Here is my problem !!
- Idle get's rough reaching the 600rpms
- More gas is injected to raise the rpms, so acceleration goes up and down from the 600 rpm to about 1500 rpm.
- This happens when approaching stop light
- Sometimes car engine stops, but start again if I press the start button.
- Problem has been happening for a few months, sometimes I might go for about 2 weeks without it.
- Since yesterday I starting hearing a buzzing noise that sounds like air flow noise. But noise comes a go away.
- Engine light came, I took it for a scan and gave me P0171 and P0174, which is system too lean in bank 1 and 2.
This is what I have done:
- Took it to dealer for Tune UP thinking spark plugs were bad (misfiring)
- Dealer changed oil too
- I replaced the Ignitions Coils (my self) with the oem Bosch brand.
- Clean the MAF Sensor ( I saw in the forum this could be the problem).
Now I am reading a lot of post that point me to way too many directions, so I am hoping some else had seen exactly my problem.
Please let me know if you have any suggestions
Thanks
Stan
The first thing I'd do would be to smoke test engine to check for intake leaks and run a crank case pressure check to see if the CCV is bad. If the pre-cat O2 sensors are at or past their service like (100k), replace them.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
It is a vacuum leak. The car idles like crap but runs normally off idle, correct? The plugs and coils would not fix a lean fault. As the previous commenter said, need it smoke tested. Could be a torn intake boot after the MAF sensor.
I will be checking all the hoses that can have a vacuum leak this weekend, but I have a question about the Oxigen sensors, can they affect the iddle? or this is just to comfirm there is leak if their reading is bad?
Thank you guys
I would think, unless you are have faults for the heater circuit (if BMWs) have one or if you have slow movement faults, there isn't a problem with the O2 sensor.
I haven't worked on a BMW with O2 sensor faults yet so i could be wrong.
It is called a sensor for a reason. It only senses. It does not perform any actions itself. All it does it read the amount of air/ oxygen passing by it. The info is then processed by the DME and fuel trims are adjusted accordingly.
Vacuum leaks can mess with idle. I had an E46 a couple weeks back with a rough idle and check engine light. At the dealer I don't ever look at the P codes. The BMW ones are easier to remember. But the car would drive fine but idle real bad and sometime feel like it would die at any moment. Pulling it in I knew it was a vacuum leak. That is the classic sign, rough idle and smooth off idle.
Did a smoke test and turned out to be the vent valves, vent tubes and the car had faults for secondary air so the diverter valve and broken vacuum lines to it were also replaced.
This is common problem for high mileage cars. Start with the smoke test for leaks. See where that takes you. Don't keep throwing parts at it. A monkey can do that. Knowledge is power. Start with the vacuum leaks and then drive it. If the codes come back, then investigate the O2 sensor. Don't worry about trying to find everything on the first try. Do it in steps so you don't replace things the car doesn't need.
I took my car for a smoke test, not to the dealer because you need an appointment and they always behind, so I went to a local shop by my house and they told me there was a leak in the gasket from the valvetronic motor? they know I work on my car my self so they told me I could replace my self cause was easy. The mechanic also told me there was a suspicious leak from the CCV area but nothing big. I did purchase the valvetronic servo motor gasket $15.00 from the dealer and replace it. That didn't fix the problem.
The car also has an air noise (getting worse) and when is at the loudest (today) I am not able open the oil cap (huge vacuum).
Reading at other posts and looking videos of vac leak, people keep saying is a failed CCV and/or some of the hoses attached to.
I have been trying to find a video, diagram or picture that show me the location of the CCV in this car and I can't find it.
What I want to do is to purchase the CCV and hoses, my car has a 118K miles I love and want to keep for another 3 years, so I need to fix it.
If someone has a parts diagram of the CCV and hoses please reply.
I will keep looking
and thanks for all your advice
Stan
Stan stop throwing parts at the problem and get it diagnosed by someone qualified, it could be something very simple. Also you mentioned your mechanic said there was another leak at ccv? There should be no leaks at all, I'm not sure why this wasn't addressed as well. Look for a good local independent shop that specializes in European vehicles before more damage occurs.
