| Author |
Message |
Office Drone
Guest
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 Posted:
Mon Nov 08, 2004 7:32 am Post subject:
Cold nights cause a temperature-dependent max achievable spe |
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This had been a problem for a long while, outliving all repairs I have
done on the car.
Lately I have to drive on a daily basis, and this winter the problem
became a royal pain.
The colder the night was, the lower will be the maximum speed I can
get to. At that max threshold speed the car would buck, jerk as if
ignition is not happening, and can even stall, if forced.
The oddity is that warming up the engine on idle has little effect,
compared to driving under max achievable speed.
After about 5 minutes of driving, that maximum speed will start
increasing, after 5 more minutes it will gain another +10mph, and in
about 30 minutes I can drive fine at any speed until next cold night.
There are no error codes, starting, idling, stopping, accelerating,
going at 80mph are all fine, there's no jerking or stalling other than
in the situation described.
At warmer weather I won't notice the problem, or that max speed would
be around 70mph, where it doesn't bother me so much.
This issue survived:
* transmission rebuild
* engine change
* three MAF sensors change
* spark system change (plugs & wires)
* ICM change (ignition control module)
* O2, camshaft, crankshaft sensors change
* new catalytic
* new injectors
* fuel filters change
Throughout the years it's as solid as my appetite. And it's as
disturbing. Imagine how you wake up in the middle of winter, you need
to drive to work, and you aren't able to drive above 20mph for good 5
minutes. Now imagine that you're a police officer, sitting in your
vehicle, enjoying your morning doughnut, and then a rusty old car
crawles right in front of you at a treacherously low speed, and then
you see it again and again, as I make several circles around the area
trying to get the car to the speed where I could pull on the highway.
This picture can make even the most breakfast-minded detective
concerned.
I'm looking for any pointers, anything I could try to diagnose what
the hell is so profoundly wrong with my otherwise great beast.
It's a 1988 GM with 75K engine, no distributor (coil packs),
injection, V6.
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« Paul »
Guest
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| Posted:
Mon Nov 08, 2004 7:47 am Post subject:
Re: Cold nights cause a temperature-dependent max achievable |
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Office Drone wrote:
| Quote: |
This had been a problem for a long while, outliving all repairs I have
done on the car.
Lately I have to drive on a daily basis, and this winter the problem
became a royal pain.
The colder the night was, the lower will be the maximum speed I can
get to. At that max threshold speed the car would buck, jerk as if
ignition is not happening, and can even stall, if forced.
The oddity is that warming up the engine on idle has little effect,
compared to driving under max achievable speed.
After about 5 minutes of driving, that maximum speed will start
increasing, after 5 more minutes it will gain another +10mph, and in
about 30 minutes I can drive fine at any speed until next cold night.
There are no error codes, starting, idling, stopping, accelerating,
going at 80mph are all fine, there's no jerking or stalling other than
in the situation described.
At warmer weather I won't notice the problem, or that max speed would
be around 70mph, where it doesn't bother me so much.
This issue survived:
* transmission rebuild
* engine change
* three MAF sensors change
* spark system change (plugs & wires)
* ICM change (ignition control module)
* O2, camshaft, crankshaft sensors change
* new catalytic
* new injectors
* fuel filters change
Throughout the years it's as solid as my appetite. And it's as
disturbing. Imagine how you wake up in the middle of winter, you need
to drive to work, and you aren't able to drive above 20mph for good 5
minutes. Now imagine that you're a police officer, sitting in your
vehicle, enjoying your morning doughnut, and then a rusty old car
crawles right in front of you at a treacherously low speed, and then
you see it again and again, as I make several circles around the area
trying to get the car to the speed where I could pull on the highway.
This picture can make even the most breakfast-minded detective
concerned.
I'm looking for any pointers, anything I could try to diagnose what
the hell is so profoundly wrong with my otherwise great beast.
It's a 1988 GM with 75K engine, no distributor (coil packs),
injection, V6.
|
About the only thing not yet changed out is the fuel pump.
