Thread: What is this? Performance speed chip on ebay. Look!

it's junk and can hurt your engine. It tells the PCM its colder then it really is outside.

Just as Vinnie said it spoofs the PCM and causes it to add timing. This is also how the Happy Knob works, although it's adjustable and people with tuners will adust the IAT versus Spark table to work with the adjustable selector.