924Board.org

Beartooth · Joined: 05 Apr 2022 Posts: 314 Location: Roberts, MT

I think I might have a solution. Not plug and play, but looks like one that would only require minor modifications. I noticed that some of the later VW K-jet relays are still available. The versions in question would be KAE 3.300.210/220/230. Those will not plug into a 924: the pinout is different, except 30 and 87, but those pins are significantly bigger. Still, out of curiosity, I bought one off RockAuto (WVE branded that turned out to be KAE). It seems to make it work, I'd have to trim down the sides of terminals 30 and 87, and rework the socket. It appears pin 15 [ground] swaps sides, pin 31 [to overboost switch for turbos; to ground on others?] takes its place, and pin 1 [coil terminal 1] either gets moved to the bottom left or wired externally. If there were some way to getting the socket for the VW relay, that would probably make things easier, but I'm guessing it's part of a relay block and not something you could separate. One other option - possibly - is to de-solder the main circuit board and solder it to the base of the original relay. Internally, the relay is two circuit boards in an L shape, with the base of it just making up the male end of the socket, which may or may not be easily grafted to the original relay. My car had no relay when I got it, so I've only got what I can find online and what's in the Haynes manual to go off of.

There are some advantages to the VW relays: similar to the 928 relay Eliza mentioned, they have a "prime" feature, and *may* have a rev limiter. I'm going off this information sheet someone put together: http://www.cabby-info.com/Files/Relays_Kjetronic.pdf. Also, notice that you'll probably want to avoid the KAE 3.300.220/230 relays as some circuit boards are defective and may not work properly or at all. I popped mine apart, and of course it's one of the affected boards. Apparently, the KAE 3.300.210 (used in 83-87 1.8L VWs) won't have one of the defective boards. The rev limiter seems a little fuzzier, unfortunately. That pump relay guide indicates that some VWs had a limiter built into the rotor, and may not have had a limiter in the relay. The 3.300.210 relay, assuming it has a limiter, is probably going to cut out between 7500 and 8000. So maybe not that useful (not sure where our motors start to come apart). The later relays are lower (6500 for the .230), but again, there's a batch of those out there that are defective. Anyway, I'm going to give the relay I've got a try; hopefully I don't run into any big issues getting the wiring set up. I think before I adjust any wiring in the car itself, I'll make some jumper wires and just see if it'll work. If I make any progress, I'll update as I go.
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1980 931 diamond in the rough

Riggard · Posted: Wed Oct 05, 2022 5:15 am Post subject:

Sounds good! keep us posted about the journey, I'm curious.

I don't know the exact available space available, but I could also imagine 3d printing an 'adapter plate' where you basically plug in the new relay and re-route the wires to the 924 pinning. Kind of like your Jumper solution, but a bit more robust.

Yannick931 · Joined: 05 Sep 2023 Posts: 1 Location: Germany

bear924 · Posted: Sat Nov 11, 2023 10:24 pm Post subject:

A little while ago I have away my spare fuel relay to resurrect someone's 924 and have been searching for a new spare since then. Today I tried a 92861511301 and it worked fine ... plug in, no mods required.

I purchased this from Design911 (no affiliation) for 50 pound ... seems they have a supplier who is making these now. I couldn't find a 924 or 928 relay elsewhere without spending silly $$$ on a used one.

So in short... if you need a relay, Design 911 has the 928 one at a reasonable price.