I want to hook up an external tach to adjust my idle speed. I have an old multimeter type tester that has a tach on it but all the instructions for hooking it up are for old american V8s, 6s and 4s.. The manual (Chiltons and Haynes) says I need a special harness used to hook up a tach to ignition coil harness connector of a TBI engine. They both list a part number but the dealer says no such number and they don't even know what part I'm talking about.
Is there a hack for hooking up a tach under the hood to adjust idle speeds?