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Cadillac runaway acceleration



 
 
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  #1  
Old May 15th 15, 09:29 PM posted to rec.autos.tech
The Real Bev[_5_]
external usenet poster
 
Posts: 570
Default 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.
Ads
  #2  
Old May 15th 15, 10:05 PM posted to rec.autos.tech
Bill Vanek
external usenet poster
 
Posts: 173
Default Cadillac runaway acceleration

On Fri, 15 May 2015 13:29:55 -0700, The Real Bev
> wrote:

>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.


Yes, that was a common problem, and years ago. I don't know if I
remembered to mention that one, though.

There might be some specialty shops that can replace the bushings, or
there might be aftermarket throttle bodies somewhere. At some point,
though, it's not worth the expense.
  #3  
Old May 15th 15, 10:22 PM posted to rec.autos.tech
The Real Bev[_5_]
external usenet poster
 
Posts: 570
Default Cadillac runaway acceleration

On 05/15/2015 02:05 PM, Bill Vanek wrote:
> On Fri, 15 May 2015 13:29:55 -0700, The Real Bev
> > wrote:
>
>>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.

>
> Yes, that was a common problem, and years ago. I don't know if I
> remembered to mention that one, though.
>
> There might be some specialty shops that can replace the bushings, or
> there might be aftermarket throttle bodies somewhere. At some point,
> though, it's not worth the expense.


He checked his aftermarket sources. If it was possible to find a
wrecked unit from a wreck that happened 20 years ago I'd be OK with
that, but apparently you have to replace injectors too.

I'm looking at several $thousand in AC and shock replacement in addition
to this plus comfort-only stuff. I don't think so.

--
Cheers, Bev
================================================== ======
His men would follow him anywhere, but only out of morbid curiosity.
  #4  
Old May 15th 15, 10:49 PM posted to rec.autos.tech
Brent[_4_]
external usenet poster
 
Posts: 4,430
Default Cadillac runaway acceleration

On 2015-05-15, The Real Bev > wrote:

> 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.


There's where the air is getting in causing the increasing speed/rpm. It
depends on what the bushings look like but they can probably be
easily made, found generically as hardware, or removed from any number
of GM cars.

> The AC is shot, along with the shocks.


Shocks get expensive with someone else replacing them.

> The front tires are 12
> years old. The headliner is held up with long ball-headed pins to keep
> it from flapping.


GM has been using headliner glue that lets go after 15 years for 30+
years.

> The driver-side window will only go down 6" or so.


regulator issue. Probably a broken gear. A plastic gear knowing GM.

> 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.


With the issues you're talking about miles aren't the problem but years.
It's all materials degrading over time and exposure to the elements.





  #5  
Old May 16th 15, 01:21 AM posted to rec.autos.tech
Ashton Crusher[_2_]
external usenet poster
 
Posts: 2,874
Default Cadillac runaway acceleration

On Fri, 15 May 2015 13:29:55 -0700, The Real Bev
> wrote:

>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.



For $8K you can buy a nice one owner one.... Always garaged...
http://classiccars.com/listings/view...innesota-55302
  #6  
Old May 16th 15, 03:16 AM posted to rec.autos.tech
Scott Dorsey
external usenet poster
 
Posts: 3,914
Default Cadillac runaway acceleration

The Real Bev > wrote:
>
>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.


Bingo. That's exactly the sort of thing I was suggesting and the reason
why I was suggesting playing with the throttle by hand.

Take the throttle body off (you can do it yourself, it's not a big deal)
and take it to a machine shop. Have them see if they can rebush it.
They'll have to cut new bushings on a lathe out of oilite stock, but it's
not really all that difficult.

> 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.


GM quality has improved a lot since this car was made. It hasn't improved
enough, mind you, but things are much better today.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #7  
Old May 16th 15, 08:21 AM posted to rec.autos.tech
The Real Bev[_5_]
external usenet poster
 
Posts: 570
Default Cadillac runaway acceleration

On 05/15/2015 02:49 PM, Brent wrote:
> On 2015-05-15, The Real Bev > wrote:
>
>> 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.

>
> There's where the air is getting in causing the increasing speed/rpm. It
> depends on what the bushings look like but they can probably be
> easily made, found generically as hardware, or removed from any number
> of GM cars.
>
>> The AC is shot, along with the shocks.

