On startup in the morning it sounds like it has aftermarket mufflers, then about a minute later it quiets up, which happens in just a second or two as if some exhaust valve is closing. I assumed the wategates were wide open, then closed after xx time, but I wanted to verify and the wastegates didn't move. No this not coming from the cam chains etc, this out the tail pipes and sounds perfectly normal, if it had some muffler bypass valve or something.
I'd much prefer if the car were quiet all the time, I do not want to annoy my neighbors at 5am for no reason. Any idea why this is happening?

 

Man, cold starts are the BEST!!! The 550 sounds good, but I have had a couple 63s with the resonators cut out and they were absolutely eargasmic.
But yeah, at 5am I can feel a little conspicuous lol. That's when I wish I had a garage. Or did, until my neighbour told me he loves it too

This Is Why Cold Starts Are So Loud

 

Not my car, but this is a pretty good representation of what I used to wake up to. No idea what is up with those dangly bits lol

 

Thanks for the reply and examples, but I don't believe for a second it's the fuel. I've never had a car do this before and adding extra fuel to an engine has never it made it even slightly louder in the hundreds of times I've done it to a variety of engines. Just like carbureted engines don't make more noise with the choke on.
Now cam timing I could see, like if the ex cams shift to open substantially earlier in a cold start I can see it making more noise, and from an emission standpoint I think that makes sense to advance them. It also seems about the same time frame it takes for a cam to shift from one extreme to the other so I guess I should check that on my new OBD2 dongle.
Mine is basically identical to that red Audi in the first link at the 45sec mark. I'm quieter overall of course, but that shift in sound is spot on.

 

My 13 E550 runs at high idle for approx. 30 seconds to allow the converters to heat up, and then the idle speed will drop.

 

yes, during cold start, the idle is higher to accelerate the heating up of the catalysts and O2 sensors, it also does a cam adjuster test, but that is not very noticable. I too leave early for work and the 3" straight exhaust was VERY loud. I had my tuner delete the "cold start" function from my current tune and my family and neighbors are THRILLED! Much quieter now. Still does the cam adjuster test though. I can hear idle change when this is happening, but only takes 3-4 seconds to perform then back to lower idle.

I think I might have a copy of my straight-piped cold start on my phone. If I do, I'll try to get it posted up here...lol

 

I am of the belief that MB dials them up a bit and makes them extra noticeable on certain vehicles where the ownership demographic is likely to enjoy them.
The AMG forums are 99% giddy for them.

 

nota_amg:
So they tuned it out? Wth? As in it starts just fine without whatever that is? More importantly, if it's not the cams, and I don't have an exhaust diverter valve, then what could possibly cause it to be louder during that time???
I'm baffled as to how this is physically possible. And of course, if it works without it like yours, then I'm also baffled as to why they did whatever it is they did to make it louder in the first place?

I don't suppose you've played with the CAN bus on your car? After not finding anything wrong with my car and no codes, I got an Autel dongle which can read more codes and it showed several U codes. All of those crying about comms not working on the CAN bus yet of the things I could test, like steering wheel position and headrest memory position, work fine. So I assume they're old codes, as in one glitch one day stays there until you erase it? I was hoping clearing them would bring my power back but no such luck...
So I ordered an oscope that uses your laptop as the screen so I can watch live data on the CAN.

 

Yeah, just something they figured out how to switch off in the tune. I also have my I/C pump tuned to be on all the time when the key is on. No need for cutting/adding/routing wires in the engine bay! I've done nothing with my CAN system, all still stock, afaik...
I think the loudness just comes with the rpm it's running. My car actually will drone on the highway, but only at 1150-1200rpm, exactly where the "cold start" idle is...I only see it when cruising slowly in 7th, I think it's somewhere around 60mph, but I'd have to go drive it to be sure.

 

Oh yeah, with the cold start coded out, my "cold start" is simply start, 650rpm. After about 3 seconds the car runs the cam test and the rpm goes up to around 800 or so for about 4-5 seconds, then back down to 650.

 

I think it'll be hard wiring for my water pump. So what does it cost when you ask them to do stuff like that? I have an OE tune which is cheaper than most but still 1K, so I figured it's not cheap to have them do anything. I'd LOVE to have whatever software they use to mod it because I hate being at the mercy of someone else doing something I want. Tranny programming too.
If I bring my rpms up to the cold idle level it's still very quiet. Even under the slight load as I drive away from my house it's still quieter. Oh well, another electronic car mystery...
It seems my high intake temp is all about those stainless intake tubes so I was thinking about wrapping them. Have you done that? I was thinking that DEI gold tape but I worry about what will happen over time. like will it start breaking up and/or the glue dries and is bonded like epoxy?

 

love the roar on startup sounds beefy. should sound like that when idling it is a 8 cylinder yeah!

