W221 S65 AMG Low boost
#26
No, my ECU has no DTC. Another thing I noticed is the specified boost pressure never exceeds 2000 hPa. On my tuned S600 it will pin to 2600 hPa. It 100 percent in the ECU. I also deleted my catalytic convertor on the S65. Shardul had mention'd to me that the tube from the back of the passenger side intercooler going to the boost control solenoid had a leak his vehicle when he replaced it, his problems all went away. I am going to replace this next, I plan on just running it over the intercooler. .
#27
Super Member
Thread Starter
Yes your cars behaviour is exactly the same as mine!!
I have my cats but no rear mufflers. I have checked everything that star says to (lambda control both pre and post cats etc). All normal.
I checked that pipe today, mine has no leak in it at all. It will hold pressure and a vacuum without any trouble! I did not check to see if it had a leak with the valve actuated, as STAR cannot actuate that valve on the 221, I have to get access to the connector to do that.
I am surprised, because if that line has a leak the car would overboost.
The wastegates are held closed by spring pressure. When the ecu actuates the boost pressure control solenoid it routes boost pressure to the wastegates which opens them. If there is a leak in this pipework the car would overboost.
On my car, if I pinch that line, I get an overboost code.
This is from the M275 training doc:
"If the hose lines between the vacuum cells (110/3), vacuum transducer (Y31/5) and charge air cooler on
the right cylinder bank (5/2) are leaking, the error "Boost pressure too high" is stored in the engine
control module."
I have my cats but no rear mufflers. I have checked everything that star says to (lambda control both pre and post cats etc). All normal.
I checked that pipe today, mine has no leak in it at all. It will hold pressure and a vacuum without any trouble! I did not check to see if it had a leak with the valve actuated, as STAR cannot actuate that valve on the 221, I have to get access to the connector to do that.
I am surprised, because if that line has a leak the car would overboost.
The wastegates are held closed by spring pressure. When the ecu actuates the boost pressure control solenoid it routes boost pressure to the wastegates which opens them. If there is a leak in this pipework the car would overboost.
On my car, if I pinch that line, I get an overboost code.
This is from the M275 training doc:
"If the hose lines between the vacuum cells (110/3), vacuum transducer (Y31/5) and charge air cooler on
the right cylinder bank (5/2) are leaking, the error "Boost pressure too high" is stored in the engine
control module."
#28
When data logging i notice the map sensor down stream will have a higher reading then the upstream sensor. Once this occurs I can feel the car buck and boost levels outs. In first and second gear if engage the gas progressively I have gotten it to go to 2200 hPa. Also what % does your boost control solenoid reach under full acceleration?
#29
Super Member
Thread Starter
I will check it out when I get somebody to watch STAR whilst driving. I suspect its not much more than what you are seeing.
Its a bit odd that your downstream sensor reads higher than your upstream, are you sure your device is not confusing the names. The ECU can close the throttle valve to limit boost pressure, in this case you will see higher values upstream than downstream.
Are you able to log boost control solenoid duty cycle via a 3rd party OBD tool?
Its a bit odd that your downstream sensor reads higher than your upstream, are you sure your device is not confusing the names. The ECU can close the throttle valve to limit boost pressure, in this case you will see higher values upstream than downstream.
Are you able to log boost control solenoid duty cycle via a 3rd party OBD tool?
#30
Yea, iCarsoft will show it in pressure sensor actual value feed.
Have you tried replacing the seal ring out of the turbos? I am going to do this as soon as they can get here.
Here is the part number so you can reference it
0279979948
Have you tried replacing the seal ring out of the turbos? I am going to do this as soon as they can get here.
Here is the part number so you can reference it
0279979948
#31
Super Member
Thread Starter
aha, but no way to log it under driving conditions, will have to get a mate to come and sit with me!
I have those seals sitting on the shelf. They showed no leakage whilst I was boost testing though so I have not replaced them, I will do so when I replace my spark plugs.
I have those seals sitting on the shelf. They showed no leakage whilst I was boost testing though so I have not replaced them, I will do so when I replace my spark plugs.
#33
Super Member
Thread Starter
Around here there are MANY speed cameras and small roads, its hard to drive under full throttle and look at the screen at the same time
Shame it cant log to file!!
Shame it cant log to file!!
#35
Super Member
Thread Starter
ECU map has been checked by 3 companies now (including EC) and is NOT the cause of the low boost (makes sense, seeing as it was an issue before tuning too).
