Jaybird123

I have recently concluded I need to replace my Bank 1 (passenger) Intake Camshaft Adjuster, given the recurrent P001177 code accompanying the cold start rattle. I'm not happy and a bit anxious about this repair. :/

My m278 falls into the 'needs tensioners, not check valves' group per later revision to TSB so I also have that kit on hand from FCP Euro. I already replaced the solenoids (with cable whips) and cam position sensors.

I bought the 2780504900 replacement adjuster, and the tool kit containing the T60 socket and camshaft lockdown bars...however I have seen a few different methods for adjuster replacement and I feel conflicted about best/proper approach. Any guidance most appreciated?!

IF I go the valve cover removal route, what other seals and tools do I need to have on hand? It seems a high press fuel pump gasket and something else related to fuel rail...? Do I need another T60 socket as well?

Is it even advisable to go a different (non-valve cover removal) route? While this job must get done, I do love my car and wish to get another 100k miles out of it if possible!

Lastly, I know there are several Youtube posts related to this job...however most are using the m276, and often with engine out of car. I need more clear real-world m278 advice/links/docs...help?

Jaybird123

Proceeding along with my m278 cam adjuster job...front cam plate removed, wiring harness, coil packs, fuel rail/injectors removed. Currently struggling with HPFP removal. Can anyone share tips/docs to assist here?

Incidentally, blunder along the way and now also earned myself a radiator replacement. Any doc on that also appreciated. Good times lol

@konigstiger @S-Prihadi

Siegmann

How far have you gotten with the HPFPs?

Jaybird123

Ha not far at all...I paused on pulling the Bank 1 valve cover until I finish the Bank 2 work. I foolishly considered Bank 2 the 'easy job' since I had no cam adjuster to replace on that side. Of course, now I'm replacing water pump, turbo coolant lines, oil filter housing gasket, and just finished swapping the cam chain tensioner! Once those steps are completed, I aim to resume tackling the passenger side. Make sense?

My biggest fear/confusion on Bank 1 relates to engine timing correction. I believe I have all the tools and replacement parts necessary, but I do not understand how to correct the timing. I know the mark is off on the broken intake cam adjuster, and the car wasn't running optimally. I can rotate engine to 40deg Overlap and see the exhaust cam mark in correct position...but that's where my knowledge/understanding ends unfortunately

Jaybird123

Folks, I need more of your wisdom pretty please?

I completed the cam adjuster replacement on Bank 1 intake, along with cam chain tensioner replacements on both banks. I also recently replaced all cam position sensors and solenoids.

Everything buttoned back up and I get the new (and only) CEL for p001685. I have also noticed a longer than usual startup effort (4-6 chugs before it catches) and my Eco button no longer lights up at ignition

I thought maybe there was some easy dealer STAR fix, but upon reading here I am growing more concerned...

I would also like to know if anyone can advise whether it poses risk to drive car with this current CEL/condition?

Chevota

I suppose it suggests a cam is not on the right tooth? or the something... I'd say don't rev it much past idle because at idle and in that general zone the valves are reasonably clear of the pistons, so even if off a tooth I'd imagine you're fine. If you rev it too high the cams shift and valves are closer to pistons. So you can see the issue if a tooth off puts them closer, then rev it right into making contact. Then you have to pull the heads, which I know you won't like doing.

If you get a cheapo OBD dongle and an app like Torque Pro, you can see the cam positions at idle. I bought a cheapo translucent blue dongle on Amazon for ~$10 and Tq Pro is ~$5? Cheap... It should tell you exactly how many degrees what cam is off.
Honestly it's been so long since I used that app I can't clearly recall seeing the cams, but I'm fairly certain. Even if not it's a keeper tool to play with. My other fave is Autel MaxiAP 200, which is like $70 and very much worth it for a variety of reasons. I see it's on sale: Amazon # B07QD4GZW4 If you don't have it, or similar, I highly recommend it. It's kinda a pita to use the price to power ratio is about as good as it gets.

