RPM drops to 1000 at highway speed ??

Can anyone shed light on my issue? 96 Ranger 4L 4x4 auto 93,000 kms

Trans rebuilt 6,000 kms ago... i am noticing that when cruising at
about 100 km/h (about 60 mph), RPMs are at about 2100, if you let off
the gas they drop to like 1600, seems normal, but then if you just
coast for a couple seconds more, the RPMs dip to like 1000 and back to
about 1500 and back and forth a couple times...you can hear the engine
speed changing...as deceleration continues eventually it levels out
again. Hitting the accelerator brings it back to 2000+ with no
stumbles, slipping or other issues. What could be causing this? Torque
converter issues? I thought the TC unlocking was the initial RPM drop
from 2100 to 1600. I dont know how it can go as low as 1000 at such
high speeds. Sensor issues? Anyone know where to focus my attention? No
check engine lights, very stable idle at about 800, no OD lights...i do
have a 3-1 downshift deceleration 'clank' when coming to a stop, i
think comes from the tranny ... please help

thanks

Idle air control valve?

On Wed, 12 Jul 2006 19:32:48 -0700, Ashton Crusher >
wrote:

>On 11 Jul 2006 08:25:24 -0700, wrote:
>
>>Can anyone shed light on my issue? 96 Ranger 4L 4x4 auto 93,000 kms
>>
>>Trans rebuilt 6,000 kms ago... i am noticing that when cruising at
>>about 100 km/h (about 60 mph), RPMs are at about 2100, if you let off
>>the gas they drop to like 1600, seems normal, but then if you just
>>coast for a couple seconds more, the RPMs dip to like 1000 and back to
>>about 1500 and back and forth a couple times...you can hear the engine
>>speed changing...as deceleration continues eventually it levels out
>>again. Hitting the accelerator brings it back to 2000+ with no
>>stumbles, slipping or other issues. What could be causing this? Torque
>>converter issues? I thought the TC unlocking was the initial RPM drop
>>from 2100 to 1600. I dont know how it can go as low as 1000 at such
>>high speeds. Sensor issues? Anyone know where to focus my attention? No
>>check engine lights, very stable idle at about 800, no OD lights...i do
>>have a 3-1 downshift deceleration 'clank' when coming to a stop, i
>>think comes from the tranny ... please help
>>
>>thanks
>
>
>The TC locking and unlocking rarely causes the rpm's to change more
>then a few hundred. What you are describing sounds like the
>transmission is not working right when you are coasting. Some of the
>internal parts there to prevent other parts from rotating at the wrong
>time, like when you are coasting. I'm not familiar with any of the
>detailed internals but I suspect the problem could be as simple as a
>bad solenoid all the way up to the transmission being about ready to
>go out.

On 11 Jul 2006 08:25:24 -0700, wrote:

>Can anyone shed light on my issue? 96 Ranger 4L 4x4 auto 93,000 kms
>
>Trans rebuilt 6,000 kms ago... i am noticing that when cruising at
>about 100 km/h (about 60 mph), RPMs are at about 2100, if you let off
>the gas they drop to like 1600, seems normal, but then if you just
>coast for a couple seconds more, the RPMs dip to like 1000 and back to
>about 1500 and back and forth a couple times...you can hear the engine
>speed changing...as deceleration continues eventually it levels out
>again. Hitting the accelerator brings it back to 2000+ with no
>stumbles, slipping or other issues. What could be causing this? Torque
>converter issues? I thought the TC unlocking was the initial RPM drop
>from 2100 to 1600. I dont know how it can go as low as 1000 at such
>high speeds. Sensor issues? Anyone know where to focus my attention? No
>check engine lights, very stable idle at about 800, no OD lights...i do
>have a 3-1 downshift deceleration 'clank' when coming to a stop, i
>think comes from the tranny ... please help
>
>thanks


The TC locking and unlocking rarely causes the rpm's to change more
then a few hundred. What you are describing sounds like the
transmission is not working right when you are coasting. Some of the
internal parts there to prevent other parts from rotating at the wrong
time, like when you are coasting. I'm not familiar with any of the
detailed internals but I suspect the problem could be as simple as a
bad solenoid all the way up to the transmission being about ready to
go out.

Sounds like a "possible" coast clutch concern... IIRC, this will be solenoid
controlled.... a code scan may be in order or diagnostics performed by
someone hat can actually do some hands on testing.

What warranty was offered by the rebuilder?

> wrote in message
ups.com...
> Can anyone shed light on my issue? 96 Ranger 4L 4x4 auto 93,000 kms
>
> Trans rebuilt 6,000 kms ago... i am noticing that when cruising at
> about 100 km/h (about 60 mph), RPMs are at about 2100, if you let off
> the gas they drop to like 1600, seems normal, but then if you just
> coast for a couple seconds more, the RPMs dip to like 1000 and back to
> about 1500 and back and forth a couple times...you can hear the engine
> speed changing...as deceleration continues eventually it levels out
> again. Hitting the accelerator brings it back to 2000+ with no
> stumbles, slipping or other issues. What could be causing this? Torque
> converter issues? I thought the TC unlocking was the initial RPM drop
> from 2100 to 1600. I dont know how it can go as low as 1000 at such
> high speeds. Sensor issues? Anyone know where to focus my attention? No
> check engine lights, very stable idle at about 800, no OD lights...i do
> have a 3-1 downshift deceleration 'clank' when coming to a stop, i
> think comes from the tranny ... please help
>
> thanks
>

