N53 cold start misfire - Ignorance is bliss?
Discussion
I have a 2009/59 E92 330i with the N53 engine on 148k. Since I bought it in October 2014 on 126k miles it has suffered with a cold start misfire, starting up in anything less than 8C results in a stuttering idle. Very rarely it will eventually stutter enough to trigger an engine management light which gives a combustion misfire code in varying cylinders. After the first 30s-60s of driving the car is absolutely fine, this problem is exclusively with start ups on cold days. I only run the car on Shell V Power from a few different petrol stations so I do not think fuel is the issue.
The car has had all coil packs replaced by BMW as a recall. It's on its original injectors and HPFP, being a 2009/59 car the injector part numbers are the latest versions but the HPFP is not the latest 2010 version. In my 22k of miles the spark plugs have been replaced and it's had oil changes aplenty, the cold start misfire is always there in winter weather and has not got any better / worse.
If you look into the N53 issues there are plenty of cases on nearly new mileage and high mileage like mine where replacing the injectors is a temporary fix (the underlying cause is still there). My gut feeling is the HPFP is causing the issues and will need to be replaced, I think I'm between the fixes for the HPFP issues. You can hear the pump prime when unlocking the car (later version) and I think mine has escaped the complete HPFP failure but isn't 100%, presumably the newer version is golden as it has been in service since 2010.
I've posted here previously asking for advice on what the cause could be. This time I'd like to know if it's wise / unwise to ignore the issue. I'm not running the car on a shoestring, I've replaced shocks / springs / discs and change the oil every 9k. If the problem persisted as the car warmed up or I had any sniff of an issue at any other time I would sort it. But this is isolated to cold starts and plenty of people throw £££ at the N53 cold start hiccup and find the problem comes back. My next move would be diagnostics including fuel pressure at a specialist but if I get a bill of £££ to replace the HPFP (assuming components further down the chain is not in need of replacement) I'd still grumble as the problem doesn't seem to be getting worse. The big fear is that I'm causing more harm than good by running a car in cold weather which is poorly.
The car has had all coil packs replaced by BMW as a recall. It's on its original injectors and HPFP, being a 2009/59 car the injector part numbers are the latest versions but the HPFP is not the latest 2010 version. In my 22k of miles the spark plugs have been replaced and it's had oil changes aplenty, the cold start misfire is always there in winter weather and has not got any better / worse.
If you look into the N53 issues there are plenty of cases on nearly new mileage and high mileage like mine where replacing the injectors is a temporary fix (the underlying cause is still there). My gut feeling is the HPFP is causing the issues and will need to be replaced, I think I'm between the fixes for the HPFP issues. You can hear the pump prime when unlocking the car (later version) and I think mine has escaped the complete HPFP failure but isn't 100%, presumably the newer version is golden as it has been in service since 2010.
I've posted here previously asking for advice on what the cause could be. This time I'd like to know if it's wise / unwise to ignore the issue. I'm not running the car on a shoestring, I've replaced shocks / springs / discs and change the oil every 9k. If the problem persisted as the car warmed up or I had any sniff of an issue at any other time I would sort it. But this is isolated to cold starts and plenty of people throw £££ at the N53 cold start hiccup and find the problem comes back. My next move would be diagnostics including fuel pressure at a specialist but if I get a bill of £££ to replace the HPFP (assuming components further down the chain is not in need of replacement) I'd still grumble as the problem doesn't seem to be getting worse. The big fear is that I'm causing more harm than good by running a car in cold weather which is poorly.
Have a look at the first video in this thread I posted a couple of days ago. One of the fault symptoms described is poor idling from a cold start; http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Not sure why N53 isn't mentioned in the video but the solenoids are known to give problems on N53s too. Here is a thread mentioning N53s http://www.bimmerforums.co.uk/forum/f125/2007-e93-...
Have a search online and I think you may find other N53s with sticking VANOS solenoids, very easy to take out, inspect and clean. If the wear is severe then a pair of new solenoids ( inlet and exhaust ) are about £190.00
HTH
Not sure why N53 isn't mentioned in the video but the solenoids are known to give problems on N53s too. Here is a thread mentioning N53s http://www.bimmerforums.co.uk/forum/f125/2007-e93-...
