kevm14

Was bored and poking around Xentry while my E63S continues to sit in the garage for the winter.

Car has 103k. Curious what people think and what your values are. Obviously that left intake is on a path that concerns me but I think this is about where it was when I bought the car last year. I did replace all 4 of my cam position sensors last year and didn't attempt to make it relearn anything but again I think the values are about the same as they were then. I didn't document it, though.

Anyway I assume the limit is about 6 degrees before it starts throwing cam correlation codes. Thoughts?

JettaRed

iTrader: (1)

This is from my M276 3.0 bi-turbo (45k miles), but I have similar readings on my M276 3.5 NA engine. They both have one value that seems whacky. The left intake for the bi-turbo.

JettaRed

iTrader: (1)

Here are the readings from my M276 3.5 NA engine. 124k miles.

Chevota

One of mine reads something like 1.5 deg off but it's not like I'm going to pull the valve cover off for that. If I were 4 deg off I'd probably dig in there, especially considering it'll only get worse with time, so that would help push me to do it. If you're down for the winter then now is as good a time as any?
I can retard my intakes 4 deg and I think it helps at peak power, but really hard to tell and might be my imagination. I adjust 8 deg and I can't tell it's any different than 4 deg. So I leave them 4 deg retarded at peak rpm and tell myself it helps, but who knows. I've never retarded it at lower rpm or loads, which would no doubt cost power because advancing them does help a little.
At 6000rpm your cams are 12 deg more retarded than my oem settings, so an additional 4 on top of that I dunno... Probably no big deal but only one way to find out.

kevm14

I thought since the ECU knows about this, it compensates. My cam timing should be the same as everyone else's, no?

JettaRed

iTrader: (1)

Except no one's is the same, at least between @kevm14 and me. We need more people to post. My first reading (M276 Turbo with 45k miles) is using XENTRY and the second (M276 NA with 124k miles) is using my LAUNCH Creader Elite 2.0 BENZ. My "high" numbers are Left Intake and Right Exhaust. Go figure.

kevm14

That's my point. The entire purpose of this value is to denote actual cam position vs expected (based on crank position), and then use those figures as an offset while operating the adjusters. This works within a set range (such as -6 to 6 degrees, and then would set a CEL beyond that, and sometime beyond that, probably hit mechanical limits of the adjusters).

The only way to fake it would be to slip the reluctor on the cam, to lie to the ECU about actual cam position. Then you could claim there is a set advance or retard beyond factory intent.

Chevota

That plate is why its off, so dont look at it as correcting xx degrees but rather making it wrong by xx deg.

kevm14

So you are saying that deviation on my left intake is actually a slipped reluctor plate and my cam timing is wrong on that cam as a result? Very interesting.

That leaves me with two questions:
1) Is there a way to "tap" those back into submission without taking the top of the engine completely apart?
2) How can I use this data to assess timing system health? Chain, gears, guides, etc.

I guess another question is, are positive numbers retarded and negative advanced? I am trying to pull from my tuning days where advanced ignition timing was actually degrees before top dead center (meaning negative, though we usually spoke it as "20 degrees"). This is cam timing so maybe my brain has it backwards.

juanmor40

Deleted because of duplicate when editing

juanmor40

NOTE: I have not done this, so take it with a grain of salt.

Let us assume the camshaft, reluctor wheel, and the adjuster were a single rigid piece with no play. When the engine is timed correctly, and we look through the camshaft position sensor hole, we should be able to see the reluctor wheel empty section, and the edge as shown in the picture (taken from BenzWorld https://www.benzworld.org/threads/m2.../post-18455486 )




I assume that the position of the edge must be unique when the engine is on time, no stretched chain, no slipped reluctor wheel and any discrepancy should be associated to damage somewhere. Possible sources of damage:
1 - Chain stretching. possible, but I would say unlikely unless engine has been mistreated for a while and lot of mileages.
2 - Slip between the VVT adjuster, and the camshaft itself. Nearly impossible since there are two locking pins, and the valve is tightened to 130 Nm
3 - The reluctor wheel slipped, . Likely the problem

Q: is there a spec anywhere is WIS about what we should expect when looking through the Camshaft Position sensor port holes? Listen to the video explaining the 53-degree crankshaft positioning and the CPS port hole view.

