jdmvtecboi
New Member
Throttle Body is a part that seldom gives any trouble under normal conditions and therefore in standard manuals there may be no mention of perceivable symptoms attributed to malfunctioning in this area. However practical experience shows that over a period of time this part gets affected by the build up of carbon which in turn does not allow the throttle plate to properly take a fully closed seating position. If and when you drive in this state you will observe that it is difficult to maintain it in a stable idling condition and your car does not sound normal when you release the accelerator. These odd symptoms being listed no where you might get perturbed as to what is wrong with your vehicle and whether to try your hand on it or it would be wiser to hand it over to the garage for repair.
The first thing what you should not do is “jumping to conclusions”. Do not try to meddle with any tuning up procedures like changing of spark plugs, fuel injection system cleaning, replacing air filters or the vacuum hose etc. These will help you in no way to resolve this problem. Just try to check whether or not the throttle plate is in fully closed seating position. If it is not then you should observe what is preventing it from taking a fully closed seating position. In all likelihood you will find a build up of carbon preventing it from taking the fully closed position. This leads us to conclude that this carbon build up is the culprit and needs to be removed to get back the original performance.
To commence the cleaning operation you should get yourself equipped with a 5mm socketed hex (Allen) driver. Since the throttle body is connected to the intake manifold, with the air intake hose from the intercooler connecting on the opposite side, you should start by unscrewing the air intake hose clamp. Next you need to pull the intake hose from the throttle body keeping a note of marking on the intake hoseof the correct mounting orientation. This is important because you will have to align in the same orientation while re assembling after the cleaning operation. Now pull the throttle position sensor connector from the throttle body.
Now you have to pull out the throttle body from the intake manifold.
If your car is a non-DBW (drive-by-wire) with the AEB engine, you have to remove the lower end of the connecting rod on the throttle body out of its bracket thus freeing the throttle body of the car. Remove the four screws holding the throttle body to the intake manifold with the 5mm hex driver. Having done this you will be able to easily pull the throttle body and gasket from the intake manifold. Also remove the throttle cable by moving the cable through the maze on the throttle body.
Now take a look inside once you have removed the throttle body and you can possibly see a build up of carbon at the junction where the throttle plate meets the throttle body walls and it is this build up that is responsible for the throttle plate not fully closing thereby affecting performance.
The throttle body can be cleaned using a “throttle body cleaner”. Put some of the throttle body cleaner on a cotton/paper towels and clean off the throttle body to get rid of the carbon build up. Remember to clean the edges of the throttle plate with some elbow grease. Having accomplished this it is the turn of the old gasket to be removed. Next clean the mating surfaces of the throttle body and intake manifold. Throttle cleaning is done.
Reassemble all parts in the reverse order keeping in mind the matching to be done as per markings on the throttle body. Take care that Bolt tightening parameters for the throttle body is 84 in-lbs / 10 Nm.
A few useful points to keep in mind for this maintenance activity are:
It is a good practice to use fully synthetic oils with an occasional engine flush added prior to draining old oil.
Preferably the first throttle body cleaning should be taken up at 30k miles
Monitor at regular intervals for any carbon build up on the throttle body walls. If you find more than a thin coating of carbon on the throttle body walls, then there could be carbon buildup on your valves and piston heads as well.
For the valves, Techron or BG 44K can be used whenever you fill up gas next.
Remember that you reach the primary target of cleaning by just lifting off and removing the top half of the intake manifold.
Lastly, screw all bolts on, a little at a time, just the same way when you put the lugs back on for a wheel. When all bolts have been screwed a little, then start with tightening a corner bolt, then the one on opposite corner from it, and so on. This helps to evenly screw in the bolts correctly. This ensures that there is less likelihood of warping or misalignment."
You should make it a practice to place on ground upon disassembly all the parts in relation to the engine. This will enable you to relate the parts to the location of from where you removed them. The layout description would read as (From left to right):
two bolts from bracket under the throttle body,
two lower bolts from the throttle body,
two upper nuts from the throttle body,
two front bolts from the manifold,
one small bolt from the bracket on top of the manifold,
two bolts from the middle of the manifold, and
two bolts from the rear of the manifold.
