As the title says P0218 code has come up on my Livernois Tuner a few times now. CEL does not come on but it is stored/pending. I've had a few hard driving high-speed (highway) episodes where my car will "tapout" after running a WOT for a relatively short time. It goes into what feels like a transmission limp mode where it won't down shift any longer and feels sluggish. Basically I can do about a 80 to 120-130 highway run ONCE. When I turn around and to comback it will either refuse to downshift and feel "limp" or it will accelerate to 100+ and "tap out". Feels like I let off the gas abruptly and I can hear the  bovs open then does the limp mode thing. Its obviously not right even considering that it is nearly 100 degrees down here in SATX practically ever day. My understanding is that there is a valve that opens for the transcooler on my MKS. I'm wondering if its stuck or just opening too late. Anyone's ever bypass it or had similar issues? I plan on running an external cooler but if the valve is sticking or opening too late it wouldn't be much use. Thanks for any input.

Trans fluid is new Ford Mercon LV and level is good... Actually a little over as suggested.

First time I have seen the P0218 code mentioned, ever!  Fans shouldn't be needed at those speeds, what did the coolant temps look like?

The trans cooling and ac condenser functions are all-in-one unit.

Engine temp is fine... 185-195 range. Maybe a little warmer but still within the normal range.

ok, so no issues with fans or anything, most likely.  Maybe siphon off the fluid a bit to between the hashmarks and see.  Maybe your MKS does not quite like the overfill.  The trans TStats have never failed that I know of, but always a first time.

Is anyone aware of any good working apps with a Bluetooth adapter that can tell me transmission temperature readings? I've tried a few with no luck including torque pro.

I use Forscan Lite with an OBDLink MX Bluetooth for my datalogging.  I believe Forscan will have the PIDs for your MKS.

Have you tried the thread about custom PIDs for Torque Pro.  Might have a trans temp pid in there.
https://www.ecoboostperformanceforum.com/index.php/topic,3141.0.html

I remember seeing that post a while back before I even got torque pro and completely forgot about it. Thank you sir. Just added the pid and I will see what readings I get from it.

Well here's the problem... Now as to WHY. 😤 Now I will say I hit 130 when this happened but theres videos of guys making 140 mile runs for several minutes/miles in a SHO with no issue.

287° is where the trans temp pegged today during my drive home and it limped out again. Let the diag begin...

287!?!?! WOW!

That's no bueno. Like at all.

Yikes. I am cringing for you.

Yea.. I went all in just to see how hot it was actually getting. I'm glad SHOdded directed me to those pids so I could get those readings. The good news is it is only under extended WOT load when it happens and it's only been a handful of times during relatively short burst. Not during normal daily driving.

WHOOOOOOOAAAAA!  Still, fluid breaks down very quickly at those temps, so no more Mexico for YOU!

Try taking a bit of the fluid out as I mentioned earlier.  Maybe it is foaming during high speed operation coz it just doesn't like how much is there in the trans.

Definitely. I was having hard shifts when I first did the V11 tune and it had definitely improved since overfilling it so it may be a bit of a give and take. Also I was thinking of installing that SHO PP transmission t-stat valve but I'm not sure if they are actually identical parts... I have 2 part numbers. The MKS and SHO PP but no verifiable pictures of them. They only run like 40 bucks so they are cheap ins... Or actually just bypass the tstat all together and add an larger stacked plate cooler. I'm not sure. Any experience on the board with doing either or? I mean my starting temp here is around 100 degrees right off the bat so I normally add one anyway. I had confidence in the stock trans cooling external style system but at this point thats been shot to hell.

As for the SHO PP part number the seemed to be a little uncertainty by the end of the install thread so any confirmation is appreciated.

The normal operating temp for the 6f5x transmission is 180°F-200°F (82°C-93°C) , but the FSM says the bypass valve opens ABOVE N.O.T.  So you would definitely benefit from the SHO PP trans TStat.  You have the correct part number for that.  You will want to take a pic of the existing TStat first.  If the stamping is different from that shown for the PP part, then that is a good confirmation.

QuoteThis vehicle is equipped with an external transmission fluid cooler. The transmission fluid cooler is part of the A/C condenser and cannot be serviced separately. The transmission fluid cooler is mounted in front of the engine radiator. The cooling system also consists of a transmission fluid cooler thermal bypass valve which is mounted on the transaxle main control cover. When the transmission fluid is below normal operating temperature, transmission fluid travels from the transaxle to the transmission fluid cooler thermal bypass valve and back to the transaxle. When the transmission fluid is at or above normal operating temperature, the transmission fluid cooler thermal bypass valve opens allowing transmission fluid to travel from the transaxle through the cooler and back to the transaxle. The transmission fluid cooler transfers heat from the transmission fluid to the outside air.

However, if there IS a blockage in the cooling system, first thing I would check is cooler inlet and outlet temps after getting the trans temps raised above the NOT range, either with a thermal imager (available on some phones now) or an infrared heat gun.  Inlet and outlet temps on the TStat assembly as well.

Thanks man. Idk why ford has that tstat open so late In my opinion. I'm assuming to keep from overheating during long drives or maybe for cold weather warm up. Whatever the case down here the cooler the better.