Re: [T3] Dual Carbs

[Jim Adney <jadney@vwtype3.org>]

On 7 May 2004 at 19:03, Aaron Clow wrote:

> Anyone know approx how warmed up a 71 FI is when the
> engine slows down to normal idle? I usually sit in the
> car with the engine running until the idle changes to
> the low idle. It's usually about 2-3 minutes. Is the
> engine "fully" warmed up at this point?

I think your engine is actually better off if you drive it sooner than that. 
You don't want to make major demands of it when it is cold, but moderate 
driving will actually warm it up faster, and the extra richness of the cold 
idle mixture is actually harder on the engine. I usually recommend that people 
get in and start the engine, make sure the idiot lights go out and then make 
themselves at home in the car. Fasten your seatbelt, etc. That will use up a 
good fraction of a minute and let oil get to all parts of the engine. Then you 
can drive off casually.  

The FI idle actually drops slowly over a rather long time. More like 10-15 
minutes if it's just idling. I suspect that you're just noticing the first step 
in the process. It's a hard process to observe, because the AAR is just 
admitting extra air in an attempt to compensate for the fact that a cold engine 
has more viscous friction. Naturally, this compensation is not perfect over the 
whole warmup cycle, so what you observe is just the "error".  

If it were perfectly compensated the idle speed wouldn't change at all.  

-- 
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Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
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