If the laser marking between the wheel and the reluctor wheel are still there, we need to remove the front time covers, and the VVT to see the front markings. If there is a back marking, we need to remove the head covers.

I am open to being corrected/taught on this topic since I need to be ready when the time comes for my M276s. I am aware how the reluctor wheel marking should be flush with the head surface, but the covers must be out to see those. See below

kevm14

Check this out.
200k mile early M276 with apparently a slipped reluctor. They tap it back into position through that inspection hole.

Chevota

yes, the plates move so you dont really know wth is going on. the giveaway is when one doesnt match. yes you can move the plate back but the question is; are there marks so know where it goes, and how to lock it from moving again. you only need to remove the valve covers btw. if i ever do mine ill post if there are alignment marks, and can i just peen it to lock it forever or what?
On the intake 30 degrees is more retarded than 20 degrees. on the exhaust -10 is more retarded than -20. fun huh?
its because they count int at moment of opening and ex at moment of closing and 0 is tdc opposite the firing stroke. so 5 int means it opens at 5 atdc. a 5 on ex is it closed 5 atdc. -5 int is opens 5 btdc and -5 ex means it closes 5 btdc.
id assume the adjustment #s follow the same rules but who knows.

juanmor40

That will be a temporary solution since the more we slip the wheel on the camshaft, the less friction the next time around -> faster to slip next time.

The solution, my guess, is a weld spot. Not a chance from the port hole.

kevm14

Wishful thinking alert: a failing adjuster can cause hammering action to accelerate. Also, poor oil pressure at the adjuster may also result in a similar hammering action as opposed to smooth, in-control operation.

kevm14

Ok running with that for a moment, my left intake value of 3.87d means that my driver's side intake cam is 3.87d late (which I guess means retarded but I think I prefer "late and early" terminology in this scenario). And my left exhaust value of 1.54d means it closed late so, again, retarded. Meaning the reluctor slipped "backwards" against the direction of rotation, in both cases.

Also, if this is true, what impact does it have on engine characteristics?

Chevota

I'd assume the cams aren't actually too far off and the plate on that oddball needs to be moved to match. If you want to see how far they're really off it would be rather involved.
In the pix of mine below, at idle, it's supposed to be 36 & -25. There is no adjustment happening here, this is against the stops. So when I see 35 and 37.5, well, wth am I supposed to make of it? Maybe there's 1.5 chain stretch and 37.5 is spot on and the plate slipped 2.5 on the other one. Or maybe the 35 is accurate, or maybe both are physically at different random spots and each plate may or may not have moved and ended up with these #'s.
People assume the factory installed them perfectly in the first place, but I don't believe that for a second. From their perspective it doesn't matter if they're a few deg off because the adjustments will take care of that. Well, assuming the plates don't move, which is exactly what they thought. So maybe your plates haven't moved at all and that oddball is just how it always was. Or maybe there's factory error, plus chain stretch, plus the plates moved.

You could degree the cams but that's involved, and the TDC mark on the balancer is probably wrong anyway. Even you did degree them, can you adjust the cams if they're off? I don't believe you can without modifying them, but if you did you still have set the plates perfectly of it won't work. Or if they're all off + or - some random degrees, accurate plate position on each cam is still all that matters. The only realistic way to do that is if they have marks on the cam and plates for alignment.
I'm hoping someone will chime in to say yes, or no, on those marks, because someone here has been in there and knows, just have to get them to respond.

