[SnapCoupe]

Alright, i'm finally breaking down and making a post of my own because I am officially stumped to what could be causing my long cranks on cold starts.

Here is the car:

2011 335i, N55, Manual. Mods in signature.

Here is the environment:

Cold starts in anything less than about 50 degrees F where the car has been sitting longer than 3-4 hours.

Here are the symptoms:

Upon pressing the start button, the car will crank for around 10 seconds before starting OR sometimes the car will continue to crank without starting at all. If I interrupt the long crank by pressing the button again, followed by attempting to start the car once again, it will fire up immediately.

Attempted remedies:

I have tried "priming" the ignition (even though the pump primes on unlock of the car) by pressing the start button with my foot off the clutch and giving it a few seconds with the ignition on. This does not change anything.

I have tried assorted maps (Stock, COBB Stage 1,2 and MHD Stage 2 and my custom map) this happens on all of them. No changes in symptoms.

I have tried resetting all adaptations and also using assorted maps with the cold start delete. All the same.

The car is all caught up on maintenance, and runs PERFECTLY other than this long crank. Plugs are <10k miles old, and I just installed a new battery.

I work at a BMW dealer, and I have pulled codes using BMW software and I have found nothing. MHD is showing a shadow code for HPFP, but almost everyone I know that has MHD has this shadow code, even on a fresh pump. My car HAS NOT had a new HPFP installed, and this is because I have had a master tech run multiple tests on it, proving it is not on it's way out. My MHD logs support this with my fuel rail pressure being right where it should be. If I was to replace the HPFP now, it would be a miracle if it solved the issue.

Right now, I am holding out for the MAFLESS update for MHD to see if it could potentially be the MAF sensor affecting the cold starts. Unlikely, but there is still a chance.

Thoughts?

[braus427]

Just thinking out loud, you said you had replaced battery.......is cranking speed ok? Any low voltage codes in any module? Had a few with oddball issues caused by ground cable(s).....but they came with codes in several modules.

[Boo$ted_in_ri]

Might be precat 02 sensor that’s what’s causing my long cranks and sputtering. Make sure you order the right harness when buying one as well

[SnapCoupe]

Originally Posted by braus427

Just thinking out loud, you said you had replaced battery.......is cranking speed ok? Any low voltage codes in any module? Had a few with oddball issues caused by ground cable(s).....but they came with codes in several modules.

Nope, no low voltage codes anywhere. Everything seems to be fine in that respect.

[SnapCoupe]

Originally Posted by Boo$ted_in_ri

Might be precat 02 sensor that’s what’s causing my long cranks and sputtering. Make sure you order the right harness when buying one as well

Funny you say that. I literally just got a pre cat 02 sensor code today. I haven't gotten one ever before and this issue has been happening since I purchased the car 10k miles and 6 months ago.

[bbnks2]

You dont need low voltage codes to have a weak cranking battery.

I run a weak 20lb battery and in 20f weather the car barely starts. It's painful listening to it slowly turning over. No codes though.

[Johnny Boost]

Originally Posted by SnapCoupe

Alright, i'm finally breaking down and making a post of my own because I am officially stumped to what could be causing my long cranks on cold starts.

Here is the car:

2011 335i, N55, Manual. Mods in signature.

Here is the environment:

Cold starts in anything less than about 50 degrees F where the car has been sitting longer than 3-4 hours.

Here are the symptoms:

Upon pressing the start button, the car will crank for around 10 seconds before starting OR sometimes the car will continue to crank without starting at all. If I interrupt the long crank by pressing the button again, followed by attempting to start the car once again, it will fire up immediately.

Attempted remedies:

I have tried "priming" the ignition (even though the pump primes on unlock of the car) by pressing the start button with my foot off the clutch and giving it a few seconds with the ignition on. This does not change anything.

I have tried assorted maps (Stock, COBB Stage 1,2 and MHD Stage 2 and my custom map) this happens on all of them. No changes in symptoms.

I have tried resetting all adaptations and also using assorted maps with the cold start delete. All the same.

The car is all caught up on maintenance, and runs PERFECTLY other than this long crank. Plugs are <10k miles old, and I just installed a new battery.

I work at a BMW dealer, and I have pulled codes using BMW software and I have found nothing. MHD is showing a shadow code for HPFP, but almost everyone I know that has MHD has this shadow code, even on a fresh pump. My car HAS NOT had a new HPFP installed, and this is because I have had a master tech run multiple tests on it, proving it is not on it's way out. My MHD logs support this with my fuel rail pressure being right where it should be. If I was to replace the HPFP now, it would be a miracle if it solved the issue.

Right now, I am holding out for the MAFLESS update for MHD to see if it could potentially be the MAF sensor affecting the cold starts. Unlikely, but there is still a chance.

Thoughts?

Which hpfp codes are you getting?

[maddmatth]

For a while my car also only had HPFP shadow codes and my car had long cranks only when cold. When warm, it started instantly. The car only stuttered while driving twice in the space of a year, triggering a check engine light and another fuel pressure related code.

