1999Porsche911

Short of removing the discs or pads, the way we used to do it years ago was to take a coarse grit sandpaper and sand ACROSS the disc from inside to outside. The intent is to scratch the surface which will also deglaze the pads when the brakes are next applied. However, I find it unlikely that this is causing any brake problems due to the fact that the design of the rotors should be preventing glazing in the first place. Are you saying that ABS does not kick in when the brakes are applied hard? If it does, then there is no problems with the pads or the discs. If not, could be air in the brake line. I still have the original pads and discs on my car and after 45,000 miles of hard street driving, there is no fade.

Contrary to many on this board, oil consumption is not normal for these engines or any engine. It is an indication that either PCV valve is bad, rings are bad or a problem with the valves. However, it appears that burning oil at the rate you state is common for some flat sixes. I burn absolutely no oil nor do any of the other p-car owners I hang with. Will your oil burning hurt the engine - no, as long as keep refilling the crank case. Can it be fixed - probably not without rebuilding the engine (if it is caused by valves or rings). I believe much of the oil burning is caused by improper beak in. Below is what I follow for every car I have ever owned and none of the cars have ever burned oil. Even my 180,000 plus mile Honda Accord. Proper breakin must be done in the first 100 -200 miles and below is the proper procedure: 1. Always bring engine to FULL operating temperature before high revs. 2. Drive the car easy for the first 10 miles or so, varying the rpm's from 2,000 - 5,000. 3. Then, start bringing the engine up to maximum rpm's and letting the engine bring the revs back down by coasting in gear. 4. Repeat several times in order to create maximum heat in the cylinders. 5. Drive around at lower RPM's for several more miles, remembering to vary the speed of the engine every couple of miles. 6. Repeat number 3, 4 and 5. 7. Park car and let the engine cool down overnight. 8. Repeat all the above 2 more times. Your engine is now fully broken in correctly and can be driven hard from here on. JMO and experience.

Turn your air conditioner off.

The sceen is not intended to decrease the airflow but to control is resonance. If it is removed, you may experience incorrect flow readings due to the air being to turbulent and lumpy.

You might have air in the cooling system. Happened to me right after I bought the car. Have you ever flushed the system. Should have been done at least once by now. It will clear out any clogs there may be. The fan on the trunk should not run ever, unless the engine compartment is extremely hot. The sensor is located on bank 2 (passenger side) on the top of the engine between the back 2 intake runs. It's hard to see it, but you can find it by feel. When you disconnect the wire to this sensor, (engine key on) the fan should immediately start. How is the temperature when the light comes on?

Do NOT blindly believe that code. This code quite often is caused because of something other than the camshaft. It may simply be an open circuit and NOT the actuator being faulty. The mechanic should have told you this if he knows anything about the variocam system. If the P1539 code is acurate and the cam is not shifting, you will be able to tell by the performance of the engine when you get on it above 3000 rpm's. There will be a noticable loss in power at higher rpm's. If there is no perfromance loss, ithe actualor is working and the problem is in the wiring or the sensor on bank 2.

Must be different here, regular unleaded is 92 octane, premium is 95 or 98, all from the pumps at most gas stations. He was comparing 98 Shell with 98 BP or Mobil. The drivers manual for my 99 996 C2 says 98 Ron/ should be used, 95 can also be used but the knock sensors will adjust the timing. Maybe its different in US cars. I also felt the same as you, most good brands are going to be very close, I'm sceptical when people say this ones better than that but he says his dyno tests show a difference. Theres nothing in it for him. <{POST_SNAPBACK}> Sorry...didn't see that you were not in the States. Isn't the octane rating over there calculated differently than here. I think you use the research octane (RON) rating and we use the motor rating (MON) 96 RON equals 92 MON.

In the States, all the brands are almost exactly the same for each grade. You can, however, have dirty tanks at a specific station, but, everything being equal, I don't believe you could measure much of a difference between non-racing fuel. (93 octane and below) Rattles: your guy is not measuring performance with street gas, but is using a 98 octane which is more of a racing fuel.

I thnk some people are desperate to find an answer to the occasional RMS leak, and I don't think the weight of oil you use has anything to do with it. JMO.

SPR: If that is the Hypoy C 75W-90: , that is what I plan on putting in my C2 this summer. Good stuff.

Sorry I confused you. In your example above, the first sensor you come upon when starting folloing the pipes from the headers (3 pipes joining to one), is the BEFORE cat sensor. The next one following the same pipe is the AFTER cat sensors. This is athe sensor closest to the muffler. This is the sensor in question. This is true for all cars.

No...the other one on the pipe that goes into the passenger side muffler.

P1117 is for the left bank exhaust, which is the driver's side. There are 2 sensors on each side of the car, but they are not for the same bank on the engine. The after cat sensor you are looking for is actually located on the right side of the exhaust since the exhaust exits on the opposite side of the car. The sensor is on the pipe right before it enters the right side muffler. I forgot what size wrench, but the sensor can easily be removed with an open end wrench. Let the engine cool and disconnect the sensor connector and unscrew the sensor from the pipe. Install the new one and reconnect.

