[bmwmsport11]

I've had my 06 330xi for almost a year now and it was going great until the odometer started getting close to 100k.

here's the problem i've been having: Long cranks every time ambient temperatures rise up.

First it was a bad battery. Car worked fine but one day it took a dump on me and I ended up replacing the battery with a new one. Started fine. Week later gave me the first long crank. The starter would cycle for 4-5 seconds and it would fire up, but the engine would sputter alittle and return to normal if you gave it some gas. Got the battery tested at autozone and was told it's weak. Took the car to have the charging system reset at a BMW shop(i figured it was worth a shot since I didn't have it done yet). Worked ok. Got the battery tested again and was told the charging systems fine but the battery is shot.

I used the battery warranty and swapped in a new one this past Sunday afternoon. Monday evening I start the car and AGAIN: long crank. Tested the battery just now and it's showing full charge.

I noticed this long crank ONLY happens when ambient temps go from cold to warm outside. On both occasions the temp rised from 30-40 to around 70 degrees(Arkansas weather) It starts normal even when its 20 degrees out.

searched this issue all over the forums and either come to a conclusion of a bad battery(my battery should be fine), or a bad essentric shaft sensor. I don't have any symptoms of that issue(engine idles good, engine is responsive, starts normal almost every time)

What else could be the cause? I'm leaning torwards fuel pump but this isn't a HPFP car. From what I read the pumps aren't a common issue. Could it possibly be a bug from the battery being disconnected? Or my MAF sensor due to the CAI I have installed? Sadly I left my OE box at home. I don't want throw in anymore money than I need to...

[Phil325i]

Get the fuel pump delivery pressure checked would be my first step...

[avocet]

is it a long slow crank? might be your starter on the way out?

[bmw201113]

I was thinking starter as well maybe alternator

[rjahl]

Sounds like slow cranking caused by a bad Starter or bad Electrical Connections.

Too bad you can't get a voltmeter on the starter terminals and measure the voltage at the starter motor while someone cranks the motor. Does the negative wire go all the way to the engine block or does the starting current run through the bonding strap?

[matteblue3er]

A discharged battery will always test bad. You're suppose to load test a fully charged battery.

My stab in the dark is a vacuum leak

[Mattb0601]

Mine does the same thing sometimes, except it will do a slow crank as well. Around 100k people have been replacing starters. I plan on doing it soon I'm at 98k, I would just replace it to take that out of the equation, I think it's only a 200$ part.

[X-M]

Ok try this.
Turn the car on to ignition 2 (push the button without the foot on the brake and key inside) and wait 10-15 seconds. Start the car. If this fixed your problem it's something to do with the fuel pump. If it didn't it's probably your starter and you should get that diagnosed asap since it eats batteries for breakfast.

[bmwmsport11]

Starter cranks fine. Not a slow crank, it just cranks for a long time. Almost like the car's immobilizer system didn't register the chip. I've already replaced the battery on the key and on Both occasions I put the key into the slot to start the car(even though I have keyless start).

Alternator is fine from what I was told by Autozone and my cheap $12 battery/charging tester. BMW Indy didn't point anything out other than the large amount of short trips. Said it could possibly be the essentric shaft sensor due to the mileage/age but no guarantees without having sorting through all of the codes(would take him 2-3 weeks).

The thing that gets me is that it starts fine right after and works fine for however long it wants. All i know as of now is that this issue arises when it goes from cold to hot out. It was 77 degrees out today and it started normally.

[PhaseP]

Originally Posted by Phil325i

Get the fuel pump delivery pressure checked would be my first step...

+1
If this is only happening after car is sitting at least half an hour or more, you may have fuel pressure regulator/filter not holding the pressure shut down. It could be your fuel pump also not holding pressure after shut down.

I had occasional long starts, it turned out to be fuel pressure regulator not holding the pressure after shutting down. Checking that is easy, you connect a fuel pressure gauge at the fuel rail schrader valve and check running pressure and watching how the pressure holds after shutting down. Mine was slowly going down, which was supposed to hold at least 20 minutes if I remember correctly what Bentley manual was saying. The fuel pressure is supposed to be 72.5 psi.

[E90_slides]

Originally Posted by PhaseP

+1
If this is only happening after car is sitting at least half an hour or more, you may have fuel pressure regulator/filter not holding the pressure shut down. It could be your fuel pump also not holding pressure after shut down.

I had occasional long starts, it turned out to be fuel pressure regulator not holding the pressure after shutting down. Checking that is easy, you connect a fuel pressure gauge at the fuel rail schrader valve and check running pressure and watching how the pressure holds after shutting down. Mine was slowly going down, which was supposed to hold at least 20 minutes if I remember correctly what Bentley manual was saying. The fuel pressure is supposed to be 72.5 psi.

thought the only check valve was on the fuel sender/pump (rear passenger) side? I suppose the plunger inside the regulator is supposed to hold some vacuum but I thought it was for controlling fuel delivery during quick braking and holding steady cruising pressure while engine is running?

[PhaseP]

Just took a look at my Bentley manual. It has a diagram showing the elements of fuel system. There are two check valves in that diagram inside the fuel tank. Both of them are drawn at internal fuel hoses that are close to the fuel filter + regulator. The fuel filter+regulator+left side fuel gauge unit comes with the hoses that go between the pump and itself. So the check valves are part of that unit, not the pump.

[gunnerxq]

Codes. What are the codes?