P0306, Rough Idle, White Smoke

jameshigg23 · 03-25-2023, 02:34 PM

Hi everyone, apologies if there's already a thread for this.

A week ago I bought a 325i e92 which despite its age (2006) only had 60k. Had been owned exclusively by an older gentleman who could no longer drive. Car seemed perfect, had it serviced straight away as even though the oil only had a few thousand miles on it hadn't been serviced for a few years due to lack of driving.

Yesterday I was WOT on a lively b road near me and I got a CEL for about a minute which disappeared then came back. Pulling onto the drive the car seemed to be running very rough. I restarted the car and it sounded normal, CEL had gone so I took it slowly around the block. Similar symptoms, intermittent CEL and was running very rough and transmission seemed to be struggling to get in and out of gears. At this point I ran an OBD2 (cheap one) and got a p0306 code. I was pretty calm about this as was going to chnage the spark and coil packs anyway. However this morning I went to check out the car and got some white smoke, very rough idle and the smoke seemed to get worse if I applied any throttle. Bit of a fuel smell, but smoke seems to smell like burning coolant (although I may be imaging this - I hope!). Coolant level also is also low when checking reservoir (but I've had no lights on this or any overheating light).

Could this all be caused by a dodgy spark plug, coil pack or fuel injector or would you think, like I now do, that my head gasket has gone?

Thanks,
Jake

Chappers 71 · 03-26-2023, 12:51 PM

Never heard of anyone having to replace head gasket.
It will most likely be leaking oil from the valve cover, oil filter & sump gaskets though & you may have a coolant leak from bottom of the rad which could explain the coolant loss. Although they do use a bit of coolant. I’d top off the coolant & have a good look around for oil & coolant leaks. Pretty common issues & there’s plenty of info on BP regarding oil leaks.

If you haven’t already done so I’d put in a new set of plugs & coils.

These cars do put out a look of water vapour when cold, which can be mistaken for white smoke.

Hope it’s doesn’t work out to costly to sort.

jameshigg23 · 03-29-2023, 08:51 AM

Thanks Chappers,

Was going to chnage the coil and plugs nyself but got someone coming to pick it up and have a look on Friday. Once I smelt Petrol and noticed the coolant I thought it best to get someone to have a look. I'll update you when I know! Cheers

jameshigg23 · 04-03-2023, 03:36 PM

Thanks again, new coils and plugs seems to have fixed it!

03-25-2023, 02:34 PM	#1
jameshigg23 New Member 3 Rep 6 Posts Drives: E92 325i (2006) Join Date: Mar 2023 Location: North East UK iTrader: (0)	P0306, Rough Idle, White Smoke - Head Gasket? Hi everyone, apologies if there's already a thread for this. A week ago I bought a 325i e92 which despite its age (2006) only had 60k. Had been owned exclusively by an older gentleman who could no longer drive. Car seemed perfect, had it serviced straight away as even though the oil only had a few thousand miles on it hadn't been serviced for a few years due to lack of driving. Yesterday I was WOT on a lively b road near me and I got a CEL for about a minute which disappeared then came back. Pulling onto the drive the car seemed to be running very rough. I restarted the car and it sounded normal, CEL had gone so I took it slowly around the block. Similar symptoms, intermittent CEL and was running very rough and transmission seemed to be struggling to get in and out of gears. At this point I ran an OBD2 (cheap one) and got a p0306 code. I was pretty calm about this as was going to chnage the spark and coil packs anyway. However this morning I went to check out the car and got some white smoke, very rough idle and the smoke seemed to get worse if I applied any throttle. Bit of a fuel smell, but smoke seems to smell like burning coolant (although I may be imaging this - I hope!). Coolant level also is also low when checking reservoir (but I've had no lights on this or any overheating light). Could this all be caused by a dodgy spark plug, coil pack or fuel injector or would you think, like I now do, that my head gasket has gone? Thanks, Jake
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03-26-2023, 12:51 PM	#2
Chappers 71 Major General 5480 Rep 5,427 Posts Drives: Beige G31 40ix m sport Join Date: Feb 2016 Location: Kent, The Garden of England iTrader: (0) Garage List 2018 G31 xdrive 40i ... [4.00] 2006 E92 335i SE [9.50]	Never heard of anyone having to replace head gasket. It will most likely be leaking oil from the valve cover, oil filter & sump gaskets though & you may have a coolant leak from bottom of the rad which could explain the coolant loss. Although they do use a bit of coolant. I’d top off the coolant & have a good look around for oil & coolant leaks. Pretty common issues & there’s plenty of info on BP regarding oil leaks. If you haven’t already done so I’d put in a new set of plugs & coils. These cars do put out a look of water vapour when cold, which can be mistaken for white smoke. Hope it’s doesn’t work out to costly to sort. __________________ G31 40ix M Sport E92 335i. E36 328is coupe E39 540i V8 6SP manual E34 3.6 M5. E34 525i sport. VW Jetta Mk2 GTI 16v. 1679cc 1967 resto-cal beetle
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03-29-2023, 08:51 AM	#3
jameshigg23 New Member 3 Rep 6 Posts Drives: E92 325i (2006) Join Date: Mar 2023 Location: North East UK iTrader: (0)	Thanks Chappers, Was going to chnage the coil and plugs nyself but got someone coming to pick it up and have a look on Friday. Once I smelt Petrol and noticed the coolant I thought it best to get someone to have a look. I'll update you when I know! Cheers
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04-03-2023, 03:36 PM	#4
jameshigg23 New Member 3 Rep 6 Posts Drives: E92 325i (2006) Join Date: Mar 2023 Location: North East UK iTrader: (0)	Thanks again, new coils and plugs seems to have fixed it!
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