AOS - Question
 

My son has a bad AOS on his 2003 base.
We have ordered the new part but it will not be here until Wed.

Here is the question.

1. Is he safe to run the car until we can change the part?
2. If not can he run the car if we disconnect the hose (and plug the port) going to the intake and leave the AOS hose open?

We don't want to damage the car but its his only form of transportation.

Please let us know.

Bart

How badly is it blowing smoke?

I would not run it. Besides evacuating vapors from the crankcase for emission purposes, the AOS also places the crankcase under a vacuum. This is important for the low tension piston rings to seal. If i am AFU I see JFP in PA is on and will correct me. :)

When you first start it there's a fair bit smoke. (smoke cloud)
After you run it for a bit it clears up.
Shut it down for 10min and it does it all over again.

Don't run it, it simply is not worth the risk.

Agree, Don't drive the car.!
Look at it this way, the part failed in a convenient location and has done no other damage.
Renting a junker or borrowing a car will still be cheaper than this repair would be if you had to get towed or pay a pro (no offense JFP!!).

Luckily, it is a pretty easy replacement on 2003's....all from the top. Get or borrow the hose clamp tool....you know, the one that has the extension to reach into places you can't get pliers on.

When you first look down at the clamps and bolts that have to be removed it will look pretty tough. Just be patient and you'll find you can get to everything without having to do anything special. A magnetic pick up tool helps to remove the AOS bolts you've loosened.

Put some protection over the trunk and fender as their's a fair bit of leaning over to get the AOS.

One of those little inspection mirrors will help a lot when replacing that lower bolt!

Don't run it! My AOS cost me my engine at 105K miles.

As others have said, don't run it.

Would you walk into a casino today and lay down a $5,000 bet? If not, then don't run it. If so, then it looks like the weather in Bracebridge is in the high 70's so it should be a perfect afternoon for a nice drive. :)

We have taken your advice and parked it until the parts come in.

Bloody dealers say this that and the other thing...

I gave him my spare car until I can go over it in the nest couple of weeks and bring it up to where we have a bench mark.

Once again we want to thank you guys for having our back!!!

Cheers!

Bart

well this is where were at...

I just changed the AOS and here is what we did etc.

1, Started the eng and we got less smoke than normal. (check eng light was still on) After 5-10 min the smoke was all gone.
2. let it ideal for approx. 15min
3. took it for a test drive. After approx. 3 mile. It was running rough, check eng light was flashing.
4. shut it off
5. restarted - running rough. shut it off
6. re started, started for home. It started to run better and the check eng went to solid and not flashing. Shut it off
7. Got home and re started. Runs like **************** and is making noises.

Here is the video.

https://vimeo.com/182244036

You will have to cut and past as I don't know how to make it an active link.

Please Help!!!

It ran perfect after the first fire up with the new AOS.
I have no idea why this is happening.

I'm assuming you do not have a Durametric, so what I'd do is pull your spark plugs, you may have fouled a few when ingesting the remaining oil while idling. Hopefully the banging and clanging is the DMF being thrashed about. Good Luck

Why is dmf.

DMF is dual mass flywheel. It is designed to dampen harmonic vibrations from the crank. Basically a sprung weight.

Your MAF could also be oily and needs cleaning. These are side effects of running with a failed or failing AOS (fouled plugs, dirty MAF) - oil gets into areas it shouldn't and causes issues after the AOS is changed.

Hello Muskoka Minute,

so the car did run well for a short time (3 miles) and than these noises and the engine light came up. That noise doesn't sound good.

That noise is not a DMF. You will hear a bad DMF only if you engage the clutch at the point between slip and engagement - mostly in first or reverse gear at lower revs.