Thanks for the replies,
Went for a drive with the trans tech guy and scan tool, there were no
stored codes (no surprise since the engine light has not come on).
Everything checked out normal except some fluctuations from the MAF
sensor in time with the RPM changes. But the torque converter unlocking
was the initial 2000-1600 RPM drop. After that the engine
just..stumbles and hunts for a bit while you are coasting. I am going
to try cleaning the MAF I think, and see if that helps. I do know my
air filter was pretty much black when I changed it last.
As for the downshift clunk, again the scan readings were normal, but it
was confirmed the clunk/bump is felt and heard right at the 3-2 shift.
They have suggested dropping the rear driveshaft to eliminate the
chance its because of driveline slop (but i recently had it checked out
and was ok...) and driving it in 4wd to see if the clunk is still there
on the downshift. they agreed to try this next week. There is a 12,000
km (or maybe, hopefully, miles) 1 yr warranty on the rebuild (done in
March, 6000 kms ago). They seemed stumped with this and claim 4r55e's
do not generally have this particular issue. They are clearly reluctant
to drop the trans again to look for internal issues.
Tomorrow, hopefuly I am going to put the truck on a hoist and lift the
rear wheels up and get my buddy to hit the throttle until 3rd gear, and
then let off the gas and allow it to downshift on its own and
look/listen for the exact location of the clunk, assuming it will still
happen (it does when coasting to a stop).


Jim Warman wrote:
> Sounds like a "possible" coast clutch concern... IIRC, this will be solenoid
> controlled.... a code scan may be in order or diagnostics performed by
> someone hat can actually do some hands on testing.
>
> What warranty was offered by the rebuilder?
>
> > wrote in message
> ups.com...
> > Can anyone shed light on my issue? 96 Ranger 4L 4x4 auto 93,000 kms
> >
> > Trans rebuilt 6,000 kms ago... i am noticing that when cruising at
> > about 100 km/h (about 60 mph), RPMs are at about 2100, if you let off
> > the gas they drop to like 1600, seems normal, but then if you just
> > coast for a couple seconds more, the RPMs dip to like 1000 and back to
> > about 1500 and back and forth a couple times...you can hear the engine
> > speed changing...as deceleration continues eventually it levels out
> > again. Hitting the accelerator brings it back to 2000+ with no
> > stumbles, slipping or other issues. What could be causing this? Torque
> > converter issues? I thought the TC unlocking was the initial RPM drop
> > from 2100 to 1600. I dont know how it can go as low as 1000 at such
> > high speeds. Sensor issues? Anyone know where to focus my attention? No
> > check engine lights, very stable idle at about 800, no OD lights...i do
> > have a 3-1 downshift deceleration 'clank' when coming to a stop, i
> > think comes from the tranny ... please help
> >
> > thanks
> >

What about the rpms dropping to 1000???

On 12 Jul 2006 22:27:40 -0700, wrote:

>Thanks for the replies,
>Went for a drive with the trans tech guy and scan tool, there were no
>stored codes (no surprise since the engine light has not come on).
>Everything checked out normal except some fluctuations from the MAF
>sensor in time with the RPM changes. But the torque converter unlocking
>was the initial 2000-1600 RPM drop. After that the engine
>just..stumbles and hunts for a bit while you are coasting. I am going
>to try cleaning the MAF I think, and see if that helps. I do know my
>air filter was pretty much black when I changed it last.
>As for the downshift clunk, again the scan readings were normal, but it
>was confirmed the clunk/bump is felt and heard right at the 3-2 shift.
>They have suggested dropping the rear driveshaft to eliminate the
>chance its because of driveline slop (but i recently had it checked out
>and was ok...) and driving it in 4wd to see if the clunk is still there
>on the downshift. they agreed to try this next week. There is a 12,000
>km (or maybe, hopefully, miles) 1 yr warranty on the rebuild (done in
>March, 6000 kms ago). They seemed stumped with this and claim 4r55e's
>do not generally have this particular issue. They are clearly reluctant
>to drop the trans again to look for internal issues.
>Tomorrow, hopefuly I am going to put the truck on a hoist and lift the
>rear wheels up and get my buddy to hit the throttle until 3rd gear, and
>then let off the gas and allow it to downshift on its own and
>look/listen for the exact location of the clunk, assuming it will still
>happen (it does when coasting to a stop).
>
>
>Jim Warman wrote:
>> Sounds like a "possible" coast clutch concern... IIRC, this will be solenoid
>> controlled.... a code scan may be in order or diagnostics performed by
>> someone hat can actually do some hands on testing.
>>
>> What warranty was offered by the rebuilder?
>>
>> > wrote in message
>> ups.com...
>> > Can anyone shed light on my issue? 96 Ranger 4L 4x4 auto 93,000 kms
>> >
>> > Trans rebuilt 6,000 kms ago... i am noticing that when cruising at
>> > about 100 km/h (about 60 mph), RPMs are at about 2100, if you let off
>> > the gas they drop to like 1600, seems normal, but then if you just
>> > coast for a couple seconds more, the RPMs dip to like 1000 and back to
>> > about 1500 and back and forth a couple times...you can hear the engine
>> > speed changing...as deceleration continues eventually it levels out
>> > again. Hitting the accelerator brings it back to 2000+ with no
>> > stumbles, slipping or other issues. What could be causing this? Torque
>> > converter issues? I thought the TC unlocking was the initial RPM drop
>> > from 2100 to 1600. I dont know how it can go as low as 1000 at such
>> > high speeds. Sensor issues? Anyone know where to focus my attention? No
>> > check engine lights, very stable idle at about 800, no OD lights...i do
>> > have a 3-1 downshift deceleration 'clank' when coming to a stop, i
>> > think comes from the tranny ... please help
>> >
>> > thanks
>> >