need frequency valve help

["Walter" <Whalt@xxxx>]

I've had an on-going cold acceleration problem in my Delorean and haven't
had much luck getting advice on how to fix it. Maybe someone on this list
can help?

So far I have tried unplugging the electrical connection to my frequency
valve, and it makes absolutely no difference to how the engine runs.

The engine coughs, sputters, pops, and runs rough until it completely warms
up. When I force the engine to run richer by pulling a vacuum on the
delayed side of the control pressure regulator, then the engine runs fine!
I have checked the fuel pressures and they are within specs.

My question to the group is: How can I tell if my frequency valve is
working? I've tried unplugging it and this makes no difference. I've tried
unplugging the Lambda ECU and this makes no difference either. I've put a
volt meter across the wires going to the frequency valve and measure
nothing. I realize that a volt meter is probably the wrong tool for this,
but I don't have access to an oscilloscope. Is there some other diagnostic
tool that is appropriate here? I could check for flow with a fuel pressure
gauge, but I hate to take those connections apart if I don't need to. I do
get continuity through the coil, but that won't help if nothing is going to
it.

For those of you who like to read, here is an earlier message I wrote to the
DML that never got posted. It explains more of my symptoms:

What can cause a Delorean to hesitate during acceleration, but forcing the
control pressure regulator to make it run richer cures the problem? I've
checked the fuel pressures, and they are all normal. I get primary pressure
of 5.1 bar. The control pressure regulator gives 2.9 bar with cold engine,
3.7 bar with fully warmed up engine.

Pulling a vacuum on the delay side of the control pressure regulator drops
the fuel pressure under 2 bar and cures all my problems. But, the fuel
pressure isn't supposed to be that low. So is this compensating for some
other problem? And if so, what is it?

At idle, my vacuum reading is 15 inHg, but it jitters +/- 2.5 inHg. Is this
normal? My vacuum at 2000 rpm is 17 inHg and smoothes out. Is this a
symptom of a stuck valve or is this normal?

This problem has been intermittent in the past and would only happen to a
cold engine. Now it happens all the time, and it doesn't really matter if
the engine is cold any more. Now even after the engine is warmed up, I get
hesitation, coughing, sputtering and even backfiring.

When I start the engine, it tends to stall. Any pressure on the accelerator
makes the engine hesitate, cough, sputter and pop. When I release the
accelerator, the engine speed actually picks up for an instant and then
drops back to a rough idle. This keeps up until the engine is hot. Before
I drive the car, I have to let it warm up for at least 5 minutes. After the
engine is fully warmed up and I turn it off and let it sit for 30 minutes, I
have to let it warm up all over again before I can drive it.

Walt Tampa, FL