What to do:

1. step)

• If you have a Durametric or any other diagnostic tool note all error codes and check their meaning.
• Unconnect the starter battery.
• Pull all spark plugs and clean them. There might me oil and crust on them. Check the electrode distance.
• Turn over the engine while the sparks are out. Aprox. 2 times for 5 seconds. Check if oil is coming out of the spark plug hole and how much.
• Put in all sparks.
• Remove the MAF and clean it.
• Remove as much of the air intake system after AOS and MAF and clean it. There will be lots of oil in it.
• Put everything together, connect the starter battery.
• If you have a Durametric or any other diagnostic tool reset all errors.
• Start the engine.
• If it runs without unususal noises or anything else – OK.
• Do a test drive.
• If you have a Durametric or any other diagnostic tool check error codes.
• If you don't have codes or anything else – repair done.

If you have the same noise and the engine is not running well like in the video, we have a bigger problem. In that case do not drive the car or start the engine.

2. step)

• Do a pressure test for each cylinder.
• If all cylinders are in the same compression range, use an endoscope to take a look at all cylinder walls.
• Drain the engine oil. Check what you find in the oil filter.
• Unmount the engine oil pan. Check what you find in the oil pan.

If can't find something unusual, start the engine and check if you can identify where that hard knocking noise is coming from / if you can locate it.

Hint: Don't do a compression test without engine oil in the engine. ;)

Hope you don't need to do the 2. step.

Regards, Markus

Thanks Markus I was trying to be optimistic that's why I said hopefully! I think there needs to be a sticky somewhere on the steps to take after an AOS failure, I modified your steps as a first attempt. Hope you don't mind


What to do: Do Not attempt to start the engine until all steps below have been completed as serious damage to the engine can result!

1. steps to take after AOS failure.

• If you have a Durametric or any other diagnostic tool note all error codes and check their meaning.
• Pull all spark plugs and clean them. There might me oil and crust on them. Check the electrode distance.
• Remove Fuel pump relay.
• Turn over the engine while the spark plugs are out. Aprox. 2 times for 5 seconds. Check if oil is coming out of the spark plug hole and how much.
• Put in all sparks plugs.
• Remove the MAF and clean it.
• Remove as much of the air intake system after AOS and MAF and clean it. There will be lots of oil in it.
• Install fuel pump relay. Start the engine.
• If it runs without unususal noises or anything else – OK.
• Do a test drive.
• If you have a Durametric or any other diagnostic tool check error codes.
• If you don't have codes or anything else – repair done.

Hi Guys,

We are currently trying out the procedure listed above. We swapped the upstream O2 sensors between bank 1 and bank 2 (bank 1 is misfiring). We cleared the codes for the vehicle and started it up. Still idling poorly and making the noise in the video above.

The CEL did not come on, but we are getting code P0012 which says "intake camshaft position timing -- over-retarded (bank 1)". Along with P0300, P0301, P0302, P0303. All relating to misfires of cylider 1-3 (Bank 1).

We have cleaned the MAF and now replacing all 6 spark plugs.

Is anyone familiar with these symptoms? Especially P0012.

Thanks!

Hey Sean; Before you reinstall those spark plugs, I'd recommend doing a compression test. If you do not have one there are loaners available from AutoZone, O'reilly's etc. Unfortunately it may be time to implement Markus' phase 2 plan. Hoping for the best!

Perhaps it would be useful diagnostic evidence to use a stethoscope to locate the exact source of the metallic clattering noise ?
The splash shield underneath the engine is already removed(?) so access is easy.

We just completed a compression test on all 6 cylinders and they are all reading ~210 PSI.

I have read some things about the camshaft variable timing solenoid. Should i be investigating this solenoid? I heard you can remove it, and apply voltage to them to see if they are actuating. Others mentioned about the VCT sensor?

Any ideas on next steps would be great. We are continuing on Markus' step 1. The oil was replaced a few weeks ago with the recommended Mobil One oil and a new filter was installed.

Thanks,
Sean

Hello SeanBuller,

problem is i don't have a conversion table from Porsche DTCs to OBD2 for the ECU.

This website lists the error P0012 as: A Camshaft Position (CMP) Timing Over - Retarded (Bank 1) P0012 OBD-II Fault Code, Camshaft Position - Porsche

There is a Porsche DTC 112 that says hall effect sensor 1. But that doesn't make sense, because if the hall sensor didn't work, the engine didn't run the way it does.

