needed... while apr uses an good brand cat it’s to “their level” and doubtfully built to the EPA complaint standard/specs from GESI. So it’s makes perfect sense that mixed with it location so far down stream that the small insert that your mechanic installed works for YOUR SPECIFIC setup.

The notion that he hasn’t driven enough (he already said he did 150miles) sure could be a thing but it’s slim... those rare cases are because the car is driven on too short of trips consistently or driving on only a long trip that didn't consist of various unique driving patterns.
 
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El_bigote_AJ

Autocross Champion
Location
Las Vegas
Car(s)
2019 GTI bunny
If your car is truly not able to receive the data it expects to receive from the O2 sensor, I'm fairly certain you'd have a CEL immediately.
wrong.

It pops Immediately if it’s getting to strong/high of a signal (sensors work via a preprogrammed voltage scale) or if if it’s getting to low/zero signal that a BAD o2 would send... that “test” would show nothing.
 

launchd

Drag Racing Champion
Location
New York
Car(s)
2018 GTI, 2021 A7
wrong.

It pops Immediately if it’s getting to strong/high of a signal (sensors work via a preprogrammed voltage scale) or if if it’s getting to low/zero signal that a BAD o2 would send... that “test” would show nothing.

What?

I literally damaged my wiring harness when installing the Vibrant J spacer and had an immediate CEL.

However, when I tried a different spacer that didn't do what I needed it to (prior to the Vibrant J/prior to damaging the wiring harness), the CEL (P0430) didn't occur until 50ish miles into driving. This is the exact opposite of what you are saying...

Edit: Actually, I have no idea what you're saying here... Are you agreeing with my previous statement or disagreeing? If you are disagreeing, read this comment. If you are mistaken by what I said previously and actually agree, disregard this comment.
 
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launchd

Drag Racing Champion
Location
New York
Car(s)
2018 GTI, 2021 A7

Chogokin

Autocross Champion
Location
So Cal
Car(s)
GTI Sport | Audi A3
What does the "defouler" actually do? Is that the same as a mini cat? It looks like it does something similar as the spacer in moving the o2 sensor farther back.
 

GTI Jake

Autocross Champion
Location
Charlotte, NC
What does the "defouler" actually do? Is that the same as a mini cat? It looks like it does something similar as the spacer in moving the o2 sensor farther back.

It’s literally the same as a o2 spacer. Just a 18mm threaded spacer (22mm flats).

But, that’s not it’s intended purpose which is why it’s a Defouler or non-fouler. It’s intended purpose they make/sell them for is “defouling” spark plugs in beater cars that burn excessive oil. It screws in the spark plug hole and protects the spark plug from fouling (aka getting soaked with oil) because the hole on the end is little.

For o2 sensor purposes, you drill that little hole out to 1/2” and boom, you’ve got a o2 spacer for $5 (actually $2.50 because they come in two packs).
 

Nickmk7

New member
Location
Socal
Car(s)
mk7.5 GTI SE
Just putting in my two cents. Ultimate racing downpipe with 02 spacer option hasn't triggered CEL and has set readiness.
 

up4speed

Go Kart Newbie
Location
Long Island
Car(s)
2015 GTI
Just putting in my two cents. Ultimate racing downpipe with 02 spacer option hasn't triggered CEL and has set readiness.
Out of curiosity, does that built in spacer have a full open hole into the pipe, or does it reduce it a little to limit the flow?
The reason I ask is because I bought the Ultimate Racing 400 Cell catted downpipe (I will install when weather improves), and I opted for the one without the spacer built in. My reasoning was that by purchasing the straight, and J Vibrant spacer, I now have every combination of flow rate (4 different diameter options), and spacer type, so I can make sure that I get proper flow to prevent the CE light from coming on, and to allow the Readiness indicators to set.
All that said, based on my research, I was thinking of starting out with the straight spacer and the medium sized insert, and see what happens.
Thoughts?
 
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