05 4.8is Transmission GA6HP26Z Snap-On Code 4F8A

[PUREVIL]

Originally Posted by TwinsPoppa

The only difference is I don't get the TRANS FAILSAFE MODE message.

Mine won't register the code if I back off the throttle right away when I feel it start to slip.
It will register it every time if I keep my foot to the floor through the slip.

I'm guessing yours would do the same if you stay on the gas hard enough.

I read somewhere that the adaptives can be reset by turning the ignition on (without starting the car) and holding the throttle to the floor for 25 seconds, then start the car.
I tried this the other day. It did NOT cure the problem but it may have helped me isolate it.

[thedweeb]

Does it do it in manual ? I dont think its the TC ,as I believe the lock up happens at around 35 -40mph.
I had a gear monitoring and a TC fault on mine where the lock up was very prenounced and wouldnt stay locked up, which resulted in the trans /TC being replaced.
Dweeb

[PUREVIL]

Originally Posted by thedweeb

Does it do it in manual ?

To be honest I haven't really used the manual or sport modes. I've only had this X5 for a couple weeks and my schedule doesn't really allow for much seat time right now...

[TwinsPoppa]

Originally Posted by PUREVIL

TwinsPoppa -
Nope. Other than the slip under hard accelleration I currently have ZERO issues with the trans.
Thanks for the links to the literature. I've been spending my time searching for info on the issue but everything I find seems to be coupled with some other ailment (like yours).

I don't know if I'm just catching this so early on that I haven't had time to wreck anything else or what.

The closest thing I could find to my issue was on a ZF 5 speed. It wound up being an axial needle bearing failure that wiped out an internal seal. It was allowing a pressure drop under load, causing slipping of the effected clutch.

I've got an appointment with my local indy on Thursday. Fingers crossed... Hoping for a sticky valve or solenoid. I just can't see rubuilding a trans with 60k on it. I won't consider replacing the trans. If it has to come out, it's getting rebuilt and stuffed right back in. That'll teach it!

Yes, I read something about the axial needle too here. Something about an o-ring going bad I think.

Hmmm, I think I was kind of hoping your reverse is like mine. Your symptoms are the closest to mine except the TRANS FAILSAFE PROGRAM.

See, I don't remember if that's been like that from the beginning or not (reverse hesitation). Regardless, the weird "slipping" I know wasn't there before so I know something is off.

I don't know how much teardown is needed for the torque converter but I'm thinking cost might be close to a rebuild anyways.

Worst case, I will have it examined by a tranny place, opened and rebuilt. I'm hoping if it comes to that it won't be more than $3-3.5K.

I don't have a garage or the time to do a rebuild on my own. I probably will let the pros do what the pros do on this one.

Keep us informed. I'm really curious what yours turns out to be.

[PUREVIL]

So... On my way home tonight I decided to find out if the problem would occur in manual or sport mode.

I got a very minor slip in sport mode. It almost seemed as though the higher revs before attempting to shift made the transition smoother.

When I switched into manual mode, everything went great until the 4-5 shift. BINGO - the slip was there and so was the FAILSAFE error. Coincidentally, the service engine soon light popped on shortly after.

I pulled over, shut the car down and let the trans failsafe error clear out. I then re-started the car and took off in regular automatic mode.

Now I've been positive that this slip was occurring going into second or third gear all along but I WAS WRONG. Now that pay even closer attention, I realize that 1,2,3,4 shifts are so smooth I wasn't even feeling them. It is now certain that the code I read yesterday was correct.

I guess this info should be useful to my indy shop on Thursday. Plus I'm glad to be sure myself.

Now about that pesky service engine soon lamp...

[red rocket]

Just read your posts purevil and your description of the noise and slipping of the transmission is exactly what I am going through now. You posted 12/21/2011 and I was wondering if you found a fix for the problem. I talked to my local BMW mechanic today and they are guessing what is wrong and want to try a few things ?? The code they read after I had the Trans Failsafe Prog. come up is the same as your s 4F8A Ratio Monitoring gear shift. My BMW is a 2005 X5 408is - fun car to drive but the repairs are more than most cars. AL

[PUREVIL]

Red Rocket -
I haven't figured it out at all. Basically, I simply decided to live with it until summer. I can prevent it from happening by using the manual mode while blasting up hills and backing off while making the 4-5 shift. I also have trained myself to take it easy on the throttle while starting out in automatic mode. It's been a pretty easy problem to live with but I have no intention of living with it for long.
My other vehicle is a slammed F150 with sport tires on 20" rims. So it's completely useless in the winter months. Once the warm weather sets in and I can disable the BMW for a while I will get the problem resolved.

My Indy is pretty certain it's a valve body issue but I'm leaning more toward a failed o-ring allowing a pressure drop.

If you or anyone else ever come up with an answer for this problem sooner than I do, please post the answer here and PM me. Any way I slice it, I have a feeling it's gonna be an expensive repair...

[red rocket]

Thank you for your quick reply, after reading your post from December it was like you were driving my car. I have looked all over the web and could find no close match until reading yours. Was at the Indy today in Denver area and he is doing searches over the internet with his contacts. Leaning towards the problem being in the Mechatronics Valve Body - replacement just in parts $2,000. WOW
For the past few weeks I have been trying to get the slip to happen to show the Indy what is going on and now that he understands it I'll be doing what you are doing with driving it carefully. When the car is cold it has no problems, but after warm up of the trans it will slip if I get on it. The slip comes at 35 mph in regular mode and to me it is from 3rd to 4th gear. In sport mode it is a quick slip at 40 mph. I have 62,000 miles on it and of course am very disappointed in BMW after my experience and seeing all the other trans. problems posted. I will keep you posted when we have more news on the problem.

[PUREVIL]

I would almost bet that your slip is the 4-5 shift. I originally thought mine was lower as well but the code is for gear ratio monitoring 4-5. I was able to confirm this by putting the trans into manual mode and shifting through the gears while holding the accellerator to the floor. Sure enough, she slipped between 4&5. The 1-2 shift is so butter smooth on mine you can't even feel it. If you watch the tach closely you can see it "flinch" during the 1-2 shift, then count 3,4,slip,5,6.

I was also quoted around $2k for the mechatronics but further research has me doubting there is a fault with it. The valve body is rebuildable if you can find someone willing to tackle it and the kit is a fraction of that.
I also have a quote of $2k for a full out trans rebuild and I may choose to jump on that when I can get my lowrider out of storage this summer. I bought the car with this problem after being assured there was "nothing wrong with it" and flying 2500 miles to pick it up. I may opt to spend my $2k on a lawyer to go after the rotten bastards at the dealership that sold it to me but I've never been the litigious type. I just want my BMW to drive as good as it looks...

[PUREVIL]

RRPhil - I was reading your extremely knowledgable posts regarding transmission problems and was hoping you could shed some light on the issue that redrocket and I are having. We seem to be the only two in the world...

Any help would be greatly apprectiated. Tried to PM you but cant.