New Headers for my '04 S - Page 3 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Stroked & Blown · 05-29-2008, 08:41 AM

There are a couple hacks that I've seen to avoid the CEL on other vehicles.
The first one involves modifying a spark plug non-fouler to limit the amount of exhaust reaching the sensor:
http://www.energeticforum.com/renewable-energy/1387-o2-sensor-modification-using-spark-plug-non-foulers.html

http://forums.evolutionm.net/showthread.php?t=215795

Do the O2 sensors on the Box use standard threads? I assume they are std Bosch units.

The other option is to use an O2 simulator, but it looks like there aren't any available for Porsche yet: http://www.o2simulator.com/

Topless · 05-29-2008, 11:33 AM

Quote:

Originally Posted by Stroked & Blown

There are a couple hacks that I've seen to avoid the CEL on other vehicles.
The first one involves modifying a spark plug non-fouler to limit the amount of exhaust reaching the sensor:
http://www.energeticforum.com/renewable-energy/1387-o2-sensor-modification-using-spark-plug-non-foulers.html

http://forums.evolutionm.net/showthread.php?t=215795

Do the O2 sensors on the Box use standard threads? I assume they are std Bosch units.

The other option is to use an O2 simulator, but it looks like there aren't any available for Porsche yet: http://www.o2simulator.com/

Surely you are joking right??

Never mind the CEL... If the primary O2 sensors are not in and working a Porsche will run like dog doo. Kinda defeats the purpose of adding headers don't you think?

Stroked & Blown · 05-29-2008, 02:12 PM

Is the CEL issue due to the fore (header/manifold) O2 sensor or aft?
The fore 02 controls closed loop fuel trims, the aft sensor tracks catalytic efficiency and has no bearing on fuel trims. If you remove the cat between the two O2 sensors, you can use the non-foulers on the aft sensor without a problem.

Is Porsche using the fore O2 for fuel trims AND precat efficiency?
If so, is this the case for all model years, or just 00-04?

pacific986 · 05-29-2008, 08:03 PM

As to the sound vs. desnorkeling; I'd say the sound benefit from the desnokel seems to be the same and it seems like I hear it from the driver side vent not the exhaust pipe itself. I have EVO intake and no snorkel. The headers seemed to have changed the actual exhaust sound in a minor way, though I do hear a difference, and I do like it; though it is subtle. The actually throttle response seems to have improved a bit, especially at the low end. By that I mean it revs easier under load and at very low RPMs it is easier to modulate. That is what I notice more than the sight change in sound. Day 2 and I'm still happy with the upgrade.

After more research on this forum yesterday afternoon I found the link for the Durametric software. I think I will go that route if the CEL comes on.

Topless · 05-30-2008, 07:56 AM

Quote:

Originally Posted by Stroked & Blown

Is the CEL issue due to the fore (header/manifold) O2 sensor or aft?
The fore 02 controls closed loop fuel trims, the aft sensor tracks catalytic efficiency and has no bearing on fuel trims. If you remove the cat between the two O2 sensors, you can use the non-foulers on the aft sensor without a problem.

Is Porsche using the fore O2 for fuel trims AND precat efficiency?
If so, is this the case for all model years, or just 00-04?

You would get multiple error codes if the primary (fore) and secondary (aft) O2 sensors were not reading exhaust gas. Once the car is warmed up the DME switches from a generic fuel map to a tuned fuel map based on information from the MAF, primary O2 sensors, air temp, engine temp, and driving style. Without primary O2 sensors in and working the DME gets confused and might get the tuning really wrong or just switch back to a generic fuel map which would lower performance and HP. The secondary O2 sensors are for emissions only.

On 2000 - 2004 cars the stock headers have O2 sensors before and after the first set of cats. Ignoring the primary O2 sensors and CEL just doesn't work. The car runs poorly. The trick is to add high flow cats, reprogram the DME to look for new exhaust gas values so it will be able to switch to a tuned fuel map again for max performance and HP. This is best done on a dyno by someone who knows these cars well like Farnbacher Loles. Now the car will run great and pass the Smog sniff test as long as no one looks under the car. Still not smog legal by the book. In California headers are legal on "track only" cars. I don't know of any simple backyard/shadetree/over the counter solution to this issue.

97-99 cars don't have this problem due to one set of cats only. Adding headers is a simple bolt on with no tuning issues. The DME sees normal O2 sensor values and selects a tuned performance fuel map after warmup. Still not legal on street cars in California.

Jaxonalden · 05-30-2008, 08:19 AM

Topless,

I have a question for about the O2 sensors. These headers have ports for the two sensors to screw back into. Obviously the primary sensor will read normal but the secondary will be off because of the elimination of the cat. What do you think the DME will think with that info?

Topless · 05-30-2008, 08:46 AM

Quote:

Originally Posted by Jaxonalden

Topless,

I have a question for about the O2 sensors. These headers have ports for the two sensors to screw back into. Obviously the primary sensor will read normal but the secondary will be off because of the elimination of the cat. What do you think the DME will think with that info?

