Manual Auxiliary Air Valve for Bosch L-Jetronic cars (Alfa Romeo GTV6, Spider, Milano 75)
The most troublesome part of the Bosch L-Jetronic cold starting system is the Aux Air Valve. I hate the Bosch Aux Air Valve. A faulty Bosch AAV can cause the following problems: Difficult or impossible cold starting, the starts and stalls right away syndrome, poor running during warm up, irregular idle, and last but worst of all: horsepower loss.
It seems that some Bosch AAVs close fully, but don't open very far. This is optimum for horsepower but not for starting in near freezing temperatures. Others open a lot giving great cold starting but don't close all the way which robs some horsepower. With the adjustment nut and a lot of patience you can set up the Bosch AAV to suit your needs...well, sometimes...maybe.
We have found the best solution is to completely replace the Bosch AAV with a manual valve. It's a permanent fix and will never need to be replaced or cleaned. It also provides even better cold starting and slightly more power than a perfectly functioning Bosch AAV. It's operated by a manual cable - pull it out for starting and push it in after a few minutes of running.
Installation is simple & includes written instructions. The instructions are written with the Alfa Romeo GTV6 and Milano 75 in mind, but this product can easily be installed on other Bosch L-Jetronic cars such as the Bosch-injected Alfa Spider or various BMW's.
Choice of 5 different hose colors
Thank you to Larry Simpkins for the photo of the manual valve installed on his beautiful Alfa Romeo Spider!