If somebody has a conversion table for OBDII to Porsche DTC and the 7.2 Motronic maybe i can help with the Porsche DTC part.

Important part before you change sparks is to turn over the engine without sparks, this way you get all oil out if the cylinders.

My problem is the hard knocking noise in the video starting at 00:20. That doesn't sound good. Can you locate where it is / was coming from? Sounds like a valve banging on a piston.

Regards, Markus

EDIT:
If all cylinders have 210 psi – good value, maybe a bit too high. ;)
Noise could be caused by a not properly working hydro.
Don't think it's a solenoid problem of the camshaft adjuster.

Hi Markus,

What do you mean by hydro may not be working properly? Is there any way to test this? Also what exactly is the hydro?

We just cleaned the air intake/throttle body and replaced all spark plugs.

Thanks,
Sean

Hello Sean,

by hydro i mean hydraulic lifter. Sorry, some german to english mistranslation. ;)

You can test hydraulic lifters. To do that you have to remove the camshafts first and than have to remove the hydraulic lifters. To do that you'll need some special tools. So this is more for the advanced DIY mechanic.

If you can hear that the noise is coming from the valvetrain, it might be caused by a valve or hydraulic lifter.

But before testing hydraulic lifters i would recommend to go through all easy to do test steps listed above.

If the noise does come from another part of the engine we have to investigate more into that.

At the moment i would recommend to let the engine run as little as possible and don't rev it up.

Regards, Markus

Thanks for all the help guys, we really appreciate it!

Update:

We cleaned the MAF and air intake (throttle body). There was a fair bit of oil in the tube, not quite a puddle, but it was definitely present. We replaced all of the spark plugs, a couple of them were quite black and have definitely seen better days.

We noticed that one of the hoses going between the intake and AOS was loose, so we believe this is the cause for the rough idling. When we just started the engine up, the idling seemed completely normal and only a little bit of white smoke came out of the exhaust on initial start.

We tried giving the car some throttle (around 1800 - 2000 RPM) and that rattling noise is still present. We are no longer getting any misfire codes, but we are still getting P0012, which is the intake camshaft position over-retarded.

Are you still thinking that it could be the hydraulic lifters? To me it seems possible that it is the timing sensor and/or solenoid?

Thanks again,
Sean

P0012 - how much retarded ? Need Durametric for that .Could the the solenoid btwn Exhaust & intake failed?

Hi Sean,

my opinion:

A timing sensor wouldn't cause a mechanical noise like that. The engine would just die.

A bad camshaft adjuster solenoid could cause a wrong timing. But to me it sounds more like a single valve problem than all valves of one cylinder bank or something like that.

Also if you would have a completely bad camshaft timing at one bank you wouldn't have perfect compression in that bank.

But it is always hard to do a diagnosis from a video. ;)

That is why i asked to locate the noise. And that is why i suspect a hydraulic lifter. Because if it fails there must be no negative effect to the compression.

Gelbster's question is also a good one. How much retarded?

Regards, Markus

Maybe the retard is because the knock sensor is being activated by the clattering?
Markus - insomnia?

Thanks for the prompt responses!

We do not yet have a Durametric, we will be able to determine how retarded it is once we get that information. It's hard to locate the noise as we are afraid to run the engine for too long. What are your thoughts on running it and holding it at 1800 - 2000 RPM while we locate the noise?

It makes sense to be the hydraulic lifter, but I am confused why the code is showing up saying P0012. Could that just be a red herring?

Gelbster, those are good questions. Unfortunately I don't know enough about engines to answer them.

Thanks,
Sean

In theory - and I stress theory! -you could disconnect the knock sensor on that bank and see if the retard goes away.
I would be too timid to do that. I would rather locate the source of the noise. Based on your video, it sounds too loud to be a lifter.One collapsed lifter makes a ticking noise.Your noise sounds 'bigger' like a heat shield/exhaust banging together. Hopefully not a bearing. But a noise generated outside the crankcase would not activate the knock sensor .
Before you start dismantling the engine, please understand this is not a simple task, nor inexpensive. Get skilled,knowledgeable help.The M96 is very unforgiving !

