Edward Jones

thanks in advance

kj217

intake airbox->turbos->intercoolers->throttle body->intake manifold->combustion chambers->headers->exhaust

laz74

don't forget the turbos btwn headers -> exhaust

headers -> turbos -> exhaust

Edward Jones

can you describe function and location of throttle body?

can you tell me if air from side scoops to intercooler to rear bumper outlets is filtered? I had leaves in all my filters so wondering about that air path too. Thanks

Macster

The TB should be located in the large pipe/inlet just before the intake distributor (manifold). It is a large rectangular/irregular shaped aluminum casting capped on one side (the right side looking at the engine from the rear) by a black plastic (non-metal anyhow) cover.

The side scoops that feed the charge coolers (intercoolers) are not filtered.

I asked a tech about this and he said they do not pick up any trash.

They are located in a pretty clean location, unlike the radiator ducts which when the radiator fan is on act like a hoover vacuum sucking up every bit of trash on the road.

My Turbo's radiator air intakes -- and the 3rd/center radiator -- get trashy just sitting still. Every time I take the car in the techs use shop air to blow as much of that stuff out of there as possible and every year or so I have them remove the front bumper cover and do a thorough cleaning. Costs me an hour's labor but price new radiators, condensers and one hour labor is a bargain.

Sincerely,

Macster.

Edward Jones

thanks for info. I'll look for throttle body. Is it just forward of big black y pipe that sits on top of motor? What is function of it.


I assume I'll get a cel if my front radiators are clogged and motor begins to over heat. Mine must be really bad based on condition of cabiin filter and main air filter.

Macster

With the engine compartment open two rubber hoses one from each side of the engine compartment connect -- one hose each -- to the arms of the Y. Where the arms of the Y come together this single leg -- large pipe -- connects to the intake manifold.

In this area -- this large pipe -- where it connects to the intake manifold is the throttle body.

The TB is a rather unassuming piece of hardware, though of course its correct operation is vital.

What does it do? Well, briefly it is responsible for converting the direction and amount of gas pedal movement into butterfly valve direction and movement.

Press down on the gas pedal and the TB causes the butterfly valve inside it to open and allow more air to flow to the engine. More air means the DME can inject more fuel. More fuel (and air) means more torque.

Release the gas pedal and the TB closes the butterfly valve and reduces even cuts off air flow to the engine. Less air flow, less fuel is injected. Less fuel (or no fuel in some cases) means less or even no torque is produced.

Very unlikely you'll get a CEL no matter how clogged the radiator ducts get, unless the ducts are so clogged as to prevent any air flow through the radiators.

In this case, the CEL you get is like seeing chunks of iceberg on the deck of the Titanic. The car, the engine anyhow, is doomed if you see the CEL for overheating.

More likely the in-dash overheating warning light will come on/flash. Still a very very serious matter and you should strive to keep the car in good shape to avoid *ever* seeing this or any other warning light come on.

Regardless, why wait for a CEL or a warning light? The radiator ducts collects trash as the car is driven.

Clean them out unless you know they are clean. Even then every so often you will need to clean them again.

Be aware some of the worst of the trash can be between the condenser -- which sits in front of the radiator -- and the radiator. You can't remove this trash without removing the bumper cover and unbolting -- carefully! -- the condenser and swinging it (gently!) out of the way a bit to provide you access to the trash that collects between these two items.

My experience is the 996 Turbo engine's air intake is it in a fairly clean location, gets a fairly clean supply of air.

The cabin intake air filter is not so lucky.

If the cabin air filter is left in service too long the air flow into the cabin can be affected. Yet another unpleasant side effect is the thing can develop a sour/moldy/mildewy smell. The cabin air filter should probably be replaced more often than it is in most cases.

Sincerely,

Macster.

Edward Jones

great great info. Thanks so much

I was thinking that as radiator got covered the engine temp would start to go above 180 and that would be a signal that there was a developing problem. Oh well I guess I'd better learn how to get front and rear bumpers off.

Don't know if you saw my turbo leak question to you. I assume air goes from turbos to intercoolers to big black y pipe to intake to throttle body, and to combustion?

So then if I built leak tester and but it on y pipe or hose that would normally be connected to y pipe I could listen for leaks- right?

Macster

Unless you have some way of monitoring coolant temp in real time the in-dash gage is really useless for knowing much about the coolant temp.

Really the in-dash temp gage is there to fill the space between the tach and the oil pressure display.

The warning lights -- idiot lights -- are the real harbingers of trouble, but by the time you see one of those on... too late. Usually.

I've seen them come on in both my Boxster and my Turbo. In the case of the Boxster after hitting some road debris which busted a radiator and this let the coolant leak out. I coasted on closed throttle to a stop to allow what heat load the engine had to be removed as best as it could be.

I hit a deer with the Turbo with the same result. Loss of coolant.

In both cases though no permanent damage was done but one can't assume he can continue to run the engine with any warning light on.

There is no exchange of air between the intake system and the intercoolers. There is only an exchange of heat. The intercoolers cool the incoming heated air (heated from the compression of the turbos).

I'm not able to give you much help regarding how to test the Turbo intake system for leaks. I've never had to do this and if I needed it done I'd probably just have it done at the dealer's service department. The techs there would know how, have the proper tools, and get it done with better results than I.

I can tell you the techs tell me that one of the most common sources of an intake leak is the intake hoses are installed and a bit of the inner hose material folds back and this is a leak. To avoid this happening the techs take particular care in installing the hoses and they use a 'special grease' (what it is I have no idea) to lube the hose to help it slip onto the housing with less friction and less (nearly no) chance of having a piece of the hose fold back and create an air leak.

Sincerely,

Macster.