[Mr. Rothstein]

Howdy,

So here's the problem: the car's starting very rough and the RPM goes up and down for a few seconds. This is not a cold start; this is a warm start after the engine has been off for 10-15 minutes or so after driving.

I shot a little video to illustrate it:

Previously, the RPM used to just go up and down after starting, now it sometimes goes so much down that it dies in the first attempt (as seen in the video).

Other than that, it runs fine, which is weird. The OBD has no error codes, everything in the electronics seems to be fine.

Has anyone of you encountered this behavior and, more importantly, does anyone know what may be causing it?

(We're dealing with a 2011 328i, just to be clear.)

Thank you!

[Mr. Rothstein]

No replies, huh. Have I yet again discovered a completely new problem no one has ever encountered before? Although, as fun as discovering new abnormalities in a Beemer is, the problem itself is not that fun :P

[alfazrus]

Clean the solenoids, see that helps.

[Mr. Rothstein]

Originally Posted by alfazrus

Clean the solenoids, see that helps.

Thank you, but can you be more specific?

[alfazrus]

this

[alfazrus]

try again

[alfazrus]

location

[gbalthrop]

Originally Posted by Mr. Rothstein

...the car's starting very rough and the RPM goes up and down for a few seconds. This is not a cold start; this is a warm start after the engine has been off for 10-15 minutes or so after driving...Other than that, it runs fine, which is weird. The OBD has no error codes, everything in the electronics seems to be fine...2011 328i

Well, Sir (may I call you by your first name? ;-) if (1) there is ONLY a problem with the idle stabilizing for the first 5 seconds after warm engine start (and sometimes dies after first crank/start, as shown in video), (2) it runs fine after 5 seconds, whether at idle, full throttle, or anything in between, (3) there are NO codes saved in DME memory, AND (4) this doesn't happen on cold start, it suggests there is an issue which only occurs after "heat soak" or for ~ 5 to 30 minutes after full-warm shutdown.

Heat soak issues are usually more likely to occur when ambient temps are higher than those in Chicago at the moment, but they CAN occur at most any ambient temp. They are most noted after you drive for ~10 minutes or more, stop/shutdown for 5 or 10 minutes to get something, and then restart. How long have you had ANY ragged idle after warm start issue?

Stall on first warm restart (due to heat soak) is due to fuel having vaporized in the fuel rail (over the warm engine, with NO air flow due to closed hood). When the VAPOR bubbles get injected instead of liquid, the fueling is too lean, and idle speed drops, or the engine dies, and this "ragged" idle occurs for several seconds until all the vapor is expelled from the rail. You could test at home to see if heat soak is the cause of your ragged idle on warm restart, by simply leaving the hood in raised position for ~ 5 minutes after hot shutdown, and then seeing if restart is "normal."

Whatever is causing the problem is NOT setting a code or warning light, is basically an irritant which perhaps requires a 2nd start attempt, and does NOT affect driveability or pose a safety issue. If it were cutting out while driving, at lights, etc. THAT would be a safety/driveability issue. The issue is likely caused by momentary, transient fueling issues, such as fuel boiling/ vaporizing in the fuel rail as a result of heat soak, a failing check valve at the fuel pump, fuel pressure regulator (FPR) issues, etc.

Unless you have the N51 engine, your vehicle likely is out of warranty as far as any repair/replacement of whatever is causing the issue. If you DO have an N51, you might elect to take it to a Dealer to see if they have documentation of your issue being caused by a component under N51 warranty, such as FPR.

My suggestion is to keep notes of exactly WHEN (how long after hot shutdown) the issue occurs, and to experiment with leaving hood open after hot shutdown for ~ 5 minutes. The first diagnostic step is to determine WHAT transient issue or mechanism is causing the ragged idle & sometimes stall, BEFORE you start just throwing parts at it.

The only objective test I can think of on an N51 or N52 engine is to attach a pressure gauge to the Schrader valve at the front of the fuel rail, and see if the rail is maintaining proper pressure for 10 minutes after shutdown. Since boiling/ vaporization point of any liquid is based upon BOTH temperature & pressure, a bad check valve, allowing rail pressure to be lost, would explain fuel vaporization in the rail due to heat soak.

