SMG Problems

[why_m3]

I had the same issue and couldn't figure it out. I thought it was my EWS failing. I'd drive then stop and couldn't restart the car. Would not crank. Then I ditched the SMG

[oceansize]

I had the same issue and couldn't figure it out. I thought it was my EWS failing. I'd drive then stop and couldn't restart the car. Would not crank. Then I ditched the SMG

Thanks for posting. Really helpful.

[beyondm3]

Well I'm back and need some assistance. I've finally gotten around to getting some readouts from INPA and I need some help sifting through the data. I have attached two word docs. error1 is the SMG fault readout and error2 is the s54 fault readout (I know there is an EGT error on the S54 report, I plan on ordering a new one today/tomorrow). Also attached are two photos from the SMG status readouts. One being normal operating (normtemp) temperatures where I can stop and start the car on demand and the second being when the car is hot enough to the point it won't restart (hottemp).

I hate to throw all this out there expecting someone else to do the work but I'm just not familiar enough with the systems to know what to look for. I appreciate anyone taking the time to look things over and giving their input. And just to recap, ONLY when the car is hot enough, the car will not (re)start. The SMG will remain in neutral and the car will not start or shift into any other gear. Only after an hour or two of cooling off will the SMG regain functionality. When I drive the car, it displays no issues whatsoever, just once it gets hot enough the symptoms kick in once the motor is turned off.

Lastly, attached is a photo of the only possible issue I can divulge in regards the SMG. I ran the Hydraulic Pressure Reserve and it came up short. This tests gets the same result whether the car is cool and will start or hot and will not start.

Thanks again to anyone who takes the time. It is much appreciated and hopefully I can get back in the drivers seat more than once in a while.

[oceansize]

Thoughts:

1. Your accumulator is not building the required 29 bar during testing, hence the failure you see.
2. Your car is likely dropping out of gear because it cannot build sufficient pressure. The SMG prevents shifting when this occurs and uses reserve pressure to drop into neutral.
3. The accumulator could be your issue.
4. The pump motor could also be the cause. Perhaps age coupled with temperature is preventing the motor from performing to spec.
5. The seals inside the pump could be leaking, causing the motor to work too hard, which can in turn cause elevated temperatures which could then contribute to number 4 above.
6. Code 59 is almost always the clutch slave cylinder. But this code can occasionally pop and mean nothing as some have seen this code in combination with relocation and Burkhart hydraulic fluid (I have not).

Questions:

1. How long, in seconds, for first prime of the day?
2. After starting the car and pressure is built how long does it take for your pressure to decay to the point where the motor starts again?
3. How many shifts before pressure needs to be built again?

[robgill]

One simple thing I would try is to use the INPA procedure to bleed the pump and clutch. I had an issue with hot SMG shifting poorly at low speed and neutral while stopped. INPA SMG clutch bleed fixed it.

[beyondm3]

One simple thing I would try is to use the INPA procedure to bleed the pump and clutch. I had an issue with hot SMG shifting poorly at low speed and neutral while stopped. INPA SMG clutch bleed fixed it.

Thanks, I was going to look into this as well. I read some more things online about it and I was debating giving it a go. I also read that you should not do the adaptation unless the clutch is new.... is this true?

[oceansize]

One simple thing I would try is to use the INPA procedure to bleed the pump and clutch. I had an issue with hot SMG shifting poorly at low speed and neutral while stopped. INPA SMG clutch bleed fixed it.

This is a good idea and free. OP, make sure your battery is fully charged and/or on a batter tender. SMG system/tests don't like low voltage.

[oceansize]

Thanks, I was going to look into this as well. I read some more things online about it and I was debating giving it a go. I also read that you should not do the adaptation unless the clutch is new.... is this true?

You can run into problems which then typically means you have larger issues, but in the end if you crack the system open you will have to bleed the clutch, actuator, and then run adaptations.

I have had better luck running adaptations while the car is at operating temperature.

[sapote]

Also attached are two photos from the SMG status readouts. One being normal operating (normtemp) temperatures where I can stop and start the car on demand and the second being when the car is hot enough to the point it won't restart (hottemp).
.

