[Ashish726]

My 2007 BMW 335i just had all of its injectors replaced with brand new index 12 injectors as well as replaced all of the spark plugs when the injector swap was done. This morning the cold start was kind of rough for a couple of seconds with fluctuating RPM needle, I guess it was enough to throw a "Service Engine Soon" light so I went to go read it at Advance Auto using their OBD scanner and found codes P0304 and P0306 (cylinder 4 and 6 misfire). The car only does that "misfire" roughness during cold starts. When you start driving the car it's fine like normal. Wondering what the problem behind those codes could be? Could it be a HPFP going out? Although I don't really get long cranks? Any help or input would be appreciated. The car has 57K miles on it, thanks.

[dstrickland]

Originally Posted by Ashish726

My 2007 BMW 335i just had all of its injectors replaced with brand new index 12 injectors as well as replaced all of the spark plugs when the injector swap was done. This morning the cold start was kind of rough for a couple of seconds, I guess it was enough to throw a "Service Engine Soon" light so I went to go read it at Advance Auto using their OBD scanner and found codes P0304 and P0306 (cylinder 4 and 6 misfire). The car only does that "misfire" roughness during cold starts. When you start driving the car it's fine like normal. Wondering what the problem behind those codes could be? Could it be a HPFP going out? Although I don't really get long cranks? Any help or input would be appreciated. Thanks.

Have you checked your coils? Also, has the HPFP been replaced already?

[Ashish726]

Originally Posted by dstrickland

Have you checked your coils? Also, has the HPFP been replaced already?

HPFP has been replaced a while back sometime in 2011 or so. Haven't checked coils yet. Car only has 57K miles though.

[limitdown]

If you buy an older model, these should all be ripped out and replaced as soon as you buy the car.
Coils, plugs, injectors, hpfp, lpfp, all lambda sensors

Get a walnut blast.

Were the injectors coded properly?

[Ashish726]

Originally Posted by limitdown

If you buy an older model, these should all be ripped out and replaced as soon as you buy the car.
Coils, plugs, injectors, hpfp, lpfp, all lambda sensors

Get a walnut blast.

Were the injectors coded properly?

Yeah I'm assuming the injectors were coded properly, I know he coded them but maybe he made a mistake, don't think so though because when I give it full throttle the car acts like normal, no hiccups or stuff. Walnut blast was done at 55K miles.

[Boland01]

I would first pull and check the plugs condition then swap to different cylinders. If they are worn replace them. If that doesn't fix it on to the coils. First swap positions and see if it follows them. Replace all of them if you find a suspect one.

It gets more pricey after that. Injector coding issues and fuel pumps. Do you have a tune?

[Ashish726]

Originally Posted by Boland01

I would first pull and check the plugs condition then swap to different cylinders. If they are worn replace them. If that doesn't fix it on to the coils. First swap positions and see if it follows them. Replace all of them if you find a suspect one.

It gets more pricey after that. Injector coding issues and fuel pumps. Do you have a tune?

I just put it new plugs in with the injectors less than 200 miles ago. I'm not tuned. Car is stock power.

[MadeInPhilly]

i'd replace coils first since that is cheapest. Also, get INPA and verify the injector coding.

[dstrickland]

Originally Posted by Ashish726

I just put it new plugs in with the injectors less than 200 miles ago. I'm not tuned. Car is stock power.

Just swap #4 & 6 coils with other cylinders. See if the code moves with them. Once you rule out coils, double check the injector coding.

[Ashish726]

Originally Posted by dstrickland

Just swap #4 & 6 coils with other cylinders. See if the code moves with them. Once you rule out coils, double check the injector coding.

Yeah, taking it back to the shop tomorrow, hopefully it's something simple. Or preferably HPFP since I could have it replaced under warranty.

[noname00]

Hi. I am having the same issue with my car, runs rough and misfires when cold (sometimes it doesn't like at all to accelerate), but after a ~5 minutes it's smooth, after a few more minutes (~10) it's perfectly fine.
For now I only changed the spark plugs and switched the order of the ignition coils, but nothing changed. Next week I will get a walnut blast, even though I am pretty sure that won't fix my issue. The car has 80k miles.

You did not write here, but what was the fix for your car? (and please don't say "buying and M3" :P )

Edit: For me the fastest way to get rid of the roughness of the engine and the misfire is to restart it. I did not wait for it to run smoothly by itself.

[Ashish726]

Originally Posted by noname00

Hi. I am having the same issue with my car, runs rough and misfires when cold (sometimes it doesn't like at all to accelerate), but after a ~5 minutes it's smooth, after a few more minutes (~10) it's perfectly fine.
For now I only changed the spark plugs and switched the order of the ignition coils, but nothing changed. Next week I will get a walnut blast, even though I am pretty sure that won't fix my issue. The car has 80k miles.

You did not write here, but what was the fix for your car? (and please don't say "buying and M3" :P )

Edit: For me the fastest way to get rid of the roughness of the engine is to restart it. I did not wait for it to run smoothly by itself.

Hey, it was actually 2 faulty coil packs that was causing the issue. If you said you've already gotten new spark plugs and coil packs installed then I would be thinking about your injectors if they're not Index 12.

[noname00]

Originally Posted by Ashish726

Hey, unfortunately it ended up being the fuel injectors. I had an 07 335i (N54) and had to upgrade to all new Index 12 fuel injectors.

Thanks for the fast response.

From the original post I understood that you had the issue with the new injectors.

I will first try to swap injector 6 with another one, just to see if the misfire moves with it.

[Ashish726]

Originally Posted by noname00

Thanks for the fast response.

From the original post I understood that you had the issue with the new injectors.

I will first try to swap injector 6 with another one, just to see if the misfire moves with it.

Sorry, ignore the injector post. I thought I was replying to a different thread, my issue was actually two coil packs. I replaced them with new ones and all was well.