[T3] Cold idle Problem

SCS Crewcab scscrewcab at bellsouth.net
Wed Jul 20 22:41:04 PDT 2011

Thanks for the suggestion, but again, if I had a bad electrical 
connection, it seems it would run lousy when I revved it up. I've got 
good compression and the car runs well except at cold start up. 
Actually, Bobsnotch seems to be on to something. Reading up on the AAR, 
it supplies extra air to a cold engine to match the extra fuel supplied 
by the ECU. If the AAR is malfunctioning, there wouldn't be enough air 
to match the extra fuel. This would create a rich condition until the 
engine warmed up enough to make the ECU reduce the volume of fuel. 
Although this seems reasonable, I do not notice black sooty exhaust when 
the idle is acting up.

On 7/21/2011 12:08 AM, Jim Adney wrote:
> On 20 Jul 2011 at 23:55, SCS Crewcab wrote:
>> OK, but, if it's caused by either of these problems, wouldn't it also
>> run lousy when I revved it up?
> Yes. If it's only at idle that it runs poorly, then I'd check
> compression; it doesn't sound like a FI problem. That makes me wonder
> if you've got a bad cylinder. You can test that by pulling one SP
> wire off the dist cap at a time.
>> Is there anything on the Type 3 FI system that performs the same
>> function of the choke on a carbed car?
> The temp sensors work with the brain to adjust the richness according
> to the head and air temps.
> There's another FI possibility. It's possible that you're not getting
> good electrical connection at one or more of the injectors. Try
> pushing those connectors sideways while idling to see if that changes
> anything. If it does, you'll need to back the connector pins out of
> the plastic bodies, snug them up very carefully, and reinstall them.
> Replacement injectors came with very slightly thinner pins, and this
> sometimes catches us. I don't recall if it causes your particular
> symptoms, but it does cause rough running. The best way to diagnose
> this is with the Bosch tester, but try the test above.

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