I have a '90 780 that has had the hot start problem for years. Tried the usual suspects: the RPM sensor, relays, power stage, etc., but it still happens.

Lately, it seems that it will fail even after shorter and shorter drives and in not so hot weather conditions. It used to take an hour+ drive in warm weather, now it happens much more regularly.

Also, I am getting a "woosh" and engine vibration with air being pushed out of the front grill when I turn the key to the II position. It sounds like a fan, but the fan is not turning. Just a woosh and some air coming from the grill. It's almost like some cars have a fan that comes on after being turned off. My car has never had this before. This happened in conjunction with the more recent hot start fails, but I am not sure it is related to the hot start fail itself.

Any ideas? Does the increased frequency of hot starts in milder conditions point towards something specific I can check out? Does this grill air/vibration thing sound related?

Thanks in advance for any ideas. This board has been a great resource, you guys are keeping us on the road.

-gonzo