Why did you need one before the cat?
6
Emissions and forcing 02 readiness
- Thread starter james9120
- Start date
kennega
Ready to race!
It's a delicate balance between signal too high, signal too low, and no signal on the CBFA. I haven't found a one size fits all approach yet - some people run a single spacer, others run a combination of 3-4 spacers. I passed emissions previously, but now I've got a CEL, so it's a matter of finding the right combination. I've just been too lazy to do so since emissions testing isn't for another 7 months
But why do you need one before the cat, what does that sensor do? I have signal below threshold currently.. With one spacer after the cat, about in the middle adjustment facing towards the front. Should I move the sensor closer, or farther from the exhaust?It's a delicate balance between signal too high, signal too low, and no signal on the CBFA. I haven't found a one size fits all approach yet - some people run a single spacer, others run a combination of 3-4 spacers. I passed emissions previously, but now I've got a CEL, so it's a matter of finding the right combination. I've just been too lazy to do so since emissions testing isn't for another 7 months
kennega
Ready to race!
Try moving the spacer to face towards the rear, clear codes and see what happens.
You may need 2 spacers because the stock CBFA setup has 2 catalysts - pretty stupid for both to be monitored though considering if one goes bad you're swapping out the entire downpipe anyway.
Will do!
Gotcha, forgot about the first cat.
Wouldn't the second and third 02 sensors throw faults, instead of just one sensor if that was the case? What I mean is, I have one code for efficiency, but technically shouldn't I have two codes?
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flipflp
Autocross Newbie
CBFA engines have 3 o2 sensors, the first on the turbo for air/fuel ratio, the second PRE-second cat for efficiency and the third for POST-second cat efficiency.
When you install an aftermarket DP, you lose the first cat outright. You need one spacer that limits gasses getting to the second o2 that will allow that sensor to see just enough gas to fake a catalyst being there. Since no aftermarket DPs use a high enough cell count cat to make up for the whole first cat missing, let alone for the high flow low cell count one on the DP you need a spacer on the 3rd o2 as well to do the same thing.
The theory is you need a bigger (read: longer) spacer with a smaller internal hole on the first spacer, and the same or smaller with a bigger hole on the second spacer. The best recommendations now suggest having the spacers pointing forward helps, I assume because the sensor is not getting a direct "hard" exhaust flow.
When you install an aftermarket DP, you lose the first cat outright. You need one spacer that limits gasses getting to the second o2 that will allow that sensor to see just enough gas to fake a catalyst being there. Since no aftermarket DPs use a high enough cell count cat to make up for the whole first cat missing, let alone for the high flow low cell count one on the DP you need a spacer on the 3rd o2 as well to do the same thing.
The theory is you need a bigger (read: longer) spacer with a smaller internal hole on the first spacer, and the same or smaller with a bigger hole on the second spacer. The best recommendations now suggest having the spacers pointing forward helps, I assume because the sensor is not getting a direct "hard" exhaust flow.
Thank you, so what I'll do is leave the bigger spacer on the last 02 sensor (post cat) and use a spark plug fouler on the second 02 sensor (pre cat). Hopefully that works
flipflp
Autocross Newbie
I've seen a lot of different setups, and there is a big thread on here with a lot of what has and hasn't worked.
Here is one that is active: http://www.golfmk6.com/forums/showthread.php?t=33907
From this thread, I would suggest buying 2 RAI J-Spacers and one or two non-foulers.
Start with:
Front spacer med jet pointing forward
Rear spacer small jet with non-fouler pointing forward
If you get rich codes, add more non-foulers and thread out the spacers
If you get lean codes (which I dont think is likely) drill out the non fouler or use a larger jet
EDIT: I was just re-reading that thread and it looks like a few people have run just one spacer on the last o2 spacer with medium jet working well. I think a lot of this comes down to the quality of the cat and possibly the gas you put in it.
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You won't get any lean or rich codes - its either you get catalyst inefficiency (p0420) or you don't. The only way to scientifically find a combination is by monitoring the voltage reading from the o2 sensors and comparing them to a stock setup (which is a pain).
I installed the recommended Vibrant 02 spacer with the medium setting, facing towards the engine. P0420 10 minutes later. So now what? The only thing I can think of is I didn't thread the spacer in all the way, I left it out by 1/8 with the nut.
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Nineeightgolf
Ready to race!
Are u running this spacer with no spacer on the middle bung?