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SVO rough idle

Date: Fri, 12 Dec 1997 14:03:32 -0600
From: "Weideman, Gary" <weideman@ihcmail.ih.lucent.com>
Subject: Rough idle still happening

Gary wrote:

Well I took the pony back where they put on the timing belt and had them
check the timing again, it was off (at 20 degrees BTD !). They reset it
to 10 degrees BTD and that helped a decent amount but the idle is still
a little rough.

Gary, when I had my belt done a couple of years ago, it too was "off" as
well, & the tensioner wasn't set, nor was the ignition timing. It was so
retarded that I could hardly accelerate! Tough to find good shops! The
idle however, on my higher mileage car was fine, at that time.

I changed the plugs,cap, wires and rotor all with FOMOCO parts. That
helped a little more but..... the idle is still not rock steady and
missing occasionally at idle.

What's next ?? I've got 29K original miles on the car. The auto tech
scoped the FI pulses and said they look good. He suggested a FI cleaning
if the plugs and wires didn't take care of the problem (which I had not
put on yet when they reset the timing).

I have a rough cold start idle for some time now. It lasts about 30
seconds, where the vacuum reads low & engine shakes, until the idle
speed increases & stabilizes. Ford dealer wasn't able to cure the
problem, after replacing plug wires, fuel filter, & flushing the
injectors. Cap, rotor, plugs are all good. I've read that FI clogging
was a problem in the 80s due to poor gasoline additives, but shouldn't
be a problem with name brands (like EXXON) today. What's next? I don't
know but FI cleaning hasn't worked for me. 

Here's what the the Ford 1985 Emission Diagnosis Manual suggests for
"Rough Idle":
Cooling - Electric fan loose or cracked
Vacuum leaks
Ignition - scope for: plugs, coil, wires, cap, adapter, & rotor
EGR - valve & vacuum regulator
PCV Valve
EVAP - Components
Ignition Timing - Base plus advance & retard functions
EEC - codes & diagnostics
Exhaust - pipes, muffler, catalyst
Basic Engine - Compression, valve train, camshaft, intake manifold

Since the camshaft & timing have just been worked on, this may be your

I've seen a rough idle cure procedure on the Texas SVO site. Is this my
next step ??

What does this involve? I'd be interested in seeing this, if you have

Also I put on a K&N. I removed hose coming from the black box (what is
it ?) underneath the original air cleaner. This box also has what looks
like a vacuum line going into it (?). Now when I shift at a moderate
throttle level I hear a noise when engaging the clutch (sounds like a
faint rattlesnake). Should the inlet on the black box (where the air
cleaner hose attached) be covered and the vacuum line disconnected to
this box ?? Is this what may be causing my rattlesnake ?? 

This "black box" is this the carbon canister? If so, this is part of the
EVAP system, which feeds fuel vapours from the tank to the engine, where
they're burned. These hoses should be reconnected. This may also be
responsible for your problem, as listed above.

Any help is greatly appreciated !!!

Gary Weideman
>White '86 SVO Comp Prep


Hope this helps! I welcome any input on my own cold start problem, as
I've replaced the TFI, PIP sensor, the TPS is within range, have cleaned
the throttle body, tested the coil, etc, etc. Could this be intake valve
carbon? O2 sensor, or BYP valve? It has stymied the dealer & myself!

Fred Kuzyk
'85 SVO