2017 Mirage P285a and P0746

[Fummins]

Got a call yesterday about a Mirage that wouldn't move from a stop, they had someone push it and heard a bang then it started driving again. They got it back to their location and I went to pick it up this morning. Car drove fine down for the first 15-20 mins on the highway doing 70mph. Then I came to a stop light. When it turned green I hit the throttle and the car didn't respond. It felt like a dead pedal. I was about to get out and push it when it started to slowly move and get up to 30-40mph. I still had two more lights to drive through and a couple left turns to make....The shift indicator was flashing, it looked slow to me so I didn't think it was overheated.

I two-footed it the rest of the way, keeping the revs up while stopped at a light. Hoping the nanny system wouldn't kick in and kill power like it does when you drive two footed...I made it back the last 5 blocks. Tried to get a video of it acting up leaving a stop sign but of course it worked fine. It does seem low on power though with crappy throttle response, almost like it's starting out in high gear or the cat is plugged. When you floor it even in neutral it takes a second to respond and rev up.

This cvt is from a 2015(iirc) and has about 340k kms/211k miles. I replaced it last July.

Right now it's throwing P285A 2nd gear/interlock fail and P0746 Pressure control codes. I'll drop the pan and take a look. I don't know if I have any parts cvt's laying around that have a likely good valve body.

I have one good cvt on the floor that I was going to install in a car that has a cvt with a cracked case. I installed it years back and found it was cracked and leaking. Long story short, instead of spending a dollar and having the case repaired properly a penny was spent and I've had to remove it 3 times now and it still leaks. I'll pull the valve body from that car and toss it in this one and see what happens.

Edit: I had to pull this car off the hoist and when I put it in reverse it made all kinds of neat metallic bad bearing type noises. It also vibrated far more than usual. Just when you initally put it into reverse. I'm not sure if that's related or if maybe one of the engine mounts is taking a dump?

[Fummins]

So I got this back inside. Swapped the valve body out. Haven't filled it back up yet. I'm fingering the vibration in reverse is caused by the dogbone mount packed with mud and gravel. Again so that's good.

I tried to measure all the fluid that came out of this thing. I got about 2.5L from the drain plug, and another 2.5L between pulling the pan and loosening off the valve body and letting it drip/drain out for 3 or so hours. So altogether about 5L. I'll pour that much back in and verify proper fluid level as per the temp chart from the service manual.

The car that I pulled the "good" valve body from was low on fluid(as expected cause it leaks...), only about a liter drained from the plug. I didn't measure what else came from the pan and valve body.

I pulled the "good valve body" out and installed one from a junk cvt. Knowing the cvt in this donor car is going to be replaced anyways I dumped in what I thought was enough to get it out of the shop and out of the way for now.(I normally would have just pushed it out but the shop floor is 2' below parking lot grade and it's just easier to have a slightly mobile car than a dead one...

I poured about 3 1/2-4 Liters in and it started to move, enough to get off the hoist then stopped and the engine wouldn't rev up in any gear(even neutral and park). Level was too low, dumped another qt/liter in and it drove out but I could the pump was whining a bit-like an old ford power steering pump. This cvt is going in the trash anyways.

Hopefully this post makes some sense...If you skipped most of that, I'll report back later today or tomorrow if this replacement valve body fixes the problems in the first post.

[Fummins]

That didn't work out. I took it for a good longish drive for about 30 mins close to home incase it piled up. Started getting brave after it worked flawlessly the entire time. Pulled onto a busy road and it wouldn't move faster than a crawl, eventually it picked up speed and I got it off the road. No codes stored, no flashing indicator. Fluid temps was around 60c

Shut it off, let it sit a few minutes then drove it back to the shop. I ran it in the parking lot for a while, reving it up to 2000-2500 for about 8 mins til trans fluid temp got up to 80c. Checked fluid level and it was perfect right, in the hot marks.

So I hoped maybe that was a one and done, shift relearn quirk...Took it for another drive hoping to get it to act up while monitoring a few parameters. After another 10 mins or so it acted up while making a right turn at low speed. I slowed down afterwards to pull over and the throttle went dead. Still, no codes stored.

Shut off and started heading back to the shop again, the next right turn it acted up again. This time there was a cel on upon restart. P0746 fluid pressure code was stored.

[bunio14]

Easy fix: make sure to avoid right turns You are welcome

[Fummins]

I hate to throw this transmission in the trash in a way. I'm still thinking it's something in the valve body that's acting up. I might pull it out and open it up, make sure there's no crap in it and give it one more try. I looked back in the records of a 2015 that was acting similarly with the same p0746 code, and a "new"/used valve body cured it's problems. It's still going years later with 450+k kms.

It is weird how it works fine when it's cold then at random quits working. It acts exactly like the valve body donor car did when I tried to pull it out of the shop when it was low on fluid.

It'd be more efficient to just replace the entire unit rather than spend more time trying to make this thing work again. Worse yet is I'm getting interrogated as to why it's not working and it's being suggested that I try to fix what's wrong with this cvt...It'd look cheaper on paper to the bean counter but in reality a complete waste of time and money imo. Another classic case of spend a dollar to save a penny. It happens far too often in front of me and I finally realized it's just to make that one person appear to be saving the company money. They should get into politics.