Hi Dave,

P0170 "Fuel Trim Malfunction (Bank no.1). ECU is struggling to maintain fuel trim (mixture) possibly due to MAF.

I would firstly reset the ECU memory and see whether P0170 comes back again. If so then move forward.

HOWEVER since the code is only on ONE BANK and the MAF is common to both (Is this assumption correct? since I'm more familiar with M112 320V6) I suspect that it MAY be pointing to the injectors.
Under these circumstances...since I don't like spending ANY money, I would change injectors from one bank to the other temporarily and see if you get P0171 instead.

Note: You may be OK with a clean but don't hold your breath (subject to my assumption above). Don't soak the sensor. Rather swirl it around or blast it with cleaner and then blow of with air (carefully). The sensor is a thin film which can't actually be seen when you remove the sensor from the housing. You will require a security Torx socket to fit the securing screws.

You appear to be describing the crankcase breather pipe. If this is defective it will certainly cause problems since it is part of the emmisson control system but I would have expected an electronic code (not sure which one without some research) to be set.

Stuart

 

Additionally, I'm going to repace the Motor and Transmission Mounts.

Why?....or do you have more symptoms that you haven't "shared"?

Stuart

 

Stuart,

Though I'm not Mechanically Literate, nor Technologically astute as it pertains; I'm replacing the mounts as part of my own PMC&S (Preventive Maintenance Checks & Services). The left side is stiff, the right side is kinda pliable, and the transmission mount is an added precaution. I do understand how torque wants to twist the engine and transmission. If movement is not enabled due to hard, stiff, cracked or broken mounts (no fluid in them), all of the vibration translates to the frame. I understand that if transmission mount is worn or hard and there's no movement, it may cause it to bind. So, all things working together to preclude engine or transmission failure, and to preclude as much vibration or the possibility of vibration from these areas, I'm changing them out.

To update you further, I've replaced the crankcase breather hose (41.00 + TAX) and man what a difference! (However, I could have purchased it online for $30.00, but why wait?) Everything is running pretty much as it should. I have restored power. My baby has got some pep back in her step, and my transmission doesn't feel like it'sloping or slipping, nor does it feel like I've got a vapor lock,or stopped up nose, or whatever it was that it was doing! My codes are clear, and have not duplicated. However, I do have a concern as to why the CEL didn't come on? I've read that under such circumstances that the CEL doesn't always have to come on.

I am going to clean the MAF anyway once the cleaner arrives UPS.

Thanks for all of your input, Stuart. One thing is for certain, I've spent a considerable amount of money here lately, when all's I had to do was replace a $40.00 hose.

I've replaced:

All Spark Plugs
All Ignition Coil Paks
Both Lower Ball-Joints
Both Sway Bar Links
Both Sway Bar Bushings
5 New Pirelli P-Zero Nero M+S (P235/55/17's)
Fuel Filter
Replaced K&N Filters back to Stock
Changed the Engine Oil/Filter
Changed the Transmission Filter/Fluid
Engine Coolant Temp Sensor

All because the engine wasn't breathing, because of a hose that was ate up! DAMN!!!

And gonna perform the following:

Clean the MAF
Replace Engine/Transmission Mounts
DriveShaft/Center Support Bearing/Flex Discs
Serpentine Belt
Timing Chain, Gears & Guides(if necessary)
All 02 Sensors
Wheel Alignment

And in May, I'll have all of the fluids flushed/changed:

Differential Re-Seal
Engine Coolant
Power-Steering

This is a considerable expense, as I drive my automobile a lot, and at least these things as part of my own PMC&S will have been done!

David

 

hi Dave,

Usual problem with mounts is that the rubber / steel bonding goes (old age / oil contamination) and this allows the engine to "jump" / move about on its V mounts when the car goes over a bump and of course as you state the noise transmission characteristics change.

Sure your CEL light comes on during startup checks?
It is possible to select an override in the ECU coding that turns the CEL permanently OFF!
I learned this the hard way suspecting the LED had gone. However the LED was OK and after telling my local MB dealer that there must be an override....which they laughed at!!...they finally found it on a hidden Star Diagnostic menu but only after selecting the USA market market code. The option isn't available if you put in UK!! My car is a UK car but it had been selected at some point, by someone!!

MB do this when they have a troublesome customer and they can't find the reason for the CEL coming on.

You live and learn!

Stuarty.