Re: Differential Pressure Regulator

[steveb@falcon.kla.com (Steven Buchholz)]

> The continuing saga of the stumbling, sputtering 86 4000CSQ
> continues. Some of you graciously offered advice on this one 2 or 3
> months ago (Weird Running). A pattern now seems to be developing.
> Generally starts good, but may stumble a bit after driven a few
> blocks. Need to rev the he~ out of it (Full Throttle) to get it to run
> smoothly through the accelerators' range. If shut down for 15 to 30
> minutes in our Minnesota winter temperatures and then re-started, it
> will barely idle. Again, the reving is needed.
> 
> New developments;
> 1. The Differential Pressure Regulator (hangs on the side of the fuel
> dist) seems to leak fuel, not only from the O-ring area, but also from
> the holes that are molded into the plastic body. 2. When the car
> barely idles after being shut down for 15 min., and I disconnect the
> 02 sensor, the idle smoothes out and car runs reasonably well,
> although young son (his car) claims that it lacks punch.
> 
> As near as I can tell, The Differential Pressure Reg. is fed from the
> computer, which gets its' signal from the engine temp sensor during
> warm-up and then from the 02 sensor after warm-up. Questions: 1. Has
> anybody seen a Regulator leak like this? If so, is it the part, or
> could it be something down stream of the part that is causing a
> excessive pressure build-up? The Regulators' coil resistance seems to
> measure a bit high, but could be the meters' calibration. 2. Does
> anyone have a regulator from a parted-out car that we could use -
> either from a diagnostic standpoint and/or purchase? 3. We thought
> that our 02 sensors' heater might have opened - could have fit the
> failure pattern I think. However, the coil has continuity. 4. Do I
> (the car) have multiple problems? 5. Hope I can eliminate the computer
> from the picture??
> 
... I don't know if I'll be able to help too much, but I can answer some 
of your questions and offer some suggestions ...

I doubt that you can eliminate the computer from the picture.  What is 
probably happening when you disconnect the O2 sensor is that the computer
is sensing the failure of the O2 sensor and going into open-loop, limp home
mode (which might explain the loss of power and you'll probably notice quite
a reduction in fuel economy).  Someone may have direct experience that may 
be able to tell you exactly what is wrong, but I'll bet that you're going to 
have to figure this one out yourself.  IMHO, the Bentley manual has an excel-
lent troubleshooting procedure for the CIS-E system so I'd recommend that you 
use that ... but since it is rather expensive you might want to get the Bosch 
handbook on the CIS-E (AKA KE-jetronic).  They are available from several 
sources and should cost less than $20.  Another good book is Probst's Bosch 
FI book.  This book will describe the basic theory and the components but it 
will not have precise information for your car ...

If you are interested in a fairly complete list of EFI references and other 
information and have WWW access, look up:

	http://www.dcc.edu/vettenet/efi_ref.txt

HTH!
Steve Buchholz
s_buchho@kla.com
San Jose, CA (USA)