993 Faq Frequently Asked Questions about the Porsche 1994-1997 993


RS pulley update

Filed under: Engine — Jeff 993TT @ 4:22 am

In the 993 RS cars, there was only 1 pulley which drives the alternator and fan. In normal 993 cars, there are seperate pulleys.

If you are changing your belts, I would strongly recommend upgrading to the single pulley instead. Instead of spending $60 for the updated pulley halves, you could spend $100 and get the RS pulley instead.

Easier to replace the fan belt if it should break. Can _actually_ be done roadside because it uses ordinary metric bolts instead of impossibly small 5 mm allen head bolts.

Usually, when the alternator belt breaks, it takes out the other 2 belts ( fan/AC ) With 1 less belt, this possibility is reduced.

Cleans up the engine bay

Spins the alternator _slightly_ slower. So there is a therotical decrease in charging time. However, of the many people on the board who have done this, none have had any charging issues.

Here’s a link to an alterantor DIY that we did where we also upgraded to the RS pulley.

RS pulley DIY

Note the dremel’ing that we had to do to get the existing setup off. If you look at the final pic, you’ll see that there are just standard hex head bolts which hold the fan belt pulley in place instead of those $%#^Q&* 5 MM allen bolts.

You can just imaging how impossilbe that would be if you had to do that roadside in the night.


Smoking exhaust on startup ( TT cars )

Filed under: Engine,Turbo — Jeff 993TT @ 11:07 pm

If your car starts smoking upon startup and DOES NOT go away after a seconds, you make have a different problem.

Usually, smoke starts pouring out of the left side ( driver’s side ) exhaust. White billowly clouds behind your exotic sports car. Not a good sight.

Most owners notice this after an oil change which included changing the oil filters.

Here are the symptoms:

a) Smoking on left side tailpipe ( driver’s side )

b) Small drips of oil under the right turbo ( passenger side )

c) Excessive oil in the turbo intake pipes

d) Excessive oil in the intercooler ( there should just be a very light film of oil in there. )

e) No other driveability problems, ie getting full 0.8 bar boost, etc.

f) Strong oil smell when the car is idleing or turned off after running it.

Usually, smoke in one side of the exhaust points to points to a bad turbo seal. These seals are like piston seals and DO NOT degrade over time. The normal lifespan for turbos ( which have NOT been abused or hot shutdown’d ) is about 75K miles. If you have a low mileage TT, I would not suspect faulty turbos just yet.

Here are the diagnostic procedures:

a) Drain both turbo oil tanks. You should get the same amount of oil in each. If they are drastically different, then you may have a bad turbo seal. If they are pretty much the same, then you should keep looking. Your turbos are probably fine.

b) Do another oil change. But this time, verify, I mean VERIFY that the engine oil filer ( the small one ) part number ends in 03. There was a TSB about older filters not working properly. There is a check valve in the filter which is VERY sensitive to how tightly the filter is screwed on. Follow the service manuals which state to HAND TIGHTEN, then do another full turn with the wrench. If you don’t tighten it sufficiently, then the check valve will not make contact to the engine nipple.

c) Do not overfill the engine. Fill it to the lowest twisted mark on the dipstick.

d) Use 15w50 Mobil1 oil. I can’t confirm that this really does anything, but the two times I’ve used 0w40, my smoking returned.

e) Clean out your turbo intake hoses and intercooler for any residual oil. Even if you fix the problem by using the correct oil filter or tightening it correctly, you will still see smoke if there is oil in these 2 areas.

Following these procedures, I’m smoke free. Even the smoke puff on startup is gone. However, usually, after I do another oil change, I will get smoking/oil drips again. I can never seem to get the oil level just right and habitually overfill it. DOH. The oil level is VERY SENSITIVE, DO NOT OVERFILL!

I’ve helped over 15+ TT owners fix their smoking problems with these procedures. If you’ve done all these and you still have problems and can confirm that your turbo are still good ( via the oil level of the turbo oil tanks ), then there is another solution.

Andial in Santa Ana, CA ( southern California ) sells modified turbo oil lines to prevent the oil from collecting in the turbo. They are specially modified and bent oil lines which replace the current ones.

