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Hello everyone! I've been combing through the forums a bit and trying to diagnose some issues with my e39 M5 at 170k miles.. It's new to me and I noticed that at almost any RPM it seems to vibrate quite a lot despite the engine mounts looking like they are in good shape. It also has some kind of sound that at first I thought was rod knock, but I checked the oil, filter, and lower pan and did not see any metal (or plastic) whatsoever despite the oil looking like it had been run for 5,000 miles. The shop I had the seller take it to for a PPI didn't notice anything unusual with how the car ran, but as soon as I picked it up I noticed something did not seem right. I did my usual routine to check over the car and did a compression test. The numbers were all over the place (180 - 260) so I found the "TECH: How to accurately compression test an S62 engine" guide and followed it. What I found was the following:

Bank 1 (1-4): 185psi +/- 2.5
Bank 2 (5-8): 225psi +/- 2.5

The numbers were extremely consistent between each bank but strangely Bank 1 seems to be 40 psi lower. This alarmed me quite a bit so I went and bought a leakdown tester and checked both sides (cold):

Bank 1: <8% all cylinders
Bank 2: <4% all cylinders

I did replace the timing chain tensioner with a new one in case the noise I was hearing may have been related to chain slap, and it seems that the old one I removed had been replaced at some point as it was missing the metal washer on the cap. When I removed the old tensioner, it did not look like it was fully extended and may not have been providing tension to the timing chain (as if it was in the locked position while still new). The previous owner is said to have done the chain guides but there was no documentation for that, despite there being receipts for almost everything else. While the tensioner was out I was doing the valve cover gaskets as well and had a look into the timing valleys and saw no unusual wear or missing pieces of the guides, they did look relatively new for an engine with 170k miles. I'm suspicious that the timing on Bank 1 may have jumped because of this. You can also clearly hear the difference in the compression between cylinders when you crank the engine with plugs in and no fuel. It does not have the 'even' sound I associate with an engine in good mint.

The engine does sound a bit 'lopey' when it's running but that may have more to do with the aftermarket headers. I also am trying to verify the catalytic converters are still good as I am also suspicious one may be partially clogged (due to engine sound and also the car reeking of fuel when it runs.)

Also worth note there are no codes or CEL.

TL;DR version: It looks like Bank 1 isn't performing as well as it should but is still within spec. Is it possible there is a timing issue?
 

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Why don't you start thinking in a more basic way. The car has variable valve timing. Maybe you should start by confirming the the valves are opening when they should. This is a pretty complete forum and other than arguments on what oil you should use or which wheels are the coolest the next most popular topic is the Vanos. The vanos just has to work properly.
Look to see if there is a chance something is off in that system, I will venture a guess that the vanos has had no maintenance and that you still have more than half the original cps in the car.
Original Cps did not work correctly that is why they were updated, if you have original versions in the car then there is a strong likelihood the valve timing is off.
Start with an easy task and pull the bank 1 cps and see if they are old or new. easy to tell skinny are old fat are new.
946655
 

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Discussion Starter #3
For context, I've owned a number of e36 and e46 M cars, so I am not new to general BMW mechanical shenanigans like VANOS. I am new specifically to the e39 platform and the s62, however.

Followed your suggestion and the Bank 1 CPS' are in fact original. If I understood, your next suggestion is to replace both CPS' on Bank 1 and see if it turns up codes for timing issues?
 

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Followed your suggestion and the Bank 1 CPS' are in fact original. If I understood, your next suggestion is to replace both CPS' on Bank 1 and see if it turns up codes for timing issues?
No, well not really, I said if you have an old CPS in place you likely have errors. So are you going to try and fix things by leaving errors in bank 2? Replace all 4, that is one of the starting places for this engine. If your performance off with a lack of power? Then might as well order new MAFs as well. They start degrading slowly and people don't notice the difference. Put the old ones on a shelf and after the car is running better and you know more about what to look for you can put them back in as a test and look for the difference. Even if they are working it will not be a waste because they will go bad at some point, they all do. Again a starting point. After you do the vanos maintenance you should change the O2s because that is another starting point. There are things to look for to decide how old they are but likely they will be the ones the car was born with. All these things work with the Vanos and there is little help from the car deciding if the Vanos is working correctly, it just has to work for the engine to perform the way it was designed to.
It is an endless stream with this car because it is performance. It is just better to replace some parts to get yourself to a solid starting place. The differences are minor but very noticeable. There are so many parts on this old car that you will just have to replace to get it to perform like the day it rolled off the factory floor.
Your previous experience will help with changing components, but will not help you with the engine diagnosis. Dual vanos is a totally different beast, and relies on principles that are not part of previous methods.
 