So please let us know of any test results or vehicle behavior you observe that you believe either IS/ IS NOT consistent with heat soak.

George

[Mr. Rothstein]

Wow, George. Thank you for the lengthy explanation.

If I remember correctly, I have the N54 engine. And I’m indeed out of warranty.

But the symptoms are exactly like you described—it only occurs after the engine has been running for 10+ minutes and then been off like for 10-15 minutes. If I restart within five minutes, the problem does not occur.

I’ve thought maybe it’s a fuel pump/filter issue, could that be it? I haven’t had a fuel system flush in forever, even though the dealer suggested it once, like a yearly thing or something. Could that be the cause?

Also, should I do what the previous poster suggested and clean the solenoids?

Thanks again!

[gbalthrop]

Originally Posted by Mr. Rothstein

...If I remember correctly, I have the N54 engine. And I’m indeed out of warranty...I haven’t had a fuel system flush in forever, even though the dealer suggested it once, like a yearly thing or something. Could that be the cause? Also, should I do what the previous poster suggested and clean the solenoids?

The N54 engine (and N55) is twin turbo, and the vehicle is badged 335i/xi. The 2011 328i as sold in the US either had the N52KP (ULEV) or N51 (SULEV) engine. If you raise the hood and look at the labels in the front of the engine compartment, you will see emissions system information and something identifying your engine as ULEV or SULEV.

If you have the SULEV (N51) engine, some components have a federally-mandated 100,000 mile warranty from BMW (NOT a Dealer thing ;-)

Never heard of a "fuel system flush." Is that like an "Italian Tuneup?" If you drive the car regularly, using "top tier" fuel which contains some type of Techron or injector & intake cleaner (in a port-injection N52 or N51) then you are "flushing" or cleaning those components, including your intake valves as you drive. Suggestion regarding Dealer/Seller advice (whether "Salesman" is selling goods or services):

Ask questions and make the person explain his terms in layman's language. If he can't explain it in a way that is logical to you, then he probably doesn't know what he is talking about, OR you may be misunderstanding him.

No offense to my Neighbor, Alfazrus, but I can't see how VANOS Solenoids would ONLY create a 5-second issue after warm start. But then, I've never had to diagnose a VANOS Solenoid issue, so perhaps he, or others, can explain.

As stated before, I would simply try the open hood for 5 minutes after hot shutdown test, and compare restart characteristics with those when hood remains closed. That's the best simple test I can think of. You might try removing the engine cover, AKA Coil Cover which can also provide some insulating or heat-trapping effect. These are NOT proper fix for whatever is causing the issue, but simply tests to determine if Heat Soak in the fuel rail is the cause of the ragged idle/stall. After confirming/ ruling out heat soak we can either find the cause of heat soak or look for another explanation.

There are other potential contributing causes such as low coolant level, air in cooling system that has NOT been purged, coolant pump and/or radiator fan NOT running for a minute or two after hot shutdown, etc., but the first step is to confirm under-hood temp or Heat Soak as the condition causing ragged idle only at start.

George

[Efthreeoh]

I'd look at replacing the eccentric shaft sensor ("ESS"). Or, as George alluded to, check the fuel pressure; the fuel pump may be going bad. Also, scan the car with a BMW scan tool, you may find BMW codes that are not showing under OBDII. I do not think there is an equivalent OBDII code for ESS errors.

And not a flame... but it's "Bimmer", not "Beemer". Beemers are BMW motorcycles.

[xpro6000]

Did this started happening shortly after an oil change?

[Mr. Rothstein]

Originally Posted by Efthreeoh

I'd look at replacing the eccentric shaft sensor ("ESS"). Or, as George alluded to, check the fuel pressure; the fuel pump may be going bad. Also, scan the car with a BMW scan tool, you may find BMW codes that are not showing under OBDII. I do not think there is an equivalent OBDII code for ESS errors.

And not a flame... but it's "Bimmer", not "Beemer". Beemers are BMW motorcycles.

The ESS was replaced recently, like last fall, so unless it's already failed, it can't be it.

I'll try to find someone who has a BMW scan tool and see from there.

Thank you!

[Mr. Rothstein]

Originally Posted by xpro6000

Did this started happening shortly after an oil change?

