28B8 code ????

[wonton]

BMW 3 series E46 325i wagon 2004 72,000 mile

Just did oil change, mobil one, new filter, that's all.

After driving the car for 30 minutes, engine stumbled and got the engine light. Peake meter showed 28BC code:Exhaust camshaft bank 1: stiff
And a 28B8 code: Exhaust bank 1-mechanical.

I've read a few posts and the results were incomplete. I thought with this much time passed that more knowledge of these codes may have arisen.

I am wondering if the exhaust vanos solenoid was bad, that this could be the cause. Cam shaft sensor for this has been replaced in the past 2 years.

Did the following:

checked new oil level... on the button.
Installed new exhaust camshaft position sensor. (yes again).(purchased from Pelican)
Switched vanos solenoids to see if code changed from exhaust to intake. (It did not)
Tested solenoids and they actuated well.

Code 28B8 returned--exhaust side again. Engine rough at about 700 rpm.

Any thoughts would be appreciated. Thanks...

[wonton]

Problem Solved: (photos included)

Simply put; the piston that the exhaust-vanos-solenoid drives, (to direct the proper oil flow), was found to be stuck. After taking off the solenoid I put my finger into the hole and felt the end of the piston where the solenoid pin would usually press. It felt very solid–when it should have slid forward and then backwards when my finger applied pressure. Also it could not be pulled out with a 90 degree pair of long-nose pliers. I was gentle though, as I did not know the piston’s properties regarding how it really should be acting and what a proper method of extraction would look like.

I did have a novel solution to the problem. I have a tiny clip-clamp with rubber feet, (see photo), that happen to fit right onto the end of the piston, within the hole the piston fit into. I put a little wooden wedge into the clamp to make it seize the piston end more tightly. Then I rotated the piston back and forth and finally it came loose. Even when it was out halfway it was difficult to get it to slide. When it came out, I looked at everything about the piston very carefully, but the truth is, I found nothing that would account for the binding: no dirt, no jellie-fied oil, no wear marks or shiny spots on the piston surface. I cleaned the cylinder wall and nothing came out of the cylinder cavity either.

The aluminum piston appears to have an anodized surface. I was careful not to scratch it and cleaned it off, making sure no cloth or fibers were left behind–then poured fresh 5w-30 mobil one on it and re-inserted it very slowly into the cylinder. It took a little bit of gentle rotation and then it seated just fine. It went back and forth with a moderate amount of finger pressure. The spring end of the piston goes in first. If you test the spring before you put the piston in, you will know how the piston action should feel in terms of finger pressure.

After this, I put the solenoid back in, cam shaft sensor back in, reset the electrical connections and then started it up. It ran like a top, very smooth, no hesitation or shaking with the engine. Cleared the codes and went driving. Smooth running, no reappearing codes.

After driving it for a while, I realized that it had not idled this smoothly in my memory (of how this car handled in general). So I now think that there was already a piston issue and that somehow the oil change created the final event.

In reading other posts on 28BC and 28B8 codes, of which there have not been that many, I came across only one where a stuck piston was referred to. Most seem to have gone the route of a total vanos rebuild–which would work as usually everything is taken apart and cleaned. Also, it is disturbing that an engine of this caliber could turn into a hair puller from just an oil change!

Misc: The wiki on E46 BMWs says that you can get your codes read by going to AutoZone. I was denied this service, saying, “...we don’t do that anymore”. O’Reilly’s and Pep Boys, also here in the Los Angeles area refused the service when I went there. I am pleased that my Peake Reader, assessed the problem exactly... stiff mechanical–exhaust side. However, others recommended that one, “...put your Peake back into the glove box...” and get another reader to generate codes. I think this is still good advice, which I did--getting a P0014 from my truck OBDII. I went to Harbor Freight, that old standby to get some speciality pliers that would make de-coupling the BMW plug units easy. But, HF no longer carried these units I wanted. I want to lament here that many tools that use to be taken for granted in their availability to the general population, have disappeared due to many of our manufacturing jobs being shipped overseas, so corporations could make more money.

Finally, I never see it, but I think there should be some mentioned here somewhere: that DYI Car Service is something of an art form, and that there is something to be said for the quality of confidence that is established in the individual--upon solving a complex seeming issue, (even though it turns out to be extraordinarily simple). Simple does not mean easy. Solving my particular issue took a couple of weeks of stress and seeming dead-end conclusions. People did not seem particularly knowledgeable about this problem, and its always a bit depressing to set up and join a forum and then have zero responses to your well stated dilemma. But this is the nature of the beast. I would like to recommend, to those of you who have an interest, that you ready the book: Zen in the Art of Motorcycle Maintenance by Pirsig. It deals in quite an entertaining manner, with the issues of one’s developing a resilient mind, the inventor’s or trouble-shooter’s mind--that is so necessary to working in and solving problems related to car maintenance. This “mind”, often makes the difference between an outcome that is--to our dismay, not resolved, even at great expense, ie.: (“I took it to the dealer and even they could not fix it!”)–and the other outcome, which by patience and insight--the issues become fully worked forward to a successful conclusion. And in addition, your sense of well being and moving forward in the world is strengthened as well. I want to thank all those who did help me and were supportive even if their suggestions did not pan out.

[DJDV]

YOU ARE A GENIUS - THANK YOU SO MUCH FOR POSTING THIS THREAD !!

I have struggled with this problem for almost 6 months now not knowing there were pistons or Variable Valve Timing Solenoid Control Valves behind the solenoids.

I appreciate the time you spent to share your findings with the rest of the world.

Thank you.

David
Madera, CA

[Dmitry at Pelican Parts]

Really great write up and something that I'm sure other members will greatly appreciate (DJDV included ) - If you have other DIY articles that you've written, you may be interested in becoming a DIY Project Expert with us; if we publish your article, we'll give you a 10% off code. I've attached a link below if you're interested. Thanks again.

Enthusiast Tech Article Submissions - Pelican Parts


-Dmitry