Hey guys. So lately I've noticed that my car has a slight rough idle and what sounds like a misfire for about a minute or so when I start her up in the mornings which goes away completely once the car has warmed up.It's not throwing any fault codes. Coils and plugs were replaced in the last 2 months. I suspect it may be a vacuum leak which I want to check and maybe attempt to diy this weekend if that's the case. Apart from the upper and lower intake boots, is there anything else that I should check?
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Cold start rough idle
- Thread starter Bavs108
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graan13
Active member
Had a prob sounding much the same as this a while ago. I had run the car pretty empty at one point and thought it may have been dirt come through and fowled a plug or injector. It was only first start up and went away like you say after a minute or so. I am not sure what cured it but did change fuel stations and it seemed to get better and kinda went away! either that or I just did not take note :fishwack:
I did find at one stage a pipe that had perished coming off the top rear side of the injection/air box system just off the right side of the engine as you look into the bay, it was a thin pipe that had perished where it attaches to the box and had not noticed it as it had dropped down slightly. Apparently it is not a major problem, just a vacuum pipe of some description that can cause splutter on initial start and slightly increased consumption initially. I managed to reattach with another piece of rubber hose cut to measure on the end to fit over the existing pipe and connection stub off the main box. If I recall, you wont miss it as there are 2 of the thin hoses, one under the other. Since then I have not experienced any splutter either, so which of the two remedies I did cured it, I'm not sure - probably the latter :=):
Apologies for the poor description but i'm sure you will notice/know which part of the system I'm trying to describe :rollsmile:
(2002 e46 300i)
I did find at one stage a pipe that had perished coming off the top rear side of the injection/air box system just off the right side of the engine as you look into the bay, it was a thin pipe that had perished where it attaches to the box and had not noticed it as it had dropped down slightly. Apparently it is not a major problem, just a vacuum pipe of some description that can cause splutter on initial start and slightly increased consumption initially. I managed to reattach with another piece of rubber hose cut to measure on the end to fit over the existing pipe and connection stub off the main box. If I recall, you wont miss it as there are 2 of the thin hoses, one under the other. Since then I have not experienced any splutter either, so which of the two remedies I did cured it, I'm not sure - probably the latter :=):
Apologies for the poor description but i'm sure you will notice/know which part of the system I'm trying to describe :rollsmile:
(2002 e46 300i)
Mine is also bone stock. But it only started doing this for the past month or so. I never had a rough idle before. Initially I thought maybe it was because of the cold winter, but now that it's warmed up it still does it.
I suspect one of these pipes to be the culprit which I think is the same one you talking about.
http://realoem.com/bmw/showparts.do?model=ET56&mospid=47644&btnr=11_2885&hg=11&fg=45
As for fuel, I think that also may be a possible culprit as I switched to Caltex from Engen Primax about 2 months back to take adavantage of that Standard Bank fuel rewards programme:flyfun:
graan13 said:
I suspect one of these pipes to be the culprit which I think is the same one you talking about.
http://realoem.com/bmw/showparts.do?model=ET56&mospid=47644&btnr=11_2885&hg=11&fg=45
As for fuel, I think that also may be a possible culprit as I switched to Caltex from Engen Primax about 2 months back to take adavantage of that Standard Bank fuel rewards programme:flyfun:
graan13
Active member
If you look at this picture, the rectangular box on the side of the inlet system, at the rear of it is where the two thin hoses attach. It was the top one in my case that had perished off at the connection stub.
Hope it helps :thumbs:
PS - This is not my engine..... pic off the web..... blerry filthy!
Hope it helps :thumbs:
PS - This is not my engine..... pic off the web..... blerry filthy!
graan13 said:If you look at this picture, the rectangular box on the side of the inlet system, at the rear of it is where the two thin hoses attach. It was the top one in my case that had perished off at the connection stub.
Hope it helps :thumbs:
PS - This is not my engine..... pic off the web..... blerry filthy!
Yup as far as I know those intake pipes are just below that disa valve:thumbs: I did have look down there from the top but can't really see anything wrong with my pipes. Will take out the air filter housing this weekend to have a closer look. Also read about cleaning the throttle body and idle control valve with some intake/carb cleaner which is also known to cause that rough idle when they gunk up over time. Is it also possible that a weak battery would cause that slight misfire? I noticed that when I start my car it feels a bit lazy to crank but still starts up first time every time. I suspect it's a sign that my battery may be on its way out.
S
S1NGH 001
Guest
VANOS :fencelook:
Doomsdaya said:
I got Bosch coils from diesel electric. I think they were around R380 each.
I didn't have much time this weekend to check my vacuum hoses properly. Just took out the air filter housing and couldn't see or feel any signs of wear or cracks on the pipes. Will see next weekend if i have some time to try and remove the pipes, icv and throttle body.
Hey guys. So my cold start rough idle and misfire seems to have disappeared after I changed the battery:flyfun: Would a weak battery cause a cold start misfire/rough idle? Possibly not enough power to the coils in the mornings? I fitted a new battery today and the car cranks perfectly now with no misfiring on cold start. Will see tomorrow morning if it does the same:thumbs:
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