When cold, batt=13.1V and when hot, it = 12.2V. something is not right with the reported batt voltage. You should confirm this using a voltmeter to measure at the cigarette lighter. In both scenarios the hydraulic pressure is within the spec: above 45 bar.

[beyondm3]

When cold, batt=13.1V and when hot, it = 12.2V. something is not right with the reported batt voltage. You should confirm this using a voltmeter to measure at the cigarette lighter. In both scenarios the hydraulic pressure is within the spec: above 45 bar.

I should have done a better job explaining the photos, the hot photo is when the car was off as I was trying to pull the "status" whilst the car was in the problematic state. So the car was hot/off and I was attempting to restart. I was hoping the readout would be different enough to point to something obvious.

[beyondm3]

Thoughts:

1. Your accumulator is not building the required 29 bar during testing, hence the failure you see.
2. Your car is likely dropping out of gear because it cannot build sufficient pressure. The SMG prevents shifting when this occurs and uses reserve pressure to drop into neutral.
3. The accumulator could be your issue.
4. The pump motor could also be the cause. Perhaps age coupled with temperature is preventing the motor from performing to spec.
5. The seals inside the pump could be leaking, causing the motor to work too hard, which can in turn cause elevated temperatures which could then contribute to number 4 above.
6. Code 59 is almost always the clutch slave cylinder. But this code can occasionally pop and mean nothing as some have seen this code in combination with relocation and Burkhart hydraulic fluid (I have not).

Questions:

1. How long, in seconds, for first prime of the day?
2. After starting the car and pressure is built how long does it take for your pressure to decay to the point where the motor starts again?
3. How many shifts before pressure needs to be built again?

Thank you for the insight, I have answered your questions below.

How long, in seconds, for first prime of the day? ~11 seconds

After starting the car and pressure is built how long does it take for your pressure to decay to the point where the motor starts again? ~ 1 minute, 55 seconds

How many shifts before pressure needs to be built again? 4 or 5. I did this test many times and came up with split results.

[beyondm3]

One simple thing I would try is to use the INPA procedure to bleed the pump and clutch. I had an issue with hot SMG shifting poorly at low speed and neutral while stopped. INPA SMG clutch bleed fixed it.

The actuator and clutch bleed went well however the adaptation failed. Attached is the error that occurred and the new fault code that came along with the COG on the dash. The car still starts, but I have not taken it for a drive just yet as weather was atrocious this evening.

You can run into problems which then typically means you have larger issues, but in the end if you crack the system open you will have to bleed the clutch, actuator, and then run adaptations.

I have had better luck running adaptations while the car is at operating temperature.

hmmm maybe I'll need to get it up to temp and try again tomorrow.

[oceansize]

Thank you for the insight, I have answered your questions below.

How long, in seconds, for first prime of the day? ~11 seconds

After starting the car and pressure is built how long does it take for your pressure to decay to the point where the motor starts again? ~ 1 minute, 55 seconds

How many shifts before pressure needs to be built again? 4 or 5. I did this test many times and came up with split results.

Your unit is building pressure a little on the slow side and your pressure decay is really fast. As an example the video below is my SMG unit running for five minutes (four and a half shown in the video) and still not needing to rebuild pressure. My pump's first prime of the day is 8 seconds. Seven to ten seconds is considered normal. Your shift decay is normal. Now the problem is determining whether the true root of your problems are the accumulator, motor, or the internal pump seals.

With all the above being said I would still try a clutch and actuator bleed followed by adaptations as robgill suggested. It is possible that air entered the system, but if air entered the system how did it get there? My first bet would be the internal o-rings where the red collet sits on the fluid reservoir that is attached to the pump. After that guesses get more difficult.

[sapote]

the video below is my SMG unit running for five minutes (four and a half shown in the video) and still not needing to rebuild pressure.

Amazing good tight system! Is this the result of pump rebuilt with new seals, and new accumulator?

[oceansize]

Amazing good tight system! Is this the result of pump rebuilt with new seals, and new accumulator?

Original accumulator but all new seals and o-rings.