5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
Hi I'm a newbie on this forum and to BMW in general. I recently purchased a 97 528i and started having a rough idle problem on cold starts in the morning. The car will start perfectly and after a couple of seconds it'll start idling rough for about 3-5 min. Since I obviously got the car used I've done the following: new plugs, ccv, valve cover gaskets, new MAF, new coolant temp sensor, new cam position sensor, and I do have the shark injector Conforti software and a CAI.
I've smoked the engine and used starter fluid to look for any vaccum leaks without any success. I've checked fuel pressure on cold start and that seems fine. I've swapped coils with another car to see if that made a difference and it didn't. I've also disconnected the secondary air pump to see if that was the source of the problem and that didn't make any difference either. The only thing that I can think left to do is check injector pressure at cold then warm and do a compression test? Does anyone have any other ideas as to what might be causing this? I'm not sure where to turn next. Any help would be really realllly appreciated. Thanks for any help.
Last edited by Blackcatecho; 03-03-2008 at 10:16 AM.
Do you have a fault code reader? Do you see any codes?
Oxygen sensors perhaps...
Yeah I've scanned it several times after each repair and I don't come up with any codes at all. The engine light never comes on either. The O2 sensor was another thought, but I figured I'd get a code with that one.
I've searched around and found tons of info on changing the double vanos gaskets, but not the single vanos gaskets. Are there any how-to articles on the single repair? I also did notice that the oil line to the Vanos unit is weeping oil as well so I'll have to replace that while I'm at it. I hope this will fix the problem.
Well here's an update. I had my buddy replace the intake manifold gasket, throttle body gasket, and injector o-rings. The problem is still there. We looked at every hose and it all was in great shape. So I don't know what it could be now. On a side note we also installed the Turner underdrive kit and I had the Schrick intake delivered, but Turner forgot to send the gaskets and I forgot to check for them before we took the stock intake off...Anyway, I have to take off the stock and put the schrick on. Does anyone know of a how to for it. I'm planning on doing this myself this time since it didn't look too difficult when my buddy did it at his shop. If anyone has any ideas on the rough cold start please let me know. Thanks for any help.
Good thing it's a 6cyl, coz' I was thinking "nikasil"
All the things I could think of, have already been suggested, esp. MAF, ICV, throttle body.
Now, what about the oil separator? Did you look into that? That causes a vacuum leak...
it'll give you a bad idling, poor acceleration, and some smoke in the tail which gets worse as the condition worsens.
Yeah, I changed that too. I wonder if the entire single vanos unit needs to be replaced. We already changed it's gasket.. I'm also wondering about that secondary air pump thing on the valve cover gasket side of the engine. We disconnected it for a couple days and plugged the line. I still noticed the stumble on cold starts, but it's the only other thing that I can think of..
It's not the VANOS gasket that causes the issue, there are little o-rings in this VANOS unit
If you suspect that valve to be bad or going bad, change it fast - as if it completely fails, the air pump goes down with it.
Yeah, you know, I read about the o-ring inside and asked BMW parts about the o-ring and they said that with the single vanos design like on my car there isn't an o-ring, just the gasket. I even questioned him on it and he told me there wasn't any o-ring to switch. Anyone have a number on the part or a diagram of the vanos unit for a '97 528i? I would love it if it was just the o-ring so I could stop searching for parts to replace!
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