Trans Failsafe
 

Well today I took my daughter to work in the 4.6iS and as driving away I thought to myself WOW this 4.6 has been pretty reliable since I purchased it and did a bunch of work to it. I proceeded to go wash it up and vacuum it to enjoy it as I have always. On the way home post wash, I got to a red light and when it turned green I gave a little gas and no movement. The RPMs started to rise snd then BAM it kicked into gear and trans failsafe popped up. The X drives fine in reverse but is shaky in D and wont really move. I limped it into the garage as I consider my options. Any ideas? Can it be the torque converter or something internal to the trans has let go? Only error in the EGS is stall speed which points to some sort of mechsnical failure. When it rains it pours!https://uploads.tapatalk-cdn.com/202...d6f3e4309e.jpg

Not sure if the 4.6 has the same connector as the 3.0i but my e53 had the connector get water in it so i suspect "wash" is directly related.

If you have a big round connector on the back/bottom of your trans take it off and look for signs of water and clean it.

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Did yours have similar symptoms to mine? This seems more mechanical. I did find a used good trans from a guy I know who has a couple 4.6 part outs.

Horrible slam shift one time but when it happened while at speed it just stayed in 5th until i went slow enough then stays in 4 th only. Makes for very anemic launch and very difficult to drive up onto a curb to climb under to fix.

I had it happen once when parked for a couple months and twice while driving and when getting splashed by slush or water from passing semi.

It's more of the coincidence of right after water incident and you mention washing the car that seems to be way too much of a coincidence. Def check the connector before doing anything else.

The shorted wires can make for just about any error and any symptom.

In my case at least the first time it shorted the pins to the selector switch and made for random gears.

Hmm.. Sounds like what happened to mine a few years ago. Same symptoms - no forward drive but OK in reverse.
One way to check if it's terminal is run the engine and go through the gears manually and if the cluster indicator says it won't select or stay in 3rd (or it could be 4th I can't remember) then you can be sure it's one of the drum packs broken.
It cost me £2100 here in the UK 3 years ago but mine is a 4.4 so the trans is more common than yours.
Check out Zero to 60 on YouTube. He is / was a BMW Australian guy and had a red 4.6 that they rebuilt themselves a few years ago. Interesting.

Yes watched their video on the Imola 4.6 trans issue. I will check the connector first and go from there.

likely your clutch a-drum seal is failed, this is a common problem, running it more will break down a bearing and start to destroy the rest of the transmission.

you may need a full internal rebuild.

there's less a chance it could be an electrical issue, after you have done some common sense troubleshooting or not.

look at your fault codes from transmission.

That's what I figured and the only error in the EGS is stall speed.

right, this is due to mis-match in input vs output speed sensor. clutches have no apply pressure and so nothing goes except for a gear 5 failsafe option.

Sourced a used 4.6 trans with 107k on it and having the torque converter rebuilt before putting it in. I will do new filter / oring / pan gasket / fluid(leaning towards Valvoline import LT71141) / torque converter seal / rear crank seal / potentially the rear coolant jacket. Inspected the bellhousing to confirm it was a 4.6iS trans.https://uploads.tapatalk-cdn.com/202...49f0627953.jpghttps://uploads.tapatalk-cdn.com/202...abe4a5c086.jpg