ITB talk

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2 alimonos: from club4ag.com

* Individual Throttle Body - 20V 4-throttle on 16V 4A-GE

Another popular topic these days is adapting the individual throttles from the 20V onto the 16V..."Can this be done?" You bet! But there are many obstacles which may hinder your attempt and here's some of them. NO! you will not be able to use the 16V ECU to run the throttle as fuel map requirements are vastly different for the 20'v throttle unit. The lower rpm ranges require much less fuel while in the upper ranges the throttle needs significantly more fuel. Since the whole idea of making precise fuel maps are the key to making the difficult and sensitive 4 throttle to work well, it is not a matter of backyard tuning by simply shifting AFM or Vacuum Sensor signals or shuffling fuel pressures. You must almost always use an aftermarket or re-computed ECU get anywhere near the operation you need...even to match the original spec of the single throttle you tossed in the garbage. Second, since the 20V's idle is controlled not by the TPS and the throttle body, but rather a secondary port called ISCV which leaks idle air in a controlled manner aft of the fully closed throttles. Since the 16V engines never had this, you have to figure out a way to devise a similar tactics through your own ingenious method. The throttle in any case must be fully closed to get idle mixture control on. The manifold will not bolt on to the 16V's intake so an adapter should be used or fabricated. Overall, not many of the private shops have successfully made such setups perform better than what can easily be done with the single throttle, even though almost all of them have succeeded in getting a car to run decently. That said, there are a handful of shops that did make things work wonderfully (all in Japan that I have seen) with the 20V throttle mechanism and kits are available. Be cautioned that they are NOT cheap and greatly exceeds the cost of swapping the entire 20V instead, because it will require a fully programmable ECU and their research results in the form of software. For many of us, a set of side draft carburetor will be a more effective and much cheaper option than grafting the individual throttles on the 16V