[alx.]

Well, i get no more errors but the car still has the shakes. Could it be a vacuum leak somewhere?

[thomas88162]

Do you have diagnostic software? There is a fairly easy method of finding vacuum leaks with it. One thing you are going to notice is your AFR will be affected by a vacuum leak. To take advantage of this, simply spray brake cleaner(carefully!) around your vacuum hoses. If you have a vacuum leak then your 02's will spike rich for a few seconds rather than constantly switching between low and high. Under normal circumstances your 02 sensors will switch constantly. A lazy 02 sensor (one not constantly switching) is a bad one. Even if you don't have diagnostic software I recommend either finding a friend with some or getting some yourself, you can find some budget oriented solutions if you look around.

[raleighBahn]

Just started reading this.

I think the camp proposing the o2 sensor(s) may be correct. It was my instinct on the first post when you mentioned it gets erratic AFTER it warms up.

Most cars don't reference the o2 sensors for the first couple of minutes because they have to be heated before they can take accurate measurements. This is why, for those that have an AFR gauge, it won't start reading for a couple minutes.

After that, the car makes air and fuel choices in part on what the o2 sensors are reporting. If one or more is giving bad values, then your car is not going to run right.

I'm a recent 328i owner and most of my experience is working on old porsches. In this case we would unplug the o2 sensor wire to see if the idle evened out. The car does not need an o2 sensor to run - it is for emissions. If it were my BMW, i'd start the car and unplug the o2 sensors one at a time and see if I could find the culprit. No doubt your car will throw codes, but I suspect it would work.

[raleighBahn]

Originally Posted by raleighBahn

Just started reading this.

I think the camp proposing the o2 sensor(s) may be correct. It was my instinct on the first post when you mentioned it gets erratic AFTER it warms up.

Most cars don't reference the o2 sensors for the first couple of minutes because they have to be heated before they can take accurate measurements. This is why, for those that have an AFR gauge, it won't start reading for a couple minutes.

After that, the car makes air and fuel choices in part on what the o2 sensors are reporting. If one or more is giving bad values, then your car is not going to run right.

I'm a recent 328i owner and most of my experience is working on old porsches. In this case we would unplug the o2 sensor wire to see if the idle evened out. The car does not need an o2 sensor to run - it is for emissions. If it were my BMW, i'd start the car and unplug the o2 sensors one at a time and see if I could find the culprit. No doubt your car will throw codes, but I suspect it would work.

If you can confirm your car runs fine when started cold for the first couple of minutes, it will help you narrow this down. As I quoted above, the first few minutes of running are in a state called Open Loop. Once things are warmed up and the O2 sensors tell the ECU (computer) they are ready, you go into Closed Loop. Closed Loop takes the inputs of many more variables (such as your o2 sensors before the catalytic converter).

Why does this matter? Because if you know which sensors are running in Open Loop, and your car runs fine in Open Loop, then all of those sensors are likely good. You can narrow your focus to the sensors that come online in closed loop. And the inverse is true. If your car runs bad as soon as you start it, and the problem is a sensor, you can focus on the small amount of sensors that run in Open Loop.

Hope this helps.

[alx.]

Originally Posted by raleighBahn

If you can confirm your car runs fine when started cold for the first couple of minutes, it will help you narrow this down. As I quoted above, the first few minutes of running are in a state called Open Loop. Once things are warmed up and the O2 sensors tell the ECU (computer) they are ready, you go into Closed Loop. Closed Loop takes the inputs of many more variables (such as your o2 sensors before the catalytic converter).

Why does this matter? Because if you know which sensors are running in Open Loop, and your car runs fine in Open Loop, then all of those sensors are likely good. You can narrow your focus to the sensors that come online in closed loop. And the inverse is true. If your car runs bad as soon as you start it, and the problem is a sensor, you can focus on the small amount of sensors that run in Open Loop.

Hope this helps.

When i first start the car the rev meter drops down to 500 as if it's about to stall. On first start for the first minutes the car actually feels sluggish and jerky. After about four minutes it runs fine.

Also i'm guessing the post cat o2's are reading the catalyst conversion or is there a separate sensor monitoring the cat?

[Phil325i]

Originally Posted by alx.

When i first start the car the rev meter drops down to 500 as if it's about to stall. On first start for the first minutes the car actually feels sluggish and jerky. After about four minutes it runs fine.

Also i'm guessing the post cat o2's are reading the catalyst conversion or is there a separate sensor monitoring the cat?

I'd try cleaning your MAF sensor if I were you. Make sure you remove it for cleaning (with contact cleaner) as you can't really clean it fully in situ. DIY removal guide here:

http://www.pelicanparts.com/BMW/tech...eplacement.htm

[alx.]

Originally Posted by Phil325i

I'd try cleaning your MAF sensor if I were you. Make sure you remove it for cleaning (with contact cleaner) as you can't really clean it fully in situ. DIY removal guide here:

http://www.pelicanparts.com/BMW/tech...eplacement.htm

already did, i guess i'll try re-cleaning it and putting the whole can into it. I only used about 5 minutes worth of it.

