Re: idle problem

["David Teitelbaum" <jtrealty@xxxx>]

I have fixed several with similar symptoms. In all cases it turns out
to be vacuum leaks. They were in different places and varied in
severity but the underlying cause was air entering the engine that
wasn't measured by the air sensor and the idle system tried to keep up
with it unsuccessfully. You have to look in the more unusual places.
It isn't always a loose or cracked vacuum hose. It can be the "O" ring
seal on the air pipe to the idle motor, hard seals on the fuel
injectors, missing gaskets or "O" rings on the air induction system,
and so on. Make sure the 3 brass screws are seated closed (clockwise)
and the throtle spool is hitting the idle micro and it is working.
Other things just make the symptoms worse like dirty fuel injectors,
old ignition wires, worn spark plugs. Typically when you have a
problem like this you wind up going through a whole tune-up to really
cure it and straighten things out. If your mode switch is hissing that
needs to be fixed. This is a case of where all the vacuum leaks have a
cumulative effect that is to say they add up so that a lot of tiny
leaks make a big problem. On many of the Deloreans you are dealing
with 20 + year old rubber which ages, is subject to heat and shrinks
and cracks. It could take replacing every piece of vacuum hose to fix.
Any piece that is hard, swollen, soft, or worn should be removed and
replaced just like every piece of hose on the cooling system.
David Teitelbaum
vin 10757 


--- In dmcnews@xxxxxxxxxxxxxxx, "Jonas P" <Delorean3543@xxxx> wrote:
> This problem usually only happens on cold starts. After starting my 
> 81 D the engine races up and down. At an idle in park it sounds like 
> someone 
> is pushing up and down on the gas peddel. When you put it in drive it 
> still happens but not as bad. Sometimes I can rev the motor to around 
> 4000 RPM's a few times and it quits. After the motor warms up a bit 
> it stops. I know for sure I have a vacaum leak, John Harvey is 
> putting 
> together a silicone hose set to replace my old ones. Would a vacaum 
> leak cause this type of problem? If not, Anyone know what would cause 
> this?
> Thanks
> Jonas 3543