[loganmecham]

Hello,

I recently replaced the starter in my 2006 330xi, in order to do so I had to remove the intake manifold and throttle body and disconnect some cables from the intake manifold in order to remove it. After replacing the starter ad manifold gaskets, I attempted to start the car.

The new starter worked great, however, it sounds like the throttle body is stuck closed and the engine is starved for air and then dies. Then, I unplug my Mass Airflow Sensor, and the car starts, Idles rough for about ten seconds, then runs like normal.

Naturally, I assume I have a bad Mass Airflow Sensor, so I ordered a new one and replaced it. It didn't fix my problem.

I'm trying to sell the car, but nobody wants to buy it with the check engine light on from the unplugged mass airflow sensor. My wife is pregnant and I just got laid off so I can't afford to take it to a stealership or mechanic. I need to figure this out and fix it on my own. I replaced all the fuses relating to the mass airflow sensor, but I still have the same problem.

When I reattached the intake manifold, there were two identical wires on the bottom that I could have replaced in the wrong slots. Does anyone have a diagram/explanation for what those wires are for?


Hopefully, someone can give me some ideas on how to proceed to fix this problem.

[PhaseP]

When the car is idling with MAF disconnected, if you smell around the intake manifold, especially around where the crank case ventilation (CCV) valve is, does it smell like oil and burned gas? Does some fumes raise out there? If so you have a not well seated, or disconnected or just plain broken line that is in that area. Either the one that goes from valve cover to the CCV (a.k.a PCV), or the one that goes from the bottom of the CCV to the oil pan, or from CCV to the intake manifold.
If one of those lines were broken, the insulation foam that those lines are covered with may prevent the fumes coming out easily and may hide them from being observed.

When I had replaced my starter, I had ran into exact same situation. In my case the line that goes CCV to the oil pan had not seated properly to the CCV and was lose. It was leaking air there, into the intake manifold. The MAF sensor not being aware of that air coming into the engine gives wrong data to the computer, causing computer to miscalculate how much gas to spray to the cylinders. When MAF is disconnected, the computer guesses/calculates the amount of air going into the engine from engine RPM and temperature. Well it doesn't know the air intake temperature in that case also because the MAF sensor also holds the air intake temperature sensor, but computer is able to adjust to still have the engine running.

When I reattached the intake manifold, there were two identical wires on the bottom that I could have replaced in the wrong slots

If you can give more idea which wires you are talking about, forum may provide better help.

[loganmecham]

Originally Posted by PhaseP

When the car is idling with MAF disconnected, if you smell around the intake manifold, especially around where the crank case ventilation (CCV) valve is, does it smell like oil and burned gas? Does some fumes raise out there? If so you have a not well seated, or disconnected or just plain broken line that is in that area. Either the one that goes from valve cover to the CCV (a.k.a PCV), or the one that goes from the bottom of the CCV to the oil pan, or from CCV to the intake manifold.
If one of those lines were broken, the insulation foam that those lines are covered with may prevent the fumes coming out easily and may hide them from being observed.

When I had replaced my starter, I had ran into exact same situation. In my case the line that goes CCV to the oil pan had not seated properly to the CCV and was lose. It was leaking air there, into the intake manifold. The MAF sensor not being aware of that air coming into the engine gives wrong data to the computer, causing computer to miscalculate how much gas to spray to the cylinders. When MAF is disconnected, the computer guesses/calculates the amount of air going into the engine from engine RPM and temperature. Well it doesn't know the air intake temperature in that case also because the MAF sensor also holds the air intake temperature sensor, but computer is able to adjust to still have the engine running.

If you can give more idea which wires you are talking about, forum may provide better help.

It does smell slightly of burning gas/oil around the intake manifold. I have not noticed any visible fumes raising from that area, but I do specifically remember that PCV hose being very brittle and it could very well be cracked inside the insulation.

I'd have to remove the cabin air filter and the rest of the plastic covers to inspect the back of the engine, I don't have time tonight. When you replaced yours how difficult was it? Did you get a kit and replace all the PCV hoses or just the one you located that was broken?

I remember there was a black plastic box mounted on the bottom of the intake manifold with three small plugs. Two were identically shaped and went right next to each other, so it was difficult to distinguish which went in which slot. I have looked online for pictures of the little electric distributor, but I can't find any.

I apologize for the lousy explanation, hopefully, someone recognizes what I am asking for haha.

[PhaseP]

Mine wasn't broken, just wasn't pushed in well enough to lock in, and during final assembly had gotten lose and was just standing there with air gap between CCV and the line, leaking air.

I had already replaced those lines a few years before I had to replace the starter, when I had replaced the CCV. Engine had started consuming oil more than I am used to, and the only culprit for me was the CCV and indeed it was.
I had just bought the lines from where ever I could at that time, not as a kit. This was years ago. My suggestion would be to buy all three hoses and if any of them break during disassembly or assembly, you can replace it. If not, you can return the new ones.

I was assuming you had already disconnected those lines for starter replacement, so you would be familiar with the difficulty. But reading what you wrote, sounds like you were able to do the replacement by just moving the intake manifold aside.

Removing those lines are difficult because of the tight space. And disconnecting the line that goes to the oil pan can be difficult. There is a quick disconnect plastic tool that makes that easy. If you search you will find more info here. The lines also have heater elements on them, which are all connected to a small distribution line at the inside folds of the intake manifold somewhere there. Disconnecting those can also be difficult, again due to tight space and not being able to see.

About those wires, you are talking about the distribution box that is bolted at the bottom of the manifold. I can't recall which goes to where. In case of doubt, I go by the natural position and shape of the cable to determine where to plug it. Cables take and retain the shape as they were sitting connected for years there after being disconnected.

[loganmecham]

Originally Posted by PhaseP

Mine wasn't broken, just wasn't pushed in well enough to lock in, and during final assembly had gotten lose and was just standing there with air gap between CCV and the line, leaking air.

I had already replaced those lines a few years before I had to replace the starter, when I had replaced the CCV. Engine had started consuming oil more than I am used to, and the only culprit for me was the CCV and indeed it was.
I had just bought the lines from where ever I could at that time, not as a kit. This was years ago. My suggestion would be to buy all three hoses and if any of them break during disassembly or assembly, you can replace it. If not, you can return the new ones.

I was assuming you had already disconnected those lines for starter replacement, so you would be familiar with the difficulty. But reading what you wrote, sounds like you were able to do the replacement by just moving the intake manifold aside.

Removing those lines are difficult because of the tight space. And disconnecting the line that goes to the oil pan can be difficult. There is a quick disconnect plastic tool that makes that easy. If you search you will find more info here. The lines also have heater elements on them, which are all connected to a small distribution line at the inside folds of the intake manifold somewhere there. Disconnecting those can also be difficult, again due to tight space and not being able to see.

About those wires, you are talking about the distribution box that is bolted at the bottom of the manifold. I can't recall which goes to where. In case of doubt, I go by the natural position and shape of the cable to determine where to plug it. Cables take and retain the shape as they were sitting connected for years there after being disconnected.

Thanks for the help. Replaced the entire set of PCV hoses and the valve and it's working great now. Two of the hoses were broken in half inside the insulation, and one was disconnected.

Runs great now after wiping the codes!