1999Porsche911

There is nothing unique about the componants of the 996 cooling system. You are right though, some people feel compelled to use only Porsche parts, oils and other additives. I guess they just like spending money unnecessarily. Enough people must do so otherwise the Dealers would not private label these items.

The Porsche antifreeze is a private label made by ELF. IMO (and this is what I do) you can use PEAK , Penzzoil or any other major brand long life antifreeze. You should be changing the coolant every 2 -3 years to be sure long life of the system.

I have changed mine twice on my current Porsche and use whatever brand is available at the time.

Or you can do it the way I did when I was a kid and couldn't afford new brakes. Simply listen for a loud grinding sound when applying the brakes, with probably one brake grabbing more than the other, causing the car to swerve into the other lane or off the shoulder of the road. No further testing is required to be sure that you need brake pad AND rotors.

OR you can to it the correct way....as Loren and ar38070 said above.

You didn't mention which tires front or rear (or both). The front tires should be fine for 20 -30,000 miles. The rears, however, as mentioned above may get approximately 10,000 miles out of them. The wear on the rears will be in the inside half of the tire and the outside half will look fine. It is not uncommon to get all the way down to the belt on the rears. This is due to the negative camber setting on the rear.

High speed straight driving is the worse for the back tires because of this setup. During quick accceleration, the back of the car is lowered which causes the tire to lie flat on the pavement. Anything less that hard acceleration will allow the tires to ride more on the inside half.

You cannot get a long lasting tire AND good traction. A trade off has to be made. I have tried all the popular tires out there and have settled for the Bridgestone Potenza RE 750. I have yet to find a better traction street tire, hot or cold, wet or dry.

You might try a wood shim betwwen the windshield and the dash. (cover it with cloth) I have never had a problems with the Porsche, but have had one with other cars and found that the Dash was rubbing against the windshield. The dealer was able to fix it.

There is no harm to the engine whatsoever. It may not be necessary, but in no way hurts the engine.

Whichever one you decide on, it is imperitive it allows you to view the live readings of the sensors. This would include fuel trim, O2 voltage, MAF, engine and engine compartment temps, timing, engine load, rpm and throttle position. Documenting normal ranges of these readings will greatly assist you in identifying causes of any future problems.

Hook your scan tool up to the car and see what the Throttle sensor read when the pedal is fully depressed. Should be 100%.

Stock 18" all around. 225/40 up front and 265/35 rear. These tires are the best I have ever driven on. Excellent in the dry or wet. As with all excellent traction tire, do not expect to get much more than 10,000 miles out of the rears. Should get 3 times that amount out of the front on aggressive street driving. A buddy of mine replaced his stock Vette rubber with these and his traction (although the Vettes traction sucks by design) is like the difference between wet and dry pavement.

If your looking for smooth ride and the best traction, stick with the softer rubber compounds.

Carefully check that none of the electrical wire are touching the exhaust. O2 sensor wires in particular.

I would fill up the coolant resevior and NOT drive to the Porsche dealer. Drive if for a few days and see if the level goes low again. Might have just been a big air pocket that corrected itself.

Make sure cooland level is correct and properly bled. An air pocket can cause the gauge to read improperly. I doubt you coolant temp is as low as the gauge indicates. You may also try resetting the computer, Many times I have gotton screwy gauge readings and a simple computer reset fixes them.

You may have a bad cell in the battery. Like suggested above, swap battery with one of your other cars and try it for a few days. Or just go to Sam's Club and get a new $50 battery.

It is not normal, but I understand very COMMON. As long as you maintain the proper oil level, it should not pose a problem. However, regardless of what Porsche or other's say, the engine is NOT designed to burn oil. 45,000 miles on my engine and never add any oil between changes.

Loren is correct that you must disable the pump using the dme. You also will lose control over the changeover valve that controls the resonance valve in the intake. You will have to find some other way to properly control this valve if you want you engine to have the proper power curve. Without it, the performance will suck.

Disabling the secondary pump relay will also disable the changeover valve operation and improper operation of the resonance valve will occur. This will greatly change for the negative the power curve of the engine. The removal or disabling of this relay will also cause a CEL

There is absolutely no reason to disable the air pump as it only operates at cold starts for a few minutes.

If, however, you do so, you will need to design an alternative method of operation of the resonance valve, or just accept the reduced performance of the engine.

What is the outside temperature?

Go out and drive the car a while after you reset the codes and dsconnect the MAF. Yes it is perfectly safe to run without the MAF. The reason you are resetting the codes is to get rid of the 1123 and 1125 DTC's that are recorded in the computer. You will immediately get a CEL for the disconnected MAF, but if you don't get the 1123 and 1125 codes, it may mean that the MAF is the problem. You may still get all the eror codes back.

I would still clean the MAF and double and triple check for vacuum leaks. If any work has been done on the engine, a hose may have been dislodged. A specific connection to check is the "Y" connection way back on top of the engine on the driver's side. If you take a flashlight and look back there, you will see that one of the black plastic (very thin) vacuum lines that is connected to the "electric/vacuum" controlled changeover valve (located directly behind the alternator) is connected to a rubber "Y" union. The other 2 ends of the "Y" should be connected as follows: 1 to a vacuum canister on the left and the other to a hose that has a check valve inline. Many times I have seen the connection to the vaccum canister disconnected. This will effect the operation of the engine very slghtly, but will increase the richness of the engine.

Another way to test what is causing the error code is to partially block the air filter. By reducing the amount of air that can pass by the MAF, you are artificially recalibrating the signal the MAF send to the computer. The computer will now be told it is getting less air and therefore will reduce the injector time, allowing the O2 sensors to operate in proper range.

Bridgestone RE750's all around. No better traction available.

Apparently your engine is running rich on both banks. Could be caused by a vacuum leak. Check all connection and vacuum pressure. I know you already checked it, but make sure the gas cap and seal is good and tight.

Also, you might try resetting the codes, disconnecting the MAF and seeing if the 1123 -25 codes come back on, You WILL get the CEL because of the MAF being disconnected, but you might see that the O2 sensors will adjust the air/fuel ratio correctly using the standard DME fail safe. If this happens, then you can assume that the MAF is faulty and reporting too much air flow to the computer. Try cleaning the MAF.

Let us know what happens.

The only real way to see if a higher octane will increase performance is to look at what the computer is doing to the timing at WOT. Take a reading of the timing on regular fuel and then with the 100 octane. If for some reason the computer is retarding the timing with the regular fuel because it is too low an octane, you will see and higher timing with the 100 octane. If you don't, you most likely will not benefit in performance with the more expensive gas.

I agree with what you said about aggressive driving when engine is cold. Although there may be a design problem or improper fit of the Crankshaft Main Bearing Seal, I do believe that aggressive driving before the engine has warmed up to operating temperature may contribute to failure. Both the engine and seal will sit more tightly when it is warm than when cold. Increased pressure on the seal when cold may push some oil past the seal and eventually cause a permanent leak.

I am, however, just guessing here since I have not had any problems in 45,000 miles. I NEVER drive the car aggressively until the engine reaches 180 degrees +.

Get a reader that will not just read the codes, but will show you the readings of each sensor.

To solve the problem at no cost, simply drive the car the way it was designed to be driven. Spirited acceleration to 5,000 rmp before shifting and you will not notice the "blip".

If you simply slip the tranny into neutral when approaching a stop WITHOUT TOUCHING THE CLUTCH, will the car stall? Is the stall happening when applying the brake at idle? Thinking vacuum leak here.