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?

 

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

 

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.

 

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.

 

The parts have been installed. Much to my surprise, the intake manifold center mount was in good condition. No obvious corrosion or cracks in the rubber seal around the plate, no nothing. The old PCV valve was still in pretty immaculate condition, which you would expect since it was only a few months old. I didn't crack it open to check for sure. But the car is not running lean anymore. So maybe it was the gaskets after all? It was off by very insubstantial margin to start with, that whatever was causing the issue was obviously not serious, and probably not serious even to be immediately obvious even with the intake manifold apart. I attached some pictures of the manifold apart. If you'll notice in the air passageways on the top half of the intake manifold they are coated in oil. This is most likely residual from when the PCV valve failed on me when I bought the car in January and flooded cylinder 4 with oil, hydrolocking the engine. The tech that did the work cleaned it up. It's probably good that I replaced the center mount anyways because it was coated in oil and magnesium corrodes from oil so I'm sure it would not have been long before I started experiencing issues with it anyways. The code for the secondary air injection pump valve being stuck open made a re-appearance, but again could simply be cleared. I'm thinking that the SAIP is probably not related to my run lean concern and only came on coincidentally, but given that it's not on at the moment and only serves as an emissions system component I am not breaking a sweat over it right now.

So to recap my experience here, for future reference:

Concern
Check Engine Light on intermittently, throwing code P2187 idle too lean bank 1. Also accompanied by P0745 and P2091, which BlueDriver described as "idle too lean" but the code reports turn up a cam position sensor and transmission control solenoid. I am not sure how they are related to, or a byproduct of running lean.

Diagnosis
I read the live data and confirmed that bank 1 was running a little bit lean. The data was within acceptable specs, but not matching bank 2. I unplugged the MAF sensors, code did not go away. I swapped the MAF sensors between the two banks, the code did not follow. I had a smoke test run and did not notice any vacuum leaks. Pulling the oil dipstick and a vacuum could be felt and a "gurgle" noise could be heard. Concluded that it must be the intake manifold center mount.

Repair
Intake manifold center mount replaced, as well as the intake manifold gaskets (which had to be replaced anyways with the intake manifold off) as well as the PCV valve.

Conclusion
This is really ambiguous because apparently the intake manifold center mount was fine, but it's also not running lean anymore, so... *shrug*

I will update this post if the CEL comes back or it starts running lean again, but I have to admit that it's probably not super useful that I wasn't able to pinpoint the exact failure point.

Throttles in the new intake manifold center mount

Look at all that oil in the air passageways, yum! Always a good idea to keep those good and lubricated so that air can easily move into the cylinders!


old mount

old mount

As you can see, very minimal lean condition to start with. This may have been very tricky to diagnose from the beginning without tearing stuff all apart anyways.

 

With the Intake Manifold out, it would be a perfect time to install a Catch Can by buying some Home Depot 1” Heater Hose to go to/from the Crank you see right there in your picture to the PCV by carefully removing the PCV hose itself with a razor being sure not to cut the ring seals on each fitting (PCV & Crank). Then you can attach the 1” heater hose to each with otecker (sp?) clamps. You’ll need some elbow fittings to run the hose from the Crank to the PCV as well to the Catch Can you buy. I bought one from a shop that specializes in Charger Hellcat and got their smallest Catch Can which I placed inside a beer Cuzzie Velcro Strapped to the backside of the Passenger side ABS between it and the Headlight.

As for the Codes, yes they must be cleared with STAR/Xentry as they don’t just “reset”, yeah that’s a big money maker for the Stealerships? It’s worth getting your own STAR/Xentry as one can’t even replace a shock or any suspension part without deflating the Airmatic beforehand!

Intake Manifold removed to be rebuilt by RMT


Carefully cutting away the PCV Hose without damaging its Ring Seal which the hose is vacuum sealed over!

On the right is the Crank Side fitting of the PCV Valve already removed from its Hose to which the 1” Heater Hose perfectly fits over secured by an Oetiker Clamp once installed.

I got some extra 1” hose with natural bends to run from the Crank to the PCV. I used that with 1 or 2 elbow fittings as a straight run to the PCV is nearly impossible, so it was a bit of a puzzle!

 

You're right, it would have been a good time to install a catch can a week ago. I have been thinking about doing that, since I think I read that they help alleviate issues not only with the pcv valve sucking oil, but with the cam phasers that are known to go bad with the M156 (but need some confirmation to know more). But like all great things in life, it is a project for another time.

 

Replying for the updates.

 

No update after this?

 

There's nothing to update. My e63 is still running fine, and I don't have any plans in the short term to install an oil catch can. The other guy must have done his catch can a while ago and was just recommending it as preventative maintenance for me.

 

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