Otherwise I'd just tweak the one plate so it's error matches the others and assume the end result is better than it was, but it's just an assumption. To know which way, I'd simply move it the direction that makes the most sense, but I'd rather use the method below:
You can check to see how the plates on the intake cams match, and the ex cams match, as viewed from the pickup holes. But keep in mind there may be some, or a lot, of play in the cam while trying to do that. The cams like to jump around as you turn the crank, then you have to wonder, does the chain have tension or slack? Does the locking pin in the VVT have slack, or I should say how much does it have, and is it locked at all? But I suppose after several crank turns you should be able to see, on avg, if the cam plates match. If not, or if they do back to square one on deciding if the plate is off, the cam is off, which one of them is off, or perhaps both are. But it should help if you want to dial in that one oddball plate, which you should not only be able to see, but now know how far to adjust. Again, assuming it needs adjusting :o


One advantage I have is I can adjust my cams in the ecu, so really I don't have a need to see, or know, how much they're off. I adjust until they work best. My disadvantage is I cannot separate the two intakes or two exhaust cams, so if the plate of one is off then it's off the whole time and I may be missing out on a little power. Assuming the odds are reasonable they were installed somewhat straight up, and only off 2.5 on the pix, I figure have a 50-50 shot they are no further off than what I see here? Maybe not, but I tell myself that and don't ruin it for me, unless of course someone can confirm there are alignment marks on the cams and I can check for sure.

GunnyNinja

Can you explain how you are able to adjust cams in the ecu?

kevm14

I assume he has HP Tuners.

Chevota

Yes sir, HP Tuners.

Fyi this is the typical M157 cam timing maps for Int & Ex. Note it isn't as simple as this because there are idle mode and catalyst heating modes that will override it. Cat mode is, well, unpredictable. So I made my cat mode match the normal chart and that goes away. The idle chart is typically full retard for Int and full advance for Ex. When it switches from idle to the normal one is hard to nail down, but at some point it does. Basically, for you, the normal, idle and cat modes are all 46 for the intake. Warm idle that is.
The Ex timing at idle is not so easy to nail down, which could vary 30 degrees at idle.
I can, and have, adjusted these to eliminate this game, plus make it so there is much less transition from idle. Meaning at idle they are already much closer to the #'s at 1500+rpm with some load so the cams don't need to move so much. The goal was to see if cam timing has any effect on throttle response off idle. It does not, at least for me.
Imo, the throttle response is all about exactly that; throttle. How to get the throttle to move quicker is something I have no real success with. So I'm still stuck with massive throttle lag, which I've had with all electronic cars. Imo you just have to wait for the ECU to process the data:
You; pedal to the floor. ECU; huh, what? Oh crap he floored it. What do I do? Hmm, let me see, check water temp, IAT, speed, gear, spark, throttle position. Do some math here, hold on a sec... Ok, got it, I will open the throttle half way, then we'll see about more later. Then the command goes to the throttle and you wait for it to open. Me; Sigh...
In theory, it could respond and rev quicker than a carburetor, but I've yet to see it. The lag is almost entirely ECU.
To make matters worse, as it opens the throttle the trans is keeping a close eye on these shenanigans, and if you start making power it will override the ECU and close the throttle quite a bit. It will continue to limit the ECU's control a lot in 1st gear, a little less so in 2nd, less again in 3rd, then in 4th it'll say ok, I'm out, do what you want. I got lucky and managed to bypass that bs, but the initial lag is something I can't seem to fix.
Ok, I digressed, so here's your cam charts:
The first one, starting at 46 at the upper left is Intake. The -25 is Exhaust.
If you like I can post the idle and cat charts for your car as well.

Chevota

To make it less confusing, or maybe more so, here are the Idle and Cat modes for M157. These are for "Warm" which is anything >122F water temp.
Then at the bottom shows all the stuff you could edit if you want, and I do because I can't leave anything alone.
Also note that these are the settings for most M157 engines I've seen. Changes would be small with other years/models, like a 2017 GLE63 had some changes to the Ex Cat mode and Split Inj, which appeared smog related to me. All the screenshots I posted are from a 2013 SL63. While I can't be certain yours is identical to the SL, I can't imagine it is not. If it isn't, it would be minor and the main chart is no doubt the same.

kevm14

Can you disable the oil pump valve in there??

Chevota

Not in HP. I did unplug it, some weeks ago, zero change.
I also loaded the OEM tune again to compare, zero change. I just have to wait until until it opens the throttle, plain an simple, and cam position at that moment means little, maybe nothing.