Replaced HPFP and no more shadow codes, car starts up instantly regardless of being warm or cold.

You HPFP is just getting tired, you'll eventually need to replace it.

[bbnks2]

Originally Posted by maddmatth

For a while my car also only had HPFP shadow codes and my car had long cranks only when cold. When warm, it started instantly. The car only stuttered while driving twice in the space of a year, triggering a check engine light and another fuel pressure related code.

Replaced HPFP and no more shadow codes, car starts up instantly regardless of being warm or cold.

You HPFP is just getting tired, you'll eventually need to replace it.

You cant rule the battery out in these instances. I get those shadow codes when I run in and out of stores doing errands.

One theory is that the constant cranking weakens my lightweight battery. I then get a long crank and shadow codes for fuel injection. Priming the rail and firing the injectors takes a decent amount amperage. A discharged battery will output lower voltage and proper voltage is what spark and fuel operation depends on.

Or, it maybe it has to do with something else, but that is the only situations I get those shadow codes and a long crank. Could be a HPFP thing, but I will just have to wait until it fails to find out I guess.

[SnapCoupe]

Originally Posted by bbnks2

You cant rule the battery out in these instances. I get those shadow codes when I run in and out of stores doing errands.

One theory is that the constant cranking weakens my lightweight battery. I then get a long crank and shadow codes for fuel injection. Priming the rail and firing the injectors takes a decent amount amperage. A discharged battery will output lower voltage and proper voltage is what spark and fuel operation depends on.

Or, it maybe it has to do with something else, but that is the only situations I get those shadow codes and a long crank. Could be a HPFP thing, but I will just have to wait until it fails to find out I guess.

Battery is fresh from BMW parts department. Less than a month old. I replaced it to see if that would have an effect on the symptoms.

[Boo$ted_in_ri]

I threw fuel codes as well due to the bad pre cat 02. That’s the important one the car needs it. So it will make your fuel pump act up. If your throwing a 02 code replace the sensor and I bet all your problems go away. Mine did. Was about 190$

[SnapCoupe]

Originally Posted by Boo$ted_in_ri

I threw fuel codes as well due to the bad pre cat 02. That’s the important one the car needs it. So it will make your fuel pump act up. If your throwing a 02 code replace the sensor and I bet all your problems go away. Mine did. Was about 190$

Interesting. I wouldn't have thought this would upset the pump on start up, I figured this would be more important while driving.

I just cleared the code to see if it will come back, if it does I will replace it.

[Johnny Boost]

Originally Posted by Boo$ted_in_ri

I threw fuel codes as well due to the bad pre cat 02. That’s the important one the car needs it. So it will make your fuel pump act up. If your throwing a 02 code replace the sensor and I bet all your problems go away. Mine did. Was about 190$

Can you post the correct part number? Thx

[BOOSTLEE]

I thought MHD turns off O2 sensor so you can run catless DP.

[Boo$ted_in_ri]

Originally Posted by HOT335MSPORT

I thought MHD turns off O2 sensor so you can run catless DP.

You need the pre cat 02 sensor it can’t be shut off only the monitoring system. The pre cat 02 sends signals telling your car how to mix your air/fuel

[Boo$ted_in_ri]

Originally Posted by Johnny Boost

Can you post the correct part number? Thx

This will depend on if your car is a harness A or B as they call it. If your B then the clips are small skinny ones. If your A then you have the bulky looking one. So part numbers depend on that.

[Pladi]

The labda o2 sensor is not used until it warms up which can take 15 seconds if the heater on it works ok. Dont see how a bad o2 would prevent you from starting the car.

What is the fuel pressure before you press the start button ? should be around 70 psi.

Cold start is open loop for some time..

[SnapCoupe]

Originally Posted by Pladi

The labda o2 sensor is not used until it warms up which can take 15 seconds if the heater on it works ok. Dont see how a bad o2 would prevent you from starting the car.

What is the fuel pressure before you press the start button ? should be around 70 psi.

Cold start is open loop for some time..

This is what I was thinking. Not sure how pre-cat o2 sensor could have an effect on start up considering there aren't even any exhaust gases flowing yet. I'll check the fuel pressure and see if where it is before start up.

[Boo$ted_in_ri]

I was throwing bad 02 sensor pre cat codes and that’s when my long cranks started. Replaced it and everything was fine. Maybe I got lucky?

[vespa]

The lambda sensor sets the long term fuel trims which are used during open loop startup. So it could be said that the O2 sensor is actually the only sensor used for mixture control during startup.

[Pladi]

Originally Posted by vespa

The lambda sensor sets the long term fuel trims which are used during open loop startup. So it could be said that the O2 sensor is actually the only sensor used for mixture control during startup.

if thats the case an adaptation reset could resolve his issues temporarily..

[SnapCoupe]

Originally Posted by Pladi

if thats the case an adaptation reset could resolve his issues temporarily..

I'll try resetting adaptations again and see whats up. Also after clearing the code and about 450 miles of driving, I have not seen the o2 sensor code come back up.