New issue, rough start.(car turns over for a bit)

[whitebimmer09]

So after just leaving the dealership (was going to have them do ac work but opted out. Car never left the receiving bay)my car now turns over for a bit and when it starts has a rough idle for a few seconds and all is fine after. Kicks out a bit of black smoke.any ideas? I will make a recording of it.

It doesn't do it on every start, some times it just kicks right up. It turned over for a bit and didn't start once, I don't know if that helps.

[MDRex]

Sounds like a spark issue. The black smokes indicated to me that it is very rich ast startup, meaning there seems to be plenty of fuel but not the required spark to start quickly. I'd say you probably need new plugs. Maybe you have a bad coil too, if you have misfires. This is just my assumption from previous cars, but I'm not really familiar enough with the BWM yet to really know well.

[JM35]

Definitely either a bad spark plug or coil. Im guessing spark plug if it kicks out black smoke.

Is the CEL or SES light going off?

[whitebimmer09]

No lights. It's been starting better but it seems slightly rougher than normal for about 5 seconds. I have been seeing a bit of smoke on cold starts.

[joe86]

Could be many things but the two most common things that cause a long crank and rough start are high pressure fuel pump (has extended warranty) and fuel injectors.

[whitebimmer09]

So I have been trying to capture this on recording but every time I have the camera out it does not do it. Yesterday after work, my car was sitting in the sun all day, I it cranked for a bit and started bumpy idle for 2 seconds and was fine. Later on after the car was in my garage for a few hours I tried to start it again and it started ok but then the aux fan kicked on for a bit. Dunno if that is related but I thought I would mention. Sometimes the car fires right up, it is strange. I haven't brought it in to BMW yet because I am looking for a better description of what it is. I also don't want it to be something stupid like a battery.

Something is definitely not right

The car runs great it is just the start up where the issue is coming from.
I know when I bring it in the car will start fine and they will look at me like I keep bringing it in for nonexistent problems.

[FactorX81]

I'm having a similar issue lately. Changed the plugs (using correct BMW plugs from dealer) and still have startup issues. It starts and runs really rough until the idle kicks down then seems okay. After driving for a while it idles just fine. Driving I notice nothing runs smooth and strong. I get no codes or lights so I am hesitant to take it in because I don't want to pay a diagnostic just to have them say everything is fine.

[JM35]

I ran into an issue the other day just after I changed my plugs. My car idles like shit now after changing them but doesn't give me a CEL or SES and it drives perfectly fine.

[JM35]

But OP, it could be a bad high pressure fuel pump, if its gone bad it could be struggling to pump gas into the cylinders to get it to fire up. But I would think that a bad HPFP would also cause issues while driving then too, correct?

[whitebimmer09]

It is strange, recently it has been starting fine. For the past few days every time I started the car I tried to record it but it has been firing right up. After doing some research I believe my issues are from the injectors but I cannot bring it in since now it is fine and there are no codes being thrown. My issue is probably waiting for the warranty to expire before it acts up again.

[FactorX81]

Originally Posted by JM35

I ran into an issue the other day just after I changed my plugs. My car idles like shit now after changing them but doesn't give me a CEL or SES and it drives perfectly fine.

Did you put your old plugs back in? I think mine got worse after the new plugs too. Is there something we have to do to the computer to tell it about the new plugs?

[JM35]

Originally Posted by FactorX81

Did you put your old plugs back in? I think mine got worse after the new plugs too. Is there something we have to do to the computer to tell it about the new plugs?

Nope, I haven't put the old ones back in. I was getting a misfire in cylinder 1 with the old ones when I would push too much boost (JB4'd) which is why I swapped them out.

There isn't anything that needs to be done afterwards, the ECU should self adjust. The N54's are great at adjusting. Therefore I thought okay maybe after driving it a bit it will adjust to the new plugs, but nope.

I know a lot of other people have had the same problems, over on e90post, and some are just issues with not fully connecting the connectors or not fully pushing the coil all the way back down. But I made sure I did both of those and still didn't help. Other people say check the spark plug gaps, but the plugs should come pre-gapped and the ECU should be able to adjust to the gap/adjust the gap. Quite a few people saying that they weren't able to figure it out and even the BMW dealership wasn't able to either.

[Dackelone]

HPFP going out...

[mleskovar]

Originally Posted by JM35

.... and the ECU should be able to adjust to the gap/adjust the gap......

This is news to me that the ecu could make up for incorrect plug gap. You may be on the right track with injection. A leaky injector could foul a plug and clear itself after some cycles. Leak down test time

[JM35]

Lots of talk on the E90 thread saying that the spark plug gap doesn't matter because the ECU is very good at adjusting.

But once I feel like it again I will pull the plugs and check the gaps just to make sure.

[FactorX81]

Originally Posted by JM35

Lots of talk on the E90 thread saying that the spark plug gap doesn't matter because the ECU is very good at adjusting.

But once I feel like it again I will pull the plugs and check the gaps just to make sure.

Keep us posted.

[whitebimmer09]

Originally Posted by Dackelone

HPFP going out...

Hey Dackelone, I why do you think it is just on certain starts? The car runs beautifully other than the first few seconds of being woken up.

[Dackelone]

Originally Posted by whitebimmer09

Hey Dackelone, I why do you think it is just on certain starts? The car runs beautifully other than the first few seconds of being woken up.

When the HPFP starts to go out... it's first symptoms are long cranks/starts only on cold starts. Soon it will happen for you on warm starts too. I'm sure you have some codes thrown in your DME memory, if you can use a scan tool to read it.

Dack

[inline sex]

Carbon build up?

[JM35]

You can buy like a $20 code scanner online, I bought one on ebay and it works like a charm for reading codes but of course not great quality.

I don't know about the carbon buildup causing this, possibly? An intake valve cleaning couldn't ever hurt though.

[whitebimmer09]

Can it still throw a code without a warning light or any signal of it doing so? Never had a light pop up or anything.

Walnut blasted last month so that isn't the issue

[MDRex]

Yes you can have codes thrown and stored without a CEL.