GC5.2 ZJ: Slow acceleration from tranny or differential??
06-02-2007, 01:21 PM
#1
Guest
Posts: n/a
GC5.2 ZJ: Slow acceleration from tranny or differential??
Hi all,
Two things I want to ask about, and forgive my ignorance in accurately
describing the following issues.
First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the time,
throughout the speedometer range. Off the line it's decent, but the
accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
should be even then. (I acquired the 93 w/209K and did tranny service (pan,
filter, new fluid), new water pump/timing chain among other things).
For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
would expect. Instead after about 2 seconds, it seems the engine RPM's "jump"
up" slightly (like a delay), not the amount one would expect though. The only
time(s) the "gear drops/RPM's jump" as expected is when I push practically 85%
of the way on the pedal-- then it moves, and when the RPMs hit high (4K? 5K?)
it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
the engine will shift to a lower gear and momentarily spike the RPMs up again
past 5K!, seemingly "out of control" (scary-- that makes one completely
release the pedal..)
I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
moderate pushing on the accelerator, off the line, and throughout the driving
range, so I'd assume the engines are similar if not identical.
The other issue, which may be related is that I've never changed the
differential fluid, and I don't know when/if it had been done before on this
vehicle, and I wonder if that could possibly be contributing to the above
problem in any way.
With respect to the differential, if I start up in the morning on a spring
day for example (not a cold day when idle would be raised by the IAC valve),
and I warm for only 30 seconds or so and switch into drive, and let the idle
move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to creep
forward. This happens sometimes. Now this ZJ has a low idle to begin with
(~620, dunno why), but I don't think that's the issue. It seems that once the
car is warmed for 5 minutes or so this doesn't happen at all. This also could
be an issue with the parking brake because when I first drive off (at a
moderate rate) I hear a 1 second "rub" from the vehicle.
I also wonder on such a high mileage vehicle, if there's any risk to getting
the differentials completely changed/flushed, and having the differential box
"cleaned out" with carb/brake cleaner or the like. I've heard/read that doing
flushes on "high mileage" tranny's can remove benficial "varnish", and I
wonder if a similar principle applies here, if my differential hasn't been
serviced for a very long time/ever.
I'm also considering putting in a bottle of Lucas Transmission Fix into the
tranny just beacuse.. How much tranny fluid would I need to siphon out and do
I add the whole bottle of Lucas? Is there any chance I could hurt the tranny
further by adding the Lucas?
Thanks in advance.
--
Message posted via http://www.carkb.com
Two things I want to ask about, and forgive my ignorance in accurately
describing the following issues.
First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the time,
throughout the speedometer range. Off the line it's decent, but the
accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
should be even then. (I acquired the 93 w/209K and did tranny service (pan,
filter, new fluid), new water pump/timing chain among other things).
For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
would expect. Instead after about 2 seconds, it seems the engine RPM's "jump"
up" slightly (like a delay), not the amount one would expect though. The only
time(s) the "gear drops/RPM's jump" as expected is when I push practically 85%
of the way on the pedal-- then it moves, and when the RPMs hit high (4K? 5K?)
it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
the engine will shift to a lower gear and momentarily spike the RPMs up again
past 5K!, seemingly "out of control" (scary-- that makes one completely
release the pedal..)
I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
moderate pushing on the accelerator, off the line, and throughout the driving
range, so I'd assume the engines are similar if not identical.
The other issue, which may be related is that I've never changed the
differential fluid, and I don't know when/if it had been done before on this
vehicle, and I wonder if that could possibly be contributing to the above
problem in any way.
With respect to the differential, if I start up in the morning on a spring
day for example (not a cold day when idle would be raised by the IAC valve),
and I warm for only 30 seconds or so and switch into drive, and let the idle
move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to creep
forward. This happens sometimes. Now this ZJ has a low idle to begin with
(~620, dunno why), but I don't think that's the issue. It seems that once the
car is warmed for 5 minutes or so this doesn't happen at all. This also could
be an issue with the parking brake because when I first drive off (at a
moderate rate) I hear a 1 second "rub" from the vehicle.
