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[ted von Kampen]

I am chasing hot start problems on my 1981 Porsche 924 NA.
On page 258 of the Haynes manual figure 11.11a reference is made to a supplementary start valve that is in series with a thermal switch. That path is in parallel with the cold start valve and its thermal switch. I understand how that cold start system works.

In the Porsche workshop manual page 25-25 there is a discussion of checking hot start valve (reduction of control pressure during hot start) for engine temps over 140°F. The picture shows the valve near the fuel distributor. My question: Is the hot start valve in the Porsche WSM the same as the supplementary start valve in the Haynes manual? ie-same valve but different name in each book.

If it is the same, how long does this valve stay open if the temp is over 140°F.
Comments welcome---Ted

[Eliza]

The valve is referred to as "supplementary start valve" in the WSM wiring diagram as well - so although I have no Haynes I would think it's the same.

It's a solenoid-type valve and like the cold start valve, only gets powered while cranking.

It temporarily opens a passage in the fuel distributor to reduce control pressure. It should click audibly when external power is applied to the 2 terminals at its bottom ( orientation doesn't matter if my memory serves me right ).

I have this valve on my '85 n/a, and it works great- no hot start probs.

Eliza
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1985 924 NA RoW
1981 931 S2 RoW