P0299 low boost code - OM647

[Tod Kinsley]

Moved from this thread to its own: https://sprinter-source.com/forums/index.php?threads/7173/page-4#post-1782571

Move this post if not in right place. 2006 Sprinter 280k miles with P0299 low boost code started last year and last 4k miles. Boost is there for 5-20 seconds with "key off, key on" while driving then shuts off. Airbox air pressure , MAF, MAP, Charge temperature, ambient temp, water temp, aux water pump, heater valve, cam position, PCV valve changed with OEM or Mercedes parts. Turbo changed and "clocked". Servo actuation checked. Turbo to intake manifold ductwork pressure tested to 20 psi - OK. It was in a "Sprinter" shop and they couldn't figure it out. Any ideas on where to look?
Tod

 

[LowBudgetT1N]

You need to look for dirt and grime, nearby will be your issue. High probability that you have a boost leak. Hard to find with pressure test on cold engine, seams open when warm.

 

[marklg]

It is way more likely to be a boost leak than any of those other things. It's unfortunate that since lots of things were changed that the resonator, O ring and charge air hoses were not changed first. Dirty oil is a telltale sign of a leak. A smoke test might work.

Are all the parts Mercedes or OEM supplier? Because any aftermarket parts might have made things worse.

Regards,

Mark

 

[ECU]

Look at the resonator. Plastic ones would be broken by 280,000.
After the cooler is a 90 degree bend. Most likely hole placement is just before the bend where crud can settle and decompose the rubber.
Second, long upper hose can split lengthwise .
Haha, 20 psi. That's the point where the turbo shuts off after detecting the leak.

 

[Midwestdrifter]

P0299 is a generic OBD2 code. A scanner which supports advanced sprinter codes is desired here. If you can report the sprinter specific code (PXXXX-X format) that would help quite a bit.

Good turbos never need "clocked". I have personally never seen a clocked turbo work properly again.

Boost pressure issues can be caused by bad turbos or turbo actuators. An actuation test is needed.

Boost pressure issues can be caused by sensor drift. With the key on and the engine off, use a scanner to compare the pressure of the ambient/atmospheric sensor, the MAP/boost sensor, and the intake air pressure sensor. They must be within 50 millibars of each other.

Rarely wiring faults to the turbo actuator can cause it to be intermittent. This requires backprobing the actuator wires and checking for good signal and power supply voltage.

 

[p3424]

A none working electric water pump eventually caused my EGR valve to fail long time ago. I kept my finger on the OBD reset button just in case I need to get out of limp mode in a hurry, I would get about a minute or more of boost after each reset. Maybe it was 0299 as I had a generic OBD at the time.

 

[Tod Kinsley]

Thank you for the quick responses. For brevity, I left off the fact that a smoke test was done at a shop, the resonator is the metal tube design, ductwork was tested to 20 psig, turbo clocking procedure was done to check position - it was good. MAP sensor was tested to 3 bar and it tracked the voltage/pressure graph exactly. What would be a good scanner to buy for Sprinter. I have the Icarsoft CR Pro now which got me the P0299. No other codes pop up.
Tod