924Board.org

[rkn]

Hello all

I am a brand new 924 owner and am just trying to get acquainted with the wonders of CIS.
I have done a lot of reading in this forum (incredibly friendly forum, by the way!), but I am an absolute auto-amateur, so I just don’t have the complete picture in my head yet.

My problem (and I can see quite a few people in here have had similar experiences): My idle is so low on cold starts that I can’t keep the engine going without additional throttle (which it will only accept very hesitantly). A glance in this forum tells me to check AAV and WUR first. I have put the AAV to the “freezer test” & it seems OK, but before I dismantle the WUR I just wanted to clarify something: The PO has cut all original wires to the cold start valve and has apparently installed a manual switch inside the cabin. It seems to work OK – when switched on, it will help out on cold starts (and then flood the engine effectively after about 5 secs, so you have to be quick ) But the idle is still horrible. As soon as the engine warms up, the idle evens out nicely at 900rpm.
So the question is: does his disconnection of the CSV wiring in any way affect the performance of the cold idle/AAV/WUR? What should I concentrate on first – recontstructing the original wiring to the CSV or check the WUR? Other suggestions?

By the way, what the heck is the point of “manualizing” the CSV in this way - is it just to avoid a possible fault in the thermo time switch, or something more complicated???

1000 thanks,
Rasmus
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1980 924NA ROW

[Mike924]

Welcome to the crowd, rkn.

The problem with cold running (assuming it gets OK when it's warm) almost certainly a stuck WUR. I don't know of anyone here who's successuflly managed to revive a dead one, so a new (or known good used) replacement is probably needed. New ones are expensive >200 Euros!

The wiring to the the CSV might be to overcome the WUR problem (in which case ), but it's also a known mod (and probably Porsche recommended on early cars) for the 'hot start' problem.

Perhaps I should add that the CSV adds neat fuel only when the engine is being cranked by the starter; the WUR then takes over the enrichment function, gradually leaning the mixture down to the normal level as the engine warms.
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[Smoothie]

Before dismantling or replacing the WUR you should check the pressures. We can get a CIS pressure tester over here from a place called "JC Whitney" for less than $60. A low priced WUR replacement goes for 3-4 times that much. -But before doing anything else, check for and eliminate any vacuum leaks, make sure the vacuum line routing is correct, and check the timing.
With the CSV rewiring being done, it may be safe to assume a previous owner was a tinkerer and may have messed with the air:fuel and idle settings also, but leave that also 'til after everything else including the pressures is checked.
The CIS pressure test will tell you if the system primary pressure is correct as determined by the fuel pressure regulator and fuel pump output - and will give you a reading of the control pressure as determined by the WUR.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[rkn]

Thanks guys,

and yes smoothie, I am already worrying about how screwed up the idle & air/fuel settings are. I can imagine the po may have messed with the idle to compensate for other problems (that's what I would do... ) I spoke to him and he said the csv manual override is the work of the owner before him

Pressure testing is a good idea - though I have no idea where to get hold of a CIS-tester in Denmark. Any Danes (perhaps Swedes) on the line?

The po has a junk 924 sitting in his front yard, he says I'm welcome to rip any parts from it. I think it's a '76 or '77 NA. Would the WUR and other CIS parts be the same as for mine, which I believe to be a late 1980?
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1980 924NA ROW

[Mike924]