Have a search online and I think you may find other N53s with sticking VANOS solenoids, very easy to take out, inspect and clean. If the wear is severe then a pair of new solenoids ( inlet and exhaust ) are about £190.00
HTH
The joy of the N53... I have one, I love it - when it's running well, unfortunately it in my 3 years of ownership it's probably been 50/50.
Mine did something similar, but also misfired under heavy load at high RPM, typically going up a steep hill at ~5K RPM in 3rd would normally do it, BMW didn't have a clue, nor did various indies. Took it to a place in Hemel who figured out the HPFP had gone in about 20 minutes (£60 lighter, but well spent) Was about £600 to swap it out. Maybe give that a blast on yours ?
Mine is now popping out of first gear, and burning a bit too much oil for my liking... might be time to chop it in
Best of luck though, feel free to message me if you need a fellow N53 owners view
Mine did something similar, but also misfired under heavy load at high RPM, typically going up a steep hill at ~5K RPM in 3rd would normally do it, BMW didn't have a clue, nor did various indies. Took it to a place in Hemel who figured out the HPFP had gone in about 20 minutes (£60 lighter, but well spent) Was about £600 to swap it out. Maybe give that a blast on yours ?
Mine is now popping out of first gear, and burning a bit too much oil for my liking... might be time to chop it in
Best of luck though, feel free to message me if you need a fellow N53 owners view
I've just finished a top end rebuild on my N53 2010 630i. 72K and 5 of 6 injectors were rubbish. I would recommend getting them tested, although your symptoms don't necessarily indicate injector problems especially as it sounds to be so temperature sensitive.
As these engines run stratified lean burn they at super sensitive to bad air fuel mix especially at very light load on idle . I had to refit the rocker cover after staring it first time after the rebuild as it was running like a dog due to an air leak. The sealing gasket on the rocker cover is critical.
To diagnose this I pulled the MAF sensor - after a few seconds of rough running with the slight air leak it managed to idle pretty well, I guess due to the ECU defaulting to a different fueling strategy due to the MAF fault and hence compensating for the lean condition created by the unmetered air leak.
Are you just getting misfire codes, or is there anything else in there? You could try pulling the MAF and seeing how it runs, if it improves it may point toward a lean condition that is only causing combustion instabilities with low ambient air temperatures and a cold engine, where wall wetting may exacerbate any lean condition. Low ambient temps will mean higher air charge so 8 deg may be the threshold where the air fuel ratio becomes too lean to burn with stability.
As these engines run stratified lean burn they at super sensitive to bad air fuel mix especially at very light load on idle . I had to refit the rocker cover after staring it first time after the rebuild as it was running like a dog due to an air leak. The sealing gasket on the rocker cover is critical.
To diagnose this I pulled the MAF sensor - after a few seconds of rough running with the slight air leak it managed to idle pretty well, I guess due to the ECU defaulting to a different fueling strategy due to the MAF fault and hence compensating for the lean condition created by the unmetered air leak.
Are you just getting misfire codes, or is there anything else in there? You could try pulling the MAF and seeing how it runs, if it improves it may point toward a lean condition that is only causing combustion instabilities with low ambient air temperatures and a cold engine, where wall wetting may exacerbate any lean condition. Low ambient temps will mean higher air charge so 8 deg may be the threshold where the air fuel ratio becomes too lean to burn with stability.
Gr44 said:
The joy of the N53... I have one, I love it - when it's running well, unfortunately it in my 3 years of ownership it's probably been 50/50.
Mine did something similar, but also misfired under heavy load at high RPM, typically going up a steep hill at ~5K RPM in 3rd would normally do it, BMW didn't have a clue, nor did various indies. Took it to a place in Hemel who figured out the HPFP had gone in about 20 minutes (£60 lighter, but well spent) Was about £600 to swap it out. Maybe give that a blast on yours ?
Mine is now popping out of first gear, and burning a bit too much oil for my liking... might be time to chop it in
Best of luck though, feel free to message me if you need a fellow N53 owners view
Thanks for your reply. Did yours start as a cold start misfire and then eventually become a high RPM misfire? Mine has been restricted to cold start misfires for the last 20k miles. Out of interest what year is your car?Mine did something similar, but also misfired under heavy load at high RPM, typically going up a steep hill at ~5K RPM in 3rd would normally do it, BMW didn't have a clue, nor did various indies. Took it to a place in Hemel who figured out the HPFP had gone in about 20 minutes (£60 lighter, but well spent) Was about £600 to swap it out. Maybe give that a blast on yours ?
