Car running again..question

[Delorean17@xxxx]

Hey list,
I just got my car back from the VW shop. It turns out that a vacuum line 
was broken and I had the timing pretty far off:) He said its the first and 
hopefully the last DMC he works on, he said its so hard to get at everything, 
I totally agree (ie, distributor) . He is a nice very nice guy to deal with 
and didnt charge much.
He said I had a small water leak near the thermostat housing. About 1/2 
way home the interior filled with smoke(back window is out,no, not from 
T-bars) and the leak got very bad and was now leaking onto the muffler 
causing tons of smoke. My house was about a 1/2 mile away so I just went for 
it and made it with one door open. Engine was not overheated(gauge at 
normal) but I got some funny looks driving a smoking DeLorean.
It is running great but it idles extremely high. At the rear of the 
engine compartment there is a black ground wire coming from the wireing 
harness that goes to the ignition advance solenoid.(about 12 inches down from 
the solenoid connection with an "0" connector on the end) When this wire is 
grounded the engine idles very high (over 2000 rpms) when its not grounded 
the engine runs and idles fine. What would cause this? am I hurting anything 
by leaving it taped up?

Thanks
David