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550i LCI project has me pulling my hair out

3K views 43 replies 6 participants last post by  spoonsc1 
#1 ·
Hey guys, its been a minute since ive been back here but im over my head.
I just picked up an 08 550i with the sport trans. picked it up with a transmission not going being able to select a gear, but now I have done a deep dive and finding a lot more things. like the engine is lucking to be idling, starts up good, then it idles down and a little after that it goes to hell. engine barely stays running, I get misfires all over mostly 5,6,7,8, all at once. I have noticed it is when the valvtronic motors spin down it turns to crap. I have already pulled the valve cover and inspected the system and all I can see was the chain tensioner is very weak. I don't have timing tools to verify timing so I have no info for that yet.

could a weak tensioner cause this? or could it have slipped timing?

I have other issues I will be back for that later!

I am using maxisys pro for data and coding.

thanks guys
 
#5 ·
ok so here is the latest. I put the VC back on after inspection, seems very clean, I pulled the vanos solenoids hoping to find the screen full of crud but barely anything. swapped the intake/exhaust locations on that head, calibrated valvetronic end-stops. started it up and waited for the warm up that usually led to the horrible running mis-fire nightmare. it never did, checked the cleared codes and had only 2A85 code (Outlet-VANOS variable cam control test) but I am unable to clear that. the engine seems much smoother, not perfect, and the throttle response seems sluggish from hitting the gas to when the engine actually revs. not sure if this has ever been lived through by someone but any info would be great,
oh and I will be ordering new solenoid orings and cleaning them, the vacuum pump orings and the valvetronic motor orings so maybe I can get the engine sealed up better.
 
#6 ·
UPDATE:
so I got the transmission finished, had to replace the #4 solenoid, replace pan/filter and fluid, no trans faults and it shifts into gear normally. I replaced the valvetronic actuator seals both banks (learned end stops), replaced the vacuum pump seals and removed, cleaned and checked with 12 volts the vanos solenoids, and reinstalled with new O-rings. started it up the first time when servicing the transmission and seemed to have run great. had a little roughness to it but revved pretty good. later on I started the engine again to check the status of the active cruise control sensors and after idle down the engine missed like crazy! since I had the scanner in hand I checked and found the entire bank 2 was misfiring (5,6,7,8, plus the multiple misfire code and a 2A85-DME exhaust vanos activation). then as fast as it came it was gone and the codes cleared themselves. what can this be? could I have an intermittent cam pos sensor?
 
#8 ·
I did not ohm the coils but I have swapped them around and the problem did not follow. I am also going off of the unlikeliness of 4 different components to fail at the same time and then all be fine at the same time when it runs without the faults.
I have a chain tensioner, O2 sensor and cam sensor on the way. the chain slaps pretty hard on start up and feels weak, the O2 numbers seem pretty different between the two banks, correct me if I'm wrong but seems like after start up and idle down the DME switches to open loop and turns to garbage.

thanks again guys, any and all information helps
 
#9 ·
UPDATE:
I am closing in on these issues. I was on the right track with the change over between open and closed loop, I swapped out the O2 sensor on that bank and put a new chain tensioner in for that bank also. started up and the same misfire thing happened, then I pulled the scanner out and cleared the codes while running and BOOM, settled down smooth as glass. has a little ticking going on that bank near the timing chain so I can only assume the slop and 175K miles has the chain less than perfect. revved awesome!!, I was so excited!! BUT THEN,..... I turned the car off to do some things and came back to start it and right back to the rough idle, scanner said the same misfires and once cleared, smooth as glass again.

what can be happening on warm start up to have that bank knock enough for the DME to cut off those injectors? I'm surely not going to drive this thing around with a scanner to clear codes all the time!!
 
#11 · (Edited)
the car misfires and run like garbage, while its running I can clear all those misfire codes with the scanner and I smooths out. a shut down and immediate restart nets the same thing, flashing MIL light and same misfires on the bank 2 ( 5,6,7,8 cyl). clear it with a scanner and back to being smooth again. plugs are all new and the coils have been swapped to the other side and didn't follow.

I also checked out the smooth running values and bank 2 stayed all negative .35 to .58 while the bank 1 stayed positive .39-.46

I decided to change the minimum valve lift from the valvetronic system from .3 to .8 mm to see if the system has some wear and if it gets better, and it did. the rev is not as smooth, but pulls through it and the smooth running values are a lot better. (sideways pic is min lift of .8mm)

if I don't end up with a smoking gun soon I may end up getting rid of this rag even after I got all the other things fixed, without a smooth running engine is all for nothing.
 