I also wonder on such a high mileage vehicle, if there's any risk to getting
the differentials completely changed/flushed, and having the differential box
"cleaned out" with carb/brake cleaner or the like. I've heard/read that doing
flushes on "high mileage" tranny's can remove benficial "varnish", and I
wonder if a similar principle applies here, if my differential hasn't been
serviced for a very long time/ever.
I'm also considering putting in a bottle of Lucas Transmission Fix into the
tranny just beacuse.. How much tranny fluid would I need to siphon out and do
I add the whole bottle of Lucas? Is there any chance I could hurt the tranny
further by adding the Lucas?
Thanks in advance.
--
Message posted via http://www.carkb.com
06-02-2007, 06:35 PM
#2
Guest
Posts: n/a
Re: GC5.2 ZJ: Slow acceleration from tranny or differential??
Try cleaning the Throttle Position Sensor:
http://members.***.net/wilsond/tb/tb.html Some stuff about how your
transmission shift points are controlled:
http://www.transonline.com/transdige...ers/index.html
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"jimboe via CarKB.com" <u15312@uwe> wrote in message
news:731b4a4f32447@uwe...
> Hi all,
>
> Two things I want to ask about, and forgive my ignorance in accurately
> describing the following issues.
>
> First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the
time,
> throughout the speedometer range. Off the line it's decent, but the
> accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
> should be even then. (I acquired the 93 w/209K and did tranny service
(pan,
> filter, new fluid), new water pump/timing chain among other things).
>
> For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
> doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
> would expect. Instead after about 2 seconds, it seems the engine RPM's
"jump"
> up" slightly (like a delay), not the amount one would expect though. The
only
> time(s) the "gear drops/RPM's jump" as expected is when I push practically
85%
> of the way on the pedal-- then it moves, and when the RPMs hit high (4K?
5K?)
> it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
> speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
> the engine will shift to a lower gear and momentarily spike the RPMs up
again
> past 5K!, seemingly "out of control" (scary-- that makes one completely
> release the pedal..)
>
> I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
> moderate pushing on the accelerator, off the line, and throughout the
driving
> range, so I'd assume the engines are similar if not identical.
>
> The other issue, which may be related is that I've never changed the
> differential fluid, and I don't know when/if it had been done before on
this
> vehicle, and I wonder if that could possibly be contributing to the above
> problem in any way.
>
> With respect to the differential, if I start up in the morning on a spring
> day for example (not a cold day when idle would be raised by the IAC
valve),
> and I warm for only 30 seconds or so and switch into drive, and let the
idle
> move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to
creep
> forward. This happens sometimes. Now this ZJ has a low idle to begin with
> (~620, dunno why), but I don't think that's the issue. It seems that once
the
> car is warmed for 5 minutes or so this doesn't happen at all. This also
could
> be an issue with the parking brake because when I first drive off (at a
> moderate rate) I hear a 1 second "rub" from the vehicle.
>
> I also wonder on such a high mileage vehicle, if there's any risk to
getting
> the differentials completely changed/flushed, and having the differential
box
> "cleaned out" with carb/brake cleaner or the like. I've heard/read that
doing
> flushes on "high mileage" tranny's can remove benficial "varnish", and I
> wonder if a similar principle applies here, if my differential hasn't been
> serviced for a very long time/ever.
>
> I'm also considering putting in a bottle of Lucas Transmission Fix into
the
> tranny just beacuse.. How much tranny fluid would I need to siphon out and
do
> I add the whole bottle of Lucas? Is there any chance I could hurt the
tranny
> further by adding the Lucas?
>
> Thanks in advance.
>
> --
> Message posted via http://www.carkb.com
>
--
Posted via a free Usenet account from http://www.teranews.com
http://members.***.net/wilsond/tb/tb.html Some stuff about how your
transmission shift points are controlled:
http://www.transonline.com/transdige...ers/index.html
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"jimboe via CarKB.com" <u15312@uwe> wrote in message
news:731b4a4f32447@uwe...
> Hi all,
>
> Two things I want to ask about, and forgive my ignorance in accurately
> describing the following issues.
