I've recently started having a variety of problems with my '06 MCS. About a month a go I started noticing a loud sound of an electric motor. This motor sound spooled down after the engine was turned off.

Then 2 weeks ago, on my way home from work, I was accelerating (not hard) and the engine shut down. The EML light went on and I was in limp mode. I pulled over, shutdown. After a couple of tries I got it restarted without the EML light on but of course the SES (service engine soon) light was on as well as the DSC (traction control) light.

I check the codes, and I find the following:

• P1688 - Metering Oil Pump Stepper Motor Circuit Malfunction
• P0107 - Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
• P1106 - Dual Alternator Lower Fault/Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent High Voltage

I took it to my local repair shop (not the dealership as I live 200 miles from the nearest). He did some checking and decided it was the harmonic balancer/crank pulley. He pulled mine off and manually inspected it. He believes that this was not the problem. He also checked both MAP sensors and also decided that the problem was poor connections.

The next day after my car was returned to me, I'm driving around town and my DSC light just lights up for no reason. A while later, the SES light goes on and the EML light turns on. Once again, I'm in limp mode. Finally get the car home. I pull into the garage and pop the bonnet while it is still running. I can definitely hear the sound of something. I stop the car and then restart. This time it stalls out. However, the whining sound continues. I pull out my stethoscope and trace the sound to the PSP (power steering pump). The fan is NOT running on the PSP but it pretty much sounds like it has only 1 leg to stand on. However, I have had no impact to my steering quality.

I checked the codes again (borrowing a scanner from a local parts store) and the only code shown is the P0107.

At this point I think that I have 2 problems:

1. My PSP is failing
2. My By Pass Valve is also failing

Is #1 the cause of the DSC light showing up? I've read up a bunch on this problem and don't remember anyone mentioning this before.

What is the best method of diagnosing #2?

Thanks!

 

So I've been doing more reading and tried a last ditch effort… I pulled the negative battery terminal. Problems seem to be gone with the SES and the EML lights.

However, the PSP still sounds like it will die at any moment.

 

where is the local repair shop?

 

The power steering pump is a simple swap on ramps...
Just be sure to use the correct fluid.
other items...may or may not be related to eachother...and swapping out random parts that fixed somebody elses issue can be a very $$$ to try to solve an issue...and frustrating.

 

PS
A failing bypass valve will not trigger a code....you may have a poer losses depending if it is stuck open or closed, or inbettween....

 

The woes continue. Getting a decent OBD-2 scanner to look at the readings for the MAP sensors. The car will sometimes stall after letting up on the gas approaching a stop light. The RPMs many times will dip to 500 and then recover.

 

Well, I've replaced the BPV with the Detroit Tuned BPV. I ended up doing it twice since the first time, I didn't have the throttle body tight against the supercharger.

After I got it replaced, I did a ECU reset. On the first test drive, the engine wasn't running optimally until a few blocks from the house. After that, smooth as butter.

The DT-BPV seems to really smooth out the throttle response.