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#12 · (Edited)
shift your attention to the timing part of the ignition

your problem is not coils, its not plugs,

its timing

the reason you know its timng.. is because you have cut off.. so the Dme can see

but you have a timing issue that is realated to temperature?

what tells the temp,
who needs to know what temp they are at?

you need to think like the computer

I like to run fuel pressure test when i have unknown ignition issues *everything you have done so far should have taken about 45 min if your going to sell this job (*back to the service writer)

your 2a85 code is the cam sensor screaming @ you


if you made a video people would hear it and say...
 
#13 ·
Burning2nd
Thank you for your involvement with my post, I have seen your advice on many others and I was hoping you would show up with a one word solution!! that first code of 2A85 has never showed up again since that one time I have posted it, so to be fair its not screaming much anymore so I assumed it was a nuisance code since it never returned. I to have been thinking about the timing, however I was trying to cover absolutely every base before I start purchasing super expensive one time use tools, expensive timing chain kit just to find out it is something else and would have been cheaper and faster to buy another motor and swap it out.

so as of now, before I up'd the minimum lift to get more data, on start up, at the idle down it starts to miss, engine light flashing and barely idles. codes are: mult misfires, almost always 6,7,8 cyl misfire, sometimes all four of that bank, as soon as the codes clear the engine straightens up. and if I shut down and start back up immediately, same thing, rough, light cleans up after clearing the code. now since the min valve lift has been increased I can start without codes, just not as smooth of a rev.

As far as the temperature related talk, im not sure what you are referring that to. a cold engine or warm engine on start up yields the same misfire.

I guess I have to make a decision on timing tools and chain/guides, or something else

thanks again
 
#15 · (Edited)
Ooooooooooooh.
I guess I will need to look into that, never considered that. I guess I will start researching that and what can be done concerning the electronic ignition.

I guess since the DME dictates through spark maps it can only be sensor error...***8230;***8230;sound right?

thanks again
 
#16 ·
Just to clarify I misspoke about the changed min valve lift not causing the misfire on start up, its the same. started today and just a minute into it, it pulled the same misfires on bank 2.
 
#18 ·
i will pay more attention to it but I don't remember seeing any crazy indication on the scanner, and started leaning toward the timing chain slop and possibly worn or broken guide. I do have a new cam sensor to install if need be, maybe I will look at the other crank sensor as well.

thank you
 
#19 ·
Hey guys, little update while waiting for crank sensor to get here.

I double checked fuel pressure at the rail and it was a solid 50 psi, I installed a new cam sensor in the bank 2 side exhaust, ran it and kept moving sensor with no change. I did check a few more things on the scanner and noticed the spark advance was showing over 186 degrees! sometime over 190. I hope the crank sensor fixes everything, because this particular car is testing me. after clearing codes it seems to settle in a more normal advance 10-15 at idle. graphs still show a spike once in a while, but im crossing my fingers
 
#21 ·
I understand and I am not equipped with a scope to do so, but thank you for your time, and let me know when you will be in SC!! :rofl:

thanks everybody, if I stubble across a repair I will let you know
 
#22 ·
For those still interested and watching this post,
today while waiting for parts to get here I decided to try something for troubleshooting purposes.
before starting the car for the first time today, I disconnected the valvetronic servos, manually ran them to full lift, 9.6 verified by the scanner and started the engine.
the engine started up, stumbled a second until it figured out it had no control of the valvetronic system and idles pretty good. revs with a small stutter with a quick snap of the throttle but revs smooth after.
only codes are the 2 servos disconnected, no misfires like before

not sure what this tells me but...***8230;.its something
 
#23 ·
What this is saying is how the programing is responding to the timing.....

honestly i think you have pressed to many buttens.. and flipped to many switches...

right now its hard for me to even follow what has been done..

a clear start, with proper code clearing, proper data retention, and proper live data.. Is what is needed...

i have faith in you though, you have the info.. your just struggling to put it all together,
 
#24 ·
What this is saying is how the programing is responding to the timing.....

honestly i think you have pressed to many buttens.. and flipped to many switches...

right now its hard for me to even follow what has been done..

a clear start, with proper code clearing, proper data retention, and proper live data.. Is what is needed...

i have faith in you though, you have the info.. your just struggling to put it all together,
Again I appreciate all the help I have gotten from everyone here, as far as just mashing buttons and flipping switches I have not made any changes or thrown parts at the vehicle. I believe I methodically NDI'd (non destructive inspection) the problem areas. I started with an unkown condition of an engine, pulled the codes on start up, led me to misfires, and knowing before I posted anything that everyone is rock hard about batteries, coils and plugs so I inspected the plugs, replaced and relocated coils and documented locations. that was the first logical step, problem remained.
inspected eccentric cam and timing change due to slap heard and found a weak tensioner, which was replaced and repaired the slap. original misfires 5,6,7,8 remain. noticed the O2 sensor on bank two not with in limits and replaced which did clean up the roughness and indicates correctly.
going off of suggestions for timing I payed more attention to cam and crank sensors, found all data seemed normal I picked up a sensor to allow troubleshooting which has netted no faults found.
bumped the min valve lift up to check for the possibility of wear, netted no positive results and back again to original settings.
just today I disconnected valvetronic to and ran them to max lift and all problems seem to be gone. I believe this is all good data, maybe I could have saved a few dollars if I would have noticed something on a scanner before I bought anything but now I have spares and a good piece of mind that it has been checked.