>
> First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the
time,
> throughout the speedometer range. Off the line it's decent, but the
> accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
> should be even then. (I acquired the 93 w/209K and did tranny service
(pan,
> filter, new fluid), new water pump/timing chain among other things).
>
> For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
> doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
> would expect. Instead after about 2 seconds, it seems the engine RPM's
"jump"
> up" slightly (like a delay), not the amount one would expect though. The
only
> time(s) the "gear drops/RPM's jump" as expected is when I push practically
85%
> of the way on the pedal-- then it moves, and when the RPMs hit high (4K?
5K?)
> it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
> speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
> the engine will shift to a lower gear and momentarily spike the RPMs up
again
> past 5K!, seemingly "out of control" (scary-- that makes one completely
> release the pedal..)
>
> I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
> moderate pushing on the accelerator, off the line, and throughout the
driving
> range, so I'd assume the engines are similar if not identical.
>
> The other issue, which may be related is that I've never changed the
> differential fluid, and I don't know when/if it had been done before on
this
> vehicle, and I wonder if that could possibly be contributing to the above
> problem in any way.
>
> With respect to the differential, if I start up in the morning on a spring
> day for example (not a cold day when idle would be raised by the IAC
valve),
> and I warm for only 30 seconds or so and switch into drive, and let the
idle
> move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to
creep
> forward. This happens sometimes. Now this ZJ has a low idle to begin with
> (~620, dunno why), but I don't think that's the issue. It seems that once
the
> car is warmed for 5 minutes or so this doesn't happen at all. This also
could
> be an issue with the parking brake because when I first drive off (at a
> moderate rate) I hear a 1 second "rub" from the vehicle.
>
> I also wonder on such a high mileage vehicle, if there's any risk to
getting
> the differentials completely changed/flushed, and having the differential
box
> "cleaned out" with carb/brake cleaner or the like. I've heard/read that
doing
> flushes on "high mileage" tranny's can remove benficial "varnish", and I
> wonder if a similar principle applies here, if my differential hasn't been
> serviced for a very long time/ever.
>
> I'm also considering putting in a bottle of Lucas Transmission Fix into
the
> tranny just beacuse.. How much tranny fluid would I need to siphon out and
do
> I add the whole bottle of Lucas? Is there any chance I could hurt the
tranny
> further by adding the Lucas?
>
> Thanks in advance.
>
> --
> Message posted via http://www.carkb.com
>
--
Posted via a free Usenet account from http://www.teranews.com
06-02-2007, 06:35 PM
#3
Guest
Posts: n/a
Re: GC5.2 ZJ: Slow acceleration from tranny or differential??
Try cleaning the Throttle Position Sensor:
http://members.***.net/wilsond/tb/tb.html Some stuff about how your
transmission shift points are controlled:
http://www.transonline.com/transdige...ers/index.html
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"jimboe via CarKB.com" <u15312@uwe> wrote in message
news:731b4a4f32447@uwe...
> Hi all,
>
> Two things I want to ask about, and forgive my ignorance in accurately
> describing the following issues.
>
> First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the
time,
> throughout the speedometer range. Off the line it's decent, but the
> accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
> should be even then. (I acquired the 93 w/209K and did tranny service
(pan,
> filter, new fluid), new water pump/timing chain among other things).
>
> For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
> doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
> would expect. Instead after about 2 seconds, it seems the engine RPM's
"jump"
> up" slightly (like a delay), not the amount one would expect though. The
only
> time(s) the "gear drops/RPM's jump" as expected is when I push practically
85%
> of the way on the pedal-- then it moves, and when the RPMs hit high (4K?
5K?)
> it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
> speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
> the engine will shift to a lower gear and momentarily spike the RPMs up
again
> past 5K!, seemingly "out of control" (scary-- that makes one completely
> release the pedal..)
>
> I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
> moderate pushing on the accelerator, off the line, and throughout the
driving
> range, so I'd assume the engines are similar if not identical.
>
> The other issue, which may be related is that I've never changed the
> differential fluid, and I don't know when/if it had been done before on
this
> vehicle, and I wonder if that could possibly be contributing to the above
> problem in any way.
