Rough start

[Scorpius]

330i zhp 2004 193,000 miles
When I first start my car after it has set for a few hours it is very rough, smells of fuel, no response when you press gas.
After 15-30 seconds it s smoothes out and runs perfect no issues at highway or road speeds once it gets running.
Recent things replaced were fuel pump that went out and also the cats threw the codes and they were replaced. This issue existed prior to both of these issues but it wasn't as bad and seems to be getting worse.
New plugs, car is sharked and has high performance ignition coils.
Shop found no codes and only commented its running a little rich by 9-10 % but codes won't throw until 15% so they appear to have Zero clue and say its old and jus live with it. They found a vacuum leak at the dipstick o ring and replaced it, no other leaks and air filter is clean. Since the vacuum leak is repaired the roughness seems to have increased. Again once started she runs like a dream.
I don't buy this line......any ideas? Oh and fuel filter replaced within last 15k

[echo46]

I think that you have at least one leaking fuel injector.

[Scorpius]

I think that you have at least one leaking fuel injector.

How would I test for that? About 6 months ago i did pull them and found a video on youtube that helped me flush them using a syringe and battery to turn them on/off, flushed them both ways with carb cleaner.
How would I test if one is leaking? or is there a way to fix it?

[yod88]

how are your o-rings on each injector? I had a very similar issue with my m3..no codes, rough idle, smell of fuel...turned out i had a small crack/tear in an injector o-ring and the it wasnt properly sealing, after replacing the o-rings car idled fine almost immediately

[Scorpius]

how are your o-rings on each injector? I had a very similar issue with my m3..no codes, rough idle, smell of fuel...turned out i had a small crack/tear in an injector o-ring and the it wasnt properly sealing, after replacing the o-rings car idled fine almost immediately
Unlikely the orings but i can check, i'm thinking of pulling them this weekend to do another cleaning, but i did it like 6 months ago and put on brand new orings so i would think no cracks.

[echo46]

I had the same issue. I pulled the fuel rail and all the injectors and kept the fuel line connected. Then I put paper towels under each injector and charged the fuel line by turning the key to pos 1. Fuel pump did its job and I quickly determined that the fuel injector nearest to the fire wall was dripping.

[alexandre]

How old are your O2 sensors ? Was your ICV cleaned recently ? Have you inspected your SAP system ? The SAP turns on for 30 secs on cold starts to warm up the O2 sensors, which correlates your symptoms.

[Scorpius]

How old are your O2 sensors ? Was your ICV cleaned recently ? Have you inspected your SAP system ? The SAP turns on for 30 secs on cold starts to warm up the O2 sensors, which correlates your symptoms.

O2 sensors changed at I think 165k all four, not sure what the icv and sap items you mention what do those stand for and how can I test them? Nevermind I looked them up secondary air and the idle control :-) no work on these but at same time no codes thrown which as I understand these either work or throw codes, no inbetweens. Would that be correct?

[yod88]

O2 sensors changed at I think 165k all four, not sure what the icv and sap items you mention what do those stand for and how can I test them? Nevermind I looked them up secondary air and the idle control :-) no work on these but at same time no codes thrown which as I understand these either work or throw codes, no inbetweens. Would that be correct?

SAP would throw a code if it wasnt working, and correct it typically either works or doesnt...

ICV works on vacuum (no sensors that i know of) so the car wouldnt know if its working properly or not...you could always try cleaning it to see if it improves or not...the gas smell is what has me questioning things though...could your fuel rail be not be 100% snug? double check all connections to the fuel related components youve replaced if you can

[Scorpius]

No vacuum leaks were confirmed. So sounds like that rules out the icv. Ill pull my fuel rail this weekend and check it

[Scorpius]

Oh and fuel smell seems to be from exhaust not the engine compartment, exhaust just smells very fuel rich

[echo46]

Let me know if you need more instructions on pulling the fuel rail. Bit of a pain, have to be careful not to break any of the CCV hoses when taking it apart. All in all not that difficult.

[alexandre]

SAP would throw a code if it wasnt working, and correct it typically either works or doesnt...

ICV works on vacuum (no sensors that i know of) so the car wouldnt know if its working properly or not...you could always try cleaning it to see if it improves or not...the gas smell is what has me questioning things though...could your fuel rail be not be 100% snug? double check all connections to the fuel related components youve replaced if you can

ICV clogs up with carbon deposits, ends up not opening/closing freely after maybe 40-50k and it makes car idles like garbage until cleaned with a can of carb cleaner. Doesn't throw codes unless actually defective.


Oh and fuel smell seems to be from exhaust not the engine compartment, exhaust just smells very fuel rich

This could be MAF... Might need a cleanup. Especially if you have a non-OEM intake. Mine went out at 160k.

[echo46]

I would try the icv, MAF and throttle body clean before pulling fuel rail