Check the pressure at idle when cold. |
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noname
Guest
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| Posted:
Mon Nov 08, 2004 7:32 pm Post subject:
Re: Cold nights cause a temperature-dependent max achievable |
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If it is a 3.8L, You need a new "reluctor" on the camshaft gear.
This is a small magnet that is held by a plastic clip that gives the cam
sensor its signal.
Every time it rotates around past the cam sensor, the sensor changes voltage
and thus makes the "pulse".
I have found almost identical symptoms in several cars like yours that need
this repair.
The magnet over time deteriorates and either falls out of the plastic clip
or just turns to mush and the sensor no longer picks it up.
"Office Drone" <fulbrighter2@yahoo.com> wrote in message
news:68497021.0411071832.1dbdd7da@posting.google.com...
| Quote: | This had been a problem for a long while, outliving all repairs I have
done on the car.
Lately I have to drive on a daily basis, and this winter the problem
became a royal pain.
The colder the night was, the lower will be the maximum speed I can
get to. At that max threshold speed the car would buck, jerk as if
ignition is not happening, and can even stall, if forced.
The oddity is that warming up the engine on idle has little effect,
compared to driving under max achievable speed.
After about 5 minutes of driving, that maximum speed will start
increasing, after 5 more minutes it will gain another +10mph, and in
about 30 minutes I can drive fine at any speed until next cold night.
There are no error codes, starting, idling, stopping, accelerating,
going at 80mph are all fine, there's no jerking or stalling other than
in the situation described.
At warmer weather I won't notice the problem, or that max speed would
be around 70mph, where it doesn't bother me so much.
This issue survived:
* transmission rebuild
* engine change
* three MAF sensors change
* spark system change (plugs & wires)
* ICM change (ignition control module)
* O2, camshaft, crankshaft sensors change
* new catalytic
* new injectors
* fuel filters change
Throughout the years it's as solid as my appetite. And it's as
disturbing. Imagine how you wake up in the middle of winter, you need
to drive to work, and you aren't able to drive above 20mph for good 5
minutes. Now imagine that you're a police officer, sitting in your
vehicle, enjoying your morning doughnut, and then a rusty old car
crawles right in front of you at a treacherously low speed, and then
you see it again and again, as I make several circles around the area
trying to get the car to the speed where I could pull on the highway.
This picture can make even the most breakfast-minded detective
concerned.
I'm looking for any pointers, anything I could try to diagnose what
the hell is so profoundly wrong with my otherwise great beast.
It's a 1988 GM with 75K engine, no distributor (coil packs),
injection, V6. |
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| Back to top |
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Office Drone
Guest
|
| Posted:
Tue Nov 09, 2004 2:25 am Post subject:
Re: Cold nights cause a temperature-dependent max achievable |
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"noname" <nospam4meplease@nospam.net> wrote in message news:<6vLjd.123$3K2.108@newsfe07.lga.highwinds-media.com>...
| Quote: | If it is a 3.8L, You need a new "reluctor" on the camshaft gear.
This is a small magnet that is held by a plastic clip that gives the cam
sensor its signal.
Every time it rotates around past the cam sensor, the sensor changes voltage
and thus makes the "pulse".
I have found almost identical symptoms in several cars like yours that need
this repair.
The magnet over time deteriorates and either falls out of the plastic clip
or just turns to mush and the sensor no longer picks it up.
|
I heard the same suggestion from a dealer a year ago.
But why a weak or deteriorated magnet would be so dependent upon the
air temperature? |
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Isaiah Beard
Guest
|
| Posted:
Wed Nov 10, 2004 2:01 am Post subject:
Re: Cold nights cause a temperature-dependent max achievable |
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Office Drone wrote:
| Quote: | The magnet over time deteriorates and either falls out of the plastic clip
or just turns to mush and the sensor no longer picks it up.
I heard the same suggestion from a dealer a year ago.
But why a weak or deteriorated magnet would be so dependent upon the
air temperature?
|
Certain magnets have been known to change their properties when heated
or cooled. It's quite possible that the temperature changes in your car
are having a similar, and affecting the behavior of the car as a result.
--
E-mail fudged to thwart spammers.
Transpose the c's and a's in my e-mail address to reply. |
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