2012 Sprinter 3.0L Turbocharger surge/hesitation after turbo replacement
2012 Mercedes-Benz - Sprinter 3500 - 3L, V6 WDYPF1CC8C5700689
Hello to all. I am looking for some thoughts on his Sprinter symptom after a turbocharger replacement. This vehicle was towed in with an exploded turbo. We couldn't find any exact cause of the turbo failure other than a severely clogged DOC/DPF filter that likely caused an overboost/overheated exhaust system that likely damaged the turbo.
The customer gave the approval for repairs. They wanted to get by with the cheapest repair possible. They wanted it running well enough to drive to the dealer to trade it in on a new one. We had found the DPF and DOC were 75% blocked off on the face of the catalyst with soot/ash so we replaced the DOC/DPF unit with OEM Mercedes. We removed intake manifolds and cleaned the and replaced oil cooler gaskets. Wear on EKAS linkages were noticeable especially on the LH intake manifold. Customer wanted cheapest way so we did not replace manifolds. We spaced the EKAS sensor on the LH manifold a bit to allow for future wear in the linkages. Thankfully the EKAS system is working properly at this time. We also installed a new turbocharger and intercooler which were also OEM Mercedes. Also replaced the air filter. After engine was reassembled we did adaption/teach in resets with Xentry for the air filter, turbo/VGT actuator, DOC and DPF and cleared all codes.
The initial test drive felt strange for how the turbo was being controlled. It would accelerate fine and boost fine on startout but then for a very brief moment the VGT actuator would derate from about 90% to about 25 -35% and then jump back up to 90% and continue boosting and accelerating properly. It seemed to be more prevalent when driving it light footed and it seemed to do it in every gear as it spooled up. I could watch the VGT percentage drop on scanner everytime it derated. Each time it did it it gave the van a little jerk/hesitation and you could hear the turbo give a little chuff/chortle.
We left it sit overnight and then performed a smoke test on both intake and exhaust sides and found no leaks on either side. We tried the same resets with an Autoland Scientech scanner with no difference. Read in Identifix that sometimes you have to try the resets a few times before they work ??? After that I test drove it for about an hour and a half and the symptoms were sporadic. Sometimes it would accelerate with no hesitation and then the next time it didn't. If you accelerated slowly it was more noticeable than when you just held the pedal to the floor. It has never derated to reduced power mode. It did show one code at one point for 11D900 The lower limit value of component B28/19 (Intake manifold pressure sensor) was dropped below/not reached. I had cleared it and it did not come back and made no difference in operation. I should check into the connector of that pressure sensor on the air filter box and just make sure it has a good connection.
I watched the pressure pids while test driving. On WOT startout I had exhaust backpressure of 3200 Hpa which in reality would be 2200 Hpa after subtracting the 1000 Hpa of Barometric pressure which would convert to 32 PSI. Boost pressure read 2500 Hpa -- 1000 Hpa =1500 Hpa or 21.75 psi. DPF pressure differential read 200 Hpa or 3 psi. Baro, Boost, and Backpressure sensor all read near 1000 Hpa Key on Engine off.
So I am hoping someone may have run into this before after replacing a turbo or possibly you have an idea what might be happening. Of course we did not get a chance to drive it before repairs because the turbo was blown so we don't know if it was doing this before. If it was doing this before the turbo blew I can believe it could have contributed to the turbo damage possibly. I had tried inspecting the SCR filter face with the exhaust disconnected but they have that air diffuser in the pipe that I could not see through.
Thanks for taking time to read this. I appreciate your input.
There are some issues with wiring rubs on some of these models. I had a similar problem on an earlier model Sprinter. I was giving an overboost code when accelerating. The numbers were not as clean as yours. Maybe in your case when the vehicle accelerates wiring moves and it gives a quick open or short on the boost signal.
Good idea. I will keep that in mind when I check it out again.
I'm not going to be very helpful other than to state that we have replaced dozens of those turbos and DPF units with no unique problems such as you are describing. I believe you can swap the VGT on that model fairly easily if you want to try your original one to compare though. Dont loose that little clip that hold the linkage rod on, they like to fly!
Thanks for the replies. We sent the Mercedes off exactly a week ago. We never did pinpoint exactly what was causing the symptoms. It seemed the more we ran it the less noticeable the problem was. It got to the point that most of the time it accelerated perfectly without any hesitation. Since the customer was wanting to get it sold they were satisfied to take it as is. We did do a software…