Rough idle during coldstart

[makethiscardriveable]

Hello,

I have been having this issue for awhile where during cold starts the idle seems to be somewhat rough, almost like it is misfiring. However no codes could be found using ISTA. After it is driven a bit the idle is fine, but I would like to nail this issue down if I can. On a probably unrelated note, there is some kind of rattle during idle, cold or not makes no difference for this. I believe it to be a exhaust bracket or something underneath the car making the noise, hopefully not the wastegates as i only hear it during idle and just recently did the transmission fluid so thats why I think its a exhaust bracket that might not have been tightened.



Parts that have been replaced:

index 12 injectors

Valve cover (genuine bmw)

Ignition coils done 7k miles ago (Bosch)

Spark plugs done about 15k miles ago

walnut blasting 20k miles ago

[CivicDuty]

No codes you say? I'm beginning to wonder if it's just normal cold behavior. Mine does it as well...only when cold...below freezing I'd say. See video.... 40 seconds in.

The rattle might be the exhaust valve in the muffler....is it the stock exhaust?

[CivicDuty]

No codes you say? I'm beginning to wonder if it's just normal cold behavior. Mine does it as well...only when cold...below freezing I'd say. See video.... 40 seconds in.

The rattle might be the exhaust valve in the muffler....is it the stock exhaust?

[Mybimmer]

Were the new injectors coded into the DME?

[makethiscardriveable]

Originally Posted by CivicDuty

No codes you say? I'm beginning to wonder if it's just normal cold behavior. Mine does it as well...only when cold...below freezing I'd say. See video.... 40 seconds in.

The rattle might be the exhaust valve in the muffler....is it the stock exhaust?

Originally Posted by Mybimmer

Were the new injectors coded into the DME?

New injectors were coded into the DME with INPA.

Also I get this behavior even when the ambient temp is say 70-90 F, way worse when below freezing but its been warm here.

I have a Borla axle back exhaust.

[08hurd]

I've always had the same issue with my 2012 when it comes down from high idle on a cold start. Made these mods around 20k and just hit 100k. Recently did plugs, injectors, fuel pump, water pump and all fluids/filters. No change since recent maintenance.

Running JB4 controller(map5), Dinan exhaust turbo back, custom down pipes and charge tube.

When it drops down from high idle to regular idle, there's anywhere from a 5-20 second period that has a chug or misfire?! I've always assumed it was compression/boost related from the JB4 but get the same results when starting in map 0(JB4 inactive and factory settings)

Watching your vid has me wondering?! Cold start sounds and behaves almost identically.

[makethiscardriveable]

Originally Posted by 08hurd

I've always had the same issue with my 2012 when it comes down from high idle on a cold start. Made these mods around 20k and just hit 100k. Recently did plugs, injectors, fuel pump, water pump and all fluids/filters. No change since recent maintenance.

Running JB4 controller(map5), Dinan exhaust turbo back, custom down pipes and charge tube.

When it drops down from high idle to regular idle, there's anywhere from a 5-20 second period that has a chug or misfire?! I've always assumed it was compression/boost related from the JB4 but get the same results when starting in map 0(JB4 inactive and factory settings)

Watching your vid has me wondering?! Cold start sounds and behaves almost identically.

Thats basically the behavior I get, if i drive it for even like 1 minute and then sit at a red light and idle its fine, its only when i first start it.

[CivicDuty]

@08hurd Now that the warmer weather is returning the idle has been rock solid on start up. I did the plugs recently but I still had the rough idle with cold temps. No further changes have been made so I dunno what the difference would be other than ambient temperatures.