Is my VANOS shot?

dmurray14 · 08-30-2005, 07:56 PM

Figured I'd try this post here, since no one seems to know over at BFC. For a while now, my car has had absolutely NO balls from a stop. When you attempt to accelerate, the car just kind of putts up to about 2500-3k rpms, and then boom, it takes off. From there on up, it's about how I would expect it to accelerate. But in the beginning, it bogs like you wouldn't believe, to the point where it's embarrasing. The engine feels like it's breathing through a straw, if you don't give it enough gas, it just sits there and stutters. It really can't even get out of it's own way until after the 2.5-3k hurdle mentioned above. Anyway, I just can't figure out what the problem is. It seems like VANOS is really the only possible culprit - is there any way to test to see? I've heard people say to disconnect the solenoid - I see the wire going into the solenoid, but I have no idea where it goes from there and where it can be disconnected. Is this safe to do? Any ideas what's going on with my car? I would REALLY appreciate any help.

Thanks!

Dan

Jeron · Jeron's Garage

What year, model, engine?
I assume it isnt 96+ with OBD-II and you dont have CEL.

Have you checked for vacuume leaks, fuel filter, plugs, TPS, ICV, MAF?

Do you have a Bentley repair manual?

dmurray14 · 08-31-2005, 08:05 AM

Thanks for the reply, sorry, I should have included the vehicle info. It's a 1993 325is. And you are correct, no CEL. I've replaced the plugs, cleaned the MAF, and am planning on doing the ICV today. I have also replaced the o2 sensor. I checked the intake boot for cracks and found none there. Haven't checked the TPS (don't know how) or CPS (again, don't know how) and have not replaced the fuel filter. Yes, I do have a Bentley manual.

Thanks!

Dan

Jeron · Jeron's Garage

My ICV caused the engine to die at idle if I didn't use the throttle to keep the idle above 1k. It also caused it to almost die as soon as the throttle was applied but once the rpms started to climb the operation was normal. This sounds different than you problem but you never know.

There are tests for the various sensors in the Betley.

It wouldn't be a waste to go ahead and change the fuel filter.

Hopefully someone more experienced or with direct VANOS experience will respond.

dmurray14 · 08-31-2005, 08:37 AM

Got it, thanks. My idle DOES occasinally bounce, but I don't think that's my root problem. If it was the idle sticking, I would think it would be at least somewhat random and not as reproducable as this. With my problem, the car does it EVERY time, at EXACTLY the same RPMs in exactly the same way, which leads me to believe something is failing, and unfortunately I think that might be VANOS. Hopefully someone can help!

Thanks,
Dan

Wayne 962 · Wayne 962's Garage

Hi there. Welcome - lots of good people who know what they are doing here.

Most of the time when people suspect the VANOS unit, it's really not to blame. It's actually a very simple device - it's just an electrical solenoild connected to a gear. Replacement of this is expensive, and doesn't typically fix the problems.

The VANOS solenoid is connected in underneath the intake manifold - very difficult to reach, although you might if you remove the oil filter console and have skinny hands. As an alternative, you can disconnect the oil line that powers the unit, and plug both the line and the inlet to the VANOS unit. This should have the same effect as unplugging it electrically.

If the unit were failing, then it would be mechanically stuck open, advancing the intake camshaft and indeed, giving you reduced power on the low end. If you pull off the valve cover, you can indeed actually see if the unit is sticking too. See this tech article for instructions:

http://www.pelicanparts.com/bmw/techarticles/E36-valve-cover/E36-Valve-Cover.htm

Let us know what else you find out, and spread the word about the technical knowledge available here!

-Wayne

Wayne 962 · Wayne 962's Garage

Also, all bets are off until you pull the codes from the computer:

http://www.pelicanparts.com/bmw/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm

-Wayne

dmurray14 · 09-01-2005, 02:35 AM

Wayne,

Thanks for the great response. I have no codes stored in the computer, and I have yet to see the check engine light coming on. The syptom you describe is exactly what I'm experiencing - no power at all on the low end. At about 2.5-3k RPMs, a boost of power hits very suddenly, and then it its fine all the way up to redline. I'll have to give the valve cover check a try - I need to replace my VCG anyway - there is a small bit of oil in the spark plug holes. Once the valve cover is off, how would I be able to check whether it is sticking?

Again, thanks for the help.

Dan

Wayne 962 · Wayne 962's Garage

Well, if you take a picture of it, we can see if it's engaged or not (stuck open).

-Wayne

dmurray14 · 09-04-2005, 06:51 PM

Thanks...

Hopefully I'll get around to doing the valve gasket this week. All I need to take off is the valve cover right? What should I take pics of?

Thanks,
Dan

Wayne 962 · Wayne 962's Garage

[imghttp://www.pelicanparts.com/bmw/techarticles/E36-Camshaft-Timing/pic27.jpg[/img]

This is what I want to see...

-Wayne

P.S. For reference:

http://www.pelicanparts.com/bmw/techarticles/E36-Camshaft-Timing/E36-Camshaft-Timing.htm

dmurray14 · 09-05-2005, 08:46 AM

Thanks, Wayne. I'll try and get a pic soon - need to grab a gasket first.

Couple of questions - in order to remove and reinstall the VANOS unit - can I use the directions from steps 21 to 27 or do I have to do the other steps too? If that's the case, I think she's off to the mechanic. Don't trust myself with the other stuff.

Also - when the VANOS is disconnected - what does it default to - advanced or non-advanced?

Thanks again for the help.

Dan