Leia89

I need some input. Ive had this automatic 2008 V6 for 2 years now. Currently has around 135k miles. At 113k I had to have the transmission rebuilt due to worn out bands and terrible transmission slipping. Since the rebuild (07/2016) I have had no issues at all.
However, about a month ago when it started to get cold I noticed the car run very rough and taking forever to warm up. Shortly after, to me, it felt like the tranny started slipping again. Shifts fine in 1st, 2nd, 3rd but has trouble finding 4th and RPM rev up. Freeway driving has become almoat impossible, as I try to accelerate RPM rev up and no power. I have to pull to shoulder and come to a complete stop again.
This problem is intermittent with no check engine light on and the computer spits out no codes.
Since I still have warranty on the tranny rebuild I figured I would get their input. Again, no codes and unable to duplicate problem while test driving. He suspected it was the engine, not the tranny. Checked for ATF levels and its not low on oil either (only been 20k miles since rebuild).
Another shop looked at it, again found no codes. They suggested I replace all spark plugs, ignition wiring and clean out all injectors etc. Had that done but problem persist. So far done:
Checked tranny oil levels
MAF
Spark plugs
Ignition wiring
Injectors etc cleaned
New battery and cables

No mechanic seems to be able to pinpoint the problem. I managed to record whats actually happening while driving. Video was shot about 5 miles into drive, starting at a redlight.. going no faster than 40mph. Has anyone ever experienced a similar issue?

JJHoover

have you tried manually shifting it? if so does it do the same thing?

Derf00

It could be servo bore wear. Usually starts with the OD servo 4-5 shift. Eventually the 2-3 servo will also exhibit the similar symptoms.

Depending on the rebuild that was installed, some companies address it, some don't unless it failed for that specific reason. Here's more info on it.

https://www.fordservoboretransmissionfixsolution.com/

A shop that rebuilds tranny's would use a sleeve in the bore itself which is easy because they have the tranny completely apart for rebuilt like this.
https://www.sonnax.com/parts/2207-ov...ore-sleeve-kit

Aftermarket though, it's not really an option so, the first link I provided gives an aftermarket solution that doesn't require dropping the and dismantling the transmission.

08'MustangDude

I would try that also, shifting upward into each gear manually. If it does not happen
when you do it manually, it's a shift-logic issue. TCM may be seeing something
it does not like in "D" -vs- shifting it manually.

Bore wear is also common on a lot of auto transmissions, which allows fluid to flow past the valve,
loosing line pressure.

CtCarl

Did you get this sorted out, Leia?

If not, I just wanted to drop this on you...the first thing I do when a modern transmission (with no dipstick) like the 5R55S starts acting up, is to take it to a shop that I trust, and have them check the ATF level.

In my experience, too many shops cheat on the ATF fluid level check procedure because it's a hassle, and as a result, there are way too many cars on the road that are over- or under-filled. Sometimes, a little too much or too little ATF doesn't seem to make a difference, and sometimes everything's just fine until it isn't.

Anyway, it's worth a check if you haven't yet.

Good luck!

Derf00

Was this fixed? If not:

Something else I thought of, there is a thermostatic valve built into the valve body on the 5R55S. This valve is meant to allow quick warmup of the tranmission fluid by remaining closed during cold weather for a few seconds at startup. It can get stuck closed or not open all the way and restrict fluid flow. This could affect the transmission if it's being starved of fluid. There is no way to check this valve without removing the the valve body from the transmission. It's not hard to do (drop the pan, remove the reverse servo, servo pack, and then the valve body and inspect the thermostatic valve.

08'MustangDude

I have seen an Exploded View and Parts List of the 5R55S, and none of them show that T-static valve.

http://www.ratiotek.com/5r55w-complete.pdf

Can't believe ford is still using bands in their transmissions...

There is a cold start VALVE you can lock it open:


The modification sent by Pat Barret of Level 10 Performance Transmission:

• Disassemble cold-start valve on the bench.
• Relocate the big spring to the other side as hown for full trans-cooler flow.

This valve restricts flow, but does not block flow, unless it's bad.
It was designed for extreme cold weather startups, like 20-30 below zero.
This cold-start valve failure is one of the most popular failing points of the 5R55W/S

According to Pat Barrett of Level 10 Performance Transmission, in an article from Muscle Mustang & Fast Fords,
he said it was best to just leave it open.

From what I read, if this were a problem, the trans would over-heat, because it would stick
closed and prevent fluid flow. If it were to stick open, then, it self modded, heh heh...

Derf00

That is the thermostatic valve. It opens/closes based on temp (no other input). Its function is a cold-start valve to help warm up the fluid faster in cold weather. I suppose thermostatic valve implied that it regulates the temperature which it does not. Anyways, Yes, that is the valve and that is the easy fix to make it stay open regardless of temp.

As for bands, ford changed that when they started using the 6R** series 6-speed auto starting in 2007. Mustang didn't get it until 2011 I believe. The 6R series uses clutch discs instead of bands.

08'MustangDude

The 5R55 also uses clutch discs, in four clutch packs; Forward, Direct, Intermediate,
and Coast. This trans also has three bands; Overdrive, Intermediate, and Reverse. I
was just a little surprised Ford was still using that many at this point. Chrysler stopped
using bands way before that, went with brakes instead of bands, and no sprags. Brakes
essentially do the same thing, from inside the drum, instead of grabbing and stopping it
on the outside. Clutch packs get "K" designations, and brakes get "B" designations, so
K1 is clutch pack one, and like B1 is brake one.

The other trans is the direct shift gearbox, love them, had one in my '13 TDI.
They are basically a manual transmission, shifted automatically. They use
only two clutch packs, no bands or brakes. One clutch for even gears, and
one for odd gears. Newer 7-speed and 8-speed DSG like transmissions are
using three clutch packs, and they even have dry clutch direct shift gear boxes.

I know, DSG is the designation for the German version, but they all now have
their own versions.

Derf00

Yep familiar with all of that including the DSG. I like them but not the way VW has them programmed, My wife's 2013 Turbo beetle has the 6-speed DSG. I like the overall feel/concept but the biggest complaints I have are 1) Not DSG specific but - Hill assist is enabled in all their cars.. You can't let your foot of the brake and whomp on the gas and go. There's literally a 1 second pause before the gas engages. Yes, you can turn it off in most models including the beetle with VCDS/VAG COM software but why should you have to?

2) brakes are not linear. You can't keep your foot at one pressure when slowing down, if you do, as you get near stopping, the brakes suddenly grab lurching you to a stop. Again a programming thing and from what I've seen you cannot completely reprogram their algorithms.
3) DSG software is not designed for smooth take take off. They purposely torque manage on the low end so you can never really "launch" a stock turbo'd vehicle. Again a programming thing but it sucks you have to buy a programmer and learn some coding for driving basics. Also, you still need to purchase a separate DSG tune for $600+ to get a really good transmission map out of the car. That doesn't include a regular ECU/Engine tune for another $600.

Off topic there