Mine is now popping out of first gear, and burning a bit too much oil for my liking... might be time to chop it in
Best of luck though, feel free to message me if you need a fellow N53 owners view
I think it is the HPFP, the injectors seem to fail because of a knackered HPFP rather than be the problem in their own right.
viperbluecerb said:
I've just finished a top end rebuild on my N53 2010 630i. 72K and 5 of 6 injectors were rubbish. I would recommend getting them tested, although your symptoms don't necessarily indicate injector problems especially as it sounds to be so temperature sensitive.
As these engines run stratified lean burn they at super sensitive to bad air fuel mix especially at very light load on idle . I had to refit the rocker cover after staring it first time after the rebuild as it was running like a dog due to an air leak. The sealing gasket on the rocker cover is critical.
To diagnose this I pulled the MAF sensor - after a few seconds of rough running with the slight air leak it managed to idle pretty well, I guess due to the ECU defaulting to a different fueling strategy due to the MAF fault and hence compensating for the lean condition created by the unmetered air leak.
Are you just getting misfire codes, or is there anything else in there? You could try pulling the MAF and seeing how it runs, if it improves it may point toward a lean condition that is only causing combustion instabilities with low ambient air temperatures and a cold engine, where wall wetting may exacerbate any lean condition. Low ambient temps will mean higher air charge so 8 deg may be the threshold where the air fuel ratio becomes too lean to burn with stability.
Thanks for replying, and well done on your N53 rebuild (I've just seen the fingers crossed success report in your other post).As these engines run stratified lean burn they at super sensitive to bad air fuel mix especially at very light load on idle . I had to refit the rocker cover after staring it first time after the rebuild as it was running like a dog due to an air leak. The sealing gasket on the rocker cover is critical.
To diagnose this I pulled the MAF sensor - after a few seconds of rough running with the slight air leak it managed to idle pretty well, I guess due to the ECU defaulting to a different fueling strategy due to the MAF fault and hence compensating for the lean condition created by the unmetered air leak.
Are you just getting misfire codes, or is there anything else in there? You could try pulling the MAF and seeing how it runs, if it improves it may point toward a lean condition that is only causing combustion instabilities with low ambient air temperatures and a cold engine, where wall wetting may exacerbate any lean condition. Low ambient temps will mean higher air charge so 8 deg may be the threshold where the air fuel ratio becomes too lean to burn with stability.
I have a slight rocker cover leak, it's been "fixed" for now by nipping the cover up (starting point, not necessarily a permanent fix). Indy was reluctant to take the cover off for fear of opening a can of worms and as the leak was only very slight, more of a weep, it made sense to try the tightening up approach. I take your point about the air leak though.
The codes are exclusively misfire in the 22k miles I have had the car, there was a NOx code present when I bought the car but this has not come back since being cleared when I bought it. I'm fussy with my cars but as I get older am learning it's not always wise to try to fix things which aren't yet a problem. As mine is only related to cold starts I'm reluctant to chuck money at it yet. Your post has got me worried that the misfire is slowly causing engine damage when it occurs.
My oil consumption is less than yours and hasn't changed in the past 20k miles. It's happier on 5w-40 than 5w-30 oil and I'm changing oil every 9k so the long life benefit of -30 doesn't seem to matter.
Thanks, the rebuild was definitely testing at times!
If the gasket is failing then a nip up may not work. What you could do is disconnect the breather pipe from the rocker cover and completely seal it up, and then start it up it in the conditions that cause the problem. If it runs fine, you know you have a rocker cover air leak problem. Taking this off and replacing a gasket is a bit of a pain but not too bad.
SoupAnxiety said:
I have a slight rocker cover leak, it's been "fixed" for now by nipping the cover up (starting point, not necessarily a permanent fix). Indy was reluctant to take the cover off for fear of opening a can of worms and as the leak was only very slight, more of a weep, it made sense to try the tightening up approach. I take your point about the air leak though
This is very suspect to me. If there is even a drop of oil getting out, then there is air getting in, and this will in turn find it's way back into the intake through the CCV system.If the gasket is failing then a nip up may not work. What you could do is disconnect the breather pipe from the rocker cover and completely seal it up, and then start it up it in the conditions that cause the problem. If it runs fine, you know you have a rocker cover air leak problem. Taking this off and replacing a gasket is a bit of a pain but not too bad.
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