Didn't you R&R the tires before replacing the bearings? Deflate tires by 15 psi and see if the noise changes.

My fault...I call that the EGR valve. That is a simple system to test. Electrically, you should hear it every few minutes when the engine is running. It makea a fast clicking sound as it is opening and closing. It connects to the cannister and to the throttlebody. The vacuum line to the throttle body has a one way valve on it so flow is only in that direction. The line to the canister should be able to hold vacuum. If not, you would look at the Operating Valve in the fender well. Possible loose ventilation lines. The only fault in the EVAP valve that would not cause another DTC would be a vacuum leak between it and the throttleody. All other defects should be reported to you either with a fault code or engine problems. I have never seen one of these valves fail.

The purge valve is in the front right fender well in front of the door.

If you read my posts, each and every one of those possiilities were mentioned. It is extremely unlikely it is fuel pressure as he has no symptoms other than the CEL. These sensors can be a pain in the *** to diagnose. Most often, the only method of identifying the problem is trial and error. Sensors are telling you that the engine is running rich and you should proceed with troubleshooting based on that fact. It is also unlikely that the EVAP system is open because of no other errors and engine operation. You have to look at the easiest and most likely things first. If it was my car, the first thing I would do is put a 220 ohm resister inline on the #4 wire of the MAF harness, thereby reducing the voltage of the MAF and eliminating the possibility that it is reporting too much air flow. If the reported air flow was too high, then this should eliminate the lean threshold error of the O2 sensors. It's an easy test and also a permanent fix of an uncalibraded MAF. Also, the specs for the idle for a C2 is 700 +/- 40 and his is fine.

Yeah because the factory doesnt know anything about the cars they build.. <{POST_SNAPBACK}> You gotta start thinking out of the box PTEC. Of course all MAF are set within the same tolerances. But lets walk you through this. What makes the same MAF read different from one car to another? Could be air filter condition. Could be engine compartment temperature. Could be the pattern layout of the intake screen. Could be difference in resistance in the main harness. Could be a slightly different idle speed. You see, there are many variables in what determines the reading of the MAF and these variable are commonly different from car to car. That is why they establish a "range" for these sensors. As far as the book you are using to get your information...if that is the book that states P1123 and P1125 means the engine is running lean, then I suggest you throw it out, because that information is wrong. Just because you read it in a book doesn't make it true.

The MAF should read below 6 g/sec on a fully warm engine and an idle of 700. This figure varies a great deal with just a slight change in engine speed and from car to car. My idle speed is 800 and I average about 7 g/sec. This is why it is important that you record the normal readings of the sensors for YOUR car before you have any problems. I have seen cars that have no problems running a high reading on the MAF and others that will generate a fault at a lower level. If you record the normal readings, then you are more abt to be able to identify the cause of the problem if one occurs. A too low of a reading woud be below 4 g/sec. If you have modified your intake system, you reading may be on the higher side of the limit. By the way, the source for all of my information is the Porsche Service Training P21 Fuel and Ignition systems book. may increase. Now you understand why many Porsche Technicians can't properly repair their cars.

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mumeh: Suggest you reset the computer and drive the car for a couple of cycles. Then, hoping the CEL has not come on yet, make a log of all the sensor readings, particularly the MAF, 4 O2 sensors, rpm's STFT and LTFT engine temp and timing....all at idle on a fully warmed engine. Then, if the CEL comes on again, make another log of the sensor readings. Your software may also give you a record of what the major sensors were doing whenthe CEL comes on. If so, report that to us also. You engine setup is completely stock, I presume? I am also curious what the MAF reading is right after startup on a cold engine.

Do not look under the car again and it won't effect you. Many cars over time will show signs of oil biuldup. It doesn't mean there is a leak. Woory about it if you start loosing oil or see drops on the ground.

Call your dealeship and ask to talk to a technician. See what they say when you tell them that. <{POST_SNAPBACK}> I really don't know what to tell you. If you are convinced that P1123 and P1125 are set because the engine us running lean, then you have been given incorrect information by someone or you hade a mistake in your typing. P1123 is for Bank 1 and the other for Bank 2. These error codes are because the sensors have reached beyond their LEAN threshold limit and the errors indicate the engine is running rich. This is not opinion, but fact. You would be wasting your time looking to solve a lean condition in your engine because you have evrything backwards. There are several books available that you can read that will explain the function of the O2 sensors, Reading them might help you understand it better. I am also sure that you could find some sites on the web that will validate what I have told you. If you got your information from a Porsche Technician, he might be playing you; or like so many of them, know little about the sensor operations on these cars.

