How I solved my Limp home no codes Ml 350 Bluetec
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Ml350 bluetec
How I solved my Limp home no codes Ml 350 Bluetec
This is for posterity, in the hopes that it helps someone.
ML350 bluetec 180k, Tune, no dpf, egr, or adblue
Symptoms.
1) Boost only between 14-16psi absolute.
2) No check engine
3) Fuse 101 blown.
4) Charge air temp sensor -50c
5) Black smoke under throttle.
Diag process.
1) Using scanner (foxtool in my case) activate vgt to make sure it's not the controller. It's not.
2) Replace Charge Air temp sensor. Still reads -50c
3) Go to the regular OBD section instead of the boost control live data from canbus and it reads 85f which is about right.
Still no boost.
4) Replace fuse 101. Road test. Boost gets stuck at full boost. Fuse blows.
5) Replace map sensor becuase it seemed frozen. (Bad idea and wrong keep reading)
6) Guessing that there was no MIL light I unplugged the swirl motors as they are on fuse 101. Fuse 101 no longer blows. Road test. No boost. Still shows 36psi absolute at idle.
7) Added 4.7k ohm resistor mod to swirl motor.
8) Verified no actual boost leaks. Road test. No boost. Map sensor reads 36psi. All other sensors ok.
9) Plugged in old map sensor. It reads 14.4 psi which is correct. Before however it didnt seem to register a change in boost pressure. This was becuase the car was in limp without a mil, somehow?
10) Road test figuring what the hell and it works normally. Operates well, boost accurate on map sensor.
The culprit was the swirl motor. It was convoluted by the bad air charge temp sensor and that my a/c fan failed at the same time. As long as the flaps are in the open position, putting in a resistor works just fine. All the bs in between that was a false road I left out.
Thank you for Maj for the help and the confidence to keep going. Just listen and answer his questions.
ML350 bluetec 180k, Tune, no dpf, egr, or adblue
Symptoms.
1) Boost only between 14-16psi absolute.
2) No check engine
3) Fuse 101 blown.
4) Charge air temp sensor -50c
5) Black smoke under throttle.
Diag process.
1) Using scanner (foxtool in my case) activate vgt to make sure it's not the controller. It's not.
2) Replace Charge Air temp sensor. Still reads -50c
3) Go to the regular OBD section instead of the boost control live data from canbus and it reads 85f which is about right.
Still no boost.
4) Replace fuse 101. Road test. Boost gets stuck at full boost. Fuse blows.
5) Replace map sensor becuase it seemed frozen. (Bad idea and wrong keep reading)
6) Guessing that there was no MIL light I unplugged the swirl motors as they are on fuse 101. Fuse 101 no longer blows. Road test. No boost. Still shows 36psi absolute at idle.
7) Added 4.7k ohm resistor mod to swirl motor.
8) Verified no actual boost leaks. Road test. No boost. Map sensor reads 36psi. All other sensors ok.
9) Plugged in old map sensor. It reads 14.4 psi which is correct. Before however it didnt seem to register a change in boost pressure. This was becuase the car was in limp without a mil, somehow?
10) Road test figuring what the hell and it works normally. Operates well, boost accurate on map sensor.
The culprit was the swirl motor. It was convoluted by the bad air charge temp sensor and that my a/c fan failed at the same time. As long as the flaps are in the open position, putting in a resistor works just fine. All the bs in between that was a false road I left out.
Thank you for Maj for the help and the confidence to keep going. Just listen and answer his questions.