>
> With respect to the differential, if I start up in the morning on a spring
> day for example (not a cold day when idle would be raised by the IAC
valve),
> and I warm for only 30 seconds or so and switch into drive, and let the
idle
> move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to
creep
> forward. This happens sometimes. Now this ZJ has a low idle to begin with
> (~620, dunno why), but I don't think that's the issue. It seems that once
the
> car is warmed for 5 minutes or so this doesn't happen at all. This also
could
> be an issue with the parking brake because when I first drive off (at a
> moderate rate) I hear a 1 second "rub" from the vehicle.
>
> I also wonder on such a high mileage vehicle, if there's any risk to
getting
> the differentials completely changed/flushed, and having the differential
box
> "cleaned out" with carb/brake cleaner or the like. I've heard/read that
doing
> flushes on "high mileage" tranny's can remove benficial "varnish", and I
> wonder if a similar principle applies here, if my differential hasn't been
> serviced for a very long time/ever.
>
> I'm also considering putting in a bottle of Lucas Transmission Fix into
the
> tranny just beacuse.. How much tranny fluid would I need to siphon out and
do
> I add the whole bottle of Lucas? Is there any chance I could hurt the
tranny
> further by adding the Lucas?
>
> Thanks in advance.
>
> --
> Message posted via http://www.carkb.com
>
--
Posted via a free Usenet account from http://www.teranews.com
http://members.***.net/wilsond/tb/tb.html Some stuff about how your
transmission shift points are controlled:
http://www.transonline.com/transdige...ers/index.html
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"jimboe via CarKB.com" <u15312@uwe> wrote in message
news:731b4a4f32447@uwe...
> Hi all,
>
> Two things I want to ask about, and forgive my ignorance in accurately
> describing the following issues.
>
> First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the
time,
> throughout the speedometer range. Off the line it's decent, but the
> accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
> should be even then. (I acquired the 93 w/209K and did tranny service
(pan,
> filter, new fluid), new water pump/timing chain among other things).
>
> For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
> doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
> would expect. Instead after about 2 seconds, it seems the engine RPM's
"jump"
> up" slightly (like a delay), not the amount one would expect though. The
only
> time(s) the "gear drops/RPM's jump" as expected is when I push practically
85%
> of the way on the pedal-- then it moves, and when the RPMs hit high (4K?
5K?)
> it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
> speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
> the engine will shift to a lower gear and momentarily spike the RPMs up
again
> past 5K!, seemingly "out of control" (scary-- that makes one completely
> release the pedal..)
>
> I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
> moderate pushing on the accelerator, off the line, and throughout the
driving
> range, so I'd assume the engines are similar if not identical.
>
> The other issue, which may be related is that I've never changed the
> differential fluid, and I don't know when/if it had been done before on
this
> vehicle, and I wonder if that could possibly be contributing to the above
> problem in any way.
>
> With respect to the differential, if I start up in the morning on a spring
> day for example (not a cold day when idle would be raised by the IAC
valve),
> and I warm for only 30 seconds or so and switch into drive, and let the
idle
> move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to
creep
> forward. This happens sometimes. Now this ZJ has a low idle to begin with
> (~620, dunno why), but I don't think that's the issue. It seems that once
the
> car is warmed for 5 minutes or so this doesn't happen at all. This also
could
> be an issue with the parking brake because when I first drive off (at a
> moderate rate) I hear a 1 second "rub" from the vehicle.
>
> I also wonder on such a high mileage vehicle, if there's any risk to
getting
> the differentials completely changed/flushed, and having the differential
box
> "cleaned out" with carb/brake cleaner or the like. I've heard/read that
doing
> flushes on "high mileage" tranny's can remove benficial "varnish", and I
> wonder if a similar principle applies here, if my differential hasn't been
> serviced for a very long time/ever.
>
> I'm also considering putting in a bottle of Lucas Transmission Fix into
the
> tranny just beacuse.. How much tranny fluid would I need to siphon out and
do
> I add the whole bottle of Lucas? Is there any chance I could hurt the
tranny
> further by adding the Lucas?
>
> Thanks in advance.