I'm starting to blame the Maf for these issues and i think i changed the injectors for nothing

[Three_thirty_I]

Try and see if you can't borrow another MAF before forking out for a new one that may or may not sort this out. I have thrown lots of money at my car's problems and also suspected a MAF issue, replaced with a new one, no difference. At least now I have a spare one, but money wasted in my case.

[alx.]

To update everyone on the parts changed to fix the issue:

Coils - slight improvement, jerk/shake still there
Plugs - no improvement
Injectors - Slightly better start-up, minor improvement
Solenoids - fixed errors, slightly better in regards to the shake but still present
MAF - fixed jerks, misses in acceleration and shifting.

Overall i am happy the car is a beast again, thanks to everyone who contributed here.

[ZeroSum]

Yeah I think I am having the same issue. I tried to clean the Vanos last weekend but its starting again. If it throws another code I might as well just buy them.

[stewey]

Originally Posted by raleighBahn

Why does this matter? Because if you know which sensors are running in Open Loop, and your car runs fine in Open Loop, then all of those sensors are likely good. You can narrow your focus to the sensors that come online in closed loop. And the inverse is true. If your car runs bad as soon as you start it, and the problem is a sensor, you can focus on the small amount of sensors that run in Open Loop.

Hope this helps.

Where could I find more info on which sensors are used during open loop vs. closed loop?

[Willsbma]

Same problem??

Idle "dip" and light throttle hesitation http://www.e90post.com/forums/showthread.php?t=1275479

[alx.]

Back to the drawing board, hesitation is still there at low rpms and stumbling/shaky idle when RAINING.

So far replaced: MAF, coils, plugs, injectors, solenoids, air filter all brand new. What could it be? Could it be the cats? ESS?

[alx.]

Problem still persists even on warm starts it struggles to stay on and the car shakes. O2 sensors are fine, took it to three different mechanics and they are all confused.

One mechanic mentioned some "ambient" sensor as he checked using INPA and it was above 1000? He told me to take the car when it has the "issues".

Btw car violently shakes when it rains... this problem is tiring.

[stewey]

Mine is worse in the rain too. I wonder if that could point to the MAF or an ignition problem (coils or wires)?

[alx.]

Originally Posted by stewey

Mine is worse in the rain too. I wonder if that could point to the MAF or an ignition problem (coils or wires)?

I personally changed the maf and coild and there was a slight difference, could it be the wires? I ll give it a look today.

[alx.]

Update:

My PRE-cat lambda sensors voltage is 2V. Post cats are 0.7. From what i understood it should not exceed 1 in voltage or it's bad, is this true?

[tdavis42]

This whole rough idle has got to be caused by some air flow issue. Between all of us we have replaced or repaired all plugs, solenoids, and injectors. I am going to tear down my intake again and see if that helps get my AC off idle above 600.

[alx.]

Originally Posted by tdavis42

This whole rough idle has got to be caused by some air flow issue. Between all of us we have replaced or repaired all plugs, solenoids, and injectors. I am going to tear down my intake again and see if that helps get my AC off idle above 600.

Ordered two lambda sensors, if this doesn't fix it i'll probably go nuts and sell the thing.

[fravel]

I'm in a similar boat and have been trying to chase down the source of 2 specific codes that keep coming back

2A2E
2A2F

All these codes tell me is "fuel mixture control, bank 1 & bank 2" respectively.

To date I have changed:
Air Filter
MAF Sensor
Oil and Oil Filter (2x)
Spark Plugs
Ignition Coils
VANOS Solenoids
Entire PCV system
Both DISA valves
Intake Manifold gaskets
Throttle Body gasket
Pre-cat O2 sensors

...all with no resolution. Car smoke tests fine, car drives fine, but this light on the dash persists.

Getting desperate here, any suggestions?

[tdavis42]

Originally Posted by fravel

I'm in a similar boat and have been trying to chase down the source of 2 specific codes that keep coming back

2A2E
2A2F

All these codes tell me is "fuel mixture control, bank 1 & bank 2" respectively.

To date I have changed:
Air Filter
MAF Sensor
Oil and Oil Filter (2x)
Spark Plugs
Ignition Coils
VANOS Solenoids
Entire PCV system
Both DISA valves
Intake Manifold gaskets
Throttle Body gasket
Pre-cat O2 sensors

...all with no resolution. Car smoke tests fine, car drives fine, but this light on the dash persists.

Getting desperate here, any suggestions?

Have you done this? Eccentric Shaft Position Sensor replacement?

http://www.pelicanparts.com/BMW/tech..._Replacing.htm

[inthehat]

Hello All

same problem here 325i n52 2006 been living with it for a while now

car hesitates on acceleration and jerks when off the throttle unfortunately no error codes ever so garages say nothing wrong!!!

done so far

cleaned the solenoids and bench tested no improvement
replaced Vanos motor no improvement
revised Throttle Pedal and sensor from Newer model

I'm looking for more ideas before checking built in PCV valve. found you can buy the part rather than replace entre valve cover. Ebay 172189766625.
I get a puff of oil every now and then so wonder if related. anyone inspected theirs?