Back to a mechanical fault but its not obivous what it is:
no boost leaks
no misfires
on leaks in any of the vaccum lines anywhere
new boost pressure control valve
Intake air temp very low (much lower than 70)
current train of thought is gearbox is limiting torque for some reason. Impossible to check though. Would be nice if I could code out torque limiting on the engine ecu to test.
Back to a mechanical fault but its not obivous what it is:
no boost leaks
no misfires
on leaks in any of the vaccum lines anywhere
new boost pressure control valve
Intake air temp very low (much lower than 70)
current train of thought is gearbox is limiting torque for some reason. Impossible to check though. Would be nice if I could code out torque limiting on the engine ecu to test.
#36
ECU map has been checked by 3 companies now (including EC) and is NOT the cause of the low boost (makes sense, seeing as it was an issue before tuning too).
Back to a mechanical fault but its not obivous what it is:
no boost leaks
no misfires
on leaks in any of the vaccum lines anywhere
new boost pressure control valve
Intake air temp very low (much lower than 70)
current train of thought is gearbox is limiting torque for some reason. Impossible to check though. Would be nice if I could code out torque limiting on the engine ecu to test.
Back to a mechanical fault but its not obivous what it is:
no boost leaks
no misfires
on leaks in any of the vaccum lines anywhere
new boost pressure control valve
Intake air temp very low (much lower than 70)
current train of thought is gearbox is limiting torque for some reason. Impossible to check though. Would be nice if I could code out torque limiting on the engine ecu to test.
btw, i am not a tuner, but i believe that tq management plays with timing to limit tq when needed...
#37
Super Member
Thread Starter
Yes Low boost is just a symptom. I am sure its pulling timing too. Dyno runs with data logging has proved inconclusive.
I am 99% sure the gearbox is causing torque limiting now.
If I force boost by manually controlling the boost pressure, the car makes another 100whp on the dyno.
Add to that, the speed difference of lockup clutch on my car shows a very high number >200 leading me to believe that the torque converter has issues.
It would be nice if i could turn off torque management in the engine ecu (to test) but i don't know how do it on the ME ecu's only diesels.
I am 99% sure the gearbox is causing torque limiting now.
If I force boost by manually controlling the boost pressure, the car makes another 100whp on the dyno.
Add to that, the speed difference of lockup clutch on my car shows a very high number >200 leading me to believe that the torque converter has issues.
It would be nice if i could turn off torque management in the engine ecu (to test) but i don't know how do it on the ME ecu's only diesels.
Last edited by alexanderfoti; 08-18-2017 at 03:26 AM.
#38
Super Member
Thread Starter
I replaced :
Torque converter
Conductor plate
TC lockup solenoid
and now the car made a little more power, but has this rocking/surging whilst the boost spools up. I still very much suspect something with the TC so I have sent the valve body away to be checked.
Boost still capped at 1.1ish bar.
Last edited by alexanderfoti; 12-12-2017 at 11:48 AM.
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#39
Super Member
Thread Starter
Valve body back.They identified leakage on the TC solenoid and bored it out and installed a sonnax TC valve.
Re-installed, reset adaptions, drove it for 100+ miles.
TC lockup is much sharper now, gear changes are much quicker. Boost now peaks at 17 instead of 15 but still no 21-22 it should be. Datalogging with a Autocom CDP (much faster than star) I can see the TC slip is now 50rpm at high load instead of 200+ with the solenoid duty cycle at 95%. The whole tc/gearbox is much smoother and sharper than before.
Running 30% meth injection and 99ron, so engine should not be knocking.but still its reducing power. I think I am going to run a boost controller on it and see what's what. Before I do that, dyno run on Wednesday to see if the power has changed.
Re-installed, reset adaptions, drove it for 100+ miles.
TC lockup is much sharper now, gear changes are much quicker. Boost now peaks at 17 instead of 15 but still no 21-22 it should be. Datalogging with a Autocom CDP (much faster than star) I can see the TC slip is now 50rpm at high load instead of 200+ with the solenoid duty cycle at 95%. The whole tc/gearbox is much smoother and sharper than before.
Running 30% meth injection and 99ron, so engine should not be knocking.but still its reducing power. I think I am going to run a boost controller on it and see what's what. Before I do that, dyno run on Wednesday to see if the power has changed.
#40
Super Member
Thread Starter
Data logging with autocom (much faster) shows that the tc situation is now all sorted, need to intake timing next:
Much faster logging than star. Can see now that there is very little tc slip under load.
Data
Much faster logging than star. Can see now that there is very little tc slip under load.
Data