[Iftekar]

Hello Guys,
I know this has been discussed millions of time and probably most of you not at all interested to even read it after seeing the title.. But for the rest of you, thanks for bearing with me.

2011 335i E93 6 spd with 107K miles on it. Mods are VRSF FMIC and Catless Downpipe with MHD Stage 2+.

I bought this car at 72K miles and since then the car randomly took 3-4 secs to start. Dealer had replaced the Fuel Pump under CPO warranty at 60K miles.
The behavior is random- like 1 out of 10 times.

Behaviors observed so far

- car sits over-night, morning start- Fine
- car is driven for few hours. Stopped. Started after few mins, 3-4 secs to start
-Typically, MHD shows Fuel pressure = 72 psi at Ignition ON, 702-720 at idle.
-After the car sitting for a while, without Ignition ON, MHD shows Fuel pressure= 55.7 psi. Once Ignition is ON, the pressure jumps to 72 psi.( so Fuel pump doing its job ?)
-Once the car starts, it idles smooth, drives smoothly and no codes for fuel pump or anything like that.
-WOT has always been fine with no codes for hpfp or any fueling issues.
-Yesterday, I was trying to see how fast the pressure drops at Ignition ON condition. It started with 72 psi and after 5-10 mins, the pressure drops suddenly to 55.7. The drop was instant and not like 65, 60, and then 55.
-Almost every time when I start the car without going to Ignition ON condition, the car takes 3-4 secs to start. Let me explain- generally I get inside the car, press start button to Ignition ON condition ( I have comfort access), the dash lights finished blinking etc, and then I start it. But if I dont do that and directly fire it up by pressing clutch and start button, it takes 3-4 secs to start.

From the other threads it could be any of these:
Fuel pressure sensor
Fuel pressure regulator
Low pressure pump or even
High pressure pump
Fuel pressure control unit ( EKP module).

Rather than throwing parts in random, I wanted to go in a methodical way and need your expert suggestions please.

Many Thanks in advance.

[Pladi]

Seems like a monitoring issue so sensor most logical but none can say for sure eventually you will have to throw parts at it.. no magic answers for such issues..

[Iftekar]

I just leant that E series N55 doesn't have a low fuel pressure sensor.
So that leaves me with- low pressure pump, regulator,EKP or even high pressure pump.

[mweisdorfer]

Originally Posted by Iftekar

I just leant that E series N55 doesn't have a low fuel pressure sensor.
So that leaves me with- low pressure pump, regulator,EKP or even high pressure pump.

Idk. My HPFP got replaced under recall back in 2010. I have never had it replaced since. Car now has 153,000 miles now.

Battery ?

If your battery is 11.9v or just barely 12v. I could see the delay. I know I had a similar delay for a while. Once I put in a new AGM battery, problem solved.

[Iftekar]

My hpfp is from the batch of part no ending wit 933 which I think didn't have much issues.
These were after the recall parts.
My battery is pretty new (6 months old). Bosch AGM and reads 12.5-12.7.
I am not sure what could be the issue.
There are several threads floating around and some mentioned "heat soak" fuel pump also can contribute to long crank as that happened only after a drive and car sitting idle for few mins.

[Iftekar]

So I realized the long crank happens only when the car is hot. Yesterday I did couple of testing- every time I try to start the car after the has been driven for a while and sitting idle for few mins. Restarting after overnight is fine.
It seems something is heatsoaking- hpfp or something else

[RomKaN54]

my car shows 11.7 volts and low pressure 55psi starts fine. i would start with HPFP and injectors.

[9krpmrx8]

You need a good scanner than can scan all the modules such as the EKP. I had a similar issue on my 2011 335i and found this:

I replaced the regulator assembly and all is good.

[Iftekar]

Originally Posted by RomKaN54

my car shows 11.7 volts and low pressure 55psi starts fine. i would start with HPFP and injectors.

Yeah..I think so too. But happens only when its warm - is that a hpfp goin bad sign?
I checked with dealer and hpfp was replaced in 2014.
Today while starting, it paused for a fraction of second- as if it will die and then suddenly fires up. I am not sure If I was about to explain- I pressed the clutch, press the start button, it tries to start and then suddenly paused for a fraction of second and then started.

[Iftekar]

Originally Posted by 9krpmrx8

You need a good scanner than can scan all the modules such as the EKP. I had a similar issue on my 2011 335i and found this:

I replaced the regulator assembly and all is good.

I think I saw this in YouTube couple of times. I have ISTA+ and INPA. I will check what else I can scan.

Originally Posted by 9krpmrx8

You need a good scanner than can scan all the modules such as the EKP. I had a similar issue on my 2011 335i and found this:

I replaced the regulator assembly and all is good.

OMG...when was the last time your nose was calibrated. Inside of the car must have stunk to high heaven before a mechanical fault was even noticed

[Hahnsolo27]

i have the exact same issue on my 07 335i. Starts in the morning but after lunchtime it hesitates to start for about 4 secs.Just replaced HPFP last weekend and a new fuel pump module m3 version. Didn't solve my issue. Still had a long crank today. My battery reads 12.1 at start up but i think I'm still going to replace and see if thats my issue. I feel your pain man! lol

[9krpmrx8]

Originally Posted by FCobra94

OMG...when was the last time your nose was calibrated. Inside of the car must have stunk to high heaven before a mechanical fault was even noticed

I have driven an uncatted rotary for the past 13 years so yeah.

[mfractal]

was this ever solved ?