Well, depends on what's "shortly." The last oil change was done in April, and it started happening in December.

HOWEVER, what I do realize is, it started happening shortly after I had filled up at BP. Now I know that was stupid at my part, but at the time I had no other option. I usually fill up at Mobil and Shell (there is no Chevron in Chicago, unfortunately). Could it just be a case of shitty fuel that hasn't yet completely flushed through the engine?

[UncleShrek]

Mine does this at cold start after valve cover cover job and ess replacement. I bought a cheap ess from china and this might be the reason for it. I have since bought a new sensor from BMW ($500!) But havent installed.
Hopefully that will fix the issue.

[xpro6000]

Originally Posted by Mr. Rothstein

Well, depends on what's "shortly." The last oil change was done in April, and it started happening in December.

HOWEVER, what I do realize is, it started happening shortly after I had filled up at BP. Now I know that was stupid at my part, but at the time I had no other option. I usually fill up at Mobil and Shell (there is no Chevron in Chicago, unfortunately). Could it just be a case of shitty fuel that hasn't yet completely flushed through the engine?

I don't think BP fuel would cause that. The only reason I asked about the oil change, is that it happened to me twice, and the person who changed the old took out the middle part of the filter housing and threw it out. Happened twice.

[gbalthrop]

Originally Posted by Efthreeoh

...I do not think there is an equivalent OBDII code for ESS errors...

While it IS TRUE that a generic P-code reader won't read a BMW FC for which there is NO P-code equivalent, I was surprised to find that there are 33 VVT system P-codes, and FIVE (5) P-codes that specifically relate to the ESS according to Bentley (searchable pdf is good for this kind of minutia ;-)

See pages 1239 & 1240 of the pdf (OBD-14 & OBD-15 in paper). Here are the 5 P-codes (w/BMW FC equiv) & their definitions per Bentley:

P102C | 2A34 | VVT Eccentric Shaft Sensor Diagnostic Error
P1006 | 2A31 | VVT Eccentric Shaft Sensor Parity Error (Bank 1)
P1014 | 2A32 | VVT Eccentric Shaft Sensor Parity Error (Bank 1)
P1019 | 2A30 | VVT Eccentric Shaft Sensor Circuit Low
P1020 | 2A30 | VVT Eccentric Shaft Sensor Circuit High

A $30-$35 range P-code reader is actually a great tool for entry-level Fault Code work, or use on NON-BMW vehicles, as INPA/ISTA takes a LOT of time getting to know. On DME or engine faults, for just reading codes, seeing a code definition, Freeze Frame Data, Clearing codes, and reading Parameters or Live Data such as Temp, Load, O2 sensor info, etc. a P-code reader is QUITE helpful.

Most cheap P-code readers CANNOT connect to other modules, not even the Transmission or Transfer Case, and won't give you Power Managment info, but for engine diagnostics, it probably makes more sense for most people than spending hours learning how to use INPA or ISTA. Rather similar to how most people other than "Power Users" use Word like an Electronic Typewriter. I say that as someone who has spent HOURS saving & translating INPA screens, tries to be (successfully so far ;-) self-sufficient in maintaining my own vehicle, has engineering experience, and is a bit of a Geek. INPA or ISTA can do WAAAY more than any P-code reader, but "a man's gotta know his limitations."

NOT having at least a P-code reader is like owning a $500 - $1,000 "Smartphone" and not being able to retrieve voicemail or text messages. The information is in your $50,000 vehicle's memory, but you can't read/ retrieve it 'cuz you didn't pay $35 more to get a code reader & take an hour or two to learn how to use it. Who owns a SmartPhone who hasn't spent more time than that figuring out how to use it?

