Re: [DML] new cat & higher idle

["Walter Coe" <Whalt@xxxx>]

> since my cat replacement the car does definitely idle higher AFTER
warm-up.
> When the engine is good and warm and few miles down the road it is idling
> about 1,000. After cold startup and during warm up it right on, hanging
> around 750.
> Is this an easy thing to adjust?

Kevin,

It seems unlikely that there is a causal relationship between replacing your
cat and having a high idle after warm-up. Did you have this idle condition
before you replaced the cat? As far as adjustments, this is a matter of
confusion for many mechanics. There are adjustment screws on the air intake
manifold, but in the case of the DeLorean, these screws are not supposed to
be used. This is a feature that was carried over from older configurations
that was obsolete by the time these engines were put in the DeLorean.
Still, that doesn't stop some mechanics from trying to adjust them anyway.
The only proper way to adjust them is to make sure that all 3 are lightly
seated all the way down.

The idle is controlled by a computer that is programmed to keep it in the
750/950 rpm range. Since you are getting 1000 rpm, this is a bit high. The
most obvious thing to check (after seating the 3 adjustment screws) is to
make sure that the idle speed mircoswitch is closing. This is a switch that
senses when your foot is off the accelerator and tells the idle speed
computer to activate. There are various things that can stop this switch
from working. Check it out and let us know what you find.

Walt Tampa, FL