The secondary O2 sensors read emissions only and don't affect DME tuning. The best solution is to get them in the exhaust flow after a set of cats and eliminate all error codes. Some guys just mickey mouse zip tie the secondaries up under the car to eliminate a CEL. This works for a while. If something happens and the cats get fouled they will not know and engine damage can occur. See other posts where this happened ending in total engine loss. An expensive lesson in hot rodding.

Jaxonalden · 06-07-2008, 07:19 AM

UPDATE;

After numerous e-mails tiring explain my problem with the clearance issue and what I need done to the pipes, I think I've finally got my point across, in Chinese.

They said it will take a week and they will send me a picture. Will keep you all in the loop when the pics come in.

j.fro · 06-10-2008, 02:52 PM

After adding headers and tying up the second set of O2 sensors on my 2000 Box S, the inevitable has happened. CEL, P-codes are 0139, 0159, 0156, and 0153. Essentially, because the second set of sensors never warms up, the DME isn't happy. The car runs fine and has a nice chunk of additional power through the mid range. Burns a bit more fuel, though

.I've hollowed out the second set of cats, so I'm not concerned about those clogging and fouling, and the car is primarily for AX/spirited driving, so I'm fine clearing CEL's every now and then and getting along with it. I will be saving some cash to have the ECU remapped to make the most of things, though.
Cheers!

Jaxonalden · 06-10-2008, 06:09 PM

J.fro,

What was the reason for tying up the second set of O2 sensors? Didn't your headers come with a second set of ports to screw them into?

fu03steve · 06-10-2008, 07:07 PM

Quote:

Originally Posted by Jaxonalden

J.fro,

What was the reason for tying up the second set of O2 sensors? Didn't your headers come with a second set of ports to screw them into?

i might have a solution! I'm never seen it doen on Porsche but tuner cars
we buy a washer and screw it in along the o2 sensor.

-o2 sensor is still in and detecting
-bring the sensors higher that way it is not detecting as much exhaust fumes

it worked on many cars not sure this one
but i mean washer is like less than $1-2
why not give it a try

if it's done, let me know if it works

Steve

j.fro · 06-11-2008, 01:37 AM

My headers do have the second set of 02 bungs, but from what I understand, the purpose of the second set of sensors is to detect catalytic converter efficiency. Being in the exhaust flow but without the cats, they measure that the exhaust gases are the same as the first set and send an error code that the cats aren't working. I'll be installing them this evening to see if the result is different.

"I have not failed. I have discovered 1000 ways that don't work". T. Edison

fu03steve · 06-11-2008, 10:19 AM

Quote:

Originally Posted by j.fro

My headers do have the second set of 02 bungs, but from what I understand, the purpose of the second set of sensors is to detect catalytic converter efficiency. Being in the exhaust flow but without the cats, they measure that the exhaust gases are the same as the first set and send an error code that the cats aren't working. I'll be installing them this evening to see if the result is different.

"I have not failed. I have discovered 1000 ways that don't work". T. Edison

i have eliminate all 4 of my cats...

headers with all 4 o2 sensor plugged in and straight pipe and borla exhaust
no CEL, one thing I do not like is that it's too annoying loud...
sound like a muscle car

so I'm going to put the secondary cat back to see how it sounds like...

Jeffrey, how does your exhaust sound like with headers and bored out secondary cat??

Jaxonalden · 06-11-2008, 04:24 PM

I can't wait to get my modified header so I can play with my O2 sensors like you guys.

I think I'll just plug my sensors in and see what happens. I know J.fro said he tied his up to prevent a CEL but without them sensing something they will throw a light, no doubt. I like the washer thing as long as part of the sensing ports on the O2 sensor is out of the exhaust stream. Time will tell after I have them installed and I get a CEL.

BoxsterLewis · 06-12-2008, 10:33 AM

You guys still havent answered the question how headers compare with the overall performance/sound compared to desnorkling...

j.fro · 06-12-2008, 04:41 PM

Desnorkling= swimming in a pool
Headers= swimming in the ocean

How's that for an analogy?

pacific986 · 06-12-2008, 09:54 PM

Car threw a CEL after 250 mile ocean swim. No worries. I'll just delete it w/ the Durametric software.

BoxsterLewis · 06-13-2008, 05:15 AM

j.fro wow didnt think it was that big of a difference lol. I mean i felt a pretty nice bump after densorkle but might have to try headers if its swimming in a ocean!

Jaxonalden · 06-13-2008, 08:55 AM

Remember guys, the engine is a big air pump and the more efficiently you can draw the air in and blow it out the more power you'll make.

That’s why opening up (desnorkeling) the air intake, installing a low restrictive air filter, adding a turbocharger, supercharging are great ways to increase the intake volume. The same can be said about headers, there're less restrictive than stock and that compliments the scavenging of the cylinder to make way for the next charge. But not as much as to burn valves by not providing the proper back pressure.

Nitrous Oxide, now that's a different animal and doesn’t follow this line of thinking.

j.fro · 06-13-2008, 03:47 PM

The headers really woke the engine up, especially from 3000-6000. However, I already had better flow from modified cats and the muffler, and a less restrictive intake system (including the desnork). But, like the ocean, I'm finding that you can get into much deeper trouble. I'm chasing a CEL, but I've got a couple of things in the works... we'll see how it goes.