98 ML320 check engine code PO173

[Matt Koenig]

my car has 41,000 and this code came up ,my tech cant find a vacum leak ,but is leaning to the left bank regulator malfunction. Does this sound right? or any other help you could give would be great

[stevebfl]

What are the adaptation numbers? That code means it ran out of correction capability. The numbers will tell you how. If it is an idle correction bust out then I would look more to the vacuum leaks. if it is a lean partial load adaptation problem numbers at 1.32 or so then good chance you have a air mass meter problem.

[Matt Koenig]

Steve thanks for yor reply,the info was from Mitchell repair info.Thier was another code given (N3/10) The tech checked the left bank load and found that the computer was adj. it to proper levels, also o2 was fine....Then the second time I started the car the light was out and hadnt come back on. Thanks again and happy holidays Matt

[stevebfl]

Since adaptation is what is faulted by that code, adaptation numbers are the tale to diagnosis. CTP additive correction or partload multiplicative correction numbers are recorded and should be viewed.

[Gilly]

You need to look at the freeze-frame data when the fault code was set and see what the self-adaptaion numbers were at that time. The values quite aften are back in spec when the vehicle is brought into the shop.

Gilly

[1995whitec220]

I just bought a used clk 320 cabriolet and the dreaded check engine light came on, The only thing I have done to the car is change the oil, disconnected the battery to check to see if the radio code worked, and changed the air filter.
I read the codes with my scanner and got p0170 and p0173, tried cleaning the MAF with tuner bath and light still comes back. Although car seems to run fine, There is black soot in tailpipe though. I hear a lot of talk about adaptation values I don't see that On my OBD2 diagnostics software though. Here are some of the numbers in my freeze frame maybe this will help

Short term bank 1: -50
Short term bank 2: -50
intake manifold pressure 11.2 in hg 38kpaa
intake air temp 147 deg farenheit
MAF rate 0.6 lb/min 4.6 gm/s
ignition advance -16.5 deg
coolant temp 189 deg f
engine load value 21.2 %
throttle pos sensor 2.7%
RPM 693

these numbers mean nothing to me, the bottom line should I buy a new MAF or is this a waste of money, I just want the light off so my wife will shut up

[stevebfl]

Boy, those are some real generic numbers.

The short term trim might mean something if I knew the units of measure it was expressed in. MB would call that value integrator or O2 something. It expresses where the control cycle is at the moment. It looks to be at the minus stop, but who knows? It really doesn't represent the adaptation values that are being faulted. it is an indication of momentary lean correction of a rich mixture.

The value faulted is either a partial load multiplicative adaptation or a CTP (closed throttle position)idle additive adaptation. The common senario on 112 and 113 motors is for the AMM to degrade such that at increasing air flow it is less accurate. (It misses more air as the volume increases). This is corrected by say a 15-25% multiplicative factor (25% more fuel). This is calculated at around 2000 rpms at a load that would probably accelerate the car. Once back at idle the AMM is more accurate and the system is now too rich due to the extra 15-25% fuel. This is delt with by a straight drop in mixture through an additive correction say -.8ms. This means that at idle with a normal injection open time of say 4.00ms a subtraction of .8ms takes place to wind up openning the injector 3.2ms.

The above example is of a car only part of the way out of range and is of the skewed type failure. Maybe more common is the straight line failure where its lean everywhere and at 32% correction it can't go no further. The limits are .68 to 1.32 on partial load multiplicative adaptation and -1.0ms to +1.0ms on the CTP additive adaption.

Anything that affects mixture affects these numbers, air leaks are high on the list.

[1995whitec220]

Uhhhh..... now I'm really lost

[1995whitec220]

well, I bent over and went to the dealer, and guess what, it was the MAF, But once you have already payed for the labor for the diagnosis there is no turning back. besides at least I have a one year warranty, by the way are adaptation values some thing that is done automatically by the computer or does it have to be done by the dealer and also when you disconnect the battery does it mess up your adaptation values and other critical data??? seems like they would put a capacitor or something in the circuit to keep all the DATA long enough for the averqage battery changeout. PARTS $304.00 LABOR $268.00

[manny]

Next time, you may want to try a " memory retainer ".
It's a plug ( like a cigarette lighter ), that you plug into the lighter socket, and has a little 9 volt battery on the end of it.
This is supposed to retain the ECU memory, clock, radio settings etc. , when you disconnect the battery for just a short time.

[1995whitec220]

thats a good idea, I think I'll get one!!!

[stevebfl]

Memory retainers are a good concept, but no way will they work in a MB cig lighter. MB cig lighters are unpowered in the key off position and a 9v battery won't nearly power everything that gets switched on the same time as the lighter.

WE use a high powered gel battery what is inside those jumpstart boxes. Every model is different but we tie into a non switched term 30 somewhere.

On that ML I think we go to the large 80amp Traction control pump fuse.

[1995whitec220]

wish I would have read your post before I bought one last nite for 13.00, But that still doesn't answer my question, will my car lose any memory that the computer will not re-learn automatically after disconnecting the battery??? Or does it have to be re-programmed by the dealer

[stevebfl]

There are a number of possible problems that can occur during voltage outages. Initialization of windows and top will take a simple manual reset. I have seen an uninitialized steering angle sensor set off BAS/ETC codes that required a scanner to reset.

I have seen D2B configurations somehow lost resulting in phone or CD problems. I have seen the variant coding lost in the AC controllers which is easiest reset with a scanner.

The 99 models are a fair bit simpler than the 2000- ones. No specific programming is installed on those cars, but many variants can need resting.