Sunday, February 12, 2006

Motor Project # 11 - Clearing Your Throat!

This project is provided by Karl Wolf and is meant to educate. This project can be accomplished by someone with average to high mechanical skills - not for beginners. CAUTION: Give careful consideration to this maintenance process as Jaguar is so concerned improper cleaning of the throttle body will occur, the factory will deny warranty to the TB even if they find evidence it has been cleaned. It is advisable to wait until after warrany has expired. Karl continues with some simple/easy maintenance items while the intake manifold is removed. Karl describes a safe way to clean carbon build up on the back of the throttle body. Jaguar uses a clearcoat on the inner surfaces and cleaned improperly or left uncleaned, air flow as well as throttle blade functions can be adversely impacted. This can be combined with project #s 5 & 10 and called an intake tuneup. Once again, here's Karl: Throttle Body Cleaning As Steve has indicated, the Throttle Body is a relatively delicate part. Standard carburetor cleaners should NOT be used under any circumstance! That being said, there is a safe way to clean the TB. Before we get to that, let's recall where the throttle body might be at the moment. If you've been following projects in this blog and are using the instructions to remove the intake manifold to change spark plugs (project # 5), then you recall the throttle body was disconnected from the intake manifold, but left to "float" in place as a shortcut so that electrical and coolant connections could be preserved. It is possible to follow these steps without removing the throttle body as it was left in project #5, however, you will be at a slight disadvantage over these pictures because the opening needing cleaning points toward the windshield. If you decide to remove the TB completely, it is water cooled and has inlet and outlet rubber hose connections that lead to the engine coolant system. Be very careful as these hoses are formed and short in length. As they get old, they become brittle. If you see any signs of this it is advised that you replace them. As a rule of thumb, if you have over 50K on the clock, or any 50K increment, replace them. It'll save you a breakdown on the road. BTW, make sure the engine is cooled down (cold) before you disconnect these hoses. They will leak coolant even if you remove some of the coolant from the system, which is advised. They reside "high" in the coolant system so you don't need to remove all of the coolant. You also have two electrical connections to remove too if you choose to remove the TB - the Throttle position sensor (TPS) and the throttle motor connector. TPS and motor are the "throttle by wire" system that is used on the 2.5, 3.0L V6 in the X-Type. PS - The diesel versions (not in the US) still use a throttle linkage. Picture 1 - Front of Throttle body (click on any picture to enlarge) This picture shows the front of a throttle body after about 15,000miles. It doesn't look bad but you can see slight darkening around the throttle blade. This is the view you would see when you remove the rubber air tube coming from the air filter. Picture 2 - Back of Throttle Body (to the intake manifold) This picture demonstrates that what you don't see can hurt drivability and performance. This carbon/oil buildup is not unique to the X Type. All throttle bodies will develop crud buildup over time. This buildup comes from the oil and fuel byproducts recirculated within the motor. The difference in the X is that it is drive by wire. As mentioned above, this means that the only connection between the gas pedal and the TB is an electrical wire. No cable activates the throttle blade. There is also no separate idle air valve. The idle is controlled by the TB butterfly. This means that air is always flowing through the butterfly so it does not have some of the self-cleaning of a conventional cable operated TB. When the butterfly closes fully, it scrapes some of the crud away. With the conventional TB, when the butterfly sticks we just press harder on the accelerator to free it. Again, Steve has listed the partial removal of the throttle body in another post. It can be cleaned without being totally removed. Safe solvents are available to clean it. The X uses a coated throttle body. This is a coating designed to reduce buildup. You MUST use a product that specifically states it is safe to use on coated throttle bodies!! You will also need a soft detail brush or your old toothbrush. (Please throw it away after use in this project!) Picture 3 - Throttle body after cleaning. This picture shows the clean throttle body along with two products safe to use. Use them carefully, making sure you keep the TB in the mounted position. You do not want to hold it sideways as the solvent may run down the butterfly shafts and damage either the throttle motor or the throttle position sensor. Use the solvents per their instructions and the brush to remove stubborn deposits. As a side note: Many X-Type owners have switched to K&N air filters. Anyone concerned about using a K&N filter should view these pictures. You should be more concerned about the junk buildup from inside your motor than the minute particulate difference between a stock and K&N filter. And yes, changing your oil regularly with a high quality oil will also reduce this buildup. Hope you find this project useful. Enjoy!


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