At idle the intake cams should be 36deg retarded at idle, pretty much the entire time, so the valve opens 36deg ATDC. Ex should be 15-25 advanced, depending on what's going on, but basically 15-25 deg BTDC. So a nice wide zone of no risk.
Once you rev it a bit, and "if" you drop out of "idle mode", the cams move. The small charts are idle mode, the bigger are not idle mode, aka normal mode.
They base the values off of TDC, so Intake opening of 5 means it starts opening 5 deg ATDC. The Ex is based on closing, so a 5 would mean it closes 5 ATDC.
The Ex usually closes BTDC, so -25 is 25deg BTDC. As you can see there is no overlap, ever, more or less.
Point being, don't rev it, and certainly don't drive it, if you think you might be a tooth off. With that code, you might be...
Then lastly a chart showing cam duration, the mechanical min/max etc

Jaybird123

Yikes ok, it'll stay put until I can collect these readings. I have iCarsoft MBII, any clue if it will pull this data? I also have one of those wifi OBDII dongles...somewhere lol. I've used Tq in the past, never the paid version iirc

I did drive the car yesterday, about 20mi total, at speeds up to 60mph or so. I wasn't very hard on it but I certainly did have it up to 2500rpm or so...

Regardless, thank you for this very detailed and informative answer...I will dive in and circle back! I searched the code on here and found 8-10 posts...all dwindled off without any outcome shared dangit

Chevota

No clue on Carsoft, also no clue on the free Torque app.
You can see on the maps where it would've moved to. Note the % load is basically 100% = no vacuum or boost. Max torque at max oem boost is ~150-160%? Idle, for me is usually ~13% +5 for AC, freeway maybe 30-40%? It varies drastically, even a normal start from a stop can break 100%, so it's very easy to get either cam as close to the piston as possible.
That brings me to my next thought, considering you drove it, maybe the cam is not off but the actuator or pickup is bad, and/or not plugged in, or plugged into the wrong sensor.
I guess it depends on when the code appeared. If the cam is off, or bad pickup, then it should give a code in seconds. If the actuator is bad then it may read fine, until out of "idle mode" and it sees nothing is happening...

Apparently the metal part the cam positioner pickup reads from can move? I dunno the story but maybe it's just pressed on? Whatever the case, apparently it can move just from being in a running engine. So hopefully you don't use it to pry on anything.
Whatever the story, once you get cam position data with it running you should be able to narrow it down

Jaybird123

@Chevota @Westlotorn @juanmor40

I have pulled what I could find within iCarSoft MBII device and attached below. Please share any thoughts on relevance to P001685 code recurrence and long start issue?

I recorded 3x, before ignition, then upon ignition, then upon reaching idle rpm speed. I also found these Cam adaptation readings....very curious there!?


before ignition

upon startup (1275rpm)

upon idle (675rpm)

Cam Adapt screen 1

Cam Adapt screen 2

Jaybird123

My initial analysis based on another related thread over in BenzW says Intake value should be 36 with up to 7.5deg variance...I see mine at 43.75, indicating I am 0.25deg out of tolerance when above idle

Is this the issue needing corrected? If so, my next question would be whether it necessitates the manual reluctor adjustment effort (in lieu of cam replacement) or some adaptation can be performed with Xentry...?

edit: Clearly I'm the impatient type. Went ahead and gave the reluctor wheel 3 careful taps with a flatblade screwdriver. Now my reading is staying below ~42deg and no more long start or CELs! Fingers crossed it stays that way for a while

Chevota

I think +-7.5 error is pretty extreme, imo. One of my intakes reads ~1.5deg retarded, per the data, and it's buggin me. I assume the reluctor moved but I can't be certain. Or perhaps that cam is correct and the 1.5 is chain stretch, and the other cams reluctor is advanced that much to balance it out. Chain stretch is what I assume is causing your other cams to be off a bit. If so, then the bad cam is really more like 5 deg off, or 2.5 at the cam itself.

