Deleting a 928's vacuum limiter - chasing down more vacuum leaks

[@patrickfish2304]

Nice! My '81 starts then immediately dies. I'll get to it this spring. Can't wait!!

[@ARfourbanger2000]

The auxiliary air valve is open when the engine is cold to add air in concert with a cold enrichment valve (aka warm up regulator) and closed when warm. They are supposed to open and close in time with the heating and cooling of the engine. Essentially, it adds rpm while the engine is cold and running rich. Heating and cooling cycles take a while, therefore, the axillary air valve moves slowly. That is my understanding, anyway. Love the content you produce, keep it up!

[@ThrottleGrotto]

Thank you!!

[@raymond06]

Road and Track article on the 928 back in '78 made mention of the loud fuel pumps audible inside the car. My '79 is the same way. Mine has both internal and external pumps. Decel valve slows the rpm drop when you release the throttle and you might hear a little popping in the exhaust when decelerating after you delete it. Also, without decel valve if you blip the throttle, rpms will dip below idle then stabilize. AAV should close fully, otherwise you'll get erratic idle speeds.

[@ThrottleGrotto]

That's some really helpful info - thanks!

[@DUBdevelopment]

That 1.4t seems sturdy enough to come out to Texas vs the world in September vw race and car show.

[@ARfourbanger2000]

I think this system has a frequency valve. The nature of the rpm drop at idle..the way it suddenly cuts out and raises back up again, seems electrical . The frequency valve is electrical. I would rule out any relay controlling it and or the electrical connection to it. On my VW with CIS injection, it is easy to diagnose because the dang thing buzzes so dang loudly when it's working. Yours may not be as buzzy. Hope this helps. Good luck! You may dread this car, but of a CIS guy like me, this content is awesome. Keep it up!

[@ThrottleGrotto]

I know the frequency valve that mounts on the CIS fuel distributor. Since this is L-Jet, it's more like a vanagon than a rabbit

[@928pcar]

I deleted my aux air valve but also not running A/C

[@OB928]

Fuel pump is readily accessible (not in-tank) and if you’re not sure of the age, you’ve eliminated a relatively inexpensive potential problem.

[@ThrottleGrotto]

it was one of those things I should have done, but I trusted the item and it bit me.

[@TheLadeef]

31 degrees? stock is 21 for US l-jet, careful there :) I deleted mine as well, fixed a low idle when warm issue.

[@orlandosantiago6398]

You seem to have glitched at 0:10 lol