The fuel trim reacts to many things. First off, no 2 injectors have the same flow. If the average flow of the 3 injectors on one bank in slightly higher than the DME is programmed for, then the LTFT will show a negative number on a normally running engine. If the average flow is less than expected, the LTFT will show a positive number. This is all in an attempt to get the fuel injection to what the DME wants. Basic Operation: The engine is started and the DME injects a specfic amount of fuel into the cylinders based on what it learned and stored in the LTFT tables the last time the engine was run. When the engine warms up and goes into CLOSED LOOP, This is what happens: The MAF tells the computer how much air is being ingested and the DME tells the injectors to inject the amount of fuel necessary to bring the air/fuel ratio to 14.5:1. THIS CALCULATION TAKES INTO ACCOUNT THE SETTINGS OF THE LTFT. Next, the air/fuel ratio is measured from the exhaust by the O2 sensor which will make an adjustment to the STFT to either increase or decrease the amount of fuel injected. This continues and after awhile, the STFT adjustment is transfered to the LTFT tables and the STFT returns to ZERO until further adjustment is necessary. ie. If your engine is running lean, the O2 sensor will increase the STFT by a specific amount; let's say 10%. If this increase continues for awhile, the 10% increase will transfer to the LTFT and the STFT will be ZERO. This is necessary, because a car that is started cold looks at the LTFT for what amount of fuel to use above what the DME is programmed for. In this example, if this table was not set, you would be running lean until the car warmed up and the O2 sensors could control fuel again. My car has a drastically different LTFT setting for each bank. Because I am using large injectors and therefor the flow is much more than stock, my LTFT currently read: Bank 1 -18% and Bank 2 -9.8 %. This simply means that bank 1 injectors flow more than do bank 2 and that the flow of moth banks is more than necessary for normal vehicle operation. Both are well within the -25%/+25 threshold. The P1123 and P1125 errors really have nothing to do with the fuel trim, but only with the voltage readings of the O2 sensors. The allowable voltage of the sensors is between .01 and .9 volts. If the sensor goes outside this range, a code is generated. The voltage goes lower when the fuel/air mixture is lean and goes high when it is rich. This voltage change directly effects and changes the STFT only. Higher voltage will decrease the STFT and lower will reduce it. Apparently the sensor went beyond their upper voltage limit and caused the codes. You have to remember that many of the computer generated codes do not give you the underlying cause for the error, but only a place to start looking. You CAN conclude tho, that these codes are accurate in the reporting of the operation of the O2 sensors. Therefore, because they exceeded their LEAN threshold (high voltage limit) Either the sensors are bad, or they are reading a rich mixture accurately but cannot adjust enough. So you eliminate bad sensors and then simply go through the old fashion steps of determining the many things that can cause an engine to run rich and eliminating them as the cause, one by one. Sorry for the long reply...it must be the laxative I took earlier. Hope it make sense.

In my experiance (virtually zero with generic scan tools), I have never seen a air mass reading that low, ever. Perhaps again this is just something that generic scan tools display differently than the PST2/PIWIS. Either way, the car is getting MORE air than it thinks it is as the fuel trim is in the plus. In that case, here is my question to you. If you state that 25% is the threshold for LTFT, then why does he have a check engine light and his LTFT is at 9%? I disagree. The car is having to add fuel. Look at his LTFT number, its positive. The o2 sensor is reporting a lean a/f mixture and the DME is trying to adapt by adding fuel, hence the positive LTFT number. Exactly. If the air mass sensor only reports 5 gm/s of air flowing into the engine, its only going to inject enough fuel to burn 5 gms of air. If the air mass sensor is defective and reading low, there is going to more air going into the engine than it thinks. The mixture will be lean, the o2 sensor will report this, the DME will add fuel up to its threshold, and the CEL comes on. P1123 and P1125 are the LEAN threshold, the car is too LEAN for the DME to adapt. If he had any of those problems his fuel trim numbers would be negative, as the DME would be subtracting fuel to compensate for the extra fuel that a bad evap valve, leaking fuel injector, or too high of fuel pressure would deliver. The fact this his fuel trim numbers are positive screams either bad maf or vacuum leak. Thats my two cents. <{POST_SNAPBACK}> PTEC: The "Lean Threshold" code means that the O2 sensors have reached their limit to instruct the DME to LEAN out the fuel mixture. It DOES NOT mean that the fuel mixture is lean. You are loking at these error completely backwards. The DME is being told that the engine is much too rich and the sensors cannot remove enough fuel to get it to the proper level. Each and every arguement you are making is the complete opposite of what is happening. The arguments have some truth to them but only for a LEAN running engine which is not the case here. This engine is running rich. The MAF is reporting 5.34 g/sec of air and assume that the amount of air is really 7 g/sec. The DME will inject fuel based on the 5.34 number. The O2 sensors will determine that there is actually more air in the mixture and therefore a reduction in voltage will occur (rich threshold) and the DME will increase the amount of fuel. If the sensor cannot reduce voltage enough to get the mixture correct, a RICH Threshold" code 1124 0r 1126 will occur. This tells you that the engine is running LEAN. It doesn't matter what scanning tool you use if the both report g/sec of airflow. The fuel trim varies in all cars and does not necessarily mean that there is a problem. In my car, I am running much bigger injectors than stock and therefore, my LTFT will always show a large negative trim percentage when idling than does a stock engine. The LTFT simply reports how much the injector pulse is being reduced or increased on average. THE LEAN and RICH threshold terms can be confusing. In the case of O2 sensors it means that the sensor is tring to reach the threshold and not reporting on it. When an O2 sensor goes towards the rich threshold (low voltage) it is increasing fuel and when it goes towards lean threshold ( higher voltage) it is removing fuel.