Carpokes Porsche Forum

danmartinic wrote: Wed Feb 21, 2024 10:02 am Most likely beats this old piece of **** I have just like the one below; when hooked to the coil, shows something under 700 rpm while tach is showing at least 900

To think I used take this instrument as gospel when adjusting the carbs on my old VWs


Tach _ Dwell meter.JPG

lol, I used to have a dwell/tach gauge just like that back when I was into 914's.

This thread has been really interesting so far, and very educational. Very much appreciate the experience and insights here.

One additional question: What role (if any) does the ISV play during cold start, and before the engine reaches temperature? Is there any provision for a "fast idle" when cold? (Mine idles at ~840 hot or cold).

Rveague wrote: Thu Feb 22, 2024 6:11 am This thread has been really interesting so far, and very educational. Very much appreciate the experience and insights here.

One additional question: What role (if any) does the ISV play during cold start, and before the engine reaches temperature? Is there any provision for a "fast idle" when cold? (Mine idles at ~840 hot or cold).

That is a very good question, especially since there are differences between the 8V and the 16V cars. The 8V cars have the idle adjustment screw at the throttle body. I have noticed on my 951 that if I have the idle screw is tightened too far (restrictive), the car struggles to start and takes a few seconds to idle properly. On my 944 S, there is NO idle adjustment screw, so the only mechanisms to help with airflow at startup are the throttle body valve (manual control via the pedal) or the ICV, which is also different than on the 8V cars (3 pin connector for 8v; 2 pin connector for 16v).

Rveague wrote: Thu Feb 22, 2024 6:11 am Is there any provision for a "fast idle" when cold? (Mine idles at ~840 hot or cold).

Idle doesn't change at all at cold start? Strange. I always have a slight change--I'd guess about +200rpm--at dead cold.

But no, there isn't a "fast idle" like that on old carbs or japanese cars ... I assume just a much richer mixture until warm up

danmartinic wrote: Thu Feb 22, 2024 3:24 pm

Rveague wrote: Thu Feb 22, 2024 6:11 am Is there any provision for a "fast idle" when cold? (Mine idles at ~840 hot or cold).

Idle doesn't change at all at cold start? Strange. I always have a slight change--I'd guess about +200rpm--at dead cold.

But no, there isn't a "fast idle" like that on old carbs or japanese cars ... I assume just a much richer mixture until warm up

Mine is the same. it's only "slightly" higher on cold start, whereas on all my other vehicles (RAM, Durango, Audi) they will fast idle around 1600-1800 for 30 seconds or so before dropping down. The cold start on my old '16 Scat Pack Charger would make it sound like the house was falling down.

NCGermerican wrote: Fri Feb 23, 2024 11:21 am The cold start on my old '16 Scat Pack Charger would make it sound like the house was falling down.

We had to teach my mom how to use her 1987 Honda Civic's manual choke. Three positions.. the furthest out idled aprox. 3,000rpm.

She'd often just leave it there