MT1083 said:
Can you call Accufab so you can get a correct answer?
Good idea. . . first, here's what they have on their website:
"How tough is the Accufab throttle body to install? Not very. In most cases, all you will need to do is to remove the old (or stock) throttle body and replace it with the Accufab throttle body. Our throttle bodies are designed to bolt to the original manifolds, in the original location using the original bolts. No grinding, beating, filing, or other fabrication is required. Typically, throttle bodies have a throttle position sensor (TPS) bolted to them. Simply unbolt the sensor from the old throttle body and bolt it on to the new one. You will need to insure that the TPS is accurately adjusted to insure a good idle. This is easily done using a Voltage Meter. You are looking to set the TPS between .98 and 1.0 volts measured between the hot wire and the ground wire. Also, the throttle stop on the throttle body has been pre-set at Accufab and does not require any adjustment. It can’t get easier than this. Same with the throttle cable. The Accufab throttle body is designed to accept the same OEM cable mechanism in the same location."
This still wasn't entirely clear to me so I called Accufab and spoke to a nice and helpful guy named George. Here were my questions and his paraphrased responses:
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1.) Do you need to set the TPS on a mustang when swapping TBs?
Yes, but it isn't that technical. If you wanted to run through Ford's established procedures to set the TPS at idle, you'd use a voltmeter and set the TPS to where the voltage reading was between .98 to 1.0.
2.) How do you set the TPS to .98-1.0 at idle if the TPS is essentially non-adjustable?
There is some (albeit a minor amount) of play in the TPS when the TPS bolts are loosened a little. This minor amount of adjustment should allow you to properly set the TPS at idle. We actually don't even use a voltmeter when setting the tps - you can essentially go by the idle speed of the motor. If the idle is too high or low, rotate the TPS one way or the other until the car settles into a nice steady factory-spec idle (I think George said it was between 650-700 but I can't remember exactly what he said.)
3.) Do you need to set the TPS at WOT?
no, it is what it is. In most cases, you can just swap the TPS without even checking the voltage and it should be just fine / within spec.
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So, it looks like everyone is correct! Sounds like if you installed your new TB and your car has a good idle but you never set the TPS, it's likely that you didn't need to in the first place. I think this is probably why most people don't have problems with a TB swap even if they didn't set the TPS because chances are it's already close/at spec. However, if anyone's ever swapped their TB and is suddenly having minor idle problems, you might look to the TPS and check it with a voltmeter to ensure the idle setting is between .98-1.0 volts.
Cool . . . thanks for guiding me down this road. Incidentally, George said the TB/Plenum is the real deal and you will "feel" the power increase . . . not that he'd say otherwise, but I'm still excited to install my new Accufab Plenum/TB this weekend!