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Discussion Starter #5 (Edited)
Replace all 4, that is one of the starting places for this engine. If your performance off with a lack of power? Then might as well order new MAFs as well.
I really do appreciate the insight, but shotgunning parts without a solid diagnosis is, frankly, a terrible idea. A MAF has absolutely no bearing on the static compression of an engine and gets me no closer to diagnosing and resolving the root issue I'm facing. If I'm still facing running issues after I have figured out why one bank might be mechanically compromised in some way, then yes, replacing the MAFs would make sense. I can understand the reasoning behind replacing CPS, as that will effectively be another diagnostic step.

I am looking for suggestions on diagnostics here. I own 4 20+ year old BMWs, I'm very well aware they're needy and expensive to maintain.
 

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but shotgunning parts without a solid diagnosis is, frankly, a terrible idea.
First this is not shotgunning parts. That is the collective knowledge of hundreds of owners on what works and must be done to these cars to make them preform. Do you have any idea how many times I have read your exact post in the years I have been here? I just read your exact post within the last month, but that user had come up with another near impossible idea that his newish flywheel must be to blame.
You likely have no idea how this vanos works, with all do respect. Unless you get the vanos working correctly there is a good chance you will have compression issues in the car. The way the exhaust transfer happens is in a totally different way than you will have any experience with.
The exhaust valves are closed early and compress that measured amount of gas, then the intake valve is held from opening until that stored energy of the compressed gas is returned to the system. If the intake valve opens earlier than it should the compressed gas released with a poof or if it opens to late draws a vacuum in the cylinder. Further if these things are not working correctly..... Sorry I just don't have the patience to do this for another time.
The MAFs and O2 sensors play a huge roll in how this all transpires, because how much exhaust gas is going to be returned is based on the air fuel ratio. since the air fuel is always trying to maintain a fixed rate and the chamber is a fixed size the only way to maintain that fixed ratio is to make the chamber smaller by adding exhaust gas to effectively make it smaller.
It is your car do what you want. You will never be able to diagnose your car correctly until you have all those systems working correctly.
Let me give you another hint because the car has sensors on the cams and the crank it likely could adjust things even if you were out one tooth, but you would have so many more symptoms that it would be easily identifiable. You would definitely get a correlation code every time you started your engine. You would at least if you had the updated CPS installed
 

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So, yes, the next step is to replace the CPS? Gotcha.
personally I would be pulling the vanos boards and doing the maintenance on them while I was waiting for the CPS. Although new CPS might reveal some codes there, the codes are only going to point you to the same maintenance. That maintenance has to be done before you decide on the next step anyway.
 

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Discussion Starter #9
personally I would be pulling the vanos boards and doing the maintenance on them while I was waiting for the CPS. Although new CPS might reveal some codes there, the codes are only going to point you to the same maintenance. That maintenance has to be done before you decide on the next step anyway.
This procedure?

 

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Discussion Starter #11 (Edited)
Pulled the VANOS solenoids and it looks like Bank 2 was definitely messed with at some point, as the dust cover had RTV and the board had extra pieces of RTV stuck on both sides... so it's probable someone only addressed one side previously. I am going to clean and redo the o-rings for both anyways. That being said they also completely destroyed a grub pretension screw for Bank 2 and it looks like they tried to hammer a 7mm allen into it before they gave up... should I try to drill and replace this to stop the solenoid from rubbing on the cover plate? I'm not keen on leaving it that way.
 

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I'm not keen on leaving it that way
It is up to you but you don't really have to touch it. The cover was bolted in place and looking at the marks on the bottom of the grubs they look like they had normal contact, if the same noid goes back the same way they came out then things should be fine. The grub screws were an update to stop the noids from rattling. They are not on the early cars. Usually you need to heat the grubs to get them out as they are locked in place. You could heat the one then drive a larger sized torx bit in heat again and it will come out likely. Drilling is higher risk but if you use a reverse drill bit you might get lucky and have it spin out while drilling.
You are in there to clean the inside of the noids not just replace the Orings. It is important that they all have a nice crisp click that is the same.
The paper gasket between the cover and vanos is merely a dust gasket it does not need to seal.
 

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You are in there to clean the inside of the noids not just replace the Orings.
Already cleaned them out and used high pressure shop air as suggested in other threads. It definitely made a difference in the sound, some of them I could barely even hear click until cleaned. Just waiting on o-rings before re-installation.

And I mentioned the RTV because I guess however was in before was not aware the gasket was just for dust, so that definitely tells me it was serviced to some degree.
 

