924Board.org

[924RACR]

Seems very strange to me that for all those shim changes, you basically had zero impact on the pressure???

As for the WUR... it wouldn't hurt to also, when you're in there cleaning things, if you have compressed air stick a blow gun into the return line to the tank, make sure it's not clogged? Since the WUR needs to bleed the pressure off that way... though yes, it's probably the WUR itself that needs a cleaning.

Good luck!!
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[elitejaso]

Cheers, yeah definitely weird that it barely changes.
With just one 0.3mm shim in there I have 4 Bar pressure. But according to the books 0.1mm adjustment should increase 0.15 Bar, not in my case.

Removed the WUR and going through that. Removed inlet filter meshes were full of crap so will replace those.

Blew out the lines to and from WUR along with tank return line as you recommended. It did have a bit of resistance initially which might have been a partial blockage freeing up.

Will put it all back together this WE and test out those control pressures again.
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1981 924 turbo (daily driver)

[Beartooth]

Interesting that you're seeing the same thing I did - where the pressure stops rising, then drops as you add shims. But as long as it's holding steady at 5.8 bar, I think you're in good shape. As I mentioned, mine was at the lower end of the range Haynes gave me (5.4-6.0), and it's been fine. The first big problem I had that took some head-scratching to figure out was the frequency valve wasn't doing anything; turned out the lambda control wasn't grounded.

The next one was the WUR clogging a few times before all the crud worked its way out (had to take it off, take it apart, and blow the screens out). It might help to pull off the lines and see if you can fill them with some fuel system cleaner and let it soak, then blow them out. I blew mine out, I think with brake cleaner (which I wouldn't leave to soak since it might be hard on the flexible line), but that didn't clear them.

I'd also dribble a bit of cleaner in the injectors to soak, then blow it back out with compressed air (try to blow it backwards, not through, so you push out anything that's gotten in the screen). There might be other things going on, but not much point in going further until you're sure all the crud is removed or worked out.
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1980 931 diamond in the rough

[elitejaso]

Interesting, dont believe mine has the lambda system being a series 2 but correct me if I'm wrong.

Cleaned and blew out the lines to and from WUR. Also installed new filter mesh into WUR inlet.

Put it all back together and ran a cold control pressure test. Same problem switching from a S.Pressure test to Cold Control pressure test it barely drops off and takes about 15 seconds to drop a bar.
If I run a Cold Control pressure test from 0 it builds quickly to 2 Bar followed by a noise and it crashes down to 0.
Ran that same test (Cold Control) but with the WUR return line disconnected into a bottle to see fuel output. Came in at approx 150ml over 30sec. Also measured the fuel output from the fuel distributor to WUR and was the same 150ml over 30 seconds.

Starting to think I might still have a fuel distributor issue. Gonna read up a bit more on how this control pressure system works exactly and if anyone has any ideas please let me know thanks.
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1981 924 turbo (daily driver)