Mercedes W204 OM646.811 hesitation on acceleration at high revs

[mersum1es]

It not vanes but two stage turbo 'feature' in OM651. Pressure is originally lifted so high, chip tuning is very difficult when waste gate opens almost at normal operation.

 

[Doug1234]

My bad , just presumed it would have vanes.

 

[mersum1es]

My bad , just presumed it would have vanes.

It do have, but problem is too easily opening waste gate. Twin turbo is complex animal....

 

[dan_mac]

It do have, but problem is too easily opening waste gate. Twin turbo is complex animal....

Hi @mersum1es ,

But my car only have one Turbo, my engine is the OM646.811 Evo, not the OM651!
I did a test on Highway with a OBD scanner and Torque to see live data and when it "hesitates", the Boost pressure, injection, air flow volume, all of them decrease and when it returns to normal acceleration all the values continues increasing!!

 

[mersum1es]

Hi @mersum1es ,

But my car only have one Turbo, my engine is the OM646.811 Evo, not the OM651!
I did a test on Highway with a OBD scanner and Torque to see live data and when it "hesitates", the Boost pressure, injection, air flow volume, all of them decrease and when it returns to normal acceleration all the values continues increasing!!

yes yes, I apologise messing thread, it was just newer engine which brought my mind those pressure related problems. Higher sample rate recoding would tell is there problem.

 

[dan_mac]

yes yes, I apologise messing thread, it was just newer engine which brought my mind those pressure related problems. Higher sample rate recoding would tell is there problem.

Which test is that "Higher sample rate recoding"?!!
Thanks

 

[mersum1es]

Which test is that "Higher sample rate recoding"?!!
Thanks

Normal xentry/DAS display refresh readings by ~0.5 -5 seconds depending your computer. But in DAS developer you can log any signal in graph, and there higher sample rate is showing ie. it can capture faster changes of signal. Like I said I have not checked where that feature is in xentry, if it exist.

 

[Egg1000]

Which test is that "Higher sample rate recoding"?!!
Thanks

Did you ever sort your car, the symptoms you describe are almost identical to what I'm suffering with. Did have EML which pointed to MAP sensor problem. Had turbo system checked for leaks. Cleaned the MAF myself, had both MAP sensors replaced, no EML at the moment, car is great most of the time, but flat spots under heavy acceleration above 3000rpm. Better in the cold and wet weather.

 

[dan_mac]

Did you ever sort your car, the symptoms you describe are almost identical to what I'm suffering with. Did have EML which pointed to MAP sensor problem. Had turbo system checked for leaks. Cleaned the MAF myself, had both MAP sensors replaced, no EML at the moment, car is great most of the time, but flat spots under heavy acceleration above 3000rpm. Better in the cold and wet weather.

Hi,

My car was at the mechanic workshop almost 1 month stopped (the entire month of August) in the parking and when he decided to check my car it didn't start, battery was dead!! He connected a boost to the battery but even with that it didn't start, turning on the key but no starter signal (too hot outside on that day)! Then we pushed my car into the workshop and the mechanic started to see the Rear SAM module that was quite hot because the hot weather on that day...he blewed air from de compressor to the Rear SAM to Refresh it and coincidence or not, the car started with the booster!!! He told me that the Rear SAM was defective and told me to get a used SAM and a new battery! He replaced the Rear SAM with a used one and programmed it to work in my car and have changed too the car battery with a new one! After that, my car runs well, no more hesitations and never failed again!! The mechanic said that he didn't do anything else on my car, that the problem was or in the SAM or in a weak battery!!