Install Throttle Body and set Throttle Position Sensor

[Xsi]

If your car is experiencing a fluctuating idle or if you have moved the TPS or swapped throttle bodies, you will need to set the TPS. I bought a stock H22a throttle body and had it bored from 60mm to 63mm. The TB I had previously was 58mm.

If the TPS has been professionally set or is still set from the factory, do not re-adjust it. Your idle problem is probably caused by something else.

The B18C, B16A, B16B, B18CR, and H22a TB's are all interchangeable with the bolt pattern so will bolt up fine; but you may have to modify the vacuum and coolant lines for them to fit. You may also have to re-use your stock throttle pulley and adjust the throttle cable.

If you know of other TB's which will bolt straight up to B series manifolds please email me with details on what is actually involved so I can put it on here.

Here is a list of the throttle body sizes:

b18c1 60
b18c spec R 62
b18a 58
b18b 60
b16a SiR 58
b16a Sir2 / b16a2 60
b16a3 58
b20b/z 60
f20c 62
d15b7 56
d16a6 55
d16y7 56
d16y8 56
d16z6 56
ZC 55
d16a1 55
d16a8 55
h22a / h23a 60
f22 / f23 60





You will need

*12mm socket

*Multimeter or voltmeter (preferably digital)

*Flat head screwdriver

*New throttle body gasket

*Sharp Knife



Removing the Throttle Body

To remove the throttle body you need to remove the four 12mm bolts holding the TB on. You also need to remove the coolant lines traveling through the bottom of the TB. These coolant lines are for keeping the TB warm in freezing climates to stop the butterfly freezing shut, and are not needed in warmer areas. If you like you can bypass the TB by replacing the two hoses with a single hose going from the Idle Air Control Valve to the spigot on the engine head. Otherwise you can do the full coolant bypass.
You also need to remove the throttle cable from the pulley and you may have to give it a firm pull if the gasket has stuck to the manifold. Some other Honda engines have the Fast Idle Thermo Valve attached to the bottom of the TB rather than the intake manifold so you will have to remove these lines.

Finally remove the TPS harness from the TPS and remove the vacuum lines.




When replacing the TB you should clean the old gasket from the surfaces and replace the gasket, if the new gasket is too small you may have to enlarge it with a knife. You may need to adjust the throttle cable in which case you loosen the two bolts and slide the cable left or right until the cable is taut.



Setting the TPS

You have to use a voltmeter to set the Throttle Position Sensor, the TPS sends a voltage signal to the computer to tell it how far open the throttle is. If it isn't set properly then the TPS will send the wrong voltage to the ECU when the throttle is closed, creating a bad idle.

To fix this you need it sending the right voltage when the throttle is closed.
There will be three wires going to the TPS.

The Green one is a ground
The yellow one is constant 5V
The red one fluctuates between 0 and 5V depending on how open or closed the throttle is, this is the one that tells the computer the throttle position.

You need to connect the voltmeter to the ground wire and the other one to the fluctuating wire by exposing some of the wires. Measure the voltage on your voltmeter, it should read 0.45 Volts when the throttle is CLOSED. It doesn't matter what it says at open throttle.

The harness must be plugged into the TPS which must be attached to the TB, therefore it is much easier to do this with the TB removed.

If you need to adjust the TPS, loosen the two small bolts holding it on and turn it either way until it gives the correct voltage. Some TPS's are attached with rivets instead, in this case you will need to use a Dremel tool or similar to remove it. If there are rivets holding it it is most likely still set from the factory and will not need setting.

If you need to adjust you idle, first unplug the Idle Air Control Valve plug, the IACV is located on the back of the intake manifold. Turn the idle adjustment screw with a flat blade screwdriver. If the screw is loose you may need some silicon to hold it still like I have. You should adjust your idle after setting the TPS.




After doing this I noticed my idle wasn't quite right. The Honda manual I have says 0.45V but when I measure my stock TPS which was still set from the factory it was 0.32V so that is what I have mine set to. Once I had it set to 0.32 the idle was fine.

If you know someone with the same car you could measure their closed throttle voltage to see what their car has but try setting to 0.45V first. I suggest you measure your stock TPS setting before moving it so you can at least revert back to the original setting. There may be other Hondas which have settings other than 0.45 volts, you can ask someone on www.honda-tech.com who may have the same car.

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