Stall problem in '93 SC 300 - hints as to solution?

[Dan Weingart]

Hi,

I have a '93 SC300 with 105K that has an odd problem:

About once every 10-14 days I will be driving and the engine will just
die. No warning - it just cuts out. Inbetween the engine runs just
fine. I take good care of it and my mechanic doesn't see anything
obviously wrong (no code in the computer either).

During these 'episodes' which last about a minute, the engine either
won't start or will start and rev at incredibly low RPM (< 100) -
though pumping the gas has no effect at all on the RPM.

After about a minute, the car starts right up and drives perfectly
normally. I've had it happen while idling, going uphill, level - no
real rhyme-or-reason though always when I've driven for at least 10
minutes.

I'm loath to start replacing parts 'hunting' for a solution. Any
ideas?

Thanks!

-Dan

[Mark S. Jennings]

Is there any patern at all to when it cuts out? Hot, cold, a certain type
of driving, 10-minutes after cold start, certain area of town, etc.?

- Mark

[Paul Whitehead]

There are certain facilities that send out very strong radio,electrical &
infra-red radiation waves or signals.
these can severly interfere with electronic ignition systems.
thus causing certain ignition systems to freeze as it were.
Might be worth noting if your problem occurs near to any Milatry, Radio, or
x-ray emmiting location.

just a thought as i have heared of it affection certain motors.

Regards.

"Dan Weingart" <UCL...@AOL.COM> wrote in message
news:10d419fa.02030...@posting.google.com...

[Dan Weingart]

Not that I can easily spot. My collection:

1) Making a right turn at an intersection (2-3mph).
2) Going up a moderate hill (25-30mph)
3) Along a flat, but slightly windy road (25-35mph)
4) Starting car after a quick stop at the supermarket.

Tempature outside ranged from 65-80. Car was always run at least
10min. Lately I've been driving alot in 2nd gear (we bought a house in
the hills). I also switched to 'mid-grade' gasoline for the last few
months. I haven't taken it on a long trip or on the freeway in quite a
while, so I don't know if the problem would happen in those
situations.

-Dan

[M]

You mention that you switched to a mid-grade fuel. If your mid-grade fuels
are like what I get around my area then it "might" explain the issue.
Mid-grade fuels frequently consist of an alcohol or alcohol-like oxygenating
mix (e.g., 10% ethanol and 90% petro). The mix is frequently not too
accurate and can be up to 25% alcohol. If you have a 1993 vehicle and you
recently switched then you have been running premium or straight regular all
the time. Over the years straight and premium can leave a slight coating of
varnish in the fuel system. Alcohol will make that make if flake off. The
debris can wreak havoc your fuel delivery system. I would think that your
ECM would give a code for lean fuel mix, but maybe not if your fuel line or
pump screen is severely clogging. It's also possible that your are sloshing
crud in the bottom of your fuel tank and stopping fuel flow momentarily.

It's also possible that you have a bad ground or wiring harness intermittent
loss of contact. I would reseat the ECM connectors and do the old wiggle
test on the wiring to see if the problem can be induced. No codes is
frequently a problem with ECM's losing power.

I agree with you that replacing parts is not a good option at this time
because your symptoms may be from very different sources.

Also, next time it does it, check to see if there is any spark or fuel
pressure. You will have to get some equipment to help you determine that
and it's typically a job that a tech or advanced DIY should do.

Good Luck.

"Dan Weingart" <UCL...@AOL.COM> wrote in message
news:10d419fa.02030...@posting.google.com...

[bruce]

Hello Dan-

I had a 93 SC300 five speed that was purchase new in 1993- I can't remember
exactly when it occurred, but I believe it was sometime in 1994 when my car
starting behaving almost identically to what you are seeing. I took it to
the dealer, they messed around and said bring it back if it re-occurs; I
brought it back in a month or so later with the same problem, so they then
replaced the main engine computer (according to them) After that time the
problem never re-occurred. ( The car was totaled in 1995) I now have a 95
SC400 with about 102K miles with no problems at all in the three years that
I have owned it.

I still have all the records, so if you really need more exact information
on mileage and dates I could probably dig them up.

Bruce.

"Dan Weingart" <UCL...@AOL.COM> wrote in message
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