slow cold start

[kolosy]

new to me '08, seems to have a hard time starting when cold. cranks for about 5-10 seconds then eventually catches. no issues when warmed up. any ideas on where to look first? could it be as simple as an old battery, should i be looking at fuel?

not sure if it's related, but it ticks pretty loudly when cold as well. goes away after a few minutes. wondering if it's the injectors ticking and if there's just a fuel issue that could tie back to the slow start?

[omgzirra_exe]

could be a couple reasons. battery is the easy check if you haven't ever changed it, it's probably a good time to get one anyways.

the other items you should replace are all under the plenum so its either buy one by one and figure it out or just replace it all at once.. fuel breather valve, injectors, spark plugs, ignition coils.

[BayAreaE93]

Codes, codes, codes, codes, codes. When I first bought the car it had misfires on all cylinders, CEL, increased emissions, rough idle when cold, long crank for the cold start, and it all came back to an O2 sensor and the Low Pressure Fuel sensor. Two easy fixes.

[kolosy]

Originally Posted by BayAreaE93

Codes, codes, codes, codes, codes. When I first bought the car it had misfires on all cylinders, CEL, increased emissions, rough idle when cold, long crank for the cold start, and it all came back to an O2 sensor and the Low Pressure Fuel sensor. Two easy fixes.

i'll scan it, but no CEL

[amrazM]

could be low pressure fuel sensor.

[kolosy]

so i finally got ISTA running and scanned it for codes. only relevant thing that came up is 2B4C DME: Intake-air temperature sensor, plausibility

I could see that causing a rough idle, but would it odd for it to slow start because of it..

New battery coming tomorrow, will rule that out then.

[kolosy]

ok so i finally pulled the battery -- it's new. OEM from august of last year. I've got plugs and a fuel breather valve on the way. Codes don't show anything relevant (intake air temp sensor is the only thing coming up, i've got one ordered and will replace but seems unlikely to cause the issue).

Does the plenum need to come off for injectors? They're $400 and OOS for BOSCH and 5x that for OEM. Would like to confirm the other two aren't the issue before plunking that down...

[Compman]

Please keep updating this thread. I'm encountering the same issue intermittently.

[kolosy]

update here.. swapped out the intake temp sensor (and checked that the wiring wasn't damaged) and threw in new plugs. no effect on cold start.

i've got injectors coming next and have the fuel tank vent valve sitting for when i do all that.

not sure where to look after that..

[irokwrx]

Originally Posted by kolosy

update here.. swapped out the intake temp sensor (and checked that the wiring wasn't damaged) and threw in new plugs. no effect on cold start.

i've got injectors coming next and have the fuel tank vent valve sitting for when i do all that.

not sure where to look after that..

I have the same issue, I have replaced all things BUT the injectors. Like you it's only on cold starts (the first start of the day). I have noticed if I cycle the ignition a few times before starting it's not as bad, but still stuggles. I am SC so I am following this closely, please let us know if the injectors do the trick.

[romero1990]

there is a store have injectors for like 20 per pop. I ordered a set and gonna see if they are good

[kolosy]

Originally Posted by irokwrx

I have the same issue, I have replaced all things BUT the injectors. Like you it's only on cold starts (the first start of the day). I have noticed if I cycle the ignition a few times before starting it's not as bad, but still stuggles. I am SC so I am following this closely, please let us know if the injectors do the trick.

will do

Originally Posted by romero1990

there is a store have injectors for like 20 per pop. I ordered a set and gonna see if they are good

yeah -- eeuroparts. that's where i got mine. willing to throw $160 at it to see if it works, was less willing to spend the $1k+ of most other places.

[romero1990]

i'm also tracing down some issues with ignition, like not always crank. Some said it may have to do with grounding. I wonder if you have checked it. Slow crank maybe just not getting enough current/voltage to the proper crank speed.

[kolosy]

Originally Posted by romero1990

i'm also tracing down some issues with ignition, like not always crank. Some said it may have to do with grounding. I wonder if you have checked it. Slow crank maybe just not getting enough current/voltage to the proper crank speed.

interesting.. no, i haven't. i'll add it to the list.

... that said, it doesn't sound slow in that way. when i say slow I mean that it takes more turns/time than i would expect, not that the frequency of the turns is slow.

[amrazM]

Get a computer and look at the low pressure fuel reading when the car is cold.

[kolosy]

Originally Posted by amrazM

Get a computer and look at the low pressure fuel reading when the car is cold.

is that something i'd want before cranking, or during?

[amrazM]

Originally Posted by kolosy

is that something i'd want before cranking, or during?

need a reading from the time you key on + ignition.

are you putting the key in, then turning on the ignition then starting the car? let it sit with ignition on for a second or two.

[kolosy]

Originally Posted by amrazM

need a reading from the time you key on + ignition.

are you putting the key in, then turning on the ignition then starting the car? let it sit with ignition on for a second or two.

haven't had a chance to plug ISTA in, but did start it. Popped the key in, hit the start button (foot not on clutch), waited for the fuel pump to prime, and hit start.

no discernible impact on start. I'll run the test, but I'm assuming that if the issue were low fuel pressure, this procedure should have had some kind of impact?

[kolosy]

got a chance to do some testing this weekend.. power up and startup fuel pressure is in range (ISTA says 5-6.5 bar, i was right around 6.5).

I see a similar issue on an E90 335, his solution seems to have been the hpfp... how transferrable is that to the S65?

https://www.e90post.com/forums/showthread.php?t=1567669

[Black.m3]

Originally Posted by BayAreaE93

Codes, codes, codes, codes, codes. When I first bought the car it had misfires on all cylinders, CEL, increased emissions, rough idle when cold, long crank for the cold start, and it all came back to an O2 sensor and the Low Pressure Fuel sensor. Two easy fixes.

What was your codes at this time ?

[BayAreaE93]

P0171 System Too Lean, P152D Idle Speed Control Valve Incorrect Value, P2196 O2 Sensor Stuck Rich Bank 1, P2097 Post Catalyst Fuel Trim System Too Rich, P0191 Fuel Rail Pressure Sensor Range/Performance

Also got codes for increased emissions and misfires on all cylinders.

[irokwrx]

Originally Posted by kolosy

new to me '08, seems to have a hard time starting when cold. cranks for about 5-10 seconds then eventually catches. no issues when warmed up. any ideas on where to look first? could it be as simple as an old battery, should i be looking at fuel?

not sure if it's related, but it ticks pretty loudly when cold as well. goes away after a few minutes. wondering if it's the injectors ticking and if there's just a fuel issue that could tie back to the slow start?

Hey not sure if you still have this issue but I had this issue for about a year. ONLY on cold starts. What fixed it was replacing the brake pump behind the driver-side finder. Super simple replacement. I did a small write-up on "What have you done to your M3 today". If anyone else is having this issue give this a go. BTW I replace every fuel and spark item in my car trying to fix this and the pump did the trick.