George

[Efthreeoh]

Originally Posted by gbalthrop

While it IS TRUE that a generic P-code reader won't read a BMW FC for which there is NO P-code equivalent, I was surprised to find that there are 33 VVT system P-codes, and FIVE (5) P-codes that specifically relate to the ESS according to Bentley (searchable pdf is good for this kind of minutia ;-)

See pages 1239 & 1240 of the pdf (OBD-14 & OBD-15 in paper). Here are the 5 P-codes (w/BMW FC equiv) & their definitions per Bentley:

P102C | 2A34 | VVT Eccentric Shaft Sensor Diagnostic Error
P1006 | 2A31 | VVT Eccentric Shaft Sensor Parity Error (Bank 1)
P1014 | 2A32 | VVT Eccentric Shaft Sensor Parity Error (Bank 1)
P1019 | 2A30 | VVT Eccentric Shaft Sensor Circuit Low
P1020 | 2A30 | VVT Eccentric Shaft Sensor Circuit High

A $30-$35 range P-code reader is actually a great tool for entry-level Fault Code work, or use on NON-BMW vehicles, as INPA/ISTA takes a LOT of time getting to know. On DME or engine faults, for just reading codes, seeing a code definition, Freeze Frame Data, Clearing codes, and reading Parameters or Live Data such as Temp, Load, O2 sensor info, etc. a P-code reader is QUITE helpful.

Most cheap P-code readers CANNOT connect to other modules, not even the Transmission or Transfer Case, and won't give you Power Managment info, but for engine diagnostics, it probably makes more sense for most people than spending hours learning how to use INPA or ISTA. Rather similar to how most people other than "Power Users" use Word like an Electronic Typewriter. I say that as someone who has spent HOURS saving & translating INPA screens, tries to be (successfully so far ;-) self-sufficient in maintaining my own vehicle, has engineering experience, and is a bit of a Geek. INPA or ISTA can do WAAAY more than any P-code reader, but "a man's gotta know his limitations."

NOT having at least a P-code reader is like owning a $500 - $1,000 "Smartphone" and not being able to retrieve voicemail or text messages. The information is in your $50,000 vehicle's memory, but you can't read/ retrieve it 'cuz you didn't pay $35 more to get a code reader & take an hour or two to learn how to use it. Who owns a SmartPhone who hasn't spent more time than that figuring out how to use it?

George

I have the Bentley manual. I didn't bother to check TBH. OBDII codes translated to BMW trouble codes can sometimes be approximations, which is why I suggested a BMW scan of his car. One time I scanned the Z3 (M44) with my newly acquired Bav Tech scan tool. It guided me to a defective DISA valve causing a SES and the engine running on a map. I vacuum tested the DISA and it worked fine by my observation, but I replaced it anyway only to still have the code. I then scanned the Z3 with my OBDII and found the P code related to the cam position sensor, which had proven troublesome in the past and I had replaced it many years prior. A new sensor did the trick. Things mechanical are imperfect; we then add software just to make it interesting.

[gbalthrop]

Originally Posted by Efthreeoh

...One time I scanned the Z3 (M44) with my newly acquired Bav Tech scan tool. It guided me to a defective DISA valve causing a SES and the engine running on a map. I vacuum tested the DISA and it worked fine by my observation, but I replaced it anyway only to still have the code. I then scanned the Z3 with my OBDII and found the P code related to the cam position sensor, which had proven troublesome in the past and I had replaced it many years prior. A new sensor did the trick. Things mechanical are imperfect; we then add software just to make it interesting.

Nice thing about INPA is that (for DME codes) it gives you BOTH the BMW FC, AND the P-code, where applicable. INPA also allows you to see component Status in real time, such as DISA valve position or Camshaft Position. A "Second Opinion" is always good -- test twice, replace once.

I have NEVER used BavTech, but I certainly would be suspicious of some of the code readers that charge $hundreds for their product, or even for a 1-yr license (a Brand beginning with "C" comes to mind ;-)

BTW, since any P-code beginning with "P1" is a "Manufacturer-specific" code, doesn't that mean that BMW provided the definition? Doesn't mean that the scan tool seller didn't make a mistake though when copying the Definition or translating from German. Somehow, I figure Bentley got them correct (at least usually), and INPA should also be correct (if I translate correctly). That's another reason I have used a "mostly German" version of INPA and done my own translation, as the Devil is often in the Details of "translation."

George

[lowrydr310]

Originally Posted by Efthreeoh

Also, scan the car with a BMW scan tool, you may find BMW codes that are not showing under OBDII.

^^^ Do what he said


You might not see any codes or have the SES light illuminated, but may have specific errors stored in DME.

For example, I never got any warnings however DME shows that I have an intermittent failure on a wheel speed sensor.