MK7 "Random / "Stupid" Questions Thread"

[Mr. Conundrum]

What’s the question? The CEL is due to cat not being efficient enough. The unplugging of the rear o2 was to prevent the enrichment but unplugging it makes the ECU unhappy so it triggers a CEL. Cobb can no longer turn off the CEL due to EPA crackdown so your best bet is to get a DP with a good cat and cross your fingers. Or dont run cobb…..

Question is if a "medium-lvl" CAT + spacer is enough to prevent enrichment. "Medium-level" cat being like a Milltek sport or Wagner, which are both EU6, but can be hit or miss with CELs. I know that combo would keep the CEL off; I don't know if it maintains AFR.

Trying to avoid the EPA GESI tax if possible. I have emissions testing, but they're primarily concerned with readiness/CEL. If I have to bite the bullet on a GESI dp, I will, but

 

[Diggs24]

Enrichment is run regardless of what you’ve done to the exhaust.

 

[Diggs24]

Unless of course it can’t see the sensor but that presents other issues as you know.

 

[Mr. Conundrum]

Enrichment is run regardless of what you’ve done to the exhaust.

Ohhh... Maybe I misunderstood. I thought the ECU was adding fuel in order to heat the cat to reduce emissions. The added fuel being based on the reading from the O2 sensor with a range from "brand new OEM cat" to "barely above triggering CEL", with more fuel being added based on cat efficiency. Is that not how it works?

 

[Diggs24]

It does both. It heats the cat at cold start and also performs efficiency checks as you drive and will purge fuel during cruising to clean it and get it back in required efficiency range.

 

[Nineeightyone]

So even with a spacer and no CEL, it will still continue to get richer and richer over time, requiring a reflash? Or is it only an issue with high flow/non-EPA cats? I may have previously misunderstood this issue.

 

[Kart17]

Considering adding Euro tails on my MK7. Not sure whether to get the Mk7 specific ones or Ali or go with the 7.5s like vlands? I’d have to retrofit dynamic signals on the mirrors if I went 7.5. Not sure what people’s thoughts are.

 

[Diggs24]

So even with a spacer and no CEL, it will still continue to get richer and richer over time, requiring a reflash? Or is it only an issue with high flow/non-EPA cats? I may have previously misunderstood this issue.

It will always purge as no cat is perfectly efficient and never has buildup that needs burned off. It will purge but the worse the cat the more it will to get back into efficiency. If it can’t it will throw P0420.

 

[Nineeightyone]

Considering adding Euro tails on my MK7. Not sure whether to get the Mk7 specific ones or Ali or go with the 7.5s like vlands? I’d have to retrofit dynamic signals on the mirrors if I went 7.5. Not sure what people’s thoughts are.

This is gonna be very personal opinion and the look you're after. I don't love how dark the mk7 specific ones look, but I also have a mk7.5 so my choice was pretty straightforward. Either way I'd go aliexpress at this point, no point in spending double so a middleman can make money and you have the same end result.
Dynamic mirror signals look dope. Be aware some coding is likely going to be necessary, and you may need a harness adapter. Running the wiring isn't bad, if @ZERO815 isn't producing harnesses anymore then you should hit up @StorableComa/SCSkunkWerks for a harness.

It will always purge as no cat is perfectly efficient and never has buildup that needs burned off. It will purge but the worse the cat the more it will to get back into efficiency. If it can’t it will throw P0420.

I see, thanks! So running an O2 sensor plugged in, regardless of a spacer, will eventually require a reflash to reset the AFR lest it get hyper-rich?

 

[Salami]

I see, thanks! So running an O2 sensor plugged in, regardless of a spacer, will eventually require a reflash to reset the AFR lest it get hyper-rich?

From what I understand this is an Accessport only issue.

@Diggs24 is that correct?

 

[Diggs24]

It’s not hyper and worry is overblown IMO.

 

[Diggs24]

From what I understand this is an Accessport only issue.

@Diggs24 is that correct?

Doubtful unless the tuning company has modified the way the ecu handles emissions. Maybe in the past they may have but in 2024? No way. But unless you drive around logging all the time you’d never know.

 

[JTM88]

Considering adding Euro tails on my MK7. Not sure whether to get the Mk7 specific ones or Ali or go with the 7.5s like vlands? I’d have to retrofit dynamic signals on the mirrors if I went 7.5. Not sure what people’s thoughts are.

I put the Vlands on my mk7. The fit was nearly as good as factory, and I used the instructions from @ZERO815 for the coding and repining of the harness. 10/10 would do again.

 

[Pineapple]

My car feels like a rubber band under low or quickly shifting powertrain load, should I go in on a full BFI mounts kit? I really think that's the issue but I don't want to go in on a $750 set that isn't what I need.

 

[JTM88]

My car feels like a rubber band under low or quickly shifting powertrain load, should I go in on a full BFI mounts kit? I really think that's the issue but I don't want to go in on a $750 set that isn't what we need.

BFI mount are probably my favorite non power adding mods I've done to my GTI. You can save a good chunk of money by doing the transmission mount insert instead of the whole mount. Even if you have to buy a new trans mount from FCP to use it.

https://blackforestindustries.com/c...n-mount-insert-stage-1?variant=42441853108471