Plug found in ICV Hose??

[Tom '74 911]

Hello!

I sourced replacement ICV (officially from PET the Idle-speed adjuster) hoses to replace the ones on my 3.2L SPEC 911 race engine that were just starting to show signs of cracking. See this thread:

Source for 3.2L idle stabilizer rubber hoses

When I pulled the old hoses off the motor, I found something weird - a plug in the upper hose...?? It looks like a piece of aluminum that's been turned on a lathe to fit the hose ID. It was right in the middle of the section and fully blocking airflow.

Is this an OIT (old indian trick) to squeeze more power out of a race motor? The motor generally ran fine, including at idle... can anyone think of a reason to plug this line and is there any reason to either leave it or remove it? The ICV was pretty clean looking and operated freely (although I don't know for sure if the electrical component was functioning, but I'd assume it was).

The plug was in the middle of hose #34...

Thanks,
Tom

[Tom '74 911]

Saturday morning bump...
Thanks,
Tom

[RedCoupe]

Definitely a home-made plug. I can't think of any reason that you would want that. Perhaps a prior owner wanted a different idle speed than what the DME obtains using the air valve. But, if it was my car, I would properly connect the ICV, set the base idle speed using the wire jumper technique (well documented in the service manuals and on this forum) and see how the idle speed is. Shouldn't make any difference at all in power or economy, as the ICV only works when the throttle is completely closed and the micro-switch is engaged.

[3rd_gear_Ted]

another attempt to address a symptom instead of the root cause

[porschyard]

Definitely not an old racers trick to get more power unless that old racer did not understand the 3.2 Dme system. The idle control valve on a 3.2 moves to a full open position when the DME gets a WOT signal increasing the amount of air coming in to the engine and thus increasing power.
With that passage blocked not only do you not have control of your idle speed via the DME but you are also down slightly on power at WOT. my sugestion is remove the plug and and as 3 G Ted alluded to try and diagnose the underlying problem.

Richard

[Tom '74 911]

Thanks for the feedback and for confirming my suspicions. I do know the DME chip is not stock... maybe it has something to do w/that?

I will not reinstall the plug with the new hoses and see what happens when I start 'er up!

Thanks,
Tom