I guess now I need to figure out what data I need to observe and what systems are included to control the valvetronic system. and what is out of spec. I can only assume is I am still finding no erroneous indications, the valvetronic control module may be faulting if all indications are good.

I appreciated everything I can get off this site, as an aircraft mechanic/troubleshooter, car guy and only dealt with M54's valvetronic system is new to me, but I feel im am totally green at all this, just learning more stuff
 
#25 ·
For the guys following this post.
after more and more research I decided to disconnect the VANOS solenoids as other have in the past to disable the valvetronic system and set the VANOS cams to a null position.
well this thing is smooth as glass, started great no hicups, idles smooth and runs great.

looks like since the problems were only bank 2 side, I can only assume this is indication eccentric cam or lever wear, or VANOS cam gear issue.

I believe I will just stare at the check engine light and drive until its engine change time.

thanks for all who posted, I was able to rebuild the drivers seat, troubleshoot and fix the idrive controller and navigation issues, repair the transmission valve body solenoid all while trying to figure this engine out. thanks everyone!
 
#26 ·
Just to add some more info for future use,
while I was messing around with the car today I found what may be a more accurate lead on the issue.
I moved some things around and reconnected the VANOS solenoid and accidently left the MAF disconnected and the codes popped up that may be a clue.
2A8D exhaust VANOS adaptation stop 2
2A91 exhaust camshaft 2 tooth offset to crankshaft

sounds like it is indeed a timing issue, whether it is mechanical or electrical timing, maybe I need to clear DME RAM.

As I continue I will keep this chain updated
 
#27 ·
How much was this project car?
 
#28 ·
Just now seeing your project thread. Following intently!
Looks like yours is a bit further along than mine. I was just about to mention maybe the VANOS solenoids arent actuating correctly, but youve already gotten to that point.
Great that it smooths out when you eliminate those features despite the CE light.

I would have expected that crankshaft code to show up a long time ago if the physical timing is an issue. Unfortunately you have to deal with the valve covers to confirm it...yikes

Good luck!
 
#31 ·
where do we stand with the cam and crank position sensor?

this motor you rebuild correct?

How did you set the pulse trigger wheel? the 2a91 code
Looking at all 4 cam positions and that adaptations I do not see anything abnormal from one another other that a larger split between adaptations. the crank sensor is new and I have a new cam sensor I put into rotation of positions with no "ah ha" moments.

this is NOT a rebuild of mine. I purchase this because of a trans will not go into a gear or leave park, shifter outputs where good, so I dropped the mechatronics and found an open solenoid number 4 and replaced it with a spare solenoid from a different job and new filter and fluid.

the running rough is not just a tune up like I was told, I see new valves diaphrams for the pcv system and a few other things that lead me to believe there was prior knowledge of this engine issue.

not sure where the spark advance gets is position signal from but my scanner shows the advance over 180 degrees at times.

beginning to think it is a physical timing issue, since the exhaust side is the longs side of the chain with a slide on that side, if that fails that extra slap may cause something like that.
 
#32 ·
#34 ·
I had mentioned verifying the cam advance earlier but didn't have the tools, I will get them now.

the underside of the oil cap is clean, not like my 02 525 cap!!

but to add to it, not sure if I had mentioned it earlier but I did change the chain tensioner because of a chain slap sound on first start. old one was pretty weak, but I still get the slap on first start, not as bad, but still there. that's why I mentioned the possibility of a chain guide being damaged on the long run side (outboard) allowing more slack than the tensioner was design to soak up. but that is just a brainstorming idea.

new oil change thinking maybe things got botched on the last one since the gasket wasn't even on the plug and leaking. no joy

but it is definitely only runs better after disconnecting the left side exhaust vanos solenoid. wont run if any other is disconnected instead of that solenoid.

whatever it is, it affects all 4 on that side so the cams are very suspect.

thanks again everyone, I will keep all informed as thing move forward.
 
#36 ·
What are your thoughts on oil pressure issues? is there any typical issues with that or a failure point? or is this just an educated guess with the discrepancy?

also, if you are keeping up with this I found the right side cams out a bit

thnx
 
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