Cadillac runaway acceleration

On 04/21/2015 04:20 PM, The Real Bev wrote:
> On 04/21/2015 03:18 PM, Bill Vanek wrote:
>> On Tue, 21 Apr 2015 14:37:57 -0700, The Real Bev
>> > wrote:
>>
>>>Two data points:
>>>
>>>(1) On the freeway, at roughly 55 mph, I gunned the engine. Passenger
>>>reported it went up to 3K before I backed off, at which point it dropped
>>>normally. Just a test...
>>>
>>>(2) Leaving a parking lot, with my foot on the brake, the involuntary
>>>acceleration started. I immediately shifted to neutral and watched the
>>>rpm rise to 2700 before I tapped the accelerator, bringing it back to
>>>normal.
>>
>> 2700 is about the limit of the ISC motor. The contact switches in
>> those can go bad, and cause that (it doesn't know it's in contact with
>> the throttle lever), or the ECM. I would think that if it was the ECM,
>> it would happen more often, but the tap test might help, too.
>
> *I* backed off; the rpm was still rising in both cases.
>
>> Regarding the ISC, the plunger is spring loaded, and you can feel the
>> contact switch with slight pressure - it will move very slightly in
>> and out. That switch could be bad, but another cause is weak throttle
>> return springs that can't push the plunger in enough to close the
>> contacts, or a sticking throttle. In fact, either of those two
>> problems can cause what might feel like unintended acceleration.
>
> Not "feel like." IS!
>
>> If this happens again, you can always put it in park, open the hood,
>> and look to see if the ISC is fully extended, holding the throttle
>> open. If it is, push the plunger in, and if it retracts then, it's
>> almost for sure a bad ISC motor, unless you can see that the throttle
>> lever is clearly not pushing against that plunger. If that's the case,
>> it's either the springs, or a binding throttle shaft, or throttle
>> plates.
>
> ...for extremely rare values of 'always'.
>
> Next week I go back to the mech with a lot of questions...

The bad news, which was ameliorated before by replacing the return
spring with a heavier one: bad bushings in the throttle body, allowing
sticking, slop, etc. No replacement possible, unless maybe from a
wreck. The AC is shot, along with the shocks. The front tires are 12
years old. The headliner is held up with long ball-headed pins to keep
it from flapping. The driver-side window will only go down 6" or so.
Lots of plastic bits are just broken.

I truly wish my mom had asked us before buying this POS. A "luxury" car
with 85,000 miles on the clock should NOT need this much crap in
addition to the crap it's already demanded.

--
Cheers, Bev
You know it's time to clean the refrigerator when
something closes the door from the inside.