Changed spark plugs on my 2011 E350. Replacement was make it easy and call it 99K even on the mileage. Swapped with Bosch Double Platinum from FEP Euro. Gap Preset but verified and cross checked as .032 per the box and OEM specs. Plugs were changed based on no documentation of previous change and almost 100K mileage. Still no documentation of when they were changed but appeared that the ones that were removed were the same type (Bosch Double Platinum) as the new ones that went in.

Changed per instructions, old ones out, even got to try ut my fancy new Torque Wrench and torqued to the 16FT lb. value as per the Y/T Video. Coil packs removed and replaced and the silicone Die Electric grease on the head of the plug before re installing coil pack. I did drop one of the coil pack torx retaining screws down the side of the Engine....Outside and to the great abyss known as the driveway and into the street but DEFINTELY not INSIDE the engine or coil. Engine runs fine, checked the coil pack connectors and nothing amiss there.

I am getting a P0172 and P0175. System RICH....Bank 1 and 2 Rich generally means too much fuel but no major noticeable change in fuel economy as in lower or higher. Idles fine and no apparent even slight misfire.
MIL/CEL comes on approximately every 60-100 miles. Clears simply enough and code is consistent each time. I checked the seal of the coil pack connectors and the rear seal of the throttle body to engine cover plate.

Any Ideas? Filled tank and put approximately 35 miles since fill up.

I have read on other models that a 100 mile drive usually gets a full system reset of all major system monitors/sensors. Is that a 100 mile constant drive as in 100 non stop?

 

I'm guessing that the air cleaner is not sealing correctly to the TB. That's really the only thing you removed that's related to the codes. If you had messed up plugs or coil connectors you'd see a misfire CEL. Im assuming that something else like O2 didn't go out as a councidence which I doubt as you'd also see a different error code.
Those codes can mean that the MAF sensor is reporting too much air entering the engine. Short term fuel goes rich to compensate. That doesn't correct the problem, so then long term fuel trim strategy goes rich over range , triggering the CEL.
The MAF is located right on top of the TB - that air cleaner rubber sealing ring MUST be secured and seated snugly around the TB opening (actually the MAF sensor ring). Go back and pull the air cleaner and be 100% sure it's seated correctly and rear clip is engaged. I add a small amount of silicone lube to the rubber seal to allow it to easily slide over the MAF ring.
I'm not sure of actual miles, but what you're referring to is drive cycle which usually completes system readiness monitors settings. Essentially related to emission component system. Not related to spark plug change, should normally be good to go immediately, no codes or system resets.
EDIT - also check the air pump hose connection at the front of the air cleaner assembly. If it's left off, then that unmetered air could cause the codes as well.

If you are able to read real-time run data, you can post STFT, LTFT, MAF/MAP and O2 readings. Those are wide-band O2 monitors, so ideal voltage readings should center around 2 to 2.5v if I remember right. Narrow band sensors switch constantly between 0 and 1v.
But essentially I look at what you may have directly impacted on your work - plugs, coil connectors, air cleaner hose and TB connections.

 

Thanks for the quick reply. Cleared and Activated at just under 100 miles.....cumulative miles not continuous. Have not checked current codes just got home for rest. I will check in a few if not tomorrow. Again no misfire and idles fine with no power loss even during acceleration and highway speeds. I will check, clear one more time and probably leave alone tonight and inspect further tomorrow. The Clamp for the aft cover plate is a definite PITA.

 

Just checked the TB/MAF SENSOR GASKET. Did I mention that the clamp is a PITA to install. Not enough leverage to get a clean fit. I had to try alternate approach. I put the clamp on first then double checked the seal and the push pin clamps. Seal looks fine but I did notice the AIR pump hose to the rear intake cover plate came disconnected. This hose looks stretched and will probably come out again. The next time I am out and about near an AutoZone I will get a new hose...Question do you think I will need a 90 degree Elbow or will a normal piece of hose with the same inner diameter? I might consider a hose clamp also. Hose looks worn and stretched at the connection ns but I don't see any tears, cracks or holes in the main body of the hose itself.

Same two codes, P0172/0175......again codes are consistent. I cleared codes at 99467. With the now established AIR pump hose disconnected I might now have a starting point if the M.I.L. comes back and hopefully a fairly simple starting point.

Additional note: The MIL Did come on during the driving cycle as opposed to coming on during the next start cycle and staying on. The normal self check during start cycle except it remained illuminated after start. I will do a follow up post in a few days.....SOONER if it comes on again.

What I meant by the 100 miles was some of the earlier W class forums mentioned that the MIL should clear and reset all the emissions sensors after approximately 100 miles. My question was whether it was 100 Consecutive as in NON STOP or 100 cumulative. I have done the 100 miles cumulative and pretty much all driving conditions, cold start, stop and go, Interstate etc...

Lets hope it is as simple as the AIR PUMP Hose and possible TB/rear intake cover seal and this is hopefully the end of it.. I guess we should find out in a few days. I will take to work tonight, and home that should be good for about 30 miles each way. I am keeping the OBD2 scanner onboard for a few days as a precaution.

 

The air cleaner assembly and the sealing ring on it that attaches to the MAF sensor housing won't cause this. You could remove the air cleaner assembly completely and the engine would still run fine (other than sucking in unfiltered air, of course). Since the air cleaner is upstream of the MAF sensor, it wouldn't be the cause of unmetered air. That hose going to the pump on the front of the cleaner isn't suspect either since it's also upstream of the MAF sensor.

I'm willing to bet that the problem is caused by the dielectric grease on the spark plug. Dielectric grease is an insulator. That is, it inhibits the transmission of electricity. You can use a bit on the inside of a rubber boot to prevent the boot from sticking to the plug and to stop stuff like water from entering.

Pull the coil packs off and use something like CRC QD Electric cleaner to clean the inside of them and flush that grease out. Pull the plugs off and wipe them clean. If you really want to use some dielectric grease, wipe a small dab around the porcelain portion. Personally I'd say just install everything dry. I use a bit of copper antiseize on the threads, but that's it.

Good luck!

 

It will be interesting to see results - I've actually corrected a P0172 code by re-fitting the air cleaner assembly and have yet to have troubles with reasonable dabs of dielectric grease. I do understand what you're saying about air entry upstream of the MAF though and don't disagree.
But just continuing the dialogue, now it's up to OP to fix!

 

As a matter if fact I did put a small dab on die electric grease on the plug head. About a 1/2 of pea size dab. I will try removing and see what comes out. So far after about 30 miles to work no MIL.

 

Application of dielectric grease is to keep the boot from sticking to the porcelain of the spark plug. No need to put it on the connector, although a touch shouldn't hurt anything.
Read this: https://www.w8ji.com/dielectric_grea...ive_grease.htm

 

So far so good and not trying to jinx myself. AIR vacuum hose connection holding, no MIL, almost 200 miles. Next step will be clamps or new hoses for the AIR vacuum hose. After that the Die Electric Grease. Trying to work easiest steps to hardest. Hopefully the Leave alone step will be the easiest.

 

While we are on the subject of die electric grease...……. Has anyone tried to install a form of silicone grease, like a small coating around the outside of the coil pack itself? Between the Coil pack and the side of the spark plug well to help lubricate and make it easier to remove on subsequent coil pack removals?

 

I believe I have solved the problem. A.I.R. Pump vacuum tube was the culprit. I will monitor and possibly get either new hose, or hose clamps but for now seems to be secure. Almost 700 miles and nary a M.I.L. Throttle response fine, no hesitation, idle fine and smooth.


Thanks for all the input and areas to check for.