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george996

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About george996

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  • From
    Seal Beach, CA
  • Porsche Club
    PCA (Porsche Club of America)
  • Present cars
    2004 Carrera 996
    2001 E430
  • Former cars

    1977 911S
    1979 911SC
    1983 944
    1972 TR-6

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  1. Yes, the adaptation was not as negative as it was positive. However I thought it was odd that same fault code appeared and the adaptation was negative one time and positive another time. You would think that the fault would be always one or the other. With this being said, another important point is that we don’t know how much time elapsed from CEL to when the adaptation was read. We would need freeze frame data to know what the adaptation was when the fault occurred. I assumed CEL was due to lean threshold being reached one time and rich threshold reach another time. This may be an incorrect assumption because we don’t have the freeze frame info. Yes, if the purge valve is stuck open it will always introduce extra fuel because the fuel is always evaporating as you said but it also introduces air. So the question is “what is the mixture being sucked into the intake”, is it rich or lean? If the valve is stuck and not able to modulate, the mixture will high in hydrocarbons at first and leaner as time goes on. So even though the purge stream contains fuel the mixture could be leaner than the required mixture making the adaptation go towards rich. I know the DME modulates the purge valve but not sure what is looking at to control it, fuel tank pressure or oxygen sensing. My guess it looks at oxygen sensing, it keeps the valve open if oxygen senses a richer mixture and closes if it senses a lean mixture. With Durametric you can see the mass of air being measured by the MAF and the total air mass, the difference is the air through the purge valve. Interesting stuff.
  2. Glad to hear problem is solved. I was wondering why the RKAT values were negative at one time and then positive another time. You would think that the problem was would make the mixture either rich or lean but you had both. Also, I was wondering why the diagnosing procedure for listed the purge valve in only the error for “below limit”. I think I know why. When the car sits the carbon canister gets loaded with hydrocarbons from the fuel evaporating. When you first drive the car the purge valve opens and these hydrocarbons are sucked into the intake manifold and burned. Eventually, after running for a while, there are no more hydrocarbons remaining and the valve should close or partially close. If the valve is sticking open then it is the same as an intake leak and the lean threshold is reached. So that explains how the “above limit” is reached. The DME also performs oxygen sensing with the valve closed to establish as baseline mixture adaptation. If the valve is stuck open during this adaptation when the canister is loaded I can see how the “below limit” is reached since extra fuel is being introduced. It seems like the purge valve should have been listed as a possible cause on both procedures. Just something to think about!
  3. Here is the "above limit" procedure. Both P1130 faults are 361. I assume you need to read the mixture adaptation values to determine if you are above or below the limit. It would be good to see the freeze fram data that goes with the fault code. DME 7.2 OBD II MANUAL WKD 483 921 above limit.pdf
  4. hello ahsai, THe manual has two procedues for P1130, above limit and below limit. I noticed that rkat was negative so that means the dme is trying to make the mixture leaner. hence "below limit" so i attached that procedure. However, in stutzchris' earlier post of rkat they were positive which would indicate the opposite. i find that interesting. He also mentioend this problem occured after installing the aftermarket exhaust so i wonder if this included the cats and could the o2 sensers be mixed up. The mass flow reading of 19kg/hr is consistant with the high idle, 770 rpm so there is no false air. i am not sure what would cause the high idle and if it is related to P1130. i had a bad voltage regulator (low voltage) and that caused my car to idle high. any ideas?
  5. take a look at the attached. you do not have vacuum leaks becasue the DME is trying to make the mixture more lean. Pages from DME 7.2 OBD II MANUAL WKD 483 921.pdf
  6. stutzchris, so P0139 returned after tightening the clamps? I was wondering if P1128 & 30 faultes ever returned since, according to the 7.2 DME technical manual , an aging problem of the down stream o2 sensor (i.e. voltage remians below or above 0.6 volts for 80 seconds) will change the mixture either more rich or lean. I thought perhaps that P0139 was the root cause for all your CEL's. However it sounds like you had two problems. On the otherhand, when your CEL went on all three codes were present simultaneously and an air leak would not casue P0139. So perhaps P0139 was the root. Good information. thanks for the feedback.
  7. did you get any faults for the duration after you tightened the clamps but before you replaced the down stream sensors?
  8. i agree with ahsai, looks like a leak. check your oil filler cap as well. Also, idle should be about 700 rpm and the fact that you are at 780 rpm is another indication of a leak. MAF should be about 1.25 volts with about 17 kg/hr at 700 rpm. Make sure you are reading the mas flow measured by the MAF sensor and not the total mass flow which is calculated. did you change the cats? if so make sure the o2 sensors are not switched (upstream vs. downstream).
