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BMW Shaking and loss of power


My BMW 325i started shaking and lost a lot of power and the check engine light turned on. Now I have been driving it like that to and from work. I can’t get on the freeway since it doesn’t go over 45 mph. I really need to get it fixed asap. It also doesn’t accelerate like it used to. It shakes all the time but mostly when I am stopped at a red light or when I try to go over 40mph. HELP!

The longer you wait to deal with this, the more it’s going to cost to fix it…Most autoparts stores will read the codes that were set when the CEL came on. Those codes will lead you to the underlying problem… Post them back here along with the model year and mileage and you will get some helpful answers. But without the trouble codes, it’s all just guesswork…So here is my guess…Plugs, wires, coils…Things to cure an ignition misfire…If ignored, the catalytic converter will be damaged / destroyed by trying to burn all the unburned fuel escaping from the engine…But before you start buying parts based on guesswork, have the codes read…

Ok codes are P1085 P0300 P1349 P1083 P0171 BMW 325xi miles 140478

I just got my spark plugs changed but somebody at the Auto Parts said they might have measured them wrong and that might have caused this. Also he said he heard some sort of air leak from one of the hoses.

P1085 - Fuel Control Mixture Lean (Bank 2 Sensor 1)
P0300 - Random/Multiple Cylinder Misfire Detected
P1349 - Misfire Cylinder 4 With Fuel Cut-off
P1083 - Fuel Control Mixture Lean (Bank 1 Sensor 1)
P0171 - System Too Lean

I’m sorry I don’t really know a lot, what does that all mean? And does any of this have anything to do with the oxygen sensors? I believe he said I would need to replace sensor 1 and 2.

I’m not the best person to explain what it means, I’m just good at finding DTC definitions :).

haha ok thank you! (:

Cross your fingers and knock on wood. This may prove an inexpensive fix. There’s probably unmetered air getting into the intake manifold, creating a lean condition in both banks, with resulting misfires.

The fuel injection computer reads a device which measures the amount air coming into the engine, and adjusts the amount of gas injected accordingly, to get the mixture to around 14 to 1. At 14 to 1 the engine will run smoothly. But if air is getting in that isn’t properly measured, there won’t be enough gas injected for the amount of air getting in, and this creates a lean condition.

Since it is occuring on both banks, the problem likely associated with air getting into the intake manifold through a vacuum hose. There are vacuum hoses from the intake manifold that snake around to variuous vacuum controlled devices. None of these devices are supposed to leak air. But if any of them do leak, you’ll get a over-lean condition. Ask your mechanic to check for vacuum leaks.

AWESOME! Thank you! Oh that just made my night so much better. All the parts he said I would have to buy added up to 592.90. I am so glad you said this! So do you think if I get the hose fixed, the shaking will stop? That would make sense since the car is loosing so much pressure.

If you open your hood, you will see a large ‘box’ near the front of the engine compartment on the driver side. That is where your air filter is located. Clipped to the rear of that box is the mass airflow sensor. It is a black plastic tube-shaped device about 4" in diameter and 5" long with an electrical connector on top. From the mass airflow sensor, a black plastic air tube runs back along the driver side of the engine. That tube may be cracked or disconnected. At the end of that tube is a rubber hood that makes the 90 degree turn in to the throttle body. If that rubber hood is original, I can promise you it is cracked. I have already replaced that rubber hood on both of my '04 BMWs. If the tube or that rubber hood are cracked badly enough, that would cause your computer codes and some of the symptoms you are experiencing. All you need to remove and replace these parts is a long and a short straight blade screwdriver and some patience. Small hands are helpful.

It sounds to me like you may have a couple of things wrong. I cannot think of any single leak that would cause the problems you describe at both idle and high RPM, but this is where I would start looking. Then report back please.

bmw … it is more likely to be a vacuum device leaking, but it could be a hose too. (& it could well be what Manolito reports also.) Any mechanic can tell you one way or the other in any event, and it is a simple straightforward test. Because the leak must be considerable to produce the effects you are reporting, my guess is that what Manolito says above, or the brake booster is leaking vacuum.