Weird jumping idol on cold startup (vids)

**m5racer** · 11-29-2008 03:24 PM

Alright so first off this isent my A4, its the real beast, the 01 M5.

I started to notice a few weeks ago that when i start the car, (cold start only) the car's idol starts to go up and down. The needle doesn't move on the RPM guage, but you can defienatly hear and feel it. Also, until the engine is fully warmmed up there is a very odd hessitation from 2-3k rpm. Once the car everything rides just fine. Here is a vid for you guys. If you can help me out that would be great!

Thanks!

**headshok2002** · 11-29-2008 10:22 PM

What the ef, eh? That's weird... I cannot believe that the rev's are not fluctuating. Your tach lies! LIES!

Seriously though... I've got nothing for you, but I hope somebody on here does. I presume you've posted this on a bimmer forum? Please update this thread if you find out what the problem is! I am curious. :P

Killer car, by the way. If I ever have a lot of garage space, I'll be after an M5... same era as your car. Back when they were cool!

**Rb26dett s13** · 11-29-2008 10:43 PM

I'm not a mechanic but something very similar happened to me in my M3.

Possibly:

Small vacuum leaks
A sticky/defective ICV (Idle Control Valve).
Replace coolant.

My problem was a defective ICV. Hope that helps.

**MacDaddy** · 11-30-2008 01:26 AM

That engine is beginning to have Vanos issues, what year is your M5?
any dieseling/pinging noises when you accelerate?

**m5racer** · 11-30-2008 03:07 PM

Alright so after seeing what people said on the m5 forums this is what i got:

Idle control Valve or

maybe a vacuum leak or

A few months later, I got a code which failed the emmissions purge valve, I think thats what its called. I replaced the valve (under the plenum) and the code went away.

Mcdaddy: the failing vanso can make sense during the shitty accleration. but is that something that will only effect the cold start? if its going wouldent it effect it the entire time? Im asking beucase your the only person to bring the failing vanso up.

Thanks

**MacDaddy** · 12-01-2008 01:13 AM

Vanos failure/failing can cause the weird idle, it will always cause a loss of power too, and the pinging/dieseling.
do you have any of those issues? (pinging, dieseling, crappy acceleration)

the noise i'm referring to can be heard on this video at 0:28 and 0:45
http://www.youtube.com/watch?v=WwaRehvvkIY

Vanos issues are more likely, but not limited to the 1999 and 2000 M5's, thats why i asked what year is it.

**Rb26dett s13** · 12-01-2008 11:38 AM

If it's the ICV.
It can be very pricey to repair.
I don't know what it will be for the M5 but im sure very close to the M3's price.

**MacDaddy** · 12-02-2008 08:10 PM

update? i'm curious if its making those noises or if you've found out what it is

**sakimano** · 12-05-2008 05:46 PM

that's weird

nothing worse than when your expensive car starts to freak out!

p.s. I like how BMW has that graduated redline for when the car is still cold. My friend's M3 has that

**sakimano** · 12-05-2008 05:47 PM

that's weird

nothing worse than when your expensive car starts to freak out!

p.s. I like how BMW has that graduated redline for when the car is still cold. My friend's M3 has that.

**jro** · 12-14-2008 04:50 PM

black smoke from exaust, Hmm, Take it for a good carbon burner down the highway at high rpm's, Could be clogged injectors, Use premium fuel with 94 octane. Ie, Chevron or petro can, And use a good quality injector cleaner, Also it wouldn't hurt to use a conditioner for water in the fuel tank, It's methanol based and it mixes with hyrates in the fuel and will burn off hydrates in the tank, try it out it's a cheaper alternative and a poor mans diagnostic.
If the rpm starts to finally jump around it could be alternator. Good luck.
Cheers

**MacDaddy** · 12-14-2008 08:11 PM

Originally Posted by jro

black smoke from exaust, Hmm, Take it for a good carbon burner down the highway at high rpm's, Could be clogged injectors, Use premium fuel with 94 octane. Ie, Chevron or petro can, And use a good quality injector cleaner, Also it wouldn't hurt to use a conditioner for water in the fuel tank, It's methanol based and it mixes with hyrates in the fuel and will burn off hydrates in the tank, try it out it's a cheaper alternative and a poor mans diagnostic.
If the rpm starts to finally jump around it could be alternator. Good luck.
Cheers

trust me, thats not going to help, and its not the alternator.

and its a M5, all that thing knows is premium fuel and redline driving.