How is VANOS Problem Diagnosed? - The Unofficial BMW M5 Messageboard (m5board.com)

TiGumz · 5th July 2002, 06:55

Just last week I start my car and the engine idle "feels" rougher.
Its a 2001 with 24k miles. I've searched through some of the past VANOS postings and can't say that I would classify the symptom as a diesel sound. No SES light. No oil on the floor. The roughness almost completely goes away when the engine is warmed up but I still feel a certain roughness in the engine. I drive the car often enought to pick up changes like this and believe me, there has been a difference in engine roughness that was not there the week before. Oil is darker than I am used to seeing (5k since last oil change, I requested the special 40/60 weight, no oil usage to speak of) After hanging out on this forum for awhile a VANOS problem is first thing I thought of, but tell me it isn't so

I'm curious as to how exactly would a VANOS problem or an impending VANOS problem would be diagnosed. By sound only? Would a fault code be triggered or stored without the SES light going on? The car needs to go in, but I want to armed with more information in case I get a SA that dismisses the problem offhand.....

TIA for your input

TCM · 5th July 2002, 07:09

I am almost positive a VANOS problem would creat an SES light and engine code. Has the weather changed recently, aka, heat wave? Maybe that could be causing the engine to run differently.

TiGumz · 5th July 2002, 13:35

Quote:

Originally posted by TCM
I am almost positive a VANOS problem would creat an SES light and engine code. ...

That's one of main questions I have about the VANOS problem, does it *always* lead to an SES light and/or code.....

>Has the weather changed recently, aka, heat wave? Maybe that could be causing the engine to run differently.<

Well, it has been warmer here in the midwest lately, but the mornings are temporate, so IMO there hasn't been a dramatic enought temp diff over the past 15 months that I've had the car to explain this sudden change in engine behavior...

TCM · 5th July 2002, 18:27

Interesting Glenn. When you bring it in please tell us what they find at fault if anything. Good luck.

Quad_exhaust · 5th July 2002, 20:31

Hey,

Just had my car in service for 1.5 weeks with a Vanos problem - left side block #2 was out. SES light did go on, no doubt there. Engine ran rough, lower idle, and felt like it wanted to "die" while sitting at a stop light. My service guy said had it not been under warranty, it would have cost $4k. He also said if I had driven on it for any length of time, I would have blown the engine, as the timing was off and would have led to more problems. You may want to call him, Jesse at SC BMW, 408-249-9070. Just tell him you know he just worked on an M5 with a bad VANOS and wanted to find out what the signs of it might be....Good luck!

Quad

Caribbean-M5 · 8th July 2002, 07:56

I had a problem with the VANOS in my 2001 M5. It turned out to be a faulty camshaft position sensor in one of the banks. Apparently a fairly common problem.
The problem was initially intermittent and the SES light would come on whenever the symptoms appeared. Eventually the problem became constant.
There was no unusual noise coming from the valve train, but the exhaust and intake noise were different and the car felt as if it was missing 100 of 400 the horses.