transmission shifting issues

[chutchy]

ok this is really weird!!

when the car is cold it shifts fine.

when its hot it doesn't want to shift when u take off it feels like it drops off the rpm goes up really high and then shoots forward, when coming to a stop the tranny feels again likes it thumoing or it stops and pushes you forward.

tranny service was done!!

when shifting in manual mode, nothing!! works just fine, no slipping.

NOW here is the kicker!!

when the ac is running nice and cold, the car shifts perfect!!! no slipping, no thumoing when coming to a stop!! nothing!!!


seems like when the ac is running its cooling something thats getter hot

[Misha]

Seems like I have similar symptoms.

The transmission sleeps between 1st and 2nd gear - during the shift the engine revvs up and then the gear kicks in and the car jerks.

It happens often on a hot transmission - never on cold.

It happens more often on OD, rather then just on D. (more often when you get into a town after driving over highway)

It is worse at mid-acceleration - I can avoid the problem by accelerating slowly with gas pedal just slightly depressed or hard acceleration.

It does not seem the problem gets worse - it is about the same as 5 years ago and 50k back.

Any thoughts?

[sheila]

Might check/replace vss (vehicle speed sensor). A slipping or harsh 1-2 shift when warm is a classic symptom.

[Bigdogg2830]

i would think the trans is over heating. with a/c on the cooling fans are on and would cool the trans fluid. maybe install a trans cooler. change filter and fluid

[chartmaker]

Originally Posted by Misha

Seems like I have similar symptoms.

The transmission sleeps between 1st and 2nd gear - during the shift the engine revvs up and then the gear kicks in and the car jerks.

It happens often on a hot transmission - never on cold.

It happens more often on OD, rather then just on D. (more often when you get into a town after driving over highway)

It is worse at mid-acceleration - I can avoid the problem by accelerating slowly with gas pedal just slightly depressed or hard acceleration.

It does not seem the problem gets worse - it is about the same as 5 years ago and 50k back.

Any thoughts?

My '01 with 111K was getting sluggish 1-2 under light throttle. I changed the filter, and fluid with Mercon V. Few days later sucked 7Q out with my vacuum jar and added back 7Q Mercon V. I am about 75% new, 25% old.

Shifting is noticably sharper in all gears, but the dragging 1-2 is GONE!

This is a utility car, local use so I do not keep it up really well, just when it calls for someting. I was quite surprised at the difference.

-chart-

[velo555]

At about 100k my 2000 started nuetralizing intermitently when the trans gets warm. Back when I used to work at a dealership I tore it down and found that the 1-2 shift accumulator piston felt loose in it's bore especially when compared to the others. Because I am cheap I did not replace the piston and accumulator body. I put a new seal on the piston, it felt great. Put the trans back together, trans worked great. About 9 months later it started doing it agian. I only work 6 miles from the house so it rarely gets warm enough. Add this to the fact that I'm cheap and I never tore it back down. It now has 212k.

[Misha]

OMG! Replacing PCV valve solved my shifting problem, which hunted me for years!

[chartmaker]

Originally Posted by Misha

OMG! Replacing PCV valve solved my shifting problem, which hunted me for years!

The PCV valve can do all kinds of harm, including ruining the engine.

Exhaust gas pass into the crankcase all the time. That contains water and other stuff like sulfuric acid. That vapor needs to be sucked out and put back through the engine and burned. The engine flow measurement of air is programmed to have the correct metered amount of air though the crankcase. If the PCV does not do the right thing, the engine tuning is off. As well it if plugs, or the hose collapses then all that exhaust with it's water is trapped inside the engine, and you have dirty water in your oil. And some acid.

Cheap part, some are hard to replace, others are a few minutes.

Just because it rattles, does not mean it meters correctly or does not stick.

-chart-

[Misha]

Originally Posted by chartmaker

My '01 with 111K was getting sluggish 1-2 under light throttle. I changed the filter, and fluid with Mercon V. Few days later sucked 7Q out with my vacuum jar and added back 7Q Mercon V. I am about 75% new, 25% old.

Shifting is noticably sharper in all gears, but the dragging 1-2 is GONE!

changing filter and transfluid (did it twice for the period I owned the car) never did any difference in my case.

[84FordMan]

Replaced both the VSS and range sensor, shifting problem still present.