I would check your Electrolyzer for a leak or a hole in the lid. You may have given the vacuum an unrestricted flow of air. Look at the lid of your Electrolyzer when you start the car – you should see the lid of the jar concave noticeably with the vacuum (only if it's the white plastic type). If not, you have a leak somewhere. Also check your air inlet/bubbling adjuster. I use it very close to the fully closed position, so there is great vacuum in the device.
You WANT the vacuum - it helps HHO production greatly. When I turn the ignition switch on and watch the bubbles, as soon as I start the engine, the vacuum more than triples the amount of HHO being produced (estimated visually).
Also read vacuum leaks.