secondary air injection chattering noise

[thomash85715]

Wondering what are most observed failure modes of this electric pumping setup on a M56 car from 2004. The 325 wagon began running a bit rough at idle with a chattering noise coming from somewhere in vicinity of this equipment on the exhaust side. When we unscrewed the oil cap, the engine nearly quit from all wrong mixture I guess. I have never seen any car do that and do not know if this is normal having never tried this. My thought was to open the cap at idle to see if chattering was coming from inside the cam cover so won't do that again. In any case, if engine is raised above idle, the chattering noise stops and power is smooth throughout RPM range. According to manual, "emission relevant components of the SULEV system are warranted for 15 yrs or 150k miles." So another question would be what if any pieces of this little network of bits falls under that umbrella. Guidance appreciated. --Tom in Tucson

[dworthy]

Tom, when you open the oil cap, that causes a vacuum leak. Now the car should idle down a bit and run rough, but if it dies, you have another vacuum leak on the intake.

So you have two choices:
1) Visual inspection from the Air filter box to the throttle body. This will be the two black rubber boots, look for crack/splits.
2) Smoke test at a Euro Shop. This I would recommend as you cannot see the whole boot all the way down without remove.

Also if you have a check engine light on, that would be nice to know as well.

[thomash85715]

Thank you for answer on oil cap vacuum. I now see where of course that would cause trouble with air flow. My other car is a V8 with oil cap on opposite bank from the PCV flow so it behaves differently of course.
There is a CEL with three codes: #5 misfire and #6 misfire and P1411 which is no activity on secondary air flow. I had tried removing fuse for that pump and reseating it. I can hear no noise nor feel any vibration from that pump. Engine is idling rough but is smooth above 900 RPM or so.

[dworthy]

Hold on a sec, that car has a V-8 dropped in? I was going off the assumption it was a 2.5l M54 straight 6 cylinder. This changes the whole thing in a matter of speaking. Do you know which V-8 is installed, as BMW built several ranging from the B30 to B44, or is this a Motorsport motor?

[thomash85715]

No no back up please. The V8 is in a jaguar; this is all original 2.5 bmw motor. Was just comparing the different behaviour of the two cars. But new info today: this car has reduced power for sure. The misfire on 5 and 6 is profoundly reducing power. There is no smoke or bad noises. Engine will willingly rev to over 5K in 2d n 3d but the power is way less than normal. So it is now acting like a 1.8 four cylinder! I am now doubting the secondary air injection is causing this. I think we had two problems happen around same time. The secondary air failure cannot cause misfiring on a third of the motor can it? Car has new plugs and coil packs x6 and is still running bad so maybe move this thread or re-name it to get misfire fixed. How to tell if injectors working OK or valve problem? Car was overheated a month ago but seemed to recover OK until yesterday. In other words ran fine for hundreds of miles after busted coolant tank fixed until this weird sudden failure.

[dworthy]

Okay, just wanted to make sure we are on the same page.

Just a couple of other question to help clear things up:

1) Mileage
2) Last service known
3) How long have you owned the car?

[thomash85715]

Car has 107k miles or I guess about 180K km?
Was serviced 5K miles ago.
We got it 15 months ago. All had been well until husband ran it out of coolant six weeks ago. Needle went red and car stopped in intersection was towed home. Next day it started and went to nearby garage who replaced ruptured coolant tank and pronounced successful pressure test of cooling system. They made note of "possible valve noise." Drove the car five weeks during which we had successful emission test. When noise was first heard after near disaster with coolant, I had removed oil cap to see if noise was louder through open valve cover but engine nearly quit from airflow change so terminated that line of inquiry. Localization of noise was inconclusive though I had thought it was coming from the air inject motor but now doubt that.
Two days ago, CE light came on and car began idling rough and lacking full power. OBD code for #5 misfire was observed so husband took car to non-dealer and had six coil packs and spark plugs put in. No improvement in performance observed. My OBD reader is now saying 5 and 6 misfire plus air injection failure.
If moderator wants to move or retitle thread feel free. This is now a serious driveability issue, not merely a noisy secondary air injection pump.
This car uses M56 sealed fuel system and siemens 45.1 management. Thank you.