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Reported fix
Replaced both o2 sensors no change. Then installed o2 sensor spacers, that took care of it.
Leading evidence: 'Combined work: Install o2 sensor spacers + Replace o2 sensors no' (1 discussions report resolution; 0 report an unsuccessful attempt). Across 1 matching discussions, the most frequently mentioned possible cause is 'secondary ones' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Combined work: Install o2 sensor spacers + Replace o2 sensors no' (1 discussions). For that action, 1 discussions report a resolution and 0 report an unsuccessful attempt. The most frequently reported fix is 'Combined work: Install o2 sensor spacers + Replace o2 sensors no', supported by resolution reports in 1 discussions. These are forum reports and suggestions, not a confirmed diagnosis.
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Reported cause · Original poster
I didn't switch the primary O2 sensors, it was the secondary ones.
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Performed · outcome unconfirmed
Then installed o2 sensor spacers, that took care of it.
Install top gear 200 cell x-pipe and sport sound mufflers
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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Unsuccessful attempts
1
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Performed · outcome unconfirmed
I installed the Top Gear 200 cell x-pipe and sport sound mufflers.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Performed · outcome unconfirmed
The exhaust was installed w/ several other mods: TuneRS under drive pulley, IPD Comp Plenum & 82mm TB, BMC filter....so it's impossible to tell what added what.
Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
The exhaust was installed w/ several other mods: TuneRS under drive pulley, IPD Comp Plenum & 82mm TB, BMC filter....so it's impossible to tell what added what.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
33 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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1 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
I noticed no difference other than noise (except pulley of course).
So I have the dreaded rattling cat syndrome on bank 1 accompanied by a DTC showing poor cat efficiency on that same side. I have priced used cats but I have found the price of the Top Gear cats to be pretty good. Looking to get the standard non xpipe version. Anyone running them and have any insight to loudness, power increase, unwanted DTC etc?
Thanks
I will have the TopGear 200cell crossover installed in two weeks when I go in for maintenance and oil change.
But there are people here who have them.
i.e. Dedens, see
https://rennlist.com/forums/996-foru...zu-tuning.html
I have the 200 cell Xpipe from Top gear. The early kline were exactly the same, but double the price.
2 years about 14k miles, no issues.
In hine sight, I may have gone with the original two pipe system with 200 cell cats instead of Xpipe.
There is a loss of seat of the pants torque at low end, but at high rpms it works very well.
Thanks for the input. I was toying with the Xpipe idea as it isn't that much more more money but right now my 3.6 makes pretty good low end torque, I would hate to loose it. I have a 987 Boxster S and the torque difference is pretty significant, I don't want to have a similar torque curve on the 996.
I had the TopGear 200cell x-pipe but went back to original due to serious loud drone at 1800-2500rpm under WOT.
I upgraded to the x-pipe together with their headers. So I cannot say if it is the cats or headers that caused the loud droning. Or that the cats amplified the sound of the headers to a drone level.
I also run an IPD pcompwtition plenum which deletes the Helmholtz resonator in the air box. Could also interact sound level wise. Further I did not have the patience to investigate, and to spent hours in swapping them, trying all possible combinations. The car is my daily driver and I wanted to protect my ears asap.
The high rpm sound of the x-pipe is indeed fantastic. I suspect the low rpm performance can be solved with a personalised tune.
I find it strange that after the group buy of the 200cell x-pipe here on the forum there is almost no feedback to find. I hope they are not so negative as mine.
But still their build quality of the headers and x-pipe convinced me to try out their crossover style 200cell cats. I received them last week. At least they look great.
Installed. Fitment was spot on, a bit louder (raspier bark) then stock and pulls better at high rpm and seems to rev quicker. The guts inside my driver side cat had come loose and was hitting the sensor, I'm sure that wasn't helping performance either.
One thing to note, the rear 02 sensors go right inside the stock cats, but on these they go downstream. Because of this, the wires can't stretch far enough to mount them in the correct pipe, so now my bank 1 sensor is in bank 2 and vice versa. Just have to remember this if I get a corresponding code.
Mine were the same way with the O2 sensors. I've been running a set this summer and am still very happy with the purchase! A bit louder for sure, combined with PSE the sound is amazing!
I wish I would have pulled the rear bumper when I installed mine! Probably would have taken the same amount of time.
I have a 2000 C2. I am running TopGear 200 Cell cross pipes with FisterD cans. I am impressed with the quality of the cross pipes. Installed with no CEL issues. I have about 500 miles on the setup. It is a bit loud (from outside the car) but no drone from inside the cabin. Below is a video of installation and startup. I did have the car's ECU flashed / tuned on the dyno.
https://drive.google.com/file/d/0Bwm...ew?usp=sharing
Post on Tune / Dyno Results
https://rennlist.com/forums/996-foru...zu-tuning.html
Mine has the Gundo PSE and sounds great too!
I can have the bumper off in less then 15 min it's not worth it to have it in the way. Just have to be careful to not damage it.
I have the 200 cell X pipe with headers and PSE and have no drone or CEL.
Under 3K rpm timid driving, leaving the neighborhood, have my wife in the car, granny driving mode it's quiet and docile sounding.
But full throttle and above 4K rpm it just screams and it's intoxicating!!!
With windows closed at normal highway driving the sound is barely noticable.
Build quality and install was above expectations.
Mark
You connected the bank 1 sensor to bank 2 cat and vice versa? If true, this will completely screw up the engine management because the DME will monitor the bank 1 o2 level based on the o2 reading of bank 2. Makes no sense.
I didn't switch the primary O2 sensors, it was the secondary ones. The secondary just monitors the cat performance. My primary sensors that report the mixture to the DME are on the correct sides.