>
> --
> Message posted via http://www.carkb.com
>
--
Posted via a free Usenet account from http://www.teranews.com
06-02-2007, 06:35 PM
#4
Guest
Posts: n/a
Re: GC5.2 ZJ: Slow acceleration from tranny or differential??
Try cleaning the Throttle Position Sensor:
http://members.***.net/wilsond/tb/tb.html Some stuff about how your
transmission shift points are controlled:
http://www.transonline.com/transdige...ers/index.html
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"jimboe via CarKB.com" <u15312@uwe> wrote in message
news:731b4a4f32447@uwe...
> Hi all,
>
> Two things I want to ask about, and forgive my ignorance in accurately
> describing the following issues.
>
> First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the
time,
> throughout the speedometer range. Off the line it's decent, but the
> accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
> should be even then. (I acquired the 93 w/209K and did tranny service
(pan,
> filter, new fluid), new water pump/timing chain among other things).
>
> For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
> doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
> would expect. Instead after about 2 seconds, it seems the engine RPM's
"jump"
> up" slightly (like a delay), not the amount one would expect though. The
only
> time(s) the "gear drops/RPM's jump" as expected is when I push practically
85%
> of the way on the pedal-- then it moves, and when the RPMs hit high (4K?
5K?)
> it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
> speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
> the engine will shift to a lower gear and momentarily spike the RPMs up
again
> past 5K!, seemingly "out of control" (scary-- that makes one completely
> release the pedal..)
>
> I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
> moderate pushing on the accelerator, off the line, and throughout the
driving
> range, so I'd assume the engines are similar if not identical.
>
> The other issue, which may be related is that I've never changed the
> differential fluid, and I don't know when/if it had been done before on
this
> vehicle, and I wonder if that could possibly be contributing to the above
> problem in any way.
>
> With respect to the differential, if I start up in the morning on a spring
> day for example (not a cold day when idle would be raised by the IAC
valve),
> and I warm for only 30 seconds or so and switch into drive, and let the
idle
> move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to
creep
> forward. This happens sometimes. Now this ZJ has a low idle to begin with
> (~620, dunno why), but I don't think that's the issue. It seems that once
the
> car is warmed for 5 minutes or so this doesn't happen at all. This also
could
> be an issue with the parking brake because when I first drive off (at a
> moderate rate) I hear a 1 second "rub" from the vehicle.
>
> I also wonder on such a high mileage vehicle, if there's any risk to
getting
> the differentials completely changed/flushed, and having the differential
box
> "cleaned out" with carb/brake cleaner or the like. I've heard/read that
doing
> flushes on "high mileage" tranny's can remove benficial "varnish", and I
> wonder if a similar principle applies here, if my differential hasn't been
> serviced for a very long time/ever.
>
> I'm also considering putting in a bottle of Lucas Transmission Fix into
the
> tranny just beacuse.. How much tranny fluid would I need to siphon out and
do
> I add the whole bottle of Lucas? Is there any chance I could hurt the
tranny
> further by adding the Lucas?
>
> Thanks in advance.
>
> --
> Message posted via http://www.carkb.com
>
--
Posted via a free Usenet account from http://www.teranews.com
http://members.***.net/wilsond/tb/tb.html Some stuff about how your
transmission shift points are controlled:
http://www.transonline.com/transdige...ers/index.html
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"jimboe via CarKB.com" <u15312@uwe> wrote in message
news:731b4a4f32447@uwe...
> Hi all,
>
> Two things I want to ask about, and forgive my ignorance in accurately
> describing the following issues.
>
> First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the
time,
> throughout the speedometer range. Off the line it's decent, but the
> accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
> should be even then. (I acquired the 93 w/209K and did tranny service
(pan,
> filter, new fluid), new water pump/timing chain among other things).
>
> For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
> doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
> would expect. Instead after about 2 seconds, it seems the engine RPM's
"jump"
> up" slightly (like a delay), not the amount one would expect though. The
only
> time(s) the "gear drops/RPM's jump" as expected is when I push practically
85%
> of the way on the pedal-- then it moves, and when the RPMs hit high (4K?
5K?)
> it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
> speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
> the engine will shift to a lower gear and momentarily spike the RPMs up
again
> past 5K!, seemingly "out of control" (scary-- that makes one completely
> release the pedal..)
