924Board.org

[Mbean]

The 1981 924 turbo has had a hot start issue for a long time. I searched the info to address the likely culprits and still have a poor start after about 15 minutes after shutting it down when hot. I started with the easy things first. I replaced the check valve, fuel accumulator, injectors, fuel filter, flushed the lines, plugs and a few other things. I apologize in advance for asking such simple questions but I’m trying to learn and get this sorted. It needs a new home, and with 26,000 miles it would make a great car for someone. Our garage is full…
My mechanic tested the fuel pressure, both running and afterwards. Pressure was in spec and it didn’t leak down much after an hour, so it seems to be holding pressure. He also replaced the vacuum lines as well.
Starts and runs perfectly from a cold start, and after about an hour after running, but starts and runs really poorly after 15 minutes.
I disconnected the power to the cold start valve, as shown in the Haynes manual and didn’t get any power (not even for a couple of seconds) when cranking with the coil wire disconnected.
A few observations and questions:
1) I get continuity between the two wires going into the cold start valve when it’s disconnected. Should I?
2) There is an old vacuum line that was disconnected that seems to go down below the distributor. On the other end it goes behind the coil and I can’t see where it goes. Suggestions?
3) There is another hose coming out of the intake manifold below the throttle cable unit. It’s capped off, what is it and should it be connected to something? If so, where?
4) I just cold started it with the cold start valve disconnected and it started perfectly. Should this be happening?
5) The coil tested within turbo spec for primary resistance but only 3.06 ohms on the secondary resistance. Could this be a cause and should it be replaced?
6) System pressure was 6.2 bars, 3.9 bars running.

Any suggestions are greatly appreciated. This is a great resource and I have learned a lot but still need some help.Can I post pictures?
Thanks!

[morghen]

I suggest you have a look on my website and get an EFI bolt on kit for your 931.


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Supercharger and EFI kits
https://www.the924.com

[Mbean]

Very interesting. How much is the kit?

Also, there’s a vacuum hose coming off the front of the throttle body at about a 45 degree angle. Where does it go? Mine has been capped off.

[BauerR]