And Another CVT problem.

[Top_Fuel]

...got a 2015 with a flashing D again.
...would be nice if these had a coolant temp gauge of some kind.

It would be interesting to see the trans temp when that D is flashing. Supposedly that means the trans temp is at least 279F/137C...which seems crazy hot.

[Dirk Diggler]

How many km on it when it was brought in?

[Tyrelirwin]

My dog ate the original post. https://mirageforum.com/forum/showth...ll=1#post80978
It just hit me, this car that had the cvt problem was the same car that was driven out here then had the cvt problems shortly after. The same car that the local dealer told me it needed spark plugs. Too late now...

I got a 2015 with a flashing D again. Drive is on the other end of town and trying to limp it back after letting it sit for 10 mins. This car has had this problem a few times over the last few years, usually when it's warmer out. I replaced the valve body on this one the first time or two it acted up. I remember it only acted up near the end of the day. It would be nice if these had a coolant temp gauge of some kind.

I’ve said it before, and I continue to wonder, would a transmission oil cooler make all the difference on these Jatco units? Just a small little external cooler like you usually see for engine oil on drift cars.

Full JDM spec not necessary

[inuvik]

I’ve said it before, and I continue to wonder, would a transmission oil cooler make all the difference on these Jatco units? Just a small little external cooler like you usually see for engine oil on drift cars.

Full JDM spec not necessary

I'm thinking it would help dramatically. Heat is the killer of CVT's.

[Top_Fuel]

...would a transmission oil cooler make all the difference on these Jatco units?

The answer is...maybe.

From everything I've read about CVTs, they are very sensitive to fluid temperature for normal (efficient) operation. The CVT fluid needs to get up to temperature quickly and stay in a certain temperature range (around 85C/185F) for the most efficient operation.

The computer limits the torque converter lockup and CVT ratios until the fluid is hot. That means a CVT isn't (fuel) efficient until it is hot. This is why Jatco pumps engine coolant through the CVT heat exchanger...to get it to heat up FAST. Unfortunately that heat exchanger also needs to cool the fluid once it's up to operating temperature to keep the trans from overheating.

Sizing a single heat exchanger to keep the CVT fluid in a narrow temperature range is an engineering challenge for a CVT manufacturer. This is especially true when you’re building a car like the Mirage and shipping it all over the world into wildly different climates and driving conditions.

If I lived in a hot climate and drove a lot of freeway speeds (this is generally when CVT fluid gets the hottest), an external cooler probably wouldn't be a bad idea. For guys in Canada, an external cooler might actually over-cool the fluid during the winter months which would reduce the CVT's efficiency (and fuel mileage). This may be one reason why Mirages don't use external coolers.

If I owned a CVT Mirage and was concerned with making it last, I would figure out how to install a trans temperature gauge. According to my 2015 shop manual, the CVT temperature warning light doesn't start flashing until the fluid temperature has reached 279F/137C. That seems crazy high to me and is hotter than any other specs I have found for other manufacturers using CVTs.

[Dirk Diggler]

The answer is...maybe.

From everything I've read about CVTs, they are very sensitive to fluid temperature for normal (efficient) operation. The CVT fluid needs to get up to temperature quickly and stay in a certain temperature range (around 85C/185F) for the most efficient operation.

The computer limits the torque converter lockup and CVT ratios until the fluid is hot. That means a CVT isn't efficient until it is hot. This is why Jatco pumps engine coolant through the CVT heat exchanger...to get it to heat up FAST. Unfortunately that heat exchanger also needs to cool the fluid once it's up to operating temperature to keep the trans from overheating.

Sizing a single heat exchanger to keep the CVT fluid in a narrow temperature range is an engineering challenge for a CVT manufacturer. This is especially true when you’re building a car like the Mirage and shipping it all over the world into wildly different climates and driving conditions.

If I lived in a hot climate and drove a lot of freeway speeds (this is generally when CVT fluid gets the hottest), an external cooler probably wouldn't be a bad idea. For guys in Canada, an external cooler might actually over-cool the fluid during the winter months which would reduce the CVT's efficiency (and fuel mileage). This may be one reason why Mirages don't use external coolers.

If I owned a CVT Mirage and was concerned with making it last, I would figure out how to install a trans temperature gauge. According to my 2015 shop manual, the CVT temperature warning light doesn't start flashing until the fluid temperature has reached 279F/137C. That seems crazy high to me and is hotter than any other specs I have found for other manufacturers using CVTs.

Is there some company making the external oil cooler? I wonder if my shop could put it on for me or Aamco.......to be continued.

[Fummins]

How many km on it when it was brought in?

This time it's at 307,000km/190,000miles. Fluid doesn't look black.

This car originally acted up in Nov 2019 at 233k km. Was throwing a P0746, I changed the valve body with a low mileage one from a car that had a bad input bearing.

