[urq] Engine Warmup Operation

[rpetrow]

Brandon,

   I take it that the idle speed should be constant during warmup, say
somewhere between 850 & 1000 RPM? It doesn't ramp up to ~1500 for a short
period like most EFI systems and then drop back to 850? 

   BTW, most of the vacuum lines have been replaced with silicone hose plus
the car idles well after warmup. Doubt that a vacuum leak exists but a
pressure check may be worth doing.

   Looking now at the air bypass valve (auxillary air device) as a possible
cause although I have watched the disk inside rotate as the internal heater
warms the coil. Maybe not enough air is getting to the intake and may need
an adjustment.

   Thanks for your response. Any other ideas?

Rick
   

-----Original Message-----
From: Brandon Rogers [mailto:brogers at terrix.com] 
Sent: Tuesday, January 24, 2006 5:02 PM
To: rpetrow; urq at audifans.com
Subject: Re: [urq] Engine Warmup Operation

Rick-
I haven't seen any responses - so I'll attempt to start some dialogue.

The engine speed should be constant during warmup - it should not idle lower

at first then increase.  However during open loop while still cold it may 
idle smoother when DC is fixed at 50%.  I have noticed many cars' idles 
become a little inconsistent when it switches over.

Have you pressure tested the system, or just looked at the hoses?  IMO, a 
visual check is inadequate.  If your fuel pressures and DC are right to 
spec - I would definitely look further into a vacuum leak.

hth

Brandon
----- Original Message ----- 
From: "rpetrow" <rpetrow at comcast.net>
To: <urq at audifans.com>
Sent: Sunday, January 22, 2006 5:02 PM
Subject: [urq] Engine Warmup Operation


> Greetings from the Pa Dutch Country,
>
>
>
> Looking for some general information on the warmup operation of my 83' as
> this may help in diagnosing a current problem. This also may be of use to
> others as I have not found a detailed description of the engine speed vs
> time for cold start conditions. Information on the components is readily
> available in all of the usual locations but even the Bosch books fall 
> short
> on this topic.
>
>
>
> My simple question for the stock WX system is what should the engine speed
> as a function of time be, preferably in seconds, for this engine as it 
> warms
> up from a cold start?  Assuming an ambient temperature of 35 - 40 degrees 
> F
> how would a plot of this look like over say five minutes with the vehicle
> parked?
>
>
>
> The patient idles at ~500 RPM during the first 60 seconds then increases 
> to
> ~ 800 RPM after the duty cycle stabilizes at 50%. (I have to manually hold
> the throttle to warmup the engine.) Closed loop operation is fine and the
> car runs great after warmup. WUR fuel pressures match the specs to tee as 
> do
> the duty cycle plot during warmup conditions; starts @ 65% then drops to 
> 42%
> and proceeds to stabilize @ 50% until closed loop kicks in.
>
>
>
> I've gone through all of the usual vacuum line and electrical connections
> but to no avail. Any info on this topic would be appreciated.
>
>
>
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