Re: [DML] Control Pressure Regulator Questions.

["Walter" <Whalt@xxxx>]

Robert,

The acceleration lag that you are describing is typical of a bad Control
Pressure Regulator. I had corrosion in the electrical connection of mine.
The cold acceleration that resulted made the car hesitate at lower RPMs, but
once past a threshold of around 2000 RPMs then the car would accelerate
fine. Replacing the plug on the wiring harness and cleaning up the socket
on the CPR fixed the problem. To keep moisture out of there, I packed it
with secondary ignition dielectric grease.

On two previous occasions, I had a similar acceleration problem due to my
frequency valve not working. Once from a bad lambda relay and then later
from a corroded electrical connection at the plug on the valve. So on your
car, you might want to listen for the valve to be sure it is running. When
I had a bad connection at the valve, I could still hear it buzzing, but the
volume would get louder when I giggled the connection.

It sounds like your poor fuel mileage is due to running too rich because of
the CPR. Don't do too much driving like this because it can overheat your
exhaust system. It can make your catalytic converter glow and melt the
webbing, and it can damage your muffler. I know of a guy who had to replace
his muffler because it was heat damaged from the engine running too rich.
His heat shield is a mess, and I'm wondering if this was also due to the
excessive heat.

While trying to diagnose my bad lambda system long ago, I was able to
compensate for it by leaving a hand vacuum pump connected to the
acceleration enrichment port of the CPR. To start the car while cold, I
would have to lift the engine cover and squeeze the pump until the hose
collapsed. Then by the time the car warmed up, the vacuum would leak off.
I wouldn't recommend this. The pump was plastic and the ambient heat from
the engine melted it.

As for fixing the internals of the CPR, I know that rebuilt ones at a local
Bosch parts dealer cost $87 with exchange. Before I knew better, I paid a
specialist $500 for one with about another $250 in labor. That was before I
had the manuals and the DML! If you are successful at finding a rebuild
kit, please let us know! I have not seen the inside of a CPR, but I can
venture to guess that the solder connection that you cannot melt is probably
a weld connection. The heating element wire is a nickel-chromium wire that
can glow red hot without melting. This would quickly melt the typical 40/60
tin/lead solder. You can probably weld this connection with a high
temperature solder commonly used in refrigeration plumbing, but there
probably isn't enough room in there for a welding torch. It takes an open
flame to melt that stuff or a very tiny electric welder made for that kind
of work. I would opt for a high temperature crimp barrel connector. It is
just like the ones you would buy at an automotive store except they are made
to take extreme temperatures. You can find them on the shelf at most
refrigeration supply stores or even Grainger.

I'm curious to know if the diaphragm can be replaced with a fuel resistant
piece of gasket material. But again, I've never seen inside a CPR (yet), so
I'm taking a guess here.

Walt Tampa, FL