>
> Shocks get expensive with someone else replacing them.


I know, but I just don't have the mental energy or painless back
required for the job any more. Long ago I thought it would be cool to
have a grease pit in the back yard. I still think it would be cool, but
not having one is an excellent reason to pay somebody else to do
something :-)

>> The front tires are 12
>> years old. The headliner is held up with long ball-headed pins to keep
>> it from flapping.

>
> GM has been using headliner glue that lets go after 15 years for 30+
> years.


GM is evil. Not stupid, evil. Not just planned obsolescence, planned
destruction.

>> The driver-side window will only go down 6" or so.

>
> regulator issue. Probably a broken gear. A plastic gear knowing GM.


Probably. The 1960 Ford broke the little plastic roller that pushed on
the window to roll it up and down. 25-cent part, taking the **** off
the door was the troublesome part. Probably the same here, except for
the gear-grinding noise at the top and bottom. More crap. Oh yeah, the
interior door-puller broke so I have to close the door by hooking my
fingers into the space between the window and its frame.

>> 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.

>
> With the issues you're talking about miles aren't the problem but years.
> It's all materials degrading over time and exposure to the elements.


The paint is in fair condition, though :-(



--
Cheers, Bev
=-=-=-=-=-=-=-=-=-=-=-=
SAVE GAS, FART IN A JAR
  #8  
Old May 16th 15, 08:22 AM posted to rec.autos.tech
The Real Bev[_5_]
external usenet poster
 
Posts: 570
Default Cadillac runaway acceleration

On 05/15/2015 05:21 PM, Ashton Crusher wrote:

> For $8K you can buy a nice one owner one.... Always garaged...
> http://classiccars.com/listings/view...innesota-55302


Thanks, I think I'll skip that one.

--
Cheers,
Bev
=-=-=-=-=-=-=-=-=-=-=-=
SAVE GAS, FART IN A JAR
  #9  
Old May 16th 15, 08:27 AM posted to rec.autos.tech
The Real Bev[_5_]
external usenet poster
 
Posts: 570
Default Cadillac runaway acceleration

On 05/15/2015 07:16 PM, Scott Dorsey wrote:
> The Real Bev > wrote:
>>
>>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.

>
> Bingo. That's exactly the sort of thing I was suggesting and the reason
> why I was suggesting playing with the throttle by hand.
>
> Take the throttle body off (you can do it yourself, it's not a big deal)
> and take it to a machine shop. Have them see if they can rebush it.
> They'll have to cut new bushings on a lathe out of oilite stock, but it's
> not really all that difficult.


We could probably do that ourselves, we have a little 5" lathe that
hasn't moved for 40 years. Not gonna do it, though. The car is at the
point where stuff is just going to start breaking and I don't want to
deal with it any more. I really am superstitious about this -- fix one
thing and the car will deliberately break something else.

>> 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.

>
> GM quality has improved a lot since this car was made. It hasn't improved
> enough, mind you, but things are much better today.


Never again. The 73 Dodge pickup is made of real metal. It goes, it
stops (well, it needs some serious brake work, but it stops if you
pump), and its problems are understandable by humans.

--
Cheers, Bev
=-=-=-=-=-=-=-=-=-=-=-=
SAVE GAS, FART IN A JAR
  #10  
Old May 16th 15, 04:55 PM posted to rec.autos.tech
Bill Vanek
external usenet poster
 
Posts: 173
Default Cadillac runaway acceleration

On Sat, 16 May 2015 00:21:13 -0700, The Real Bev
> wrote:

>On 05/15/2015 02:49 PM, Brent wrote:
>> regulator issue. Probably a broken gear. A plastic gear knowing GM.

>
>Probably. The 1960 Ford broke the little plastic roller that pushed on
>the window to roll it up and down. 25-cent part, taking the **** off
>the door was the troublesome part. Probably the same here, except for
>the gear-grinding noise at the top and bottom. More crap. Oh yeah, the
>interior door-puller broke so I have to close the door by hooking my
>fingers into the space between the window and its frame.


Those window regulators had a plastic gear, with a plastic "tape" that
ran in a channel. You could replace the tape and gear, but I don't
know if that stuff is available anymore. Relatively easy job.
 




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