re Needing info on Differential Pressure Regulator

["Smith, Kirby A" <kirby.a.smith@lmco.com>]

"Michael Theuri" <mikesoft@europa1.conwaycorp.net> wrote:

I hope I got the description right. My mech. says he
pulled an engine code that indicated my differential
pressure regulator is malfunctioning. He says that this
has something to do with my idle problem (esp. at stops)
in addition to my cracked ISV hose ( I ordered one from one
of the dealers on the audifans web page and I have already
called them once and its now going to week 3 and no show
yet). He says it works in conjunction with my Oxygen sensor.
Is it hard to replace this regulator ? Does anyone have the
procedure ? Is this a pricey part ? Thanks
^^^^^^^^^^^^^^^^^^
Mike:

I'm not sure the DPR is separable from the fuel metering head.  Check that
the connection is good to the DPR.  Put a current meter in series with it
and observe the current, it should be around 0 mA at idle, richening on
throttle application, diving negative upon release.  You may just have a bad
ground on the intake manifold.  Remove grounds, ensure stud is well planted
and locked down, add star washers to the stack of wire lugs, tighten down,
recheck codes.  If the ISV hose is cracked, the computer cannot control
mixture adequately, and may complain about the DPR as that is what it is
trying to control.

Kirby A. Smith   New Hampshire USA
1988 90q Titanium gray, 182 kmi
1988 90q Stone gray, 187 kmi 
1995 S6 Pearl effect, 82 kmi