Idle Dip at Engine Start-up | 2011 E92 M3

[CalSE]

I was wondering if anyone else has experienced this.....

1. Engine first start-up in the morning: once the cold start sequence is completed, no idle fluctuations and off I go.

2. Engine start-up about two to three hours after shutdown: about 10 seconds after the cold start sequence is completed, the idle quickly dips from about 700 rpm to 500 rpm and then quickly bounces back to up to 700 rpm. The engine sounds like it is choking and starting to die when this dip occurs.

3. Also tried start-up again after say 15 minutes but no dip. It seems to only occur when I wait two to three hours later.

Any thoughts?

[IMG]

What year is your car ? Some of the M3s have an ICV "Idle Control Valve" issues which can be replaced under warranty if that's the issue.
You run 93 octane all the time ?
Get in the habit of using a reputable gas stations,also try to run an injector cleaner every couple thousand miles.

[CalSE]

It is a 2011 E92 M3, I use 91 octane here in CA, and I go to Chevron or Shell only.

Note that the idle dip only occurs at start-up as I mentioned in the OP. No dip, at least I don't notice anyways, while driving or at a stop light.

[IMG]

Originally Posted by ///E-Rod///

It is a 2011 E92 M3, I use 91 octane here in CA, and I go to Chevron or Shell only.

Note that the idle dip only occurs at start-up as I mentioned in the OP. No dip, at least I don't notice anyways, while driving or at a stop light.

The E9X M3 S65 doesn't have an air mass meter so the rpm keeps jumping between 400-700 till it warms up.
It gets the afr from the primary O2 sensors. So you are fine and I won't worry about anything.

[thekurgan]

Every time I've had this happen on previous BMWs, I'd run a tank or two back-to-back of Techron concentrate and it cleared up. A few times, the rpms would bounce rapidly like this:

and

[CalSE]

Originally Posted by thekurgan

Every time I've had this happen on previous BMWs, I'd run a tank or two back-to-back of Techron concentrate and it cleared up. A few times, the rpms would bounce rapidly like this:

Wow! That is really bad! Makes my single idle dip seem minor. Thanks for sharing.

[BPMSport]

Originally Posted by img

The E9X M3 S65 doesn't have an air mass meter so the rpm keeps jumping between 400-700 till it warms up.
It gets the afr from the primary O2 sensors. So you are fine and I won't worry about anything.

Has nothing to do with not having a mass airflow meter. It has a MAP sensor which is arguably more accurate because you get pressure in the manifold instead of a reading of metered air flowing in.

My car did that twice in 5 years and 48k miles. Old software can cause this issue. BMW deems it "normal". Removing the cold start routine would likely get rid of that completely.

[RBB]

Originally Posted by Mike Benvo

Has nothing to do with not having a mass airflow meter. It has a MAP sensor which is arguably more accurate because you get pressure in the manifold instead of a reading of metered air flowing in.

My car did that twice in 5 years and 48k miles. Old software can cause this issue. BMW deems it "normal". Removing the cold start routine would likely get rid of that completely.

My car starting doing that this fall as the temps got colder in the mornings. The idle would bounce around during the cold start sequence for a couple seconds.

As usual, Mike is correct. I had ESS send me another version of my tune with cold start removed and I haven't had any problems since.

[tmntmn]

Originally Posted by Mike Benvo

Has nothing to do with not having a mass airflow meter. It has a MAP sensor which is arguably more accurate because you get pressure in the manifold instead of a reading of metered air flowing in.

My car did that twice in 5 years and 48k miles. Old software can cause this issue. BMW deems it "normal". Removing the cold start routine would likely get rid of that completely.

Hey Mike should we use Techron concentrate Plus in our cars? been doing searches but its been 50/50 review some say its bad some said they use it often. Even read something about BMW rebranded Techron cleaners

[Grail05]

Originally Posted by tmntmn

Hey Mike should we use Techron concentrate Plus in our cars? been doing searches but its been 50/50 review some say its bad some said they use it often. Even read something about BMW rebranded Techron cleaners

Ive been using Techron since day one and have not use any other gas station in my M3 and its been 4 years 76k miles and the only problem on idle i had within 76k miles was

1. fuel low pressure sensor (REPLACED) fixed the issue
2. bad gas recently (idle at 700 then drops to 400/500 and almost stall thens go back to normal) keep in mind that it does not go up more than 700 rpm... filled it full tank of Chevron 91 and a Techron bottle and it stopped.

so im guessing its working.

[tmntmn]

Originally Posted by Sean05

Ive been using Techron since day one and have not use any other gas station in my M3 and its been 4 years 76k miles and the only problem on idle i had within 76k miles was

1. fuel low pressure sensor (REPLACED) fixed the issue
2. bad gas recently (idle at 700 then drops to 400/500 and almost stall thens go back to normal) keep in mind that it does not go up more than 700 rpm... filled it full tank of Chevron 91 and a Techron bottle and it stopped.

so im guessing its working.

Thanks Sean

[kandersen1991]

Hate to revive a very old thread, but recently had the EXACT same issues described by OP, and my car just hit 61k miles. 2007 335i. Luckily under warranty with the dealer I purchased it from, and BMW has diagnosed as the Low Pressure Fuel Pump sensor, which once replaced, can then in turn cause the fuel pump to fail which is covered under an extended emissions warranty by BMW. So, long story short, dealership I bought from, has to pay to have sensor replaced, so that the other failing parts can be diagnosed and then replaced via factory warranty. A bit screwy if you ask me, but hey, no cost to me, and learned something new about my car!