My question is how is it off, which would keep me up at night. Since that's the one you replaced, I worry maybe you did it, and if so, what exactly did you do?
I imagine the adjuster only goes on one way, right? So then I wonder if the adjuster itself was made that much off, which is a lot so I can't imagine, but certainly possible.
A tooth off should be 20 degrees, assuming the gear has 36 teeth? So we can assume it's not that.
Based on the limited info I have, my #1 suspect is the reluctor is off. So I wonder, was it off before and you just now noticed? Or did you do it by accident when you were in there? Maybe you used an impact gun on the main bolt? Or used the reluctor to hold the cam when wrenching on the bolt? I'm guessing here, but that's the stuff that comes to mind.

If the reluctor was moved, regardless of reason, then pounding it back is reasonable imo. I would move it all the way back because regardless of what the data says, the cam will be off by that much all the time.
The only way to check is to "degree" the cam. Basically you rotate the eng by hand and check for the moment the #1 Intake valve opens and see if it matches the crank position it's supposed to be at. In this case, 36 deg ATDC. It's a little tricky because the valve barely moves so it's easy to be off by many degrees. Hydraulic adjusters complicate that.
When I'd adjust cam timing, in old school engines with a fixed cam, 2 deg off from ideal was not ok and caused a noticeable power loss, 4 deg was unacceptable. So if one cam on my M278 was off as much as yours it, it would not only be up at night wondering why, but also wondering how much power it's costing me.

So if you feel good about it, I suppose I'd call it good. I, on the other hand, would have no choice but to degree it to be sure, and fix or adjust whatever until it's pretty much spot on.

Jaybird123

I hear ya, and I've been chewing on this quite a bit too. I certainly have a hard time enjoying my rocketship of a car while worrying that I am going to have catastrophic engine failure. Plus, I drive my kid places in this thing.

That aside for the moment...my logical brain says there is no reason an engineer would want this reluctor wheel to EVER move separately from the camshaft. It would completely defeat its signaling purpose to the ECU. However, it clearly can move. I must counter one point above...I didn't pound on it at all, rather I ever so slightly tapped on it and it moved a degree or so. Another two taps would likely have put it within range of Bank 2 values.

The adjustment immediately removed the long start issue, which leads me further down the rabbit hole of ECU-governed engine performance vs physical engine capabilities. There was no actual cam position issue that caused long start...only a wheel and sensor misalignment that told the ECU to perform ignition differently. Does a measured 1-2deg from 36deg baseline equate to any difference in other parameters calculated by ECU vs a 6-7deg variance? Does the ECU adopt a 'good enough, lets go!' approach if within the 7.5deg tolerance, or does it adopt a 'something is pretty off, let's reign in the 'x' and 'y' a bit!' approach...?

I would also LOVE to hear from anyone with knowledge about the Cam Adaptation functionality I noted in screenshots above...how do these values/settings impact ECU-governed engine behavior/performance? Should the Intake position adaptation be "On"?!

Chevota

I meant pounding etc when doing the original work.
The trim adjustment is normal, but it assumes the reluctor is correct. As long as you dont get a code I'd assume all is good, ecu wise. Then the cam will simply be off by the amt the reluctor is off and cause whatever issue that causes. Its not so far off that most people would notice, but I would.
My guess is the engineers wouldve wanted the reluctor attached better, but they have bean counters in the loop trying to save every penny so you get crap like this. I think they shouldve at least peened it, but that takes an extra minute and thus a dollar, cant have that... Better to have issues for the buyer, as long as it happens after the warranty.

Chevota

And yes, the adaption should be on. I assumed it was only off when it was too far outta spec. Should be working now?

Jaybird123

oh good point! I didn’t think to check it again, going to do so right now!