BMW Master Technician
-2001 540i 6-speed
Unfortunately I haven't had an E90 with CCV leaks yet. I lie, I had one yesterday actually I think it was from the customer trying to do his own work. He destroyed the large tube running around the back of of the valve cover. That is the easiest to replace. Both connections are reasonably easy to get to. The plug for the heater is a completely separate issue. Without tiny hands and a long pick, you are stuck pulling the intake I suspect. Luckily I have tiny hands.
But the other two CCV hoses from what I am told are under the intake. Whether you can get to them by pulling the air box and intake tubing along with the throttle or if you need to remove that along with the intake is another story. I don't know enough to help you further. Not knowing your level of technical abilities, it may not be something you want to tackle. Everything is plastic under there. And it is all brittle.
A smoke test is going to give you definitive answers unless there is so much smoke coming from multiple areas you don't know how much is really a problem. But that doesn't sound like your case in this situation. You need to take it somewhere else and get some certainty. Until then, don't attempt anything else cause you are obviously wasting a ton of money.
Any updates on your car? I'm having similar problems right now.
I know this is an old post and old thread but too many of these threads go away and never get updated when a fix has been found. This is starting to become a problem on n52 engines. When the idle is erratic, lean codes are stored, a whistle noise is heard and/or the oil cap is very hard to remove this indicates a faulty eccentric shaft sensor. The sensor that monitors the position of the valvetronic. Sometimes you will get plausibility codes that only the bmw ISID can read. N52s don't suffer from the same intake leaks as much as the m54s did.
Now powered by M
Ah man your post was almost on point till i got to points to faulty eccentric sensor. In my cases, only 5 with your exact symptoms was the valve cover (plastic ones) .. Valve jammed and causing excess vacuum money
The only time I found an eccentric sensor faulty is when there are valvetronic motor faults... Like overheating or something like that.. Other than that if there is oil in that connector that is..
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Then we are experiencing different problems. I would agree that a bad valve in the valve cover might be faulty. But when you can open the oil cap and verify that the valvetronic is on full lift (default mode-works off throttle). This creates much more vacuum than the engine was designed to run at idle which causes the lean faults, and the familiar whistle sound from the front crank seal and bad idle. We have only done a few valve covers but mostly sensors. Again sensor faults are normally stored when this happens even if the cel isn't on.
Now powered by M
I imagine N52's will develop intake leak problems in the future as they age. People said M54s didnt have as many leaks as M52s but now its seeming to be the opposite, the added complexity in the M54 introduced more areas in which vacuum leaks can develop.
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Let me add to the thread. I have a N51 with 87k that is giving me both banks lean codes. No leaks found by smoke test, new fuel pump, MAF and Purge Valve. I had to remove the throttle body to replace the purge valve. While I had access to the inside of the intake manifold I wiped it out and the residue on the rag smelled like oil. I had hard starts when engine was hot and the fuel pump fixed that issue. I reset the codes and drove about 100 miles and SES did not come back on until I started the engine for the return trip and the SES light came on within a mile or so. I did notice when the smoke test was performed through the intake that when the oil fill cap was removed afterwards a lot of smoke came out. This all leads me to believe my CVV has failed. Any thoughts?
Not necessarily. You will see smoke in your valve cover because there is a vent tune coming from the back of your valve cover to the intake. Even a cracked valve cover will cause a lean condition. If you are getting lean codes on both banks and you don't have any leaks with a smoke test then I would suspect a mass air meter. This controls the fuel mixture for both banks. When you have a fault for just one bank with no leaks then I usually suspect the O2 sensor of that affected bank.
I like to check the actual fuel trim readings to before making the call to replace a maf, if they are currently over 8% then there usually is a leak, if they are reading correctly (less than 8%) then the maf is most likely sending improper values to the DME
Now powered by M
My thought is that with the engine not running the CVV should be closed due to no vacuum from the intake to open the CVV not allowing smoke into the crankcase. If the CVV diaphragm had failed it would allow the smoke to travel through the hose on the back of the valve cover, through the CVV into the crankcase. Also, it might allow oil into the intake manifold explaining why I found the oily residue when I had the throttle body removed. It is possible that the new MAF was defective when installed.
I will see if I can get it into a shop next week so they can plug in and diagnose
2010 E90 328xi N51
2012 R60 Countryman S All4
2008 E92 328xi N52
Do you have any updates on this? My car has almost the exact same problem. I chose to buy the engine valve cover.
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