Help: 1988 Lebaron stalling in the cold

Hi everyone. I'm hoping somebody in here with a little more Lebaron
experience than me can help with a solution to very nasty problem.

I have a 1988 Lebaron convertible, 2.5L with automatic transmission. On
days when the temperature drops below about 40 degrees Fahrenheit, the
car will fire up and then immediately shut down again. Total running
time never exceeds 10 seconds. It will continue to fire and shut down
until the temperature gauge reaches the halfway point or above, which
as you can imagine is a real pain when you can't run it for more than
10 seconds at a shot, and very often less than that.

I've found a sort of temporary work around, in that there is a relay
behind the battery on the driver's side of the car that I can
disconnect that will usually allow me to run the car as normal. The
only problem with this is that it shuts down my alternator, which means
my battery is no longer charging. Granted, if I can run it long enough
to get my operating temperature up, I can usually reconnect the relay
and recharge the battery a little. I don't particularly want to be
using a workaround for the rest of the car's existence though, and I'd
love to hear any ideas you folks might have on ironing out this
irritating little kink.

The only recent work done on the engine has been a new alternator belt
about three weeks ago when my old one let go, but the problem predates
that by at least a year or so. Thanks in advance.

-Steven

 

And did you CHANGE the relay that you disconnected to see if this is the
problem? If you unplugged it and the car works, sounds like you narrowed
down the problem!

 

That's an interesting suggestion and I'll certainly look into it (I
have some wiring diagrams on the way as of about 4 PM), but I have a
hard time believing that would be the culprit. It is, after all, just a
connector between two points, and I would think it has only two modes
of operation: on and off. Since the point of a connector is to be on, a
failed relay should (to my thinking) only be able to change to the off
mode, and the problem doesn't happen when it's off.

I'm suspecting a sensor somewhere, due to the nature of the problem and
what I've had to do to bypass it.

And of course if I'm grossly wrong on something, correct me.

-Steven

 

Hi Steven...

Not a mechanic, just an old retired electrical guy who loves cars...

I'd just like to respectfully correct what I think you're saying,
not only for your sake but also for any others who may be gently
mis-led.

A relay - like a pushbutton switch, or several other devices,
can be "normally open" or "normally closed" And just to gently
expand that, if it's a double throw device it can be wired so
that without the coil energized it can be either
closed or open. If single throw, it will be sold as and probably
marked normally open (no) or normally closed (nc)

Take care.

Ken

 

Ken -

I can honestly say I didn't know that. Thank you kindly for the
correction, and with that in mind, I'll definitely take a second look
at that relay.

Thanks again!

-Steven

 

Does it run real strong at good speed when it's doing this
10-seconds-at-a-time thing, or is it just barely going at a too-low
idle speed, then when warmed up it suddenly runs at a normal speed? If
this is a fuel injected motor (I bet it is but you be able to tell that
looking under the hood), these have an idle speed motor that should
raise and lower the idle depending on what the computer and temp/speed
sensors are telling it.

 

The idle speed is fine for the brief time that it actually idles. If I
rev it I can keep it alive a little longer, but it'll cut in and out
during that time and will eventually die anyway. The car is definitely
fuel injected, as was my old '85 hardtop.

I just swapped out the Hall effect sensor today to see if it would
help. I had it out and warmed up today prior to replacing it, so I
won't know if it had any impact until tomorrow. The idle speed motor
was next on my list of things I plan to look at. I guess I'll post an
update tomorrow after I get a chance to test my solution.

 

on my 85 Lebaron conv. I gave up trying to figure out the reason mine
was raising the idle way up and back down sometimes after it warmed up,
so I just waited for it to get to barely warmed up and the idle speed
was good and then unplugged the idle speed motor. It idles
sufficiently now even when cold but of course is not as precise as it
should be, but it works. It's not quite as high as it should be when
cold but keeps running, and is not overspeeding after it's warmed up.
Probably another sensor somewhere but this is good enough for it : )

 

Looks like the Hall effect sensor all but cured it. It still dies out
now and again, but those are speed/distance sensor problems that it's
had for a while, and that it's just too bloody cold out to bother
fixing.

It's not back to chariot of the gods status (it's still a Lebaron,
after all) but this is good enough for my purposes.