Re: Pressured Sensor

[stans4@ibm.net (Stan Schaefer)]

You don't ever want to play with that adjustment!.  As you noted, very
sensitive!!!! The moron that had my '71 before me had cranked the
screw all the way in, gave about 5 mpg and lots of smoke.  Also, I
think if you look in RMMW's catalog, they don't have a sensor for
'71s, at least in my copy they don't.  Now you're going to have to
scare up someone with a exhaust gas analyzer and set it up after you
get the real problem taken care of.

   Probably you have a throttle position switch that needs some
attention, I've had similar symptoms from time to time.  If you leave
the ignition on and gently push the throttle open, you should hear 20
clicks.  This is the acceleration portion of the switch pulsing the
injectors, takes the place of a carb's accel pump. On a '71, no clicks
means a problem with the switch or wiring.  There's also switch
contacts in there for totally closed(idle) and open throttle. Usually
a good cleaning and some very small adjustments to the contacts will
get it going again.  I've had some with broken wires inside, some
hookup wire and solder will fix that in short order.  I use brake
cleaner or non-residue contact cleaner to hose out the thing, gets rid
of any oil in there. Light buffing with a pencil eraser will clean up
the saw-tooth contacts in there, brown bag paper will clean the switch
contacts.  You want to make sure that the stationary switch is closed
at idle, and open any other time.  The other switch has to be open at
idle and closed any other time.  If you can get them so the one just
closes as the other opens, you'll have pretty good throttle response
taking off from a stop sign.  Very small bends are necessary, don't
pretzel things, we're talking thousandths of an inch here.  Both being
closed or open at the same time can really confuse the poor control
box.

Run the continuity tests in the Idiot's Guide relating to the throttle
switch, you could have some crispy wiring to the control box that's
parted company. I assume you have both it and the Bentley factory
manual.  You need both.

 You could also have some air leaks, check your injector nose seals
and your vacuum hoses, seals on the air distributor get hard and leak,
too.  Air leaks will give poor response and high fuel consumption.

Fix your accel problem first, then get your sensor recalibrated.

Hope that's enough to get you started.


On Tue, 2 Jun 1998 10:35:59 -0400 (EDT), you wrote:

>Hi all,
>Ok I admit that i played around with the pressure sensor and now it acts 
>all funky. Im talking bout the one that lives under the left side of 
>engine compartment.
>Scoop: The car was runnign outta steam on hills and even the slightest 
>inclines (im talking like 1% grades!) and so I adjusted the little screw 
>on the back of the pressure sensor and lo and behold plenty of zoom on 
>hills, prob solved. 
>Not quite, that car still fell a little jerky when pushing on the gas 
>pedal ( same as before a played with the adjust screw).
>So I took off the sensor, tested the ohms across the two windings and 
>both were well within specs. But I knew that the rod inside could also be 
>a culprit, so I opened it up (against my better judgement) and blew it 
>clean, was a little dirty inside, put it back together and now the 
>adjustment is way off.
>Im getting about 20 mpg in town 25 hghway. Before all this happened I was 
>getting 23 +/- in town, 28-30 hwy. ans smooooth.
>I know the poorer mpg is because I havent yet found that proper tweak of 
>the adjust screw, but the jerking?
>I was thinking of buying a new one from Rocky Mountain Motorworks. Any 
>thought to this?
>I am pretty sure even if and when I rediscover the exact adjustment for 
>that screw that the car will be fell jerky on acceleration. I think, well 
>that sensor is almost 30 yrs old, and its one moving part may very well 
>be worn.
>Help.
>John 71 Fastback
>ps Remember , John from Zagreb will be in town soon, and Im thinkin a 
>Saturday this month for a afternoon get together. Grant had responded, 
>any others?