924Board.org

staticsan · Joined: 19 Jan 2009 Posts: 450 Location: Sydney, Australia

My 924 has been a grumpy starter when cold for quite some while. Once warm and at speed, it's fine. I try to drive it at least twice a week so it stays happy but that's not always possible. The "grumpiness" is that it sounds like it's not firing on all cylinders at first. This doesn't usually last more than a few minutes.

This morning it was grumpier than normal. And it smelt very rich. This, to me, suggests that the fuel delivery is fine, but the sparking is not. Does that make sense? The spark plug leads aren't original but they aren't new either and I've not replaced them. The spark plugs themselves are fairly new, however, as are the injectors and all other filter components.

So new spark plugs are on my shopping list. Maybe a new coil, too. And I've been wanting to check the grounding of the engine for a while, too. Anything obvious I've overlooked? (If new leads don't do anything, I'm probably going to take it to my mechanic who does know the K-Jetronic system quite well.)

Wade.
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'82 British NA - Which I think I've been very lucky with!

!tom · Posted: Sun Dec 02, 2012 2:39 am Post subject:

If it is indeed spark, it's more likely the problem would be your cap and rotor than the coil.

Are your plugs gapped properly?

Are your plugs fouled?

I run hotter than spec'd plugs to prevent fouling (new motor is still on the to-do list), and consequently up the octane a bit due to the hotter plugs.

However, from what you've described, I wouldn't rule out the fuel system (WUR) yet.
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78 924 NA
5-lug

Ozzie · Posted: Sun Dec 02, 2012 8:40 am Post subject:

Check the resistance of your plug leads.
I forget the value but it gets higher the longer they are.

Could also be loss of fuel pressure after shutdown. The WUR helps when cold but you could have vapour in some of the injector lines which will not ignite but give you fuel smell out the exhaust.

Mine sometimes starts rough and takes a few seconds for all cylinders to kick in.
Same again when hot starting. (gotta floor the pedal then)
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance