RolanTHUNDER

Hi all.

quick question, does the AP1 (I have a supercharged 2001) need a mini cat for the o2 sensor to plug into when installing a test pipe? Can I get away with just a non CEL fix test pipe and not have adverse AFR or bad fuel economy issues?

Thanks.

Chuck S

Why not use a high flow cat matched to the diameter of your exhaust? So-called "test pipe" (wink, nudge) stinks for starters. A CEL fix is nothing more than bypassing part of the system, the exhaust is still dirty.

-- Chuck

flanders

Yes you can run without a CEL fix, you will obviously get a CEL but it does not affect AFR or the fuel economy.
But driving like that you wont notice if there is something else causing another CEL.
So I suggest you just get one of those cheap o2 spacers on ebay.

RolanTHUNDER

No cat's at all for me thanks I actually have a header back exhaust with a resonator in the place of the stock cat so it flows well but, I'm not happy with the darn thing. There's an odd rattle noise coming from it when I drive. I want to get it out completely and got test pipe in prep for a cat back system.
What is the smell you spoke of? currently I don't have a cat so shouldn't I get a smell?

RolanTHUNDER

Oh okay, so it wouldn't make my car overfuel (which it's currently doing. Got a 5th injector but ECU needs a tune up which I believe will resolve the over fuelling thing) or make my AFR go bad?
I'd rather not have a CEL so perhaps I should go for something like the Invidia TP? They offer two types though, one for AP1 and one fore AP2 with CEL fix. Do both have "mini cats" inside them?

flanders

You have 5 injectors? that sounds weird.
The secondary o2 sensor only monitors the performance of the cat, it doesn't affect AFR at all.
I have an Invidia test pipe with the mini cat inside and it does not work, I still got a CEL.
I had to install one of these spacer things to keep the CEL off SIMULATOR EXTENSION CEL FIX FOCUS AUDI A6 S6 VW HONDA O2 SENSOR DECAT DOWNPIPE eBay
You can get many different styles and from many different places, you might even have these for sale locally in SA.

Spartarus

Most are just backspaced out of the exhaust stream. That's usually all that's required. Some may have mini-cat's but I don't know. The downstream sensor is narrowband. It's not precise, and it's only there to monitor the catalytic converter and turn on the CEL. It doesn't affect fueling in any way. The stock AP1 ECU can not be flash tuned. I'd just buy a Haltech or AEM series 2 if I was supercharging.

RolanTHUNDER

It's for the V2 supercharger. The kit I have is actually the AP2 kit where Vortech included a 5th injector for the installation. So yeah, that's where the 5th comes in. It only really flows fuel once the engine is boosting substantially I believe. You might be able to see it on my profile pic. It's on the charge cooler itself.
Thanks for the link! That's a really small simple cheap device actually. Does your Invidia have the same thing inside it? Glad to know secondary sensor doesn't affect AFR at all.

RolanTHUNDER

Hey fellow Silverstone
I think my current exhaust which is header back has that mini cat in it. It must since I don't get any CEL. Invidia themselves say that 99.8% of AP1's are CEL free.
My ECU is stock but I have a piggyback unit called "UniChip" or "UniQ". Popular unit in these parts for easy ECU tweaking of main functions. Runs turbo and supercharged setups. I'd like the Haltech PnP in the future.