One code came up. P0876 High clutch pressure switch.
\
DTC P0876: Malfunction of high clutch oil pressure switch
.
DIAGNOSTIC FUNCTION
The TCM checks whether the high clutch oil pressure switch turns ON and OFF normally depending on the hydraulic pressure applied to the high clutch.
.
DESCRIPTIONS OF MONITOR METHODS
The TCM determines that a malfunction exists if the high clutch oil pressure switch does not turn OFF when the command pressure to the high clutch is 0 MPa or less, or does not turn ON when the command pressure is 0.2 MPa or more for a certain period.
.
MONITOR EXECUTION (STUCK ON)
The target pressure for the high clutch and reverse brake solenoid valve is 0 MPa or less.
Target auxiliary gear position: 1st
Engine speed: 450 r/min or more
.
MONITOR EXECUTION (STUCK OFF)
The target pressure for the high clutch and reverse brake solenoid valve is 0.2 MPa or more.
Target auxiliary gear position: 2nd
Transmission range: D or B
Accelerator pedal opening angle: 7.8% or more
Engine speed: 450 r/min or more
Output shaft speed: 300 r/min or more
Secondary pulley speed: 300 r/min or more
.
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
P0705: Malfunction of the transmission range switch
P0711, P0712, P0713: Malfunction of transmission fluid temperature sensor
P0715: Malfunction of primary pulley speed sensor
P0720: Malfunction of the output speed sensor
P0746: Abnormality in hydraulic control system
P0791: Malfunction of the secondary pulley speed sensor
P0962, P0963: Malfunction of the line pressure solenoid valve
P0973, P0974: Malfunction of the low brake solenoid valve
P0976, P0977: Malfunction of the high clutch and reverse brake solenoid valve
P2857: 1st gear neutral malfunction
P2858: 2nd gear neutral malfunction
P2859: 1st gear ratio malfunction
P285A: 2nd gear ratio malfunction
U0001: Malfunction of CAN communication
U0100: CAN time-out error (engine)
Sensor (The sensor below is determined to be normal)
Transmission range switch
Primary pulley speed sensor
Output speed sensor
Secondary pulley speed sensor
Line pressure solenoid valve
Low brake solenoid valve
High clutch and reverse brake solenoid valve
.

[Dirk Diggler]

This time it's at 307,000km/190,000miles. Fluid doesn't look black.

This car originally acted up in Nov 2019 at 233k km. Was throwing a P0746, I changed the valve body with a low mileage one from a car that had a bad input bearing.

One code came up. P0876 High clutch pressure switch.
\
DTC P0876: Malfunction of high clutch oil pressure switch
.
DIAGNOSTIC FUNCTION
The TCM checks whether the high clutch oil pressure switch turns ON and OFF normally depending on the hydraulic pressure applied to the high clutch.
.
DESCRIPTIONS OF MONITOR METHODS
The TCM determines that a malfunction exists if the high clutch oil pressure switch does not turn OFF when the command pressure to the high clutch is 0 MPa or less, or does not turn ON when the command pressure is 0.2 MPa or more for a certain period.
.
MONITOR EXECUTION (STUCK ON)
The target pressure for the high clutch and reverse brake solenoid valve is 0 MPa or less.
Target auxiliary gear position: 1st
Engine speed: 450 r/min or more
.
MONITOR EXECUTION (STUCK OFF)
The target pressure for the high clutch and reverse brake solenoid valve is 0.2 MPa or more.
Target auxiliary gear position: 2nd
Transmission range: D or B
Accelerator pedal opening angle: 7.8% or more
Engine speed: 450 r/min or more
Output shaft speed: 300 r/min or more
Secondary pulley speed: 300 r/min or more
.
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
P0705: Malfunction of the transmission range switch
P0711, P0712, P0713: Malfunction of transmission fluid temperature sensor
P0715: Malfunction of primary pulley speed sensor
P0720: Malfunction of the output speed sensor
P0746: Abnormality in hydraulic control system
P0791: Malfunction of the secondary pulley speed sensor
P0962, P0963: Malfunction of the line pressure solenoid valve
P0973, P0974: Malfunction of the low brake solenoid valve
P0976, P0977: Malfunction of the high clutch and reverse brake solenoid valve
P2857: 1st gear neutral malfunction
P2858: 2nd gear neutral malfunction
P2859: 1st gear ratio malfunction
P285A: 2nd gear ratio malfunction
U0001: Malfunction of CAN communication
U0100: CAN time-out error (engine)
Sensor (The sensor below is determined to be normal)
Transmission range switch
Primary pulley speed sensor
Output speed sensor
Secondary pulley speed sensor
Line pressure solenoid valve
Low brake solenoid valve
High clutch and reverse brake solenoid valve
.

Damn. Well at least you squeezed out those extra km the second go round. I won't lie, I'm emotionally invested in your fleet lol. When a ship goes down in it, I feel the pain.

[Fummins]

It still moves. I'll drop the pan and look for bad things. If it looks fine I'll refill it get hot and see what happens.

[CrazyMind2017]

If I lived in a hot climate and drove a lot of freeway speeds (this is generally when CVT fluid gets the hottest), an external cooler probably wouldn't be a bad idea.

I would be curious if anyone has installed a CVT temperature gauge can confirm this. Even when the ambient temperature is around 100F, I would think the faster freeway speed would help act as a supplemental fan. Even 100F air circulating around the engine, radiator, and transmission will help cool them because they all run at well over 100F. I'm much more concerned about running at too high a temperature in stop-and-go city traffic on a hot, humid summer day than cruising around on the highway with the A/C on full blast.

When you're driving 200 feet a time, never faster than 20mph, and then sitting for minutes at red lights, you're really relying 100% on the internal fan to keep air circulating. All the open space in the engine compartment that Doug DeMuro hates in the Mirage is probably one of the main factors in the longevity of the CVT. A few are going to have problems and nothing is 100%, but the track record of the Jatco CVT in the Mirage compared to problems with Nissan, Subaru, and Jeep speaks for itself.

Is there some company making the external oil cooler? I wonder if my shop could put it on for me or Aamco.......to be continued.

I'm sure people with mechanical knowledge and experience could figure out how to make something like this work for the Mirage: https://www.youtube.com/watch?v=pITJjj5T4Ew

It's truly just a little mini supplemental radiator.