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Discussion Starter #1
Has any (else) experienced a P2099 (mixture too rich) error in their GT4? I have Fabspeed headers, but they have been on for over 8000 miles and the error has only appeared in the last 1000 miles.
Thanks,
Phil
 

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Has any (else) experienced a P2099 (mixture too rich) error in their GT4? I have Fabspeed headers, but they have been on for over 8000 miles and the error has only appeared in the last 1000 miles.
Thanks,
Phil
Depending on how rich your car is running, it can kill the cats. Unburned fuel getting into the converters can over heat and coat the catalyst with carbon. That is what killed my first set of headers. I caught it just in time to save the second set of headers.

Hopefully it is just an O2 sensor gone bad or the O2 sensor adaptation needs deleted. Other than backpressure in the muffler, this is what appeared to fix my car recently. It takes a PIWIZ II to delete the adaption. With the PIWIZ, you can look at local values and the lamda readings at idle should run near 1.0. I think my car ran 0.9785 after the O2 sensors were changed. To get air fuel ratio multiply the number by 14.7.

Years ago, O2 sensors had a 30000 mile life. Over time, moving them from the heat of the manifold (cast iron ones, anyway), adding heater coils to maintain a fixed temperature and determining how an O2 sensor ages, allows the ECU to adjust the response curve as the senor ages to allow it to be used longer. Sometimes that adjustment (adaptation) gets out of whack and simply needs reset. The adaptation should always be deleted when the O2 sensors are changed.

V6
 

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Only have about 2100 miles, but have not seen any codes. I assume a CEL caused you to look at the code? I also have Fabspeed sport headers, but probably only 500 miles or so on them.
 

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Depending on how rich your car is running, it can kill the cats. Unburned fuel getting into the converters can over heat and coat the catalyst with carbon. That is what killed my first set of headers. I caught it just in time to save the second set of headers.

Hopefully it is just an O2 sensor gone bad or the O2 sensor adaptation needs deleted. Other than backpressure in the muffler, this is what appeared to fix my car recently. It takes a PIWIZ II to delete the adaption. With the PIWIZ, you can look at local values and the lamda readings at idle should run near 1.0. I think my car ran 0.9785 after the O2 sensors were changed. To get air fuel ratio multiply the number by 14.7.

Years ago, O2 sensors had a 30000 mile life. Over time, moving them from the heat of the manifold (cast iron ones, anyway), adding heater coils to maintain a fixed temperature and determining how an O2 sensor ages, allows the ECU to adjust the response curve as the senor ages to allow it to be used longer. Sometimes that adjustment (adaptation) gets out of whack and simply needs reset. The adaptation should always be deleted when the O2 sensors are changed.

V6
Do you know if this can be reset with a Durametric?
 

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You could try a cheap OBD reader or your ScanGauge to see if it clears. Most auto stores will do it for you in hopes of selling you replacement parts.
 

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I would buy the Cobb Accessport V3, log some data, take it to a dyno and tuner, get rid of the codes, fix A/F ratio if there is a problem, and have a smoother running car after.

Really, the thing is amazing.
 

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catted headers + frequent track events will eventually lead to blown cats, which will cause A/F values to be thrown off.
 

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Discussion Starter #9
Shop pulled the engine cover yesterday to find noise (rattle) coming from front near crankshaft. Associated with weird A/F adjustments by computer, but no obvious cause. No problems with exhaust, vacuum, intake, etc. Next stop is Porsche dealer...
 

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Wow, sorry to hear that, Phil.

Hopefully it is something run by a belt that can be easily fixed. I don't want to imagine if it isn't external.

V6
 

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I got P2099 today driving from work to home to get ready for a DE event. Fabspeed sport headers. About 4700 miles. Phil-->I recall seeing another thread where you put stock headers back on. Did you do anything else? Dare I take car to a DE event tomorrow that I have already paid for? The warning says the car is driveable. BTW: it is cold here (for NC) - I have read some things in the past (don't recall details) about O2 sensors not coming up to temp fast enough or maybe too fast and computer thinks there is an issue.
 

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Check the torque on your header bolts. Too long a story to relate here, but Phil & I had the very same issue. If you used the composite gaskets sent with the headers when you purchased them, it is quite possible you have loose and / or missing header bolts. Solution is to get new metal OE gaskets and have the headers properly re-torqued.

PM me (or Phil) if you want all the details.

Bob
 

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Check the torque on your header bolts. Too long a story to relate here, but Phil & I had the very same issue. If you used the composite gaskets sent with the headers when you purchased them, it is quite possible you have loose and / or missing header bolts. Solution is to get new metal OE gaskets and have the headers properly re-torqued.

PM me (or Phil) if you want all the details.

Bob
Bob - Thanks sooooo much! That was the issue. I have been running around like a chicken with my head cut off today. My trailer brake controller mysteriously quit working and then I got a CEL! Can't user the trailer so I have to drive to VIR.

