Is this a problem inherent to the "Lean Burn" engine, or a weather related issue?

Dear Car Talk

Dear Car Talk | May 01, 1996

Dear Tom and Ray:

In 1979 I bought a new Chrysler Cordoba with a 318 Lean Burn engine.
Routine maintenance has always been adhered to, and the car has never given
me a problem until about 10 years ago, when during wet weather the car
started to run rough and occasionally stall.

I've had it to at least half a dozen mechanics, but no one can seem to
solve this. I've had them change the plugs and plug wires, check the wiring
harness and check the distributor for cracks, but the problem still exists.
Someone told me that the Lean Burn innovation was not that successful. Do
either of you have any suggestions? -- Barbara

RAY: Well, the Lean Burn engine was not something Chrysler is particularly
proud of. When the gas mileage requirements went up, Chrysler was forced to
comply. And rather than design a new, more efficient engine, they opted to
squeeze every bit of gas mileage they could out of their old 318. And the
result was the Lean Burn -- an engine that used so little gas it was barely
on the verge of running most of the time. So it stalled if you even looked
at it funny.

TOM: But if it ran well for the first seven years, it's obvious that
something has changed, Barbara. Maybe it has just been raining more the
last 10 years. Have you checked with the National Weather Service?

RAY: Actually, the first thing you should do is make sure you have a vented
distributor cap. The car didn't come equipped with a vented cap originally,
but due to stalling problems, replacement caps for this car were vented
later on.

TOM: Once you're sure you have a vented, non-cracked distributor cap (since
you've changed the spark plugs and spark-plug wires), my guess would be
that you have a weak coil or a cracked coil tower. The coil is the thing
that actually generates the spark, and if the spark is weak to begin with,
a little moisture or rain could drain off enough electricity from the spark
plugs to make the car stall.
If that coil has been in there for 17 years, it may be no good anymore. A
new coil that gives you a good, hot spark will make this thing run as well
as it did in 1979 (which wasn't that good, but that's the best we can do).

Get the Car Talk Newsletter

Got a question about your car?

Ask Someone Who Owns One