JBO

1981 911 SC. Had been running great. Installed a pop off valve over the weekend, which appeared to be successful. However, now the car turns over, idle goes to around 1,000, then it dies. I rechecked the valve and it appears to be OK with no noticeable air leaks. Any ideas? I guess the next step will be having it towed to a "real" mechanic.

yelcab1

Check your vaccum connections to the airbox. Chances are you left some thing unconnected when you did the mod.

pjc

Usual problem with pop-off valve installation is that when engine backfires on start-up the valve lid catches on the air filter and does not close properly. This leads to too much air getting in and the usual result is a failure to start. THis means the valve is either incorrectly located in the air box or is turned the wrong way to enable the lid to catch the filter.

When I had mine fitted (by a so called Porsche specialist) they did not glue it in place correctly and the valve jumped out at the first hint of a backfire - result was failure to start. Had to do the job properly myself - I guess they did manage to drill the hole in the right place!

Your problem doesn't really sound like the pop-off valve but it is curious that the problem has occurred after installation.

PJC

JBO

Are you supposed to put anything on the o-ring? The instructions did not say to and the o-ring appears to be soft and properly in place. Maybe it is just a coincidence and unrelated to the pop off valve. A few years ago I changed the plugs in my BMW and the car would not start. Thought I messed something up and had it towed to the shop, and found out that the battery had simply decided to die at that moment and it had nothing to do with the plugs. (And I could have just jumped it off rather than the hassle and expense of towing. Oh well).