Tools & Accessories that you can use for specific applications:
Flathead screwdriver (for removing some of the hoses)
Ratchet (maybe a breaker bar too, if you want)
Torque Wrench (for bolt tightening to certain specified parameters)
Anti-Seize Lubricant (when reapplying bolts)
Throttle Body cleaner (one or more depending on dirt built up)
Towel (Paper towel or rag for cleaning manifold)
Nylon Brush (for scrubbing manifold if it's very dirty)
Pliers (for removing hose clamps)
Q-tips & Pipe Cleaners (for cleaning holes of small size).
The first thing what you should not do is “jumping to conclusions”. Do not try to meddle with any tuning up procedures like changing of spark plugs, fuel injection system cleaning, replacing air filters or the vacuum hose etc. These will help you in no way to resolve this problem. Just try to check whether or not the throttle plate is in fully closed seating position. If it is not then you should observe what is preventing it from taking a fully closed seating position. In all likelihood you will find a build up of carbon preventing it from taking the fully closed position. This leads us to conclude that this carbon build up is the culprit and needs to be removed to get back the original performance.
To commence the cleaning operation you should get yourself equipped with a 5mm socketed hex (Allen) driver. Since the throttle body is connected to the intake manifold, with the air intake hose from the intercooler connecting on the opposite side, you should start by unscrewing the air intake hose clamp. Next you need to pull the intake hose from the throttle body keeping a note of marking on the intake hoseof the correct mounting orientation. This is important because you will have to align in the same orientation while re assembling after the cleaning operation. Now pull the throttle position sensor connector from the throttle body.
Now you have to pull out the throttle body from the intake manifold.
If your car is a non-DBW (drive-by-wire) with the AEB engine, you have to remove the lower end of the connecting rod on the throttle body out of its bracket thus freeing the throttle body of the car. Remove the four screws holding the throttle body to the intake manifold with the 5mm hex driver. Having done this you will be able to easily pull the throttle body and gasket from the intake manifold. Also remove the throttle cable by moving the cable through the maze on the throttle body.
Now take a look inside once you have removed the throttle body and you can possibly see a build up of carbon at the junction where the throttle plate meets the throttle body walls and it is this build up that is responsible for the throttle plate not fully closing thereby affecting performance.
The throttle body can be cleaned using a “throttle body cleaner”. Put some of the throttle body cleaner on a cotton/paper towels and clean off the throttle body to get rid of the carbon build up. Remember to clean the edges of the throttle plate with some elbow grease. Having accomplished this it is the turn of the old gasket to be removed. Next clean the mating surfaces of the throttle body and intake manifold. Throttle cleaning is done.
Reassemble all parts in the reverse order keeping in mind the matching to be done as per markings on the throttle body. Take care that Bolt tightening parameters for the throttle body is 84 in-lbs / 10 Nm.
A few useful points to keep in mind for this maintenance activity are:
It is a good practice to use fully synthetic oils with an occasional engine flush added prior to draining old oil.
Preferably the first throttle body cleaning should be taken up at 30k miles
Monitor at regular intervals for any carbon build up on the throttle body walls. If you find more than a thin coating of carbon on the throttle body walls, then there could be carbon buildup on your valves and piston heads as well.
For the valves, Techron or BG 44K can be used whenever you fill up gas next.
Remember that you reach the primary target of cleaning by just lifting off and removing the top half of the intake manifold.
Lastly, screw all bolts on, a little at a time, just the same way when you put the lugs back on for a wheel. When all bolts have been screwed a little, then start with tightening a corner bolt, then the one on opposite corner from it, and so on. This helps to evenly screw in the bolts correctly. This ensures that there is less likelihood of warping or misalignment."
You should make it a practice to place on ground upon disassembly all the parts in relation to the engine. This will enable you to relate the parts to the location of from where you removed them. The layout description would read as (From left to right):
two bolts from bracket under the throttle body,
two lower bolts from the throttle body,
two upper nuts from the throttle body,
two front bolts from the manifold,
one small bolt from the bracket on top of the manifold,
two bolts from the middle of the manifold, and
two bolts from the rear of the manifold.
Tools & Accessories that you can use for specific applications:
Flathead screwdriver (for removing some of the hoses)
Ratchet (maybe a breaker bar too, if you want)
Torque Wrench (for bolt tightening to certain specified parameters)
Anti-Seize Lubricant (when reapplying bolts)
Throttle Body cleaner (one or more depending on dirt built up)
Towel (Paper towel or rag for cleaning manifold)
Nylon Brush (for scrubbing manifold if it's very dirty)
Pliers (for removing hose clamps)
Q-tips & Pipe Cleaners (for cleaning holes of small size).