Unless I'm mistaken, the knock sensor only retards ignition timing, not cam timing. Knock is typically due to low grade fuel burning too early in the compression stroke causing detonation and piston knock. Cam timing changes optimize low end torque or high end horsepower.

Seems strange to have good compression, with a severely retarded cam. I might suggest pinning crank at TDC cyl #1, pull the cam plug and see how the timing marks line up. I would expect to see the bank 1 cam a few degrees off. I'd then rotate the crank 360 degrees while observing bank 1 cam and make sure it rotates.

Hello and good morning,

it's now 7:10 in Germany and i'm back. ;) But i have to go to work now.

To test the adjuster solenoid of the camshaft tension element electronically a.f.a.i.k. you'll need a Durametric or PST (Porsche system tester) diagnosis system.

I attached some infos concerning the components and diagnosis. Maybe this gives a better understanding.

I don't agree with Gelbster about the noise. This can be a single valve / hydraulic lifter – believe me, it can be this loud. ;)

The question is why it could fail in a wake of an AOS failiure? Maybe hydrolock. If there was enough oil in the cylinder to prevent the valve to open the hydraulic lifter could be harmed.

Another question. In the video the noise i'm talking about is starting at around 00:20. Is it always the same that the noise comes up some seconds after the engine starts. Or does it sometimes start directly with that noise?

Regards, Markus

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We are going to get the Durametric to see what this thing is doing.

Now the question is which one can I get away with?

The Enthusiast Kits or the Professional Kits

Please let us know.

Thanks for all the help so far guys.

Cheers!

The Enthusiast is good for 3 VINs where the Professional allows unlimited VINs. You only need the Enthusiast version. Call Durametric directly and ask if they have any refurbished. Did you pull the green cam plugs and confirm cam timing?

Not yet.
I have to do some more research on how to do that.
I'm also going to check the water pump tonight on the off chance.

double post

Cam timing is easy to check. No special tools required. Just have to buy the green cam plugs to replace the ones you pull.

edit: AND you don't have to run it to check it!

I don't think that noise is from the WP. My thought is that something Mechanically changed between the crank position sensor and the cam position sensor after AOS failure. Possibly from hydrolock, but first thing you need to confirm is mechanical integrity. Since the CPS gets signal from the flywheel which is bolted to the crank it is pretty safe to assume that didn't change. The mechanical relationship between cams and crank is maintained by cam chains and their tensioners. The cams could have slipped at their adjuster plates or the cam chain tensioner and/or ramp could have failed. Either one of those scenarios would cause the cams to be retarded. However with the noise from the engine, cam chain slop is more likely. Both of these can be visually confirmed or eliminated by checking the cam timing.

I'm going to check/adjust the camshaft timing tonight.
Can this be done with the spark plugs in?
or do they have to be removed? or does it just make it easier with them out


On a side note...
I found a used Durametric - Professional for $575 US plus shipping....
Seams like a lot of money...

I don't know what to do?
How imperative is it to have one?

Finding TDC is much easier with the spark plugs out. An easy method to determine TDC on the bank you are on is about 180 deg before TDC (pin location on crank) place something finger, palm etc. over the #1 cyl plug hole (you can even use your compression tester). Then rotate to TDC you will feel/hear the air escaping if you are on the correct cylinder (Rotate crank 360 degrees to check bank 2). DO NOT ROTATE CRANK BACKWARDS.

Personally I would wait on the Durametric until you confirm cam timing. And I see no reason to purchase a professional version unless you plan on advanced application such as writing/changing code to the DME. The Enthusiast will do everything you need to do and is new from Durametric for around $285.00 and is good for 3 cars and maybe more.
Again my .02 cents. Now where are the experts??? JFP, Jake I'm absolutely certain they have experienced failure modes due to failed AOS.