1999Porsche911

I would first check the wiring for the o2 sesnors. You may have a pinched wire causing them not to heat up fast enough.

The sensitivity and range of the oxygen sensors is such that they are used only in an OFF/ON sequence. At idle the engine ECU continuously modulates the A/F mixture slightly above to slightly below the target, the ideal A/F mixture from the standpoint of minimizing emissions deemed harmful to the environment. So at idle the exhaust flow alternates between absolutely NO oxygen content and the base minimum. In short the output of the oxygen sensor, ideally, will vary up and down continuously as a function, and in sync with, the modulation of the intake A/F mixture. There are actually two parts, components, to the MAF "module", the mass airflow sensor and the IAT, the intake air temperature sensor. Colder air is denser air and at low intake flow volumes, near idle, the IAT plays a bigger part in the computation. Not to say, by any means, that it isn't always a part of the computation. As you open the throttle initally above idle, and then more and more, provided the engine is under load, the A/F mixture will begin to move away from the ideal A/F mixture insofar as emissions are concerned, and into the region of higher, richer, A/F mixture ratios wherein the oxygen sensor becomes totally and completely useless. The engine is now operating "off-the-curve" of the oxygen sensors sensing capability. It is in these conditions that the MAF/IAT module signals come into play for controlling the optimum level of fuel to mix with the intake airflow volume. As a trial I have inserted resistors in the IAT circuit, series and parallel (at different times) to modify the intake sensed temperature above and below the actual intake temperature, ~72 actual to 92F "sensed", and 72F actual down to 45F. False sensed voltages were verified via AutoTap's OBD-II scanner/reader. There was never an indication that the engine ECU "knew" or detected the flawed intake temperature signals apparently accepting them as "true" readings. The test runs, typcally over 400 miles of highway driving at a reasonably constant ~70MPH, of the vehicle in question, a 2001 AWD RX300, resulted in no meaureable difference in average MPG with the intake temperature falsified above, below or with actual sensing. But I fully believe that had I tested on a dyno the available engine HP output would have changed in the range of +/- 10% or more. So the IAT false "cold" modification that resulted in an even richer mixture than the factory default target would have undoubtedly shown itself at track time. The on/off your referred to regarding the O2 sensors if determined by whether you are in closed or open loop at the ECU. If your are in closed loop, the O2 sensors are never off but are increasing and decreasing in current in response to the mixture it reads. These adjustments are fed into the fuel LTFT. At idle, closed loop, the amount of fuel injected is a combination MAF, O2 sensors and LTFT. The MAF has no way of controlling the PROPER air/fuel ratio in the engine other than what has been mapped into the ECU. At WOT, if the MAF for some reason is reporting the incorrect amount of air and temperature (in cases where you have an intregrated MAF/IAT) then the incorrect reading will NOT be adjusted for by any other engine sensor. Modifying the air temperature reported to the ECU will also effect the engine's timing and this has been a method of fooling an ECU for years. Remember, the O2 sesors are always controlling the fuel/air mixture except in open loop (near or at WOT) whether under load or not. It's a fairly efficient method of contolling the mixture.

The MAF reading is used by the ECU at ALL times the engine is running, whether at idle or at WOT. The MAF measures the amount and temperature of the air passing by it and in turn, the ECU (based on it's mapping) decides how much fuel to inject into the engine. During times where you are not at or near WOT (closed loop), the O2 sensors then sense how rich or lean the burnt mixture was and will adjust the amount of fuel injected to obtain the proper Air/Fuel balance. As long as the O2 sensors remain within range, there should be no CEL. At or near WOT, the car goes open loop at which time the readings of the O2 sensors are ignored and the amount of fuel injected is controlled only by the MAF readings alongs with the fuel maps of the ECU. The O2 sensors continue working, but do not make any adjustment to fuel.

Yeah, the European flash ignores many of the sensors (as far as emission faults are concerned), where here in the US, we have all the bells and whistles. However, the US chips can be reflashed with the European program if you don't mind not being able to pass emission testing and can find someone willing to break federal law.

Double check that all cables are secured properly to the CORRECT coil packs for the plugs.

If the noise is coming from the bellhouseing are, it is obvious that the dealer needs to rear it apart again, at their expense and make it right. There souldbe no question of that from the dealer. You paid for, and they claimed to have fixed and nstalled a new clutch. This requies them to deliver a properly running system to you. If it is a 99 or early 2000, make sure that they completed the TSB regarding a bad release lever for the clutch. This, by itself will casue lots of noises.

