Re: Re: Alternative to Idle Speed Motor...

["content22207" <brobertson@xxxx>]

My "original" idle speed system was cantankerous and irritating.
Sometimes it worked, sometimes it didn't. Remember, however, I am
burning a replacement engine. Idle speed circuit was not transferred
per DMC design (blame a PO, not me) No throttle closed microswitch --
motor was hard wired on (am also missing the spark advance solenoid.
That's why my takeoff is uphill of throttle plates, like a
carburetor). Perhaps full time operation fried motor or ECU. Either
way, was not willing to spend $hundreds to fix.

Solenoid valve indeed on/off (one reason I was hoping for a coil). But
since I'm currently in full control with dash switch, no problem
there. In future will see how vehicle responds to coolant switch. By
the time water is hot car shouldn't need fast idle. If need be can
always leave dash switch active (kind of like an old choke cable, eh?).

May need two idle speed settings for summer and winter. Have done that
with smaller carbureted vehicles when A/C solenoid dies. Ford 460's
don't seem to notice compressor is even there...

Only brought this mod to list's attention because others seem to be
having similar problems. Of course an automatic system is nice, *IF*
it works correctly. I don't care about nice. I care about reliable.
Bypass/balancing screws stay put where I set them. As evidenced in
pics, I prefer engine distilled to its basics. No whistles, no bells,
no problems.

Note on driver's side of my block one more advantage -- distributor is
finally accessible! Have to raise upper air assembly for vertical
clearance to remove wires, but no sweat reaching them, hold down bolt,
etc. 100% improvement.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "David Teitelbaum" <jtrealty@xxxx> wrote:
> From your description of what you did it sounds like the aux air valve 
> is now either on or off. There is no in between. The origional "stock" 
> idle motor and ECU is capable of modulating ie: it can give you speeds 
> in between full open and full closed so it can hold the idle speed to 
> a specified value like when you run the A/C or in an automatic you 
> stop at a lite and are sitting in Drive with your foot on the brake it 
> keeps the idle speed up but not too high. Your system cannot 
> compensate for load changes, only temperature changes. IMHO the stock 
> system is the better way to go, it just needs to work properly and be 
> set-up correctly (something many mechanics can't seem to do).
> David Teitelbaum
> vin 10757
> 
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> 
> wrote:
> > My PRV idles with bypass & balancing screws (like a Volvo). Works
> > excellent, but lacks ability to fast idle -- especially useful on 28
> > degree mornings. Have engineered an "auxiliary air valve" from BMW 
> 530
> > to accomplish this (am not partial to that particular model; was
> > simply soonest ending eBay auction when I got bright idea). Uploaded
> > JPG's to #5939's photo album. Text below:
> > 
> > Aux air valves were apparently used by most other manufacturers of 
> the
> > time. Are solenoid or coil operated valves similar to heater core 
> shut
> > off valves. Cold, valve is open, allowing additional engine vacuum 
> to
> > operate sensor plate (fast idle). Warm, valve closes, limiting 
> sensor
> > plate movement to bypass screw.
> > My valve has 3/4" ports. Stepped down to 3/8" with brass fittings.
> > Vacuum source port also turned 90 degrees with an elbow (would have
> > preferred model that passes straight through, but hey, this one
> > works). Converted two 1/8 NPT nipples to 10x1 to fit manifold and
> > upper air assembly (anyone else noted how close those thread 
> patterns
> > are? Die down right nicely). Used mega hose to avoid collapsing 
> under
> > vacuum. Line to air sensor plate makes pretty severe bend under
> > driver's intake rail, so I reinforced with an internal spring. Also
> > had to move spark advance to a smaller adjacent port (see old pic
> > titled "R30 - Front". That's extent of my engine vacuum system BTW).
> > 
> > Was hoping for a coil operated valve but got a solenoid. Oh well, 
> what
> > do you expect for $5. Next time intake manifold is off will attach
> > ground wire to thermal switch in coolant pipe. Until then is 
> triggered
> > by a switch under the dash left over from earlier experiments. 12v
> > supply is taken from old idle speed motor harness.
> > 
> > Couldn't be happier with performance of this low tech idle speed
> > system. Removes all the gremlins that plagued my automatic motor.
> > Total investment: $20.
> > 
> > Anyone want to buy a surplus idle speed motor and ECU?
> > 
> > Bill Robertson
> > #5939