98 V8 Transmission slippery ?

[dcdyd]

My 98 V8 has 120K on the meter and the transmission was replaced with a rebuilt one from Ford at about 70K. Recently I noticed some odd behavior. If I press the gas pedal either from a stop or when it is running at 15 to 30 mph, sometimes the engine suddenly runs at 3K to 2.5K rpm. If I don't pull foot back from the gas pedal, one second later the engine return back to normal like 2K rpm. If I pull the foot back and press the gas pedal again, it will run normally.

There is engine code thrown for this.

Does this sound transmission slippery? If yes, any harmful to the transmission? Or what can I do to eliminate it?

The ATF was replaced about three years ago when the truck was at 100K. I am going to drop the pan and drain the ATF as well as replace the filter if that would help.

Comments and advises are appreciated.

 

[rs2k]

Does it feel like the transmission is in neutral when the engine revs can you feel at least some power going to the wheels?

 

[dcdyd]

Yes it acts like that the transmission is in neutral and I don't feel that the power is going to the wheels. However it is very short. Like less than one second and then back to normal. It only happens at the low speed when accelerating.

 

[Robman]

engine misfire ?

 

[rs2k]

What does the atf look like? Have you checked the fluid level? What does the transmission fluid smell like? Every slipping transmission I've smelled has a very distinctive burned smell to it. What happens when it upshifts at low throttle?

If the transmission fluid smells burned amd/or the fluid is dark then there isn't much you can do other than rebuild or replace since the damage is already done. If there's something else wrong you'll want to fix it before it causes any damage.

 

[dcdyd]

An update on this topic. I checked AT fluid yesterday. The cold level is fine (when engine is running). But the hot level is half inch higher above the indicator. The color seems to be fine in RED. There is no burning smell. AT fluid was replaced by a shop in three years ago at about 105K. (now it has 120K)

Based on this, any advice?

 

[rs2k]

I'd use a mighty vac and take some of the fluid out. The fluid should be at the correct height when at running temperature. Doesn't really matter too much when cold. Did the shop replace the transmission filter when they replaced the fluid or did they flush it?

 

[jremington59]

Do you have access to a scanner that reads tranny codes? That would be what I would do first. I suppose you can drop the pan and see if there's anything suspicious there.

I have the same problem but mine does this at high speed in OD only. And it's not showing any tranny codes. I've been to multiple shops and have been told everything from total rebuild to a possible TC problem to a bad signal from the TPS to the TC. Until it tosses a tranny code, if it does, it's all a guessing game. I don't think I'd be real concerned of the higher level at hot. It should come out the vent if it becomes to high.

 

[dcdyd]

I'd use a mighty vac and take some of the fluid out. The fluid should be at the correct height when at running temperature. Doesn't really matter too much when cold. Did the shop replace the transmission filter when they replaced the fluid or did they flush it?

I don't know what the shop did. It was threes years ago. But one thing I am sure is that they didn't change the filter. The transmission was replaced by a re-build one from Ford at about 70K when the original one only worked at low gear. At 100K or 105K, there is probably no need to change the filter.

I will recheck the fluid level again this afternoon after I drive back to home. If it is still high I will try to get some out.

 

[dcdyd]

Do you have access to a scanner that reads tranny codes? That would be what I would do first. I suppose you can drop the pan and see if there's anything suspicious there.

I have the same problem but mine does this at high speed in OD only. And it's not showing any tranny codes. I've been to multiple shops and have been told everything from total rebuild to a possible TC problem to a bad signal from the TPS to the TC. Until it tosses a tranny code, if it does, it's all a guessing game. I don't think I'd be real concerned of the higher level at hot. It should come out the vent if it becomes to high.

I do have an Windows application which is supposed to be able to read all extensive codes from Ford and GM. I tried and it didn't read anything out. If nothing else I can do I am going to drop the pan sometime in the fall.