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Old 06-08-2013, 10:47 AM   #1
max328i
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Question Cold Start Rough Idle Problem - stuck, please help!

Ok, so I've been doing a lot of research on this, but I'm stuck. I have a 328i and any time the weather is below 80 F, my car does a rough idle at start. It lasts longer in the winter, but the symptoms are the same - about every 10 seconds the RPM gauge goes lower and lower, until it ultimately stalls if I don't give it some gas.

Steps I have done to try to solve this:

1). Cleaned the MAF sesnsor several times with the MAF cleaner.
2). Replaced upper and lower intake boots - they were all cracked and old.

So now I am stuck. My mechanic says that it possibly could be the crank breather/ventilation system. I just want to get some input before I get my hands greasy again. Also if you know of any DIY's, that would be helpful.
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Old 06-08-2013, 12:27 PM   #2
smokedout328
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your problem

akk you need is a new VANOS kit which you can buy for around 30 bucks rebuild from any euro maintenance shop
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Old 06-08-2013, 12:28 PM   #3
smokedout328
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New vanos unit is what you need

you should get a different mechanic if he didnt know about this and had you spend money in other areas
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Old 06-08-2013, 12:38 PM   #4
max328i
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Cold Start Rough Idle Problem - stuck, please help!

So you mean replacing the actual VANOS?


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Old 06-08-2013, 01:22 PM   #5
willsbma
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Try cleaning iac valve. Also, you can tell if your ccv is bad by popping the oil cap while idling, listen for a groan
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Old 06-08-2013, 02:26 PM   #6
max328i
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Cold Start Rough Idle Problem - stuck, please help!

Ok I will try that. Thanks for your advice!


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Old 06-09-2013, 12:36 AM   #7
328ifanatik
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Cold Start Rough Idle Problem - stuck, please help!

I had the same issue. I ended up replacing the vanos seals and that fixed the problem. I did it back in February with not one jolt since.


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Old 06-11-2013, 08:54 PM   #8
max328i
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Cold Start Rough Idle Problem - stuck, please help!

So I did the ICV today - totally cleaned it out, and no result. Still the same rough idle. I just did my valve cover gasket a couple of months ago, so I understand that VANOS seals are in a similar location. But I don't wanna have to spend a day doing it and see no results. So question, how would the new VANOS seals have anything to do with idling on a cold start?


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Old 06-11-2013, 09:47 PM   #9
jfoj
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Skip the VANOS for now, MANY other things to address first.

Crankcase and/or intake air leaks are a many on these cars.

CCV likely needed to be replaced at about year 7. If it is original, replace it and all the hoses. Also if the fuel filter has more than 30k miles replace it.

Suggest you read the first few links in below in my signature. You will need to use a computer as they are rather involved and you will not see the signature using the App on your phone.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 06-11-2013, 10:43 PM   #10
max328i
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Thank you for your help, jfoj. I will look into it. Seems like working with the CCV is my next step - the link for the DIY you have on your first post in your signature seems to have an expired set of pictures. Do you know of any other good ones? I have a couple in mind, but they are not complete and I do not feel confident in working on the CCV yet.

Also would using starting fluid (in moderation of course, perhaps on a cold start) be safe in determining air leaks? And where would you spray it?
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Old 04-15-2015, 09:14 AM   #11
jdes
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I realize this thread is cold. However, for anyone else researching this problem, I recently fixed similar symptoms on my 99 323i simply doing routine maintenance. KISS principle must be given respect. Check your accessory belt pulleys before getting cute with trouble shooting your intake and injection.

I was doing a routine belt replacement and noticed that the folks over at bavauto.com recommended doing the belt tensioners, water pump pulley and deflection pulley. It turned out that the bearings on my deflection pulley were almost locked up completely. After changing that out, no more rough idle, no more hesitation accelerating through first and into second gear, no more random timing related codes being thrown. All of this gone by simply putting a good pulley on. KISS principle! Check your pulley before getting cute with the other likely contributors to rough idle when cold.

Last edited by jdes; 04-15-2015 at 09:16 AM.
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Old 04-15-2015, 09:57 AM   #12
jfoj
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Agree with the KISS principal, however, pulleys usually should be replaced when the serpentine belts are replaced, but this rarely happens.

As for the more common issues:

You need to read the first 2 links below in my signature.

Need to see Freeze Frame info if the SES/CEL/MIL is on and Fuel Trim values at both warm idle and a steady highway cruise between 45-60 MPH.

Read this thread - http://forum.e46fanatics.com/showthread.php?t=1057387

Read my "BMW 20 Questions" comments in this thread - http://forum.e46fanatics.com/showthread.php?t=1059972

Search YouTube for Scotty Smoke Test. Do what Scotty does or build a tester from related video. Remove the oil fill cap and make sure the crankcase fills up with smoke, put the oil fill cap back on and check for leaks around the valve cover, oil fill cap, dipstick tube and CCV hoses. Cracked valve covers are pretty common on the E46 as it ages.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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