From: bashley101@gmail.com
On 04/19/2015 01:30 PM, Ashton Crusher wrote:
> Bev,
>
> My first thought was disconnect the cruise control. I see you listed
> that it had been disconnected. What specifically was disconnected?
> Electrical connections? Vacuum connections? A control cable from a
> "box" to the throttle body?
I don't know. I assume he did it in a way that would completely
preclude it from causing the problem. It's a 1988, BTW. I stupidly
forgot to mention that :-(
> My limited experience with idle speed valves/controllers is that they
> can't "do enough" to really feel like "full throttle" although they
> could make the engine go perhaps 2000 rpm with no load and when under
> load make it like you still have your foot on the gas when you are
> trying to coast down, i.e. it might be able to keep you going 60 mph
> on a level road.
Nope, this was full throttle pedal-to-the-metal. Seriously hard braking
to get the car to actually stop such that I don't think my mom could
have done it. No idea what the RPM was -- you have to push several
buttons on a hard-to-see console to get to that, and I was kind of busy :-)
> So aside from really weird stuff like a computer gone mad, I'm still
> thinking something is going on with the cruise control system but that
> depends on how the one on this car is set up.
>
> When the car does this "sudden acceleration" does your foot on the
> brake make it stop trying to accelerate and it returns to just idle
> speed or does it fight you to a stop and keep revving till you turn
> the engine off? If tapping the brakes makes the engine stop "running
> away" and causes it to return to idle speed it sure sounds like the
> cruise control has somehow engaged.
Nope, it fights me every step of the way until I can turn the engine
off. I don't want to do this in a traffic lane on the freeway, so I
pull over to the shoulder. I've been thinking that perhaps I should
shift into neutral and shut the engine off, but steering and braking
without the engine is a nasty business and I don't like to think about
having to do that in traffic. OTOH, if I can't get over to the shoulder
that's probably the only option.
I also don't feel comfy restarting an engine until the RPM drop to 0.
Nasty sounds from the starter gears :-(
> I'm guessing this car is "drive by wire" making the cruise control
> just a bunch of speed sensors feeding a computer that then tells the
> throttle how far to open. Disconnecting some of the wires from the
> buttons in the steering wheel won't fix it if one of the parts of that
> wire going to the computer is worn thru and shorting out somewhere
> buried under the dash.
Art is pretty smart -- I would guess that he would have thought of
something like this. I don't know why the cruise control stopped
working, it just wouldn't come on the next time I tried it -- after
maybe a couple of years of never using it. I hate cruise controls and
was just testing it.
If it were a wiring problem I would guess that it would happen more
frequently. Last time it happened, BTW, was over a year ago.
> BUT, one of the other issues is that all cruise controls I've had are
> set up so that they WILL NOT engage under about 25 mph. That would
> mean it couldn't be the cruise control doing this from a dead stop
> unless the computer or wiring or sensors was seriously messed up.
The CC in the monsterhome resumes speed in a civilized manner, not a
full stomp on the accelerator. Given the wussy nature of the Cad, I
would guess it behaves the same way.
> On Sun, 19 Apr 2015 09:29:22 -0700, The Real Bev
> wrote:
>
>>This (rec.autos.driving) used to be a good group. What happened? On
>>the off chance that anybody is still actually alive, posted below is
>>what I've posted into two Cadillac "forums" with no help whatsoever,
>>although one person suggested replacing the stuff that had already been
>>replaced.
>>
>> At least 5 times (2 with witnesses) this car (which I inherited
>>from my mom in 2007 with 65K miles on the odometer and which has
>>sentimental value) has suddenly accelerated as if I had floored the
>>accelerator. I brake as hard as I can, pull to the side and shut the
>>engine off. When I start up again everything is normal. The first time
>>was from a full stop, with two more occurrences within the next 50 miles
>>at freeway speeds. One time going uphill on a mountain road, and the
>>remaining times at freeway speeds.
>>
>> I've had this stuff replaced by a trusted GM independent mechanic:
>>
>> Feb 2011 Replaced the idle speed actuator (idle air control valve
>>D6576 due to accelerating on its own.
>> Mar 2012 Replaced the throttle position connector HP4460, Throttle
>>position snsr/throttle position sensor TH38, throttle spring kit (fast idle)
>> Oct 2012 Rebuilt smog pump 32-428, serpentine belt. Disconnect
>>cruise control and inspect powertrain computer for internal failure (tap
>>test). Replace broken engine mount.
>>
>> I never used the cruise control, which stopped working while my mom
>>still owned the car. It has 85K miles now.
>>
>> It's done the runaway thing at least once, possibly twice since
>>then. No codes.
>>
>> The mechanic thinks it may be the computer dropping out and then
>>resetting itself at full throttle, which sounds even dumber than
>>deciding that a car should decelerate SLOWLY when you take your foot off
>>the gas, and that there is no guarantee that a replacement will be any
>>better.
>>
>> More recently it has started to occasionally maintain speed on
>>level ground when I take my foot off the gas, and may have occasionally
>>slightly increased speed, but braking stops this instantly. I haven't
>>talked to the mechanic about this yet.
>>
>> I really hate to junk a car with only 85K miles, especially my
>>mom's car, but even though I'm 5 for 5, it's still scary.
--
Cheers,
Bev
= = = = = = = = = = = = = = = = = = = = = = = = = = =
"I read about this syndrome called hypochondria in a
magazine. I think I've got it." -- DA
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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