Anyway on one side I had lost 5 of 9 header bolts! Luckily I hoard old bolts so I had some replacements. I'll run with the current set-up this weekend and get new gaskets next week. Will the code clear itself or do I have to?
 

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Discussion Starter #14 (Edited)
Grand-Cayman: The problem both Bob and I discovered is that once the composite gasket from FS is compromised, it doesn't matter how much you re-torque the header bolts, it's shot. You must replace the gasket with a new OEM metal gasket, and follow the correct torquing protocol. (torque using two-stage process, 11ft-lbs stage one, then 22ft-lbs stage two, in the correct order.) Whether you should run a DE with a compromised gasket is up to you. Personally, I would not do it. Also, you can only reset a 2099 with a Durametric, Cobb, or PIWIS. It will not reset itself. I ran stock headers with metal gaskets for 2000 miles, no CEL, then have had the headers on for another 2000 miles, no CEL. I checked the header bolt torque just last week -- perfect!

BTW, all my problems were due to the gasket and loose bolts. The rattle ended up being a lost nut loose in the undercarriage, hard to locate.
 

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Grand-Cayman: The problem both Bob and I discovered is that once the composite gasket from FS is compromised, it doesn't matter how much you re-torque the header bolts, it's shot. You must replace the gasket with a new OEM metal gasket, and follow the correct torquing protocol. ...I ran stock headers with metal gaskets for 2000 miles, no CEL, then have had the headers on for another 2000 miles, no CEL. I checked the header bolt torque just last week -- perfect!

BTW, all my problems were due to the gasket and loose bolts. The rattle ended up being a lost nut loose in the undercarriage, hard to locate.
Okay, thanks for the info. I'll see if I can jack the car up in the morning and check the bolts, but I suspect they are okay with just a couple hours driving. There's a guy here with a PIWIS and I'll clear the code as well.
 

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Discussion Starter #16
Good to hear. Did you install new OEM metal gaskets? If not, you will continue to have problems. Both Bob and I re-torqued the bolts using the 2-stage method, and still got the code. Sometimes it took 50 miles, sometimes 500, but it came back. The only permanent solution is new gaskets.
 

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Good to hear. Did you install new OEM metal gaskets?
Not yet, but the code cleared itself sometime over the weekend. An instructor had a PIWIS and I was going to try and use it, but ultimately did not need to. I'll order those gaskets from Suncoast this week and get them in asap. I'll swap the bolts out from the funky 6-point star design as well since I've lost a few of those.
 

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I was considering the Fabspeed exhaust. Did any of you guys that have had this issue reach out to them regarding the gasket failures? I would hope that they are now using metal gaskets on new installs. What is your verdict on the Fabspeed setup generally - worth the price? My car is so far bone stock, but I've previously owned a 600WHP GT-R so I'm not opposed to adding some mods that legitimately (and relatively safely) boost performance.
 

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Did any of you guys that have had this issue reach out to them regarding the gasket failures? I would hope that they are now using metal gaskets on new installs. What is your verdict on the Fabspeed setup generally - worth the price? ... so I'm not opposed to adding some mods that legitimately (and relatively safely) boost performance.
John at FabSpeed is familiar with the issue, but I am not sure if they have changed or not. Funny, this morning I just read a post on Rennlist that Fabspeed has the best gaskets you can get! Since I installed mine, I also learned (John knows this too) there is a preferred bolt install/torque order and a torque-loosen-retorque protocol that Porsche recommends.

I love the sport (200 cell cats) headers - they sound great, and I believe worth the price. A couple weekends ago we had more than a dozen GT4s at VIR, and I had a guy come up to me asking why my car sounded so good compared to the others! :) As far as I am concerned it is a solid add-on that is very easy to do yourself as long as you can get plenty of room under the car, and it boosts performance some.

If you get headers, as a last step do a good cleaning of the pipes so when they change colors you don't get fingerprints like I have on mine!
GT4-torque-order-header.jpg
 

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Fabspeed was very helpful in helping get the problem properly diagnosed - they directed me (us) to a local dealer of theirs and arranged for the diagnosis. This very same issue (this same code, loose and or missing bolts) has shown up for several posters us here, and Dr. Phil & I went thru this with Fabspeed at the same time. I had multiple discussions w/ Fabspeed during the diagnosis and have subsequently suggested to them that they stop sending those composite gaskets and specifically direct the use of only the OE gaskets. You should call them to see what they are now saying about this issue & regardless, if they show up with the composite gaskets, throw them away (the gaskets, not the headers :hilarious:).

Their headers (I have the catted "sport" version) are truly a GREAT addition to the car. They just sort of "wake up" the engine. Much improved in the RPM range of the infamous "torque dip", better midrange torque, and a truly transforming improvement to sound. I believe this is generally felt to be the best first mod to the GTS / GT4 platform. I also understand that a pro-tune further optimizes the header installation, but I haven't done that yet.

If I had it to do all over, the header installation would still be the #1 mod, just use the OE gaskets and rigorously follow the bolt torqueing sequence.
 
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