Stalling at stop lights

1995 SW2, automatic, roughly 66k miles. EGR valve temporarily disabled
while I try to diagnose this problem. It stalls at stop lights -- car
slows down, tachometer goes below 1000, gradually drops over the space
of a few seconds to zero. It does not matter whether the engine is
cold or warm.

I can keep the engine going by braking with the left foot and holding
the tacho at 1000 with the right foot, like I did on my 1975 Dodge
van.

This car has been reliable in the past.

 

|> 1995 SW2, automatic, roughly 66k miles. EGR valve temporarily disabled
|> while I try to diagnose this problem. It stalls at stop lights -- car
|> slows down, tachometer goes below 1000, gradually drops over the space
|> of a few seconds to zero. It does not matter whether the engine is
|> cold or warm.
|>
|> I can keep the engine going by braking with the left foot and holding
|> the tacho at 1000 with the right foot, like I did on my 1975 Dodge
|> van.

Like the Dodge Van (or mine, at least), this may be caused by a gummy
deposit between the throttle body and the throttle plate. This
reduces the non-zero air flow that should exist at idle, causing the
engine to stall. While your problem may have some other cause, it
should be easy to remove the air duct and check the throttle plate.
Do not spray cleaners into the throttle area, as they may damage
non-metallic parts; just clean with solvent on a cloth.

--
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Ned Forrester 508-289-2226
Applied Ocean Physics and Engineering Dept.
Oceanographic Systems Lab http://adcp.whoi.edu/
Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA

 

Aha, you cleared up a mystery for me. I once looked for these gummy
deposits, and concluded that they could be doing no harm, since they
were not causing the throttle plate to get stuck. I was not thinking
about the problem of non zero air flow. I will definitely look for
this.

And hopefully it will help!