>
> I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
> moderate pushing on the accelerator, off the line, and throughout the
driving
> range, so I'd assume the engines are similar if not identical.
>
> The other issue, which may be related is that I've never changed the
> differential fluid, and I don't know when/if it had been done before on
this
> vehicle, and I wonder if that could possibly be contributing to the above
> problem in any way.
>
> With respect to the differential, if I start up in the morning on a spring
> day for example (not a cold day when idle would be raised by the IAC
valve),
> and I warm for only 30 seconds or so and switch into drive, and let the
idle
> move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to
creep
> forward. This happens sometimes. Now this ZJ has a low idle to begin with
> (~620, dunno why), but I don't think that's the issue. It seems that once
the
> car is warmed for 5 minutes or so this doesn't happen at all. This also
could
> be an issue with the parking brake because when I first drive off (at a
> moderate rate) I hear a 1 second "rub" from the vehicle.
>
> I also wonder on such a high mileage vehicle, if there's any risk to
getting
> the differentials completely changed/flushed, and having the differential
box
> "cleaned out" with carb/brake cleaner or the like. I've heard/read that
doing
> flushes on "high mileage" tranny's can remove benficial "varnish", and I
> wonder if a similar principle applies here, if my differential hasn't been
> serviced for a very long time/ever.
>
> I'm also considering putting in a bottle of Lucas Transmission Fix into
the
> tranny just beacuse.. How much tranny fluid would I need to siphon out and
do
> I add the whole bottle of Lucas? Is there any chance I could hurt the
tranny
> further by adding the Lucas?
>
> Thanks in advance.
>
> --
> Message posted via http://www.carkb.com
>
--
Posted via a free Usenet account from http://www.teranews.com
06-02-2007, 06:35 PM
#5
Guest
Posts: n/a
Re: GC5.2 ZJ: Slow acceleration from tranny or differential??
Try cleaning the Throttle Position Sensor:
http://members.***.net/wilsond/tb/tb.html Some stuff about how your
transmission shift points are controlled:
http://www.transonline.com/transdige...ers/index.html
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"jimboe via CarKB.com" <u15312@uwe> wrote in message
news:731b4a4f32447@uwe...
> Hi all,
>
> Two things I want to ask about, and forgive my ignorance in accurately
> describing the following issues.
>
> First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the
time,
> throughout the speedometer range. Off the line it's decent, but the
> accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
> should be even then. (I acquired the 93 w/209K and did tranny service
(pan,
> filter, new fluid), new water pump/timing chain among other things).
>
> For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
> doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
> would expect. Instead after about 2 seconds, it seems the engine RPM's
"jump"
> up" slightly (like a delay), not the amount one would expect though. The
only
> time(s) the "gear drops/RPM's jump" as expected is when I push practically
85%
> of the way on the pedal-- then it moves, and when the RPMs hit high (4K?
5K?)
> it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
> speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
> the engine will shift to a lower gear and momentarily spike the RPMs up
again
> past 5K!, seemingly "out of control" (scary-- that makes one completely
> release the pedal..)
>
> I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
> moderate pushing on the accelerator, off the line, and throughout the
driving
> range, so I'd assume the engines are similar if not identical.
>
> The other issue, which may be related is that I've never changed the
> differential fluid, and I don't know when/if it had been done before on
this
> vehicle, and I wonder if that could possibly be contributing to the above
> problem in any way.
>
> With respect to the differential, if I start up in the morning on a spring
> day for example (not a cold day when idle would be raised by the IAC
valve),
> and I warm for only 30 seconds or so and switch into drive, and let the
idle
> move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to
creep
> forward. This happens sometimes. Now this ZJ has a low idle to begin with
> (~620, dunno why), but I don't think that's the issue. It seems that once
the
> car is warmed for 5 minutes or so this doesn't happen at all. This also
could
> be an issue with the parking brake because when I first drive off (at a
> moderate rate) I hear a 1 second "rub" from the vehicle.
