Throttle Plate Adjustment
Throttle Body (throttle plate) - The whole point of the throttle plate is to regulate the amount of air that flows through the head into the motor. When you press the gas pedal, the throttle plate opens, when you let off the gas it closes! They should rename the gas pedal the "air" pedal, because that's all it really is doing, opening and closing the throttle plate, allowing more or less air to flow into the motor.
What we want to do here is to check that the throttle is *completely* opening when we mash the gas pedal. When the car comes from the factory, it usually won't open to the maximum position. If it is partially shut, you aren't getting the best possible flow through the throttle body. The less air the motor gets, the less power it will develop.
- Phillips #2 screwdriver
- 10mm socket and ratchet
- Assistant or some mechanism to depress the accelerator while you are working on the engine
To check this the throttle plate angle, you're going to have to remove the air intake hose that connects to the throttle body on the engine. Get a Phillips screwdriver (#2 phillips) and loosen the band clamp that holds the rubber hose to to the throttle body. Once this is off, you can look in the hole and see the throttle plate. You might need to completely remove the air intake pipe to see it well. Remove the blowback hose connected to the side of the intake pipe, and loosen the band clamp by the airbox. For the next part, you're going to need a friend or a block of wood (or something else to hold the gas pedal down).
With the car turned off (don't do this with the car running! you'll blow it up hehehe..), press the gas pedal completely to the floor. Now look at the throttle plate. It *should* be open and as close to horizontal as possible. If it is horizontal, you are done. If not, then go grab a 10mm socket and a ratchet.
To the left of the thottle body there are two 10mm bolts. One of them has a ground strap attached, and they both hold a plate that has a slide adjustment on it. This plate also holds the cable that's attached to the gas pedal. Here is where you adjust the cable so that the throttle plate opens completely. Release the gas pedal. The throttle cable will go slack and the throttle plate will close.
Loosen the two 10mm bolts just enough so that you can slide the plate to the left a bit (towards the passenger side of the car). This will take up some of the slack in the cable. Only slide the plate about 1/4" or less at a time. Tighten up the bolts, press the gas pedal and see if the throttle plate opens completely. Continue adjusting like this until the throttle plate is fully open with the gas pedal completely depressed. Also note that there is a stop on the throttle body. Make sure that the stop that's attached to the throttle plate still makes contact with this point. Adjusting the plate too much will take too much slack out of the cable, causing the throttle to be open slightly when the gas pedal isn't pressed at all. This is not good.
After the adjustments are done, put the air intake hose back where it came off of. Make sure to reconnect the blowback hose from the head to the intake pipe. Start and run the motor for a bit to check that everything runs okay.
The motor is now getting the most air it possibly can through the throttle. Also, you may find that your throttle response seems quicker. This is because you don't have to push the pedal as much because most of the slack has been taken out of the cable!
A good mod to look into after this is having the throttle body bored out. This will increase the diameter of the area where the air flows into the engine, allowing for more power.
This information was obtained from the, now defunct, Sebring/Avenger Performance page at:
http://www.asog.net/wheatking/easy.htm#Throttle. Based on the URL, we credit this information to Dave Urwin, aka: WheatKing.
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Cars Modifications Power BPU Throttle Plate Adjustment