Ferrari Mailing List: Re: K-jetronic FI on QV cars

[Jeff Greenfield (coyote]

   Rick -



   You wrote: "Cold start enrichment is handled by the cold start
   injector. Warm-up idle speed is controlled by the Aux Air Valve"



   This is not entirely  correct. Cold start enrichment is helped by the
   cold start injector by way of the Thermo Time Switch (TTS), however
   the cold start injector ONLY fires during cranking.



   The warm up regulator does more to control the fuel mixture during
   warm up. CIS is dependant on fuel pressure (and the pressure
   differential in the fuel distributor) to control mixture, so the WUR
   varies the fuel pressure depending on engine temperature. If the fuel
   pressure in a CIS system is off just a little bit it will cause all
   kinds of wonky behavior.



   If there is any doubt that there are mixture issues, then the fuel
   pressure needs to be checked. This requires a fuel gauge with a 'T'
   and a switching valve so you can isolate the system, primary and rest
   pressures. This a little more involved than just plumbing a gauge into
   the circuit, firing up the fuel pump, and reading the pressure.



   20 or so some years ago, CIS was very common on VW's, Audi's, BMW's,
   Volvos, and a bunch of others. I've worked on most at one time or
   another, and am very glad that there are not many cars with CIS left
   in this world. I swore I would never own a car with CIS, then I had to
   go and buy a 308 QV :-)



   Jeff - who after all these years still does not fully understand CIS,
   but I seem to understand it well enough to diagnose and repair them.



   -------- Original Message --------
   Subject: Re: [Ferrari] K-jetronic FI on QV cars
   From: rolindsay [at] yahoo.com
   Date: Thu, December 11, 2008 6:49 pm
   To: Jeff Greenfield <COYOTE [at] acme-ltd.com>
   Cc: ferrari [at] ferrarilist.com
   The story I'm told is that the US spec cars have a higher initial idle
   to heat the cat (for emissions control). Since the Euro cars of the
   same vintage don't have cats they need only idle a little faster to
   aid warmup and to idle stable when cold.
   Cold start enrichment is handled by the cold start injector. Warm-up
   idle speed is controlled by the Aux Air Valve. Yea, it works like a
   vacuum leak. ;-P
   Rick
   Sent via BlackBerry by AT&T
   -----Original Message-----
   From: JAshburne [at] aol.com
   Date: Thu, 11 Dec 2008 18:10:56
   To: rolindsay<rolindsay [at] yahoo.com>
   Cc: <ferrari [at] ferrarilist.com>
   Subject: Re: [Ferrari] K-jetronic FI on QV cars
   Rick
   FWIW, my 400i has two of the K-Jetronic FI systems and it typically
   idles
   around 1,300-1,400 after startup but fairly quickly (< 5 minutes)
   settles down
   to 1,000 rpm idle. 2,000 rpm sounds a bit high for an idle speed even
   if
   right from a cold start.
   John
   In a message dated 12/11/2008 6:02:02 P.M. Eastern Standard Time,
   coyote [at] acme-ltd.com writes:
   Rick -
   Yes and no.
   The US cars are more complex than those sold in the rest of the world,
   and they have more stuff that affects this. I also believe (but could
   be wrong) that the euro cars don't idle as high on a cold start.
   It also depends a lot on ambient temperature. If the car has been left
   out overnight in 20 degree weather, the idle won't be as high since
   the transmission oil and other fluids being thicker will cause
   significant drop.
   When it is about 50 - 60 degrees, yes the idle will be somehere around
   1500 - 2000 for a few minutes.
   But, if the car starts ok when cold, and drives ok immediatley on a
   cold start, then everything is alright.
   If there were a problem with the AAV, it most likely would not idle
   well when cold. You could try cleaning the AAV, sometimes they get
   gummed up.
   A problem with the cold start injector, or TTS would cause an extended
   crank when cold, but once started should not have any effect.
   A problem with WUR, would cause a bunch of varying idle and
   driveability problems.
   I had a 3.2 Mondial in the shop this past summer that had come to MA
   from AZ. The AAV had been disconnected. The car wouldn't idle
   initially on a cold start. We're talking ambient temps of 60ish
   degrees in this case.
   Reconnected it and all was well.
   YMMV,
   Jeff
   Sent from my iPhone
   On Dec 11, 2008, at 4:21 PM, Rick Lindsay <rolindsay [at] yahoo.com> wrote:
   > Hey Gang,
   >
   > On your QV 3x8s and Mondials, does the idle speed run high at start-
   > up? I have heard stories of the US cars idling really high
   > (>2000rpm) when first started cold. Every book I have read on K-
   > Jetronic discussed the cold start injector and the additional air
   > valve to raise cold idle speed. My Euro. QV has none of that
   > behavior. First start-up or after a long run, engine cold, hot or
   > in between, it idles at 1000rpm. Should it have a higher idle speed
   > when cold?
   >
   > What I'm asking is whether the cold start circuit in my car is
   > working properly. It starts flawlessly but has no increase in idle
   > speed at all.
   >
   > Thoughts?
   >
   > rick
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