You may be asking why is the problem happening in the first place? It appears that the turbos are lower than the crankcase. So gravity will pull the oil down and it will pool in the turbos. That is why the system of check valves is so important. That is also why using the Andial solution should work too. It just raises the oil line so that gravity will not automatically drain the oil from the crankcase to the turbo. In the 996 turbos, they have check valves in the oil lines to address this issue. Not sure why they did not design the 993 the same way.


Smoking exhaust on startup ( NA cars )

Filed under: Engine,Exhaust — Jeff 993TT @ 11:17 am

A small puff of smoke on startup is not any cause for alarm. If it does not go away after 5 seconds, then you will have to seek the advice of your mechanic.

There are many different reasons for this:

a) Boxer engine design – Allows oil to pool in the cylinders after running, probably due the expansion/contraction of the cylinder walls, allowing a small amount of oil to seep through. This has not been verified.

b) Overfilling the oil. Check the owners manual for the proper procedure for checking a dry sump oil system.


What is dry sump lubrication?

Filed under: Engine — Jeff 993TT @ 8:16 am

All 993’s utilize a oil recirculation system called a dry sump system.

A “dry” sump is an oil system where the oil draining to the bottom of the engine is picked up and put into a separate tank.

A wet sump is referring to an oil system where all the oil drains to the bottom of the engine and then stays there. It goes directly from the bottom of the engine into the rest of the oil system.

The advantages of a dry sump over a wet one is that under heavy acceleration (both in the left-right and forward-back directions) the oil is not sloshed as much, guaranteeing an even, constant supply of oil.

With a wet sump there’s also the possibility for a large amount of oil to hit the crank and possibly giving poor performance from the extra friction. Some engines that run at extreme angles, such as serious 4 wheel drive trucks need a dry sump to avoid having a lot of oil slosh into pistons.

A dry sump also lets an engine have more oil in it’s system than what could but with a wet sump. There’s no way you could get 12 quarts of oil in a chevy smallblock and have it run, but our dry sumped 993 engines take that much and they’re overall a much smaller engine.

The wet sump on the other hand is cheaper to manufacture since it doesn’t require a separate tank and a second pump.

Note: a “dry” sump is never really dry, there’s almost always going to be at least a little bit of oil in the bottom.



Engine undertray

Filed under: Engine — Jeff 993TT @ 6:13 pm

The engine undertray is a black plastic piece which covers the engine underneath the car. It is held in place by four screws. Many have removed this tray permanently to keep the engine cooler and to avoid the valve guides from excessive heat damage causing oil leaks. When the tray is off, oil leaks could also be detected and fixed immediately.

Factory sources say the undertray was equipped on cars to comply with Swiss noise laws more than aerodynamic reasons. Some say the aerodynamic reasons only apply when driving at very high speeds.

There is quite a bit of religion on this topic. Personally, I ran my car without the engine undertray.

Oil cooler fan switch

Filed under: Do It Yourself (DIY),Engine,Modifications — Jeff 993TT @ 6:09 pm

You can override the thermostat which controls the high speed oil cooler fan. The fan operates in two modes, low speed and high speed. By shorting a wire on the climate control unit ( CCU ), you can force the high speed operation.

This has been especially useful when you are stuck in a long line of traffic or when you are coming off the track into the paddock area. It’s really amazing how fast it brings the temps back down. More information about installing an oil cooler fan switch can be found here: Installation of a manual oil cooler fan switch

Before you install the switch, you will want to verify that your oil cooler thermostat is working correctly. You can find directions here: 964/993 Oil Cooler Fan Operation & Troubleshooting

If you are concerned about premature fan failure, the fan costs about $100 to replace. I would not recommend that you run all the time in the high speed mode, but, as mentioned above, during traffic and during cool down periods in the paddock, it is invaluable. Oil is the lifeblood of your engine, be sure to keep it cool!


Auxilary Oil cooler

Filed under: Engine,Turbo — Jeff 993TT @ 5:56 pm

Reducing engine temperature is essential to engine longevity and should be considered when adding modifications to increase horsepower. This is especially important for modified TT cars and cars which are tracked frequently.

Most high end synthetics will provide protection up to 310 degrees F, however, power loss will start as low as 210 degrees F. ( Just above the 8 o’clock mark on the oil temperature gauge )

Here are some popular options:

a) Turbo S oil cooler ($800) – Standard on the 430 HP Turbo S cars. Adequate for modifcations up to 430 HP.
Advantages: Factory parts, retains A/C function, easy DIY installation.
Disadvantages: Relatively small surface area, limited cooling benefit.

b) Cargraphics GT Oil Cooler ( $1500 ) – Good for heavily modded cars (> 440 HP) and cars that are tracked very hard. The Cargraphic unit is installed next to the A/C condensor.
Advantages: Argueable the best oil cooler on the market. Over 3 times the surface area of the Turbo S oil cooler. Retains A/C function. Since it sits next to the A/C, turning on the A/C acutally increases oil cooling function.
Disadvantages: A little more difficult to install than the Turbo S cooler. Possible slight loss of A/C function on hot days.

c) Cargraphics Oil Cooler ( $1000 ) – This is two turbo S coolers, one on each side. I don’t have any information on this.

d) Modified piggyback existing oil cooler ($900) – This is a custom job with custom plumbing. Martin mentioned there are some shops in Los Angeles that do this. You can find more information about that here: Rennlist Discussion Forums: 2nd oil cooler

e) RSR oil cooler – This is installed in place of the AC condensor. Obviously, you will not hav A/C operation anymore. You can contact Rennsport Systems for more information.

You choice will depend on your car type ( NA vs TT ), your expected driving and expected ambient temperatures. For NA cars, the Turbo S cooler is usually more than adequate. For TT cars, the Turbo S or Cargrahic units would be more suitable options.

Both the Cargraphics and Turbo S auxiliary oil coolers can be ordered from Carnewal.com and Rennsport Systems.

All these options mentioned are passive cooling. The car needs to be moving before it actually does anything ( with the possible exception of turning on the A/C with the Cargraphics unit installed ). If you are stuck in traffic or at a standstill, I’d recommend that you install the oil cooler fan switch. This turns on your existing oil cooler fan on when you are stopped.


How to change out the ECU

Filed under: Do It Yourself (DIY),Electrical System,Engine — Jeff 993TT @ 5:42 pm

The ECU in the 993 is under the driver’s seat.

To remove the driver’s seat, follow these instructions: How to remove the front seats

After you have the seat removed, you will see a metal cover over the ECU. These bolts are “blind” bolts. That means that these bolts don’t have a bolt head you can use a tool to unscrew them. Use a dremel tool to square off the bolts and then remove them using pliers.

After you have removed these blind bolts, replace them with regular bolts that you can use a rachet set on.

After you remove the metal cover, you will see the ECU and can remove it.


Tapping noise on startup

Filed under: Diagnosis,Engine — Jeff 993TT @ 5:38 pm

One engine modificication from the 964 was the addition of hydraulic valve lifters to the 993 engine. Advantages are they 993 owners don’t need to adjust the valves every 15K miles.

Unforutnaltey, there is increased engine noise on startup in the form of a ticking noise. If this does not go away short after running the engine or you noice a power decrease, then you should consult your mechanic.

Modifying the ECU ( chipping the car )

Filed under: Engine — Jeff 993TT @ 4:30 pm

Modifying the ECU will provide you with HP gains. How much depends on whether you have a NA (normally aspirated) or a Turbo.

A simple ECU change can dramatically improve your HP and throttle response with a TT. On a NA car, the gains are not as dramatic. For all cars, the 1996 models were the most difficult. Usually, you will have to buy a 1997 model ECU to flash.

I’ll talk mostly about Turbo cars since that is what I have the most experience with. Of the factory kits, there was the 430 kit and the 450 kit. The 430 HP kit is the same one on the Turbo S cars.

You can easily move from a Turbo ECU to a Turbo S ecu, gaining an additional 30 hp without any other modifications. If you want to go higher, the ECU can be flashed with a different map, but then you will run into problems with other subsystems not being strong enough. Main issues are oil cooling, turbos, and possibly intercoolers.

Popular tuners for ECU changes are Rennsport Systems, FVD, and Cargraphics. There are many others out there as well.


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