I understand that but the rear O2 sensors also affect fuel trims. When the DME runs the cat tests, it looks for correlation between the two pre and post cat O2 sensor signal on the SAME bank.
Sorry, you aren't correct on this one. The rear O2 sensor signal stays at a pretty consistent voltage if the cats are working correctly. If the voltage starts to oscillate like the pre-cat O2, it will trigger a CEL for cat efficiency when it passes a specified threshold. If the voltage is consistent but low, it triggers a CEL saying the sensor is aging. That is all it does on a 996. They are there only to monitor the cat performance and the signal is not processed to determine fuel trim. If the AFR is completely out of whack on one bank (enough to overload the cat and throw a code on the rear sensor) there will be a corresponding code on the front sensor. On newer engine electronics the rear O2 has a small effect on fuel trim, but the 996 and 997.1 DME isn't advanced enough for this.
Of course, this situation isn't ideal for diagnostics, I would like to have them on the correct sides. I may make up some extension pig tails to correct this over the winter.
The bold part above is correct and that's the general common understanding. You forgot one basic assumption though. Do you know HOW the DME detects the bold part above? By comparing bank 1 precat signal with bank 1 postcat signal. Not by comparing bank 1 precat bank 1 with bank 2 postcat like you have now. Each bank performs the cat/O2 sensor responsiveness test independently. Don't take my words. Just hook up an OBDII scanner to read the four O2 sensor signal (with them connected correctly) while you're driving the car. From time to time, when you stop at the light, the DME will go full lean for a few seconds ON ONE BANK and then it measures how the O2 sensor and cat reacts ON THAT BANK. This is done per bank independently at different times.
Also, each bank precat O2 oscillates independently as well.
Yes, common understanding is only the precat are responsible for fuel trim. This is correct. However, when the DME doesn't like the postcat readings, it WILL alter the long term fuel trims (adding more fuel). You will observe this when your cats are marginal. That's why it's important to make sure the DME is getting the correct signals from the correct sensors.
Anyways, I'll stop here before getting too technical. Your situation is not ideal for the DME operation, in addition to not ideal for diagnostic. In fact, the diagnostic maybe all wrong because you're feeding the wrong info to the DME.
I was able to install the sensor in the correct spot. You need to cut some tie wraps and reroute the wires. As I recall the wiring on the passenger side was barely long enough but plenty of length on the driver�s side. You do need to pull the entire airbox to get to the wiring.
I have them, they sound good and power increase was noticeable. They caused o2 sensor CEL. Replaced both o2 sensors no change. Then installed o2 sensor spacers, that took care of it.
I routed mine to the correct locations as well. No CELs for me.
The only increased "power" I have noted is the bark at WOT. Don't get me wrong, the increased porsche-y noise was worth every penny.
This. I�m not a butt dyno expert, but I didn�t sense any power gains. I did get a little more aural bliss and I saved a ton of cash over other options. I know by going 200 cell they won�t last 85k like the OEM ones did, but I can live with that.
Just to be clear, I also have fabspeed headers and a k&n intake. I noticed a difference after installing the xpipe. I know subsequent posts are attempting to throw shade at my claim, so there's some more context.
I understand your point, but unless you measured a difference, then you can�t quantify it. That means the difference may be largely emotional. Cars and modifications are subjective and emotional unless measured. It�s not even hard to measure, but most never do.
I didn�t feel any substantial differences but I could hear some difference. My emotional calibration is lijely very different from yours.
There is a direct correlation between emotional calibraton and $$$$ spent too.
Emotion = $$$$ spent. Point proven.
What did you measure?
No this post was about my experiences in this business and hobby. It�s emotional, I get that. You do too, you just aren�t prepared to acknowledge it.
Did you dyno the car? Did you time it? Did you verify top speed before and after? Did you measure airflow at various loads and rpm?
No it feels better to you. That might be worth double the money to you, but it�s a subjective improvement.
Want to double down and get more upset about it? I said I don�t have a calibrated butt dyno, and you attempted to explain yours. That comment wasn�t directed at anyone, you just took it that way.
After countless car mods and trips down the 1/4 mile I learned $$$$ spent and mods are often nothing more than placebos. I learned it the hard way. A lot of common knowledge is just wishful thinking.
This is what I dislike about rennlist and all social media. I was actually asked to post here again to quell misinformation. I now remember why I stopped. Thanks for that.
I�m sure you�ll get even angrier just to show how mean and wrong I am. I challenge you to measure something instead.
My car felt stronger with the 200 cell cats. So does my Turbo. Aftermarket cats flow much better then stock at the expense of longevity. But for a weekend toy that�s a fair sacrifice.
My .02$. Take it or leave it. I have an 04 C4S cab 67,000 miles. Its the slowest of the 996's due to weight. When i purchased it was a very quick car to me and was bone stock. I have added a fabspeed intake, fabspeed maxflow mufflers and an RSS under drive pulley. All months apart. I noticed no difference other than noise (except pulley of course). All these manufacturers claim power gains. But they are so minimal it would be impossible for our butts to notice. Another member of the forum posted a recent thread
Here
. I am no engineer. But i did the test that he was asking and posted my results. My results posted higher than most and infact doing the math they claim, my potential hp would match very close to the manufacturers claim. I think most people expect to "feel" an extra 10 to 20 hp. But in fact it is highly unlikely you will. Not to mention i believe whatever hp claims come from a manufacturer need to be cut by 30% to see real numbers.
I installed the Top Gear 200 cell x-pipe and sport sound mufflers. I did not go w/ headers.
The exhaust was installed w/ several other mods: TuneRS under drive pulley, IPD Comp Plenum & 82mm TB, BMC filter....so it's impossible to tell what added what. I will say I like the sound and performance was up significantly.
