padenxy

Howdy folks. My 2007 e63 popped a CEL at 88,500 miles the other day. Advanced auto parts scanned it and the stored code was P2187, too lean at idle bank 1. All I did was a slight pull from 55-85 when overtaking someone, nothing major. Both Advanced auto parts and O'Rielly's computers suggested "replace MAF sensors" but I don't trust generic their generic OBDII scanners and don't want to use the parts cannon for no reason.

I did some basic troubleshooting. The idle is not erratic (I can feel the engine in the cabin but that goes away once the car warms up. Probably just old hydraulic fluid in the motor mounts?) and unplugging the MAF sensors did not result in a noticeable change in the idle. I removed the air filter housing, the OEM filters and charcoal filters were clean, the boxes were clean. I swapped the MAF sensors between the two banks and went for a little drive. The code did not change to read too lean at idle bank 2. Do I need to clear the first code before the code will swap to an idle lean condition on bank 2? Or would the computer automatically clear the code for the idle lean condition in bank 1 and start showing a lean condition in bank 2? Is there any other basic troubleshooting I can do to verify what the problem could be before I spend $500 on a set of ROW airboxes from FCP Euro? And I have seen confirmation on 10+ year old threads that replacing the intake manifold gasket can also solve this issue because they can sometimes leak air into the cylinder banks and cause a lean condition. Can I diagnose this without tearing apart the intake manifold?

padenxy

Update, problem solved-ish.

My coworker did a smoke test and found no vacuum or gasket leaks. He plugged in his much-better-than-mine OBDII scanner which picked up a code for a secondary air injection pump having a stuck valve. He cleared the codes and the CEL went away. I beat the **** out of the car on the way home and the CEL hasn't come back on. I will update if it does

padenxy

Update: The CEL has returned, again bearing the P2187. Looking at the live data it is still within healthy operating specs, but it is indeed ever so slightly lean on bank 1, off by enough to not quite be a negligible margin of error. The only difference now is that it comes with two more codes, p0745 and p2091. Technically these are for a transmission control solenoid and cam position sensor, but I choose not to believe that because 1) BlueDriver summarizes these codes as "running lean" and 2) this guy: had all the same codes (plus the same codes for bank 2) and his problem ended up being a PCV valve. Borrowing the handy oil dipstick tube trick, I popped it out and can definitely hear and feel a sucking, as well as a "gurgling" like when you have a drink with a straw and the drink is empty. (yes, there was oil on the dipstick so it's not running dry)

This was a few days ago. The engine passed a smoke test a few short weeks ago. The car DID recently have the PCV valve replaced, as well as the intake manifold gaskets due to an issue where the original PCV valve failed, flooded cylinder 4 and hydrolocked the engine. The engine survived, but unless my car is feeling suicidal it seems unlikely that it is the PCV valve since the RPMs are not jittery and do not rise when I pull the dipstick.

My conclusion, with the assistant of an acquaintance that was the shop foreman at a Mercedes dealer, is that the intake manifold center plate must be corroding. As it is well known, those are made of magnesium which corrodes on contact with oil. Because my car had the PCV valve fail spectacularly, it was probably sucking oil into the intake for a while before the near-catastrophic event with the hydrolocking... So I ordered a new aluminum intake manifold center plate from RMT, and just incase the new PCV valve was in fact bad, I got a new one of those as well. May as well, since they're not terribly expensive. When the parts arrive and I have them installed, I will update this post again with results and pictures.

P.S. The CEL randomly went away on the drive home from work. To be sure that I wasn't seeing things and the CEL bulb didn't burn out, I scanned the module again. The P2187 still shows up in regular scans, but the status of the P0745 and P2091 have been changed to "NOT PRESENT" in all-module scans, so maybe the codes are gone for real? I don't believe that the car is fixed. I'm going to have my coworker with the better-than-mine OBDII scanner scan my car, and change the intake manifold center plate anyways. It's already on its' way so no point in stuffing it in the closet once it gets here.

SallyHyatt

How is everything going?

padenxy

The parts have arrived and they will be getting installed later this week or early next. In the meantime the CEL has come back and gone away again. Not sure what thats about but I don't like having an intermittent CEL issue. The cars startup is a tad bit weak so I will have to look at the battery soon me thinks.