So what actually happens? When you ground the timing ground does it just lock what the ECU sees (5 degrees BTDC)?

When you select the option on DSMlink it locks the display at 5 degrees BTDC. Does the timing ground connection in your engine bay do the same thing?

So then when you set the timing your just aligning the engine to what the ecu sees at 5 degrees BTDC?

Sorry if I'm not making any sense.

Bypasses, or rather ignores, all "dynamic" learning components ( ISC, O2 feedback in Closed Loop, timing advance for examples ). Kinda like disconnecting your battery to clear a code but doesn't erase anything.

So when you set your base timing to 5 degrees with the CAS you don't have any extra advance/retard from the ECU. On the ISC it sets it to the center of its travel, that way the BISS adjustment will allow the ISC to compensate +/- for varying conditions ( AC, ambient air temp, etc ).

Will your idle always drop when the engine timing adjustment connector is grounded?

Is grounding your engine timing adjustment connector and selecting the option in dsmlink the same thing?

On idle drop, depends on how good your BISS/ISC setup is. As noted grounding the port/pin makes the ISC motor move to the center of its travel, so if your BISS is not adjusted well the ISC has to adjust to maintain target idle RPM.

Yes on DSMLink and Timing connector, both provide a path to ground for the ECU controller circuits.

Quoting ktmrider:
On idle drop, depends on how good your BISS/ISC setup is. As noted grounding the port/pin makes the ISC motor move to the center of its travel, so if your BISS is not adjusted well the ISC has to adjust to maintain target idle RPM.

Yes on DSMLink and Timing connector, both provide a path to ground for the ECU controller circuits.



OK so if the idle doesn't drop I have my BISS/ISC setup properly? Good to know.

That makes since too because before I reinstalled my ISC it had to adjust quite a bit and now that I have it installed it doesn't adjust at all.

can we confirm this no idle drop=good biss/isc setup indication? have always wondered this myself, especially since i've had my isc unplugged for quite some time now.

with the pin grounded, timing goes back to whatever you set it at at the CAS.

but by the book, 5deg is where it should land, with the pin grounded.

un-grounded, it would be around 12deg.

so with the timing 'retarded' to 5deg and without the other 'idle uppers' like ISC, AT, fans, etc, idle will drop...

...but this is just from my experience with 4g63's...