Thanks a bunch for the offer, I appreciate it.
Test pipes are probably the best option.
Cali doesn’t see all the rust and corrosion though. I have had to deal with a lot of broken studs for cars here because the studs snap just like on the RS4s. Having a torch or small Mapgas torch would be great to heat the nuts/studs up before trying to remove them.
What are your thoughts about getting access to torch those flange bolts without dropping trans?
something to keep in mind if your city/state/whatever is big on smog testing.
moving the cat down stream will affect the cat warm up time, and depending on how its tested, it’s possible that it can affect the #s enough to make you fail the test.
'course, if you don’t do smog tests annually, then it is a non issue. but wow, that separation at the flange.
Yea good thing about Michigan is no smog cert. The test pipe file from APR should remove any CEL’s…but obviously not pass readiness tests. I’ll probably put the cats in the downpipes, so hopefully that is close enough for them to be warm and efficient. I’m not sure exactly what happens to the secondary O2 sensors.
You can get spark plug non foulers, and put them into the downpipes some place.
That’ll trick the o2 sensors that everything is normal
Do we know for sure that it wont pass readiness on the test pipe file they have? I would think if properly coded out it will still show a ready state. On my b5 i coded out the rear o2s and readiness was still complete even without them plugged in.
I am almost positive the JHM test pipes have the bung for the secondary 02 sensor, they are just on the other side of their picture.
I called APR and was told it would not pass OBD2 emission testing. I didn’t ask many questions on the subject, since my real interest was removing CEL’s.
The J-bungs are not on these test pipes, as these cars a bit mores sensitive.
It can be done. I would prefer to use a small Mapgas torch so that I don’t run the risk of burning other components around the nuts. A normal oxy-acetylene torch usually has a huge flame so it usually doesn’t work well in tight spaces like what is available with the B8s with the transmission still in place. I have had to use an oxy-acetylene torch on some broken studs that were part of a Q5 but the transmission was out of the car so there was enough room to get away with doing that.
I think the 3.0Ts are Siemens engines so these will not work unfortunately. http://store.034motorsport.com/o2-sensor-spacer-with-built-in-mini-catalyst-for-bosch-style-oxygen-sensors.html
Interesting. I was under the impression they would pass readiness/OBDII with the proper APR tune, but just not the actual sniffer test. It’s definitely possible to code that part out. I’ll try to confirm with APR.
My B5 passes the OBDII scans with no cats with both the Vast and 034 tunes.
We do a OBDII scan here for readiness and codes, but not the actual sniffer test. TX is weird. It’s a county by county thing. Most smaller counties don’t do any emissions testing at all. Counties with larger cities do OBDII scans only, and then there are a select few that do both OBDII scans and sniffers tests.
who knows…there are guys with APR’s $20,000 supercharger kit for the RS4 who can’t pass readiness and their cars are being mothballed due to not passing emissions. I wouldn’t put much faith in APR’s ability to handle that.
Minute detail, but I ran penzoil ultimate euro 5w-30 oil this time instead of the normal factory 5-40 (castrol I believe) or penzoil ultimate euro 5w-40. I was too dumb to realize the change in weights when I bought in bulk from amazon. So in theory it’s possible the engine was running slightly warmer. I didn’t notice anything in terms of oil temps.
So the installation involves either disconnecting the O2 sensors, zip tying them somewhere or tapping our own j-bungs somewhere downstream? I’m planning on running a test pipe file and have no need to pass smog in Michigan.
I think the JHM pipes have O2 sensor bungs. They don’t have the “J” bungs that act as non-foulers (by moving the sensor further from the pipe). If I am reading Jake’s response right, the S4 was too sensitive and throwing codes even with the O2 sensor moved further away.
They absolutely have O2 bungs, just no defoulers you are correct.
Thanks for all the clarification guys. JHM test pipes ordered. Hoping this DIY goes OK, otherwise, will take it to Ray and get it done right.
Kris - what kind of HFC would you recommend putting further downstream? I’m thinking about getting them welded into the downpipes? Just go with a generic magnaflow one, or something more exotic? I’ll run the APR test pipe program, so no need to worry about secondary O2 etc.
Why is buying a single Audi OEM cat/downpipe for $900 not an option? That is the best option. Or send the cat/downpipe out to some metal fabrication shop and have them mend it.
Aftermarket catalysts are super shady. Like used prophylactics, the efficacy is below 90%.
people don’t generally care about the efficacy. They just don’t want a CEL or a restriction.
$900 is 3 times the price of a set of aftermarket catalytic converters, and 5 times more expensive than going catless.
And OEM makes your car slower. That’s why it’s not an option.
Before you argue for the environment, don’t forget that your car is chipped (illegally in California) and that your excess tire wear over 5 years from track days vs. a conventional S4 owner creates a greater environmental impact than 5 years of running catless.
This is certainly a choice. I would rather weld the cat back together than spend 900 on a new cat.
But the main issues I see are: (1) we’ve seen the stg 2 tune kill cats before, so really this is something that will eventually happen; (2) how do I know the breaking apart problem won’t happen again, even if the weld is reinforced.
The JHM test pipes will be stronger, so I doubt either issue happens going catless. Plus, I’ll get to see how the car performs without the factory restriction. I’m sure I can find an aftermarket cat that performs. The issue with the aftermarket cat will be proximity to the exhaust manifold, and the factory ECM won’t dump fuel during cold start. But I’m fine with that compared to all the other disasters on the road.