FVD Exhaust install throwing off O2 Sensors and other things.

I installed a complete Used FVD Brombacher exhaust this weekend. Headers, Cats, Mufflers, 02 Sensors. When installing the FVD exhaust I noticed that the post catalytic O2 sensors were on opposite sides of the stock headers. (2001 C2 Manual) The leads were not long enough to go to the opposite side connectors. So I plugged them into the sockets closest to them. I was able to drive for about 30 miles until the CEL light came on. I noticed the idle was a little off, would fluctuate between the 760 - 860 range I think . Car drove fine. When I got back home I checked the codes. P01030 O2 Sensor Curcuit Bank 1 P1133 P1130 Oxygen Sensing P1126 Oxygen Sensing P0300 Random Misifre Detected P0306 Misfire Cyl 6 P0304 Mis Cyl 4 P0305 Mis Cyl 5 02 Sensor Output 0.0v Bank 1 Sensor 1 I hope you enjoyed my drawings. Would this be due to the post cat O2 sensors be plugged into the opposite connectors? Plugs and tubes were replaced about 6K ago, all the coils looked fine. The 02 sensors came on the exhaust. Could this just be a bad O2 sensor? Would it be advisable to get the DME re tuned for the new exhaust?' Thanks!

No, you can't cross connect the sensors like that and expect everthing to work. Your codes are definitely at least because of the cross connections.

It is possible to extend the wires to reach to the correct connectors. Cutting them midway, put correct wires in and using the same connecters should work.

I was reading that it's not a good idea to splice the o2 sensors. That you should extend the wiring harness. Does it matter where the splice happens? Seems like you're extending the wire run either way.

I just added an xpipe to my track car and I now actually have the same errors! Same bank and everything. Prior to removing the cats, I labeled them and placed each one in a plastic bag and made sure not to touch the sensor end. I am sure they are in the spots I removed them from. Also with no cats, I don't see how swapping the post with the pre on the same bank would make any difference? I am going to check the wirring harness to ensure they were in the correct location. I am also going to check the cam deviations to make sure nothing else is going on. Also, I had no problems with cable lengths. You are not suspose to cut O2 wires since they are calibrated as an assembly. I just move the o2 connector to harness connection closer to the location it needed to go and ty wrapped the cable in the new location. Might want to try this first to see if it will clear the error.

There was a company in LA I think that makes custom length 02 sensor wires. I'll try to remmeber who it was and post back. I too have been told not to cut and splice them.

Cam, did you get the misfire errors as well? Those are what worried me the most. My plugs have about 6k miles on them. When I installed them I replaced the tubes and all the coils looked healthy. I hope it's from the crossed sensors throwing off the computer. I can't find any o2 sensor extension cables on the net. I work with small gauge wires everyday, so have no problem splicing. However, I'd rather not splice into my wiring harness if it's not needed.

JayAre, I am getting the following errors: P0300 Porsche Fault Code 62 - Misfire damaging to cats P0306 Porsche Fault Code 68 - Cylinder 6 misfire P0304 Porsche fault Code 66 - Cylinder 4 misfire P0305 Porsche fault code 67 - Cylinder 5 misfire P0139 Porsche Fault Code 17 - Sensor aging behind cat converter I was at the track last weekend and cleared them daily but they came back each day. The car is running great. I have not complaints. I had no errors prior to removing the cats and adding the x-pipe. I would really try to lengthen (make it a short run) the harness to make the proper connections with the correct O2 sensors first before any attempts to cut to ensure this will fix your problem.

Actually I think we can also swap the pair of O2 sensors from bank 1 to bank 2 to eliminate them too.

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Afer taking the sensor wires and connectors out of their retaining clips I was able get them to stretch land at the proper connectors. It's not as pro of an install as I like, they're zip tied together right below the air box. But after driving 30+ miles no codes have shown up! Got lucky there. Still feels like the ECU could use a tune to make the engine run better with the more free flowing exhaust. Thanks for the insight everyone.

Cool! Glad it worked!

Hi, I recently had the FVD 996 sport catalytic set and Sport quite version installed on my 996 tiptronic and I am experiencing sputtering when I get on the gas at start. I live in CO and just got back from the Porsche Parade in Spokane WA and the sputtering was much less of an issue there. So it does seem like it is O2 related. I see the diagram provided above, can you provide actual FVD documentation on this so that I can go back to the shop and show they did it wrong. I took it back into them after the install and they said they had no idea why, suggested maybe the mass airflow sensor. my email is [email removed]

The configuration of the o2 sensors on the DVD install matches the stock diagram

Sounds familiar. Unfortunately it is the Tiptronic that gets confused by the different readings caused by the cats. Don't ask me how. But I have been there and done that after I installed a 200cell x-pipe. Actually the hesitating you feel has to do with the slippage of the torque e converter. If you will check the ATF temperature after a long normal drive you will probably see very high values. Mine were 130degC coming of the highway and 5km of normal town traffic. Besides that I got codes for the Secondary Air Injection and for the cat efficiency etc The Tiptronic Control Unit gets a lot of values from the ECU for calculating ulaties schifting etc. There it goes most probably wrong and it starts to try to correct via the transmission and the TC lockup/slippage to compensate. The precise correlation is unknown to me. But it gets confused. Everything went back normal when I reverted to stock. I would advise you to not drive the car too long like this. The slipping of the TC lockup will cause extra wear on your transmission. I did at time an ATF change to try to remedy my problems and found a lot of clutch debris in the ATF, glittering speckles.

Thanks for the response. I also had the IMS replaced at the same time to the LNB ceramic bearing (thinking I did to much at once). It seems more like a sputter than the transmission though and the issue being more apparent at higher altitude also makes me think O2. I am not getting any errors thrown either which seems odd. Was yours manual or tiptronic, you mention clutch replacement?

It was a tiptronic car. I referred to an ATF replacement of the transmission. Fluid and filter change. Your symptom is a stutter when driving off or when changing to a higher gear. Mine were that when shifting back it stuttered. It was only weeks later the transmission started to act weird. Besides the stuttering I got unsteady power transfer in te low rpm ranges 1000-2000rpm. It has to do with the O2 values. But the ECU will try to act on them. The ECU and the TCU are very linked. So the distorted engine performance sets the TCU off to act weird. Maybe if you can make the O2 problem go away it will act again normal. But me and my Indy tried everything. The tiptronic cars are not so suitable to tweak with performance mods like exhaust. Don't underestimate the complexity of the TCU it takes a whole lot of parameters With manual cars cars no problems. Going back to stock and all problems went away. You will find out. My car is now a manual. My Indy transformed it into a manual.

I found a few that offer extensions http://innovativewiring.com/?page_id=364

I have the same hesitation in a manual car, FVD 200 cell and hacked mufflers. been chipping away at it since the install but not resolution yet.

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yes ... but you have a manual. So you engage and switch gears yourself. With a tiptronic it will also set off the adaptation values of the TCU, eventually wearing out your torque converter and transmission.

Silk, but what about the diagrams in this original post? My new FVD exhaust is wired like the stock diagram. So does this mean the shop connected the sensors wrong? How do I validate what the correct connections are, should it be like the FVD diagram?

I feel your pain brotha. My car is sitting in the garage until banks 1 and 2 02 sensors arrive. unless you love projects and problem solving. Why not just take it to the dealer and let them handle it?

Do you know if the brombacher exhaust is in the same factory exhaust location and has the same flange setup? I am considering putting non 200 cell cats on to see if that fixes the issue. Either fabspeed or magna flow. I don't have my original exhaust so trying to see if I can put them onto the brombacher exhaust.