[thekurgan]

Originally Posted by kandersen1991

Hate to revive a very old thread, but recently had the EXACT same issues described by OP, and my car just hit 61k miles. 2007 335i. Luckily under warranty with the dealer I purchased it from, and BMW has diagnosed as the Low Pressure Fuel Pump sensor, which once replaced, can then in turn cause the fuel pump to fail which is covered under an extended emissions warranty by BMW. So, long story short, dealership I bought from, has to pay to have sensor replaced, so that the other failing parts can be diagnosed and then replaced via factory warranty. A bit screwy if you ask me, but hey, no cost to me, and learned something new about my car!

I think this is a coincidence. A sensor cannot cause the mechanical failure of a fuel pump.

[OneMmmm]

Just happened to me as well for the first time in ~2 years. Guessing the cold weather may be a factor; however, I've never seen it do this in winters past. The RPMs dropped quite low... sounded like the engine was about to stall.

Also a bit concerned as I've noticed a VERY slight bounce at idle when warm and resting at stop lights. Fluctuates between ~750-800 RPMs. This seems to happen frequently.

[M.A.R.C.]

mine does this too but only on cold starts it seems; not sure about warm starts. might mention it when I go back to dealer next time.

[kandersen1991]

Originally Posted by thekurgan

I think this is a coincidence. A sensor cannot cause the mechanical failure of a fuel pump.

Yeah, I'm far from qualified to make any assumptions or to defend BMW on their statements, (I may actually be misquoting the part that they assume will fail and need replacement, which is covered under the emissions warranty)

Although, I have to say I've read many of these forums relating to the hpfp, injectors, etc. (fuel injection system). Once one thing goes, it's not uncommon for something else that works with it, to fail afterwards. I asked about picking my car up after the sensor was replaced, & the Service Advisor told me they are required to drive the car for an extended period of time after the replacement, because this issue/failure commonly happens after replacement.

If any of that makes sense, I hope?

I was also feeling a slight "rumble" from the engine when sitting at complete idle, that could be result of misfires from what I was told. Curious to see if this is all the result of a bad sensor or fuel pump.

My symptoms were; on a completely cold start (left for more than 6 hours) the car would idle unusually high (1100+ RPMS) and then work its way down eventually. If started up after only an hour or so of sitting, the car would start around 800 rpms, dipped to 3 or 4 hundred, and felt/sounded like the car was ready to stall at any moment. After about 20-30 seconds the symptoms would go away and not return for the duration of the drive.

[kandersen1991]

On a side note, are you entirely sure a sensor cannot cause the mechanical failure?

It wouldn't be possible for (theoretically, of coarse) if the sensor is in fact failing or has failed, and the car continues to be driven in this condition; wouldn't the sensor readouts cause the ECU to regulate the mechanical parts improperly, which in turn could cause a failure?

A more familiar comparison for me, would be the thermostat in a home. If the sensor is detecting that it's 80 degrees in a room that is actually a cool 65, the thermostat will still kick on and run at full-blast trying to compensate and change the temp. This happening for several hours or days without monitoring, could cause excessive work to the machine, in turn, mechanical failure.

Is there something in place to prevent the same type of issue in the e92? I'm sure I'm just showing exactly how little I know about our cars, but I'm trying, so please don't bring me down to harsh.

[thekurgan]

Originally Posted by kandersen1991

Yeah, I'm far from qualified to make any assumptions or to defend BMW on their statements, (I may actually be misquoting the part that they assume will fail and need replacement, which is covered under the emissions warranty)

Although, I have to say I've read many of these forums relating to the hpfp, injectors, etc. (fuel injection system). Once one thing goes, it's not uncommon for something else that works with it, to fail afterwards. I asked about picking my car up after the sensor was replaced, & the Service Advisor told me they are required to drive the car for an extended period of time after the replacement, because this issue/failure commonly happens after replacement.

If any of that makes sense, I hope?

I was also feeling a slight "rumble" from the engine when sitting at complete idle, that could be result of misfires from what I was told. Curious to see if this is all the result of a bad sensor or fuel pump.

My symptoms were; on a completely cold start (left for more than 6 hours) the car would idle unusually high (1100+ RPMS) and then work its way down eventually. If started up after only an hour or so of sitting, the car would start around 800 rpms, dipped to 3 or 4 hundred, and felt/sounded like the car was ready to stall at any moment. After about 20-30 seconds the symptoms would go away and not return for the duration of the drive.

The pump failure may have been masked by the sensor reading, so they replaced the cheapest part first. I have heard this sensor as problematic, there is even a DIY for its replacement (excellent pics in there too!).

[W Cole]

Originally Posted by CalSE

I was wondering if anyone else has experienced this.....

1. Engine first start-up in the morning: once the cold start sequence is completed, no idle fluctuations and off I go.

2. Engine start-up about two to three hours after shutdown: about 10 seconds after the cold start sequence is completed, the idle quickly dips from about 700 rpm to 500 rpm and then quickly bounces back to up to 700 rpm. The engine sounds like it is choking and starting to die when this dip occurs.

3. Also tried start-up again after say 15 minutes but no dip. It seems to only occur when I wait two to three hours later.

Any thoughts?

I had this exact same issue. Cold start was fine. "Warm start" after about an hour (it would always do it after i went to the gym for an hour) and it would surge. No dealer could figure it out, they replaced my ICV and no change. Ended up being the coolant temperature sensor.