More on spark plug anti-fouler O2 mod.

[Nick Gustas]

For reference I'm running labree downpipes with magnaflow cats.

The entire time I've had them, I would occasionally get catalyst efficiency DTCs on both banks, not a big deal, I'd maybe clear the codes once a month.

So, after blowing out the last inch or so of my bank 2 cat



I was getting bank 2 catalyst efficiency dtcs almost instantly


I tried the fouler mod to buy me some time until spring to deal with getting a new cat on bank 2, and it seems to work so far.


Looking in the Bentley manual, it would appear that in datablocks 046 and 047, you can almost see the health of your cats by the "time" it displays.




As you can see, values between 0 and 0.80 in field 3 will = CAT OK, over .80 will = CAT not OK.. I assume the lower the better.

Now in my setup, bank 2 has most of a cat left, and the anti-fouler mod installed, bank 1 has a normally functioning cat, and a normal O2 sensor install..




See how bank 2 on the top has a test time of 0.48, and the bottom bank 1 has a test time of .79, just barely passing? The bank 1 values explain the occasional intermittent cat DTCs I have always had with these downpipes.

I'm curious to see datablocks from other cars and see how well their cats are working, it's best if you run the car until the blocks say CAT Bx OK, but you get values before then.

If I'm interpeting the Bentley page wrong, tell me how!

[gk1]

Since the only way to measure that temperature would be with the EGT sensors which are much closer to the primary cats. Since you have DPs then I would say those values might be off, but since you are using non-foulers, and I don't fully know your whole setup then I'm really just guessing.
For the DTC I'd say you could be right...if the value goes over the preset limit of 0.8 then it sets a DTC in the ECU.

[Mihnea]

The cat temp displayed in blocks 46-47 is an ECU calculated temperature, it has nothing to do with the EGTs measured before the turbines in the exhaust manifolds. The ECU can't measure EGTs below 945 degrees C because it isn't in the operating range of the sensors. The cat check is also a pre-cat check, not a main cat check, as, the secondary O2 sensors are after the pre-cats on stock S4s.

However, Nick's experience is really interesting and I'm glad someone is doing this sort of experiments and sharing the results with the community!

HTH,

Mihnea

[Zold-manS8]

I am experimenting with two solutions to the testpipe CEL/DTC problem: one is electronic and one is foulers. If the foulers pan out I will not bother with the electronic version as it is more expensive.

which foulers are you using - 42009s? 262Q sensors right?

[PSmalls::DoggieStyle]

borderline!? Interesting.

I'm going to check that on my car to see how it is with piggie pipes, just curious.

Nice find, Nick. Now it's time to do the non fouler on both sides and test again?

[lemieux@curbside]

• http://forums.audiworld.com/s4/msgs/2239526.phtml

[Nick Gustas]

I'm on I-55 now, traffic is light

[Nick Gustas]

In your case, it's worth experimenting to see what gives lower values, try stacking three anti-foulers instead of two, etc.. Be nice to find a cheaper one piece solution too.

[mbox]