Your first gear limit with those tires at 7300 is 40.89 mph or 65.81 kph. Third gear at 6000 rpm will give you a speed of 84.46 mph or 135.93 kph. At 4000 rpm in thirid, your speed is 56.31 mph or 90.62 kph. OR: At 7300 rpm, maximum speed is as follows (MPH): 1st - 40.89 2nd - 71 3rd - 107.76 4th - 128.03 5th - 153.14 6th - 185.95 and if you want to have some fun....reverse maximum speed would be - 44 mph.

On the 996, it is NOT normal to have the fan on all the time. I am not familiar with the operation on the 997, but I would be very surprised is the fan was designed to be running at all times. It would interfere with engine warmup on cold days. Check your relay's map. If there is a relay for the fan, then it is there for a reason.

You will also have to consider your tire size to accurate calculation.

The MAF and related componants are designed to operate in a specific range, If the MAF operates outside this range, it WILL throw a CEL. If you do not have a CEL, either everything is working right, or the bulb is burnt out. When the MAF gets close to it's limit, but not enogh to throw a CEL, you may experience slight idle roughness and hesitation from stop which many times can be corrected by cleaning the MAF.

I agree that not have a front splitter will make a significant difference in the floating of the front end. I removed mine a few years ago because of damage and I could not believe how much more unstable the car was at 130+. Put it back on and the front end stayed down. Also make sure the body of the car is sitting as designed. If you have non standard size tires/wheels on the car, make sure the difference between the front body height and the back, is as specified.

Not necessary since any water that gets in will drain from filter housing anyway. Howver, the proper response to your dad would be something like: "great idea Dad, you are soooo smart".

One of the worse potential results of too much oil is foaming of the oil in the crankcase. This will not allow the thin oil film to properly form between the crank bearings and journals, which can result in a quick and complete destruction of your lower end.

ALL upshifts to ANY gear should be as smooth as butter and should be able to be accomplished using one finger or there is somethng wrong. All down shifts at a reasonable speed should also be smooth. 1st gear may be slightly harder until vehicle speed drops down to below 25 mph. People that claim that a stiffness or notchiness is normal are in denial that there car has a problem. If your transmission is not shifting smoothly and easily on a warmed engine, keep bringing it back to the dealer until it does. Most likely shifter cable(s) need adjusting. Just because something may be common does not mean it is normal.

It is not what you would call the 'hotter months' here in the UK (it was snowing lightly today), but I see 1.5 bar at idle when engine is warm independant of the weather. However it does sound as if I should not worry too much about 1.5 bar. Thanks. I was reponding to rcg412 who lives in NY and experiences 1 bar in hot weather. Definately too low. 1.5 bar as a low is fine.

I am not positive, but when it is very hot outside and the car is hot I believe I have seen the needle at 1... If you're running WATER (I mean 0W40), you can easily see 1 bar when the oil temp gets above 230F. Get rid of that weight oil if you are using it and move up to the proper weight oil in the hotter months. (15W50).

Like the oil level in the engine; if you have to much oil, it can start to get airated which is not good. It also puts additional drag on the gear rotation.

The purpose of the location of the fill hole is to insure that the correct amount of lube is put in the tranny, and NO MORE. Whether it will take 2.5 liters or 3 liters, IF the car is level, ALWAYS fill it to the bottom of the fill hole. If you want to be sure or the car being level, jack it up and remove the fill plug. Insert your finger and make sure the lube is right at the bottom of the hole. WORSE than putting too little lube in, is putting too much. The fill hole is positioned so you cannot overfill on a level car.

Use a butter knife or similar tool and it should pop off.

What's makes him think that they both failed? Extremely unlikely. Someone probably just read the fault codes which stated that the sensors were out of range. 99.9% of the time, this is an indication of a fuel/air mixture problem unrelated to the O2 sensors. The sensors are just telling you there is a problem upstream.

Please remember that the easy fix for a broken filler tube is simply reconnecting it with epoxy. Just clean it up, apply the glue and you are good to go.

If it's a C2, it may very well be a dirty idle control valve (ICV). Remove it from the throttlebody by removing the 2 mounting screws and spray with carb cleaner. Be sure not to lose the gasket which you will reuse.

If you are using 0W40 in areas that are not very cold, (and this also means if you park your car in a moderate temperature garage) change to at least a 5W-40. Water (or 0W) oil does not like to stay in the lifters too long and may bleed down too much (especially after a spirrited drive) when the engine is shut down. This allows the lifter to lose it's hydraulic effect for a few seconds when starting until new oil can replace the missing oil.

You should expect to get 10,000 - 12,000 miles out of the rear rubber and at least twice that out of the front. Normal based on the suspension specs.