540i Problems

[ChrisMcC]

I have been lurking around here for a while and thought I had solved my problems by advice given to other members but so far no luck. Here is my problem.

I seem to have the rough idling problem associated with the PCV plate scenario that others have expressed in the past. Here is what I have done so far.

Replaced both O2 sensors
Replaced the valve cover gaskets. (oil around the spark plugs fixed)
Replaced the fuel pump.
Replaced the front intake manifold gasket and the intake manifold gaskets that connect the intake manifold to the rest of the engine
Replaced the fuel filters
Replaced the PCV plate
Replaced the PCV gaskets
Replaced the PCV pipe to engine and gaskets

The intake manifold seems to be sucking oil. The car also idles really rough when this happens. This only happens during cold weather and the problem is initiated when the car is warming up and the check engine light ususally comes on as soon as the car is about half way warmed up and the car starts running like it is only running on 4 cylinders. If I run the car for a few more minutes, the check engine light turns off and the car runs fine again. Sometimes, I can't get the light to shut off at all and it runs like crap. I would appreciate any advice that you can give me at this point.

Thanks,

Chris Mc

[MBXB]

I've got the identical problem. Right now, I've got the injectors being refurbed.
I did find the Idle Control Valve to be gunked up, and the O rings on the PCV vent pipe were leaky. The ICV was so seized up it wouldn't even rotate in the barrel.
Check your sensors?

[Loppy]

I'm no expert on this motor, but I am on small block MPI chevys. On them, if I did major work to the motor via vac leaks, sensors and whatnot, I would have to kill the computer and let it recycle before the engine would come back to life.

I know it sounds simple, but have you disco'd the battery for an hour or so and let the computer "reboot" if you will?

Does this help on this system? (for the gurus)

[632 Regal]

assuming that you no longer have leaks, which you still might, the only things left are the ICV, coil packs, injectors and spark plug boots.

since it clears up at times I wouldnt think its a nikasil issue but a leak down test would confirm mechanical damage.

[tim]

A clue to the problem may be the fact the car runs in "sport mode" until it is warmed up (i.e.: the o2 sensors start signaling.) In plain english, the mixture is hard set at "rich" until the o2 sensor feedback loop, called "lambda" begins. It can take alot of time for the o2 sensors to warm up, even when it isn't cold out, but even longer of course if it is below freezing. You also didn't mention if you had run the codes. I'd like to know if you are getting a 1221 code.

The valves on your car are "VANOS", which basically means the intake and exhaust valve clearances are hydraulically actuated and continuously variable, and there are two, one for each bank. In the absence of the Lamda signal from the ECU, both banks are on fixed timing. Not that it is common by any means, but perhaps that would be a place to investigate- i.e.: maybe one is slightly off. You mentioned it sounds like it's running on four cylinders, and if the static timing were off enough... and that would help explain why after warming up it runs fine.

Unlike the m30's and m50's the PCV plate does not exhaust back directly into the intake manifold all the time, but rather the plate acts as a filter,( as Ramon said, it can get really gummed up) which maintains a certain level of crancase pressure, and vents only when a certain pressure is exceeded. I doubt you're bathing the intake manifold in crancase vapor unless your rings or cylinders were heavily damaged, and allowing constant blowby. Sure, the ICV gets greasy in time, but I would think a problem in that area would manefest whether it was cold or warm.

You didn't mention whether you changed the plugs. I have had cars improve greatly by just going back to the stock, two-electrode (f7ldcr), away from the ngk 4 electrode style or any of the various platinum "upgrade" plugs. Not a knock on NGK by any means, just an observation.

After all the work, did you do the "shogun reset"? If not- do a search. It has done wonders for some. It's a standard procedure for me, and I do it anytime I do something that requires cutting the power supply.

Finally, on a YMMV basis, I have had great success in cases of leaky injectors, carbon buildup, etc by doing the "seafoam" treatment. Look, some people think it's ********, but I think this stuff is truly valuable and not some mystery snake oil. Do a search on that. I'd remove the connection of the rubber fuel hose to the hard hose, over by the fuse box, and flood the top end with it-( I mean a couple pints here, not gallons!) wait awhile. start it up in a *well ventilated" area! you won't believe the smoke. Alternatively, you could wait until the last gallon in your tank, put in alot, and then give it an italian tune-up, btu I don't think this works as well as letting it sit in contact with the injectors and valves for awhile. Then change the plugs, change the oil, do the Shogun reset and see where you are.

I'm sure some greater minds will chime in soon so good luck and welcome.

edit- oh yeah, what Jeff said too! I just saw it after my post came up.

tim

[DaCan23]

Whats YMMV?

A clue to the problem may be the fact the car runs in "sport mode" until it is warmed up (i.e.: the o2 sensors start signaling.) In plain english, the mixture is hard set at "rich" until the o2 sensor feedback loop, called "lambda" begins. It can take alot of time for the o2 sensors to warm up, even when it isn't cold out, but even longer of course if it is below freezing.

The valves on your car are "VANOS", which basically means the intake and exhaust valve clearances are hydraulically actuated and continuously variable, and there are two, one for each bank. In the absence of the Lamda signal from the ECU, both banks are on fixed timing. Not that it is common by any means, but perhaps that would be a place to investigate- i.e.: maybe one is slightly off. You mentioned it sounds like it's running on four cylinders, and if the static timing were off enough... and that would help explain why after warming up it runs fine.

Unlike the m30's and m50's the PCV plate does not exhaust back directly into the intake manifold all the time, but rather the plate acts as a filter, which maintains a certain level of crancase pressure, and vents only when a certain pressure is exceeded. I doubt you're bathing the intake manifold in crancase vapor unless your rings or cylinders were heavily damaged, and allowing constant blowby. Sure, the ICV gets greasy in time, but I would think a problem in that area would manefest whether it was cold or warm.

You didn't mention whether you changed the plugs. I have had cars improve greatly by just going back to the stock, two-electrode (f7ldcr), away from the ngk 4 electrode style or any of the various platinum "upgrade" plugs. Not a knock on NGK by any means, just an observation.

After all the work, did you do the "shogun reset"? If not- do a search. It has done wonders for some. It's a standard procedure for me, and I do it anytime I do something that requires cutting the power supply.

Finally, on a YMMV basis, I have had great success in cases of leaky injectors, carbon buildup, etc by doing the "seafoam" treatment. Look, some people think it's ********, but I think this stuff is truly valuable and not some mystery snake oil. Do a search on that. I'd remove the connection of the rubber fuel hose to the hard hose, over by the fuse box, and flood the top end with it-( I mean a couple pints here, not gallons!) wait awhile. start it up in a *well ventilated" area! you won't believe the smoke. Then change the plugs, change the oil, do the Shogun reset and see where you are.

I'm sure some greater minds will chime in soon so good luck and welcome.

edit- oh yeah, what Jeff said too! I just saw it after my post came up.

tim

[jjw]

Have you check the codes?

[tim]

Whats YMMV?

"your mileage may vary"

generic disclaimer of responsibility.

-tim

[DaCan23]

Ahh... I love acronyms.... my GF hates, hates, when I use them....

"your mileage may vary"

generic disclaimer of responsibility.

-tim

[ChrisMcC]

Which one is the ICV? Is this the idle control valve? If so, where is it located. I do not see it on the engine diagram I have.

94' 540ia

Thanks,

Chris