  9. Could you elaborate on the small loss in low end power with the Fister exhaust? How did it manifest itself? I don't have Variocam issues, but am considering the Fister exhaust for my '99 996. The Fister mod produces great sound, especially above 2800 rpm. However, I did notice a slight loss in power when letting out the clutch. You needed to pay a little more attention and give it a little more gas. Also, my 2004 has Variocam Plus and when the intake valves switch from small to large lift you could really feel the surge much more than with the stock mufflers. I went back to the stock mufflers and could easily notice the difference. From what I read, some back pressure is a good thing and helps low end power. Although I loved the sound made with the Fister mod I was willing to give that up for easier starts and minimal surging. I also tried 997S headers with stock mufflers and had similar observations. I ended up going back to the stock headers. Currently I am running mufflers that are completely gutted, everything inside removed. The mod was done by Hergesheimer. They produce a Ferrari-ish type sound and surprisingly are just a little louder than stock. It sings at 3,500rpms. Let me state that you will not lose power with my muffler modification. The small portion of exhaust that is allowed to bypass the muffler will not decrease the exhaust gas pressure you will see in your headers which is where hp/torque is lost/gained. Your cat creates the backpressure at the headers and changing anyhing after that (mufflers) is virtually insignificant. My modification is basically a mock version of the Porsche PSE, which also does not cause power loss. A vast majority of people running my mufflers tell me they think their car actually feels faster, which is also a placebo effect of having a great sounding car. As far as a gutted muffler goes, you have exhaust gases going into a big empty can, bouncing around, trying to find their way out, with no actual path to follow. Not a very efficient design IMHO. First of all, your modification is well worth the price and sounds great. It's a great alternative for the Porsche Sport Exhaust. Just a few comments 1) backpressure is not the only factor affecting scavenging and low end power. Gas wave behavior is a big factor. 2) The added bypass may not change the backpressure noticeably but it does change the path the exhaust gas takes and how the waves reflect all the way back to the exhaust valves. 3) The Porsche Sport Exhaust also has a control module which opens the bypass valves above a certain speed (it is something like 25 kph). I believe Porsche did this not to control noise at low speed but to preserve the low end power. 4) Lastly, my observation about power loss is a low rpm and at part load. It was very slight and hardly noticeable. At high rpm and WOT it is great. Regarding the gutted cans, surprisingly they perform very well. The sound is not as aggressive as PSE or your mod.
  10. Could you elaborate on the small loss in low end power with the Fister exhaust? How did it manifest itself? I don't have Variocam issues, but am considering the Fister exhaust for my '99 996. The Fister mod produces great sound, especially above 2800 rpm. However, I did notice a slight loss in power when letting out the clutch. You needed to pay a little more attention and give it a little more gas. Also, my 2004 has Variocam Plus and when the intake valves switch from small to large lift you could really feel the surge much more than with the stock mufflers. I went back to the stock mufflers and could easily notice the difference. From what I read, some back pressure is a good thing and helps low end power. Although I loved the sound made with the Fister mod I was willing to give that up for easier starts and minimal surging. I also tried 997S headers with stock mufflers and had similar observations. I ended up going back to the stock headers. Currently I am running mufflers that are completely gutted, everything inside removed. The mod was done by Hergesheimer. They produce a Ferrari-ish type sound and surprisingly are just a little louder than stock. It sings at 3,500rpms. I was Seriously considering the Fister mod... now i'm having second thoughts... but in all honesty my stock exhaust doesn't fulfill the sounds i need from my car! The sound is great with the fister mod. The only issue is a slight decrease in low end power. I have a set for sale. PM if you are interested.
  11. Tim, I have the manuals and could not find the allowable range for Variocam Plus. The +/- 6 is for Variocam like you mentioned. My 2004 has a bank 1 deviation of 4.14 and 0.39 for bank 2. The DME diagnostics will check the deviation and report a fault code if there is a problem. There are a handful of fault codes that deal with cam postion however it looks like P0011 and P0012 are the most relevent . George
  12. I would not be so quick to dismiss the check vavle in bank one. The info that I read describes that the function of the check valve is to assist/speed up the actuation when oil pressure is not enough to overcome the force if the vavle springs, etc.. I will try find the description and post it. variocam plus.pdf
  13. I would not be so quick to dismiss the check vavle in bank one. The info that I read describes that the function of the check valve is to assist/speed up the actuation when oil pressure is not enough to overcome the force if the vavle springs, etc.. I will try find the description and post it.
  14. I took of the oil filler cap and let the engine idle, although only for about 10 mins. RKAT went to 3, then over the next ten minutes went to 2 then 1. Note that these were ALWAYS whole numbers. In case this turns out to be an actual fault on the car, can anyone tell me what sensors drive RKAT? Is it just the O2 Sensors on that bank, or is there something else involved? Is there another set of readings I should be investigating? Thanks Graham PM me with your email address and i will send you something that explains RKAT, etc. From the data you posted, your car is running rich near idle range (i.e. negative values) and lean under load (i.e. adaption greater than 1.0). All numbers are within allowable range. You mentioned that this is not a new problem, correct? Can you describe the symptom more?
  15. Could you elaborate on the small loss in low end power with the Fister exhaust? How did it manifest itself? I don't have Variocam issues, but am considering the Fister exhaust for my '99 996. The Fister mod produces great sound, especially above 2800 rpm. However, I did notice a slight loss in power when letting out the clutch. You needed to pay a little more attention and give it a little more gas. Also, my 2004 has Variocam Plus and when the intake valves switch from small to large lift you could really feel the surge much more than with the stock mufflers. I went back to the stock mufflers and could easily notice the difference. From what I read, some back pressure is a good thing and helps low end power. Although I loved the sound made with the Fister mod I was willing to give that up for easier starts and minimal surging. I also tried 997S headers with stock mufflers and had similar observations. I ended up going back to the stock headers. Currently I am running mufflers that are completely gutted, everything inside removed. The mod was done by Hergesheimer. They produce a Ferrari-ish type sound and surprisingly are just a little louder than stock. It sings at 3,500rpms.
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