>
> I also wonder on such a high mileage vehicle, if there's any risk to
getting
> the differentials completely changed/flushed, and having the differential
box
> "cleaned out" with carb/brake cleaner or the like. I've heard/read that
doing
> flushes on "high mileage" tranny's can remove benficial "varnish", and I
> wonder if a similar principle applies here, if my differential hasn't been
> serviced for a very long time/ever.
>
> I'm also considering putting in a bottle of Lucas Transmission Fix into
the
> tranny just beacuse.. How much tranny fluid would I need to siphon out and
do
> I add the whole bottle of Lucas? Is there any chance I could hurt the
tranny
> further by adding the Lucas?
>
> Thanks in advance.
>
> --
> Message posted via http://www.carkb.com
>
--
Posted via a free Usenet account from http://www.teranews.com
http://members.***.net/wilsond/tb/tb.html Some stuff about how your
transmission shift points are controlled:
http://www.transonline.com/transdige...ers/index.html
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
"jimboe via CarKB.com" <u15312@uwe> wrote in message
news:731b4a4f32447@uwe...
> Hi all,
>
> Two things I want to ask about, and forgive my ignorance in accurately
> describing the following issues.
>
> First, my 93 5.2 GC (220K) doesn't have the "snap" it should, 90% of the
time,
> throughout the speedometer range. Off the line it's decent, but the
> accelerator pedal doesn't really seem as "sensitive"/"responsive" as it
> should be even then. (I acquired the 93 w/209K and did tranny service
(pan,
> filter, new fluid), new water pump/timing chain among other things).
>
> For example, at 20 mph, when I give a moderate push (30%-60% pedal), it
> doesn't drop to a lower gear and "crank-up" the RPMs for that "burst" one
> would expect. Instead after about 2 seconds, it seems the engine RPM's
"jump"
> up" slightly (like a delay), not the amount one would expect though. The
only
> time(s) the "gear drops/RPM's jump" as expected is when I push practically
85%
> of the way on the pedal-- then it moves, and when the RPMs hit high (4K?
5K?)
> it shifts to a higher gear/RPM's drop back as expected-- *BUT*, after that
> speed "brust" if then I do not COMPLETELY let off the pedal (all the way),
> the engine will shift to a lower gear and momentarily spike the RPMs up
again
> past 5K!, seemingly "out of control" (scary-- that makes one completely
> release the pedal..)
>
> I also have a 95 ZJ 5.2 (175K) which completely flies as expected with a
> moderate pushing on the accelerator, off the line, and throughout the
driving
> range, so I'd assume the engines are similar if not identical.
>
> The other issue, which may be related is that I've never changed the
> differential fluid, and I don't know when/if it had been done before on
this
> vehicle, and I wonder if that could possibly be contributing to the above
> problem in any way.
>
> With respect to the differential, if I start up in the morning on a spring
> day for example (not a cold day when idle would be raised by the IAC
valve),
> and I warm for only 30 seconds or so and switch into drive, and let the
idle
> move the vehicle, it takes maybe 5-10 seconds before the Jeep starts to
creep
> forward. This happens sometimes. Now this ZJ has a low idle to begin with
> (~620, dunno why), but I don't think that's the issue. It seems that once
the
> car is warmed for 5 minutes or so this doesn't happen at all. This also
could
> be an issue with the parking brake because when I first drive off (at a
> moderate rate) I hear a 1 second "rub" from the vehicle.
>
> I also wonder on such a high mileage vehicle, if there's any risk to
getting
> the differentials completely changed/flushed, and having the differential
box
> "cleaned out" with carb/brake cleaner or the like. I've heard/read that
doing
> flushes on "high mileage" tranny's can remove benficial "varnish", and I
> wonder if a similar principle applies here, if my differential hasn't been
> serviced for a very long time/ever.
>
> I'm also considering putting in a bottle of Lucas Transmission Fix into
the
> tranny just beacuse.. How much tranny fluid would I need to siphon out and
do
> I add the whole bottle of Lucas? Is there any chance I could hurt the
tranny
> further by adding the Lucas?
>
> Thanks in advance.
>
> --
> Message posted via http://www.carkb.com
>
--
Posted via a free Usenet account from http://www.teranews.com
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