OOgsAggie

So.... long story long, I’m having major drivability issues I think I have narrowed to the intake side of things. I am getting a reoccurring P0170 and 173 lean bank codes. Before I pulled these codes It felt like a transmission issue. The car starts and idles almost flawlessly. In neutral besides a slight tip in hesitation (I need to do plugs and wires) it will rev through the band. When you put the car in gear the problems start. Keep in mind this problem is intermittent, which makes it so confounding. From a start the car almost refuses to move. You have to advance the petal far to much to get the car moving. After the car seems to catch its breath it surges forward. Also when coming to a stop after normal running it seems like it wants to die. That being said, once at freeway speeds it gets between 21 and 24.5mpg.

To start I did a full Trans service with conductor plate but while I’m sure it didn’t hurt, didn’t solve the issues. Replaced the fuel filter and pump still no change. Broke down and bought a scanner to pull the codes. Amid the Lean Bank codes I also pulled a Mass Air fault, a slow read on O2 sensors, and a TPS fault. Live logged the O2’s and they were well within voltage (9.4v). Unplugged the MAF and car ran a little better but problem remains. I have had to replace the TPS/PPS before and I was considering trying that again. Also between all these steps I am clearing the faults. I’m kinda at a loss here. Hoping someone has had a similar Goblin and can chime in. The MB specific codes I pulled are listed below if that helps the diagnosis at all. Thanks in advance guys and sorry for being long winded.

p2017, p2086, p2080, p200d

OOgsAggie

Bueller.... Bueller?

khomer2

You unplugged the MAF and tested.
Have you cleaned the MAF?
How old is the MAF and is it oem?

OOgsAggie

The MAF is OEM and I have never cleaned it. As far as I know when unplugged the computer defaults to a stock set of fuel tables independent of MAF readings. So if the MAF was the issue, logic dictates the problem would be gone. Am I mistaken?

khomer2

Then maybe clean it, if it's never been cleaned??
It's cheap to do and takes only a moment to do. Purchase a can of CRC MAF cleaner (always handy to have, imo)
Let it dry out before reinstalling and testing again.

Other checks:
1) water contamination in the gas - this will also create this problem you have,

2) you can check your intake system for any air leaks. Simple to do: use/spray a bit of carb cleaner.
If the engine starts to shake or change in idle speed after spraying, you may possibly have a leak on the area you just sprayed.

3) could also be your O2 sensor.

OOgsAggie

As to cleaning it’s worth a shot, but once again the problem persists with the MAF totally removed from the ECU loop.

The car has been run almost completely dry several times, especially right before fuel pump/filter replacement. Then filled at several reliable stations. If it was one single tank I’d say completely possible.

The Intake Manifold gasket (or any number of other vacuum lines) are my worst nightmare. This is at the top of the ugh list.

As mentioned both the O2 sensors were spot on at 9.4V. Another fix I was happy to avoid!

Appreciate the continued suggestions sir!

khomer2

You should try doing a smoke test, if able. Remember, this is a 17+ year old w210. The hoses are likely brittle, cracked. They need some TLC too.

Tall Giraffe

Id say do the smoke test Khomer2 suggests. I chased this problem for months and did the same part toss at it like you did. Turned out to be the hose in front and bottom of the air intake manifold. It crumbled it was so brittle and then I had to reseal the rtv gasket all around my intake manifold as it was seeping as well.

I noticed a hesitation also like a trans slip when accelerating and when I would let off the gas on the freeway, the rpms would fluctuate up and down instead of a steady decline.

OOgsAggie

Damn this is what I was afraid of.

Tall Giraffe

Im sure its frustrating, almost head shaking that it would cause such a chase if vacuum related.

Check all breather hoses, breather covers for holes, all vacuum lines into the intake, the one mentioned from underneath, and check for any moisture from around the perimeter of the intake manifold where the seam between upper and lower meet.

If you find a leak in the manifold and opt to DIY, I suggest replacing the intake manifold gaskets below, cleaning the carbon build up inside the intake clean out the EGR, cleaning out the throttle body, replacing that throttle body gasket and definitely cleaning the MAF.

If the hose from underneath is broken or deteriorating, there is not a replacement part for the hose, rather there is a work around which Ill dig up if it turns out to be that. Otherwise you have to replace the entire manifold $$$. Doesn't make sense to get a used one as the hose will be just as weak on an old one.

OOgsAggie

So...... I ended up pulling the MAF to clean it. Come to find out it was literally clean as a whistle. After several rounds of clearing codes and finding the common denominator it always came back to the MAF. I ended up buying a second hand one off an ‘02 CLK55 from EBay. Put in today and the car runs like a scalded dog. Literally like a top. Moral here is 2 fold I suppose. Always look for the common denominator. Also even though the 17yr old MAF looked clean enough eat off of, it was apparently totally bricked. Maybe a Third since in my case taking the faulty MAF out of the loop did nothing to improve/point to it as the problem. Looking forward to moving on to other minor things now that the car is mechanically set (for the moment).