AEM 20-400S 2.25' Air Bypass Valve

For 20 years I've been running true CAIs without a bypass valve. This time I figured I would. I ran it for about five minutes and took it off. Why?Any time you open the throttle fast, the valve opens. Basically any time there's a sudden change in pressure differential, it opens. Even at high cold start idle, you can hear it's partially open. My filter is an AEM Dry flow and it only has 1500 miles on it. The system is an AEM system. There are no restrictions that would cause it to open unnecessarily.Looking at the patent and inside the unit, they use foam as the diaphragm "spring." Foam changes vastly across temperatures, so it will react differently at different temperatures. At hot temps, the foam will be more forgiving and it will open almost all of the time. There's really nothing to it, yet they get $70 for it. And it doesn't even work right.I can't return mine because I wiped the outer foam with a little element oil just in case it did open. Turns out, it opens way more than you think, and what's the point of a CAI if it's just going to be sucking air from under the hood all the time?

If you are new to CAI on a vehicle, this is a requirement to have in your system. Fortunately, I learned before it was too late. My original system didn’t have a bypass and a rainy day on muddy roads almost got me. The bypass let’s your engine breathe when the filter clogs. Over time, at least in my car, the system vibrates enough to eventually break these bypasses every 3-4 years. No other substitutes work properly for my car and here I am once again. But my car runs great 17 years running.

quick shipping and it fit perfect, haven't had any issues with it.

It was shipped and received in a timely manner. The product fit my car perfectly!! Thank you

On the Fiat 500 Pop (2012) the cool air intake had one of these air bypass valves in the Mopar kit. Unfortunately, after a few years it broke and the car was sucking unfiltered air. Mopar does not supply replacement parts for the kit, so the Fiat solution is to by a new kit. This is the exact part in the original Mopar kit and has the same information and numbers on the part itself. Fit perfectly and installation is less than 30 minutes (just release 2 hose clamps), Very easy to access since it is located at the top front of the engine compartment. Since this is the exact same part, I expect it to have a similar (short) life expectancy as the original.

Work's perfectly in my daughters fiat 500,.UPDATE-- Broke just like the old one after 2 years.

Fits perfectly. Replaced a 10 year old one. Easy swap, all necessary equipment included.

Uh, it is a bypass valve. It replaces an identical unit that my intake had, and after 150k, it needed to be replaced. I think it is overpriced. But after 150k, it seems okay to replace.