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Just waiting on o-rings before re-installation.
I don't remember if this trick is in that thread, with the risk of repeating I will type it out anyway. The wires get pinched on more occasions than you would expect. The wires curve around one side of the noid. When you have placed the board, twist the noid to bring the wires closer to the noid, tighten effectively.
If someone "serviced" that board you might want to pull back the white wire sleeve and inspect those wires for pinching, very common mistake made by people.
 

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Discussion Starter #15
Alright, performed everything and still the same deal. No codes. Bank 1 lower on compression. Engine feels like it is running unevenly. Just to recap:

-New Timing Chain Tensioner
-Replaced Cam Position Sensors, Intake and Exhaust
-Cleaned Vanos Solenoids both sides, new O-rings
 

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So pull the plugs and take pictures but just replace them. If the exhaust valves have caught a bunch of crud from the valve timing being off it takes some time for that to fix itself but it does burn off. That would explain your limited leak on your leak down test. How long does it take for the pressure to fall? Were all the cyls the same or one worse than the others?
You should likely do a vanos test have you been looking for the software? It is out there just generally not talked about here. Other forums talk about them though. Ista or DIS. Inpa is also handy but it will not do the vanos test but with it you can read cylinder unrest.
 

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Discussion Starter #17
I put brand new BKR6EQUP plugs in (I do plugs as a habitual maintenance on new-to-me cars) and while taking them out lately I did notice Bank 1's plugs were already slightly dirty again after only running the engine for maybe 10 minutes total since they were put in. I'll get pictures tomorrow.

I didn't wait around too long on the leakdown but the pressures seemed steady even after leaving them for about 30 seconds. I did notice some hissing coming from the oil fill cap, but this was on a cold engine and it did it on every single cylinder, probably just ring gap. Between the cylinders on each bank the leakdown was incredibly consistent at around 8-9% on Bank 1. Bank 2 was about 4-5%.

I actually already have a dedicated troubleshooting laptop with INPA and did run the cylinder unrest (below) and I cannot for the life of me get ISTA to read my K+DCAN cable. I have a second laptop I'm putting Windows 7 on and I'm going to try again with a different distro of ISTA because I also need it for my e46M. I also have a couple more cables I'm going to try but I think they're all basically the same FTDI chipset.

When it's on idle it pretty consistently looks like this, with 3 and 2 being outliers:
946980

Anywhere off idle it cleans up almost immediately:

946981
 

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When you say off idle How much off? Looks a lot like a small leak in the high vacuum side/ICV section of that system. If you look at how the ICV feeds the throttles bank one can draw a small leak more than bank 2. As the leak gets bigger then we see bank two get affected. Depending on ho high the rpm was the throttles open and the leak becomes less significant and the effect goes away.
There is an elbow that cracks that joins the Evap system to the ICV, and it fails on these cars. My bet is yours is showing the first signs. We replace them with a metal one. Also the fuel pump vacuum line feeds bank one through a similar elbow both are worth checking and replacing because it is not if they fail but when they fail. The one part we just refer to as part 17, it is that common a failure.
You can see that if 17 leaks the two closest cylinders are 2 - 3.
Then the fuel pump regulator is here.
 

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Discussion Starter #19
Looks like after the last run all plugs look almost equally dirty for only ~10 minutes of run time. I'm guessing due to several cold starts and not being run up to temp for longer periods.

946995

946996


When you say off idle How much off?
Between 1000 - 2500 rpm.

I'll look at replacing the vacuum elbows the next time I have the plenum off. Do you have links or dimensions on replacements or is it just a "go to the hardware store" item?

My #1 concern is preventing catastrophic failure if there is an issue with timing having been skipped. Idle quality and running issues are tolerable as long as I know the engine is not going to risk bending valves. To that end I'm guessing the VANOS test should show if there's an issue?
 

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To that end I'm guessing the VANOS test should show if there's an issue?
Yes the test will tell you if the vanos is working and should detect if the valve timing is off. If you have all that stuff done now you would get a correlation code if you were out one tooth. People have in the past, that is not a guarantee. It is not hard to check the timing, but it is work and there are procedures that must be followed, and a wrench has to be ground or cut to fit.
If you are that concerned then pull the covers but there is more because the vanos has to be set in initial position so the marks line up. It is such a big job to do the chains and then set it up, it is unlikely a stupid mistake was made there and not seen. To get the marks to align you have to do it right. They may have been butchers but to get it close but not have it break would be as hard as doing it correctly.
As far as the elbows you can easily find those threads here, lots of them likely a search of keywords "part 17" will get you more than you want to read. Off hand I have no idea what size it is I use a parts store that comes to me, they either bring a selection or take the part and return with the new part the next day.I am awful at part sizes or numbers that is what I pay them for.
 
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