I see lots of these so called performance /MPG boost chips offered on sites and have thought there were / are really a farce. Has anyone used one on their Bonneville and noticed any improvement in mileage or performance? if so what brand did you get and price? My Bonneville isnt a SSEI but it still runs very well for a series II with almost 150k miles on it. Been averaging around 21 mpg round town and such which i'm happy with, but thought if there was merit to these chips I might be inclined to check one out.

No such thing. Don't believe them.

Most performance "chips" are totally bogus. They don't increase your horsepower and may actually lower it, besides increasing emissions. Most late model cars don't have a separate "chip" that you can plug into the PCM, the map is programmed in firmware. What they do give you some kind of "module" that plugs into the harness and interferes with the existing map to increase fuel mixture. (sometimes all you get is a resistor that is spliced into the MAF harness and makes the PCM think it'* colder than it is so it allows more fuel flow.) This may or may not increase power by a small amount, but since the stock engine is already optimized, it'* hard to see any benefit. There are also actual computers you can get that interface with the existing PCM on some vehicles to boost power, these are popular on diesel trucks. They increase power by increasing turbo boost and fuel flow, but this is hard on the engine, and will shorten it'* life. In my opinion, none of the junk is worthwhile, on a car especially, it'* very hard to realize any gains without actually modifying the engine itself.

yeah i kinda figured they were a hoax, but i see so many listed I figured i'd ask what people thought of them. Thanks all for reading.

This also includes your electric turbos.

Like these things? Beast Performance Chip Gas Fuel Saver All Pontiac and Saturn Models 1986 2015 | eBay

Yup, complete bogus. They also can connect to the IAT or ECT sensor, to make the engine dump more fuel because it thinks the air is colder. That'* great and everything, except the PCM sees the mixture go rich, and then backs off fueling, thus negating any gains.

If you want the computer to do fancy things, it'* custom tune or bust unfortunately, and even then you need to do a few things to even really capitalize on that.