 

Ok, check this out... This am I started it and it was its usual loud self, so I gave it a little gas to raise the rpm maybe 2-300 and it quieted right up! Let off the gas and loud, gas it and quiet again. Then I put it in D which dropped the rpm a bit and also quiet! Back in park and loud again... So apparently it not only does it for that brief time when cold, but also only at that very narrow rpm of high idle. So now I'm actually more baffled than before...

 

Figured it out and now I feel stupid for not thinking of it sooner, or first: The timing!!! Duh, which makes sense to heat cat for emissions reasons. So I charted it this am and it goes to -30

 

I've used the mylar tape on my 9mm carbine build to line the inside of the handguard, but never on a car. I imagine it would help if you used the proper material... Your intake temps are high because you are tuned. You'll need a better I/C pump. I suggest the Pierburg CWA100 that is used on the newer 4.0 AMG cars as it is rated for continuous operation, the Bosch 010 is not and will fail quickly when demanded to be on all the time. I have a couple different tunes(one for "Street" and one for "Race") and my tuner swaps them out for me as needed since one is totally custom and cannot be pushed thru OBD. I just ask them for an updated file when changes are introduced that I would like to take advantage of, and they write me a new file and push it onto the car. I'm looking for an extra ECU to purchase and clone right now so I can just swap them out and not have to go to the shop to get tunes swapped.

 

The intake temp remains the same, tune or not. Of course under full boost it would be different to some degree but I'll worry about that when I can get to full boost. Fyi I removed the tune a couple weeks ago to see if my massive power loss had anything to do with it and all that happened is I lost even more power.
I have a new 010 Bosch pump on it right now but it didn't change anything so I guess my old one was fine. When I get power back, and if the Johnson pump isn't cutting it, or fails, then I'll get the CWA100 super pump. I may choke on the price which is 4x the Johnson, but according to misc data online it flows ~2.5 times the water. I have no idea what the head pressure is so that 2.5 may be off but it still outflows the Johnson. The question I wonder is at what point does extra flow stop helping, so maybe the Johnson is fine? What's ironic is I have everything I need to measure flow, pressure, temps and efficiency at work, but I'm not allowed to bring my car in and do that, or take the stuff home.
The stainless intake tubes between the air filter and turbo, and turbo to intercooler, get really frikkin hot from the radiator air blowing straight on it which explains why the air gets so much hotter when stopped or in traffic vs the freeway. I didn't know that tape was Mylar so I think I may just wrap the tubes with a cut up mylar emergency blanket, then I don't have any glue worries. Maybe cut it in 3" or so strips and spiral wrap it a few times with silicone sealant to glue the ends down. The thought of using Mylar wrap, meaning the kind to wrap a whole car instead of painting it, may also be an option but again I worry about the glue. It would look much nicer though because the emergency blanket plan will no doubt be ugly.


I'm starting to suspect my power issue is the wastegates opening prematurely but I guess I'll have to get a vacuum gauge to watch the feed to them.
The Torque Pro app has PID to read turbo boost pressure control but it reads 0 all the time so I guess the car doesn't give up that info? I don't suppose you've tried? This power loss issue is super frustrating but you and others have been helpful one way or another. I was just hoping someone with the same issue would chime in with the fix, which is likely simple but with this car it's a needle in a haystack. At least to me it is.

 

on Torque, there is another PID for boost...I think it's called "engine vacuum"? but that may b not be correct. I have it set up on my Torque app, so I know it's there. I'm about to leave work, I'll see what it is called when I get out to the car and post it here.

Lots of good reading HERE


Cart from thread:

 

Well crap, your chart says the Johnson M30 flows less than my oem Bosch 010. I could've swore it flowed more when I researched buying it. Sigh...
I see you mentioned the Davies Craig pumps. Not sure which but back ~2000 I bought one to replace the normal mechanical engine water pump in my truck. I did all this work to make it fit and after an hour it started leaking. So they sent me another, which also leaked. And another which this time I just put in a loop of hose rather than install it, and again it leaked. From there they broke contact with me so I was stuck and out the $ and return shipping which is not cheap from the US to AU. I got the idea from a Hot Rod or Car Craft etc mag where they put it on some car. So I then wrote them about it and they said it started leaking right after the article so they tossed it. Seems bizarre a company would sell a product that obviously doesn't last more than an hour or so. I mean a company not in China that is.

In the Torque I saw boost/vacuum and MAP, which I assume MAP is just that, psia, and the vacuum version is just subtracting barometric pressure from the MAP. Right now I'm deciding if I should run a vacuum gauge inside the car to the wastegate vac line, or put my dash cam under the hood and watch one wastegate live via my phone. Not sure the cam will like the under hood temps tho. I troubleshoot all day at work so I hate stuff like this. I enjoy working to make things better than they were, but I hate working to get broken stuff back to where it was.
Well, thanks again for the info. I think we're alike in that we want to know how stuff works so we can do the best mods, and learn doing it. I hate not knowing how something works, like the ECU and TCU.

 

For sure!

Sorry about your Davies Pump...I know the feeling : Click Me!!!

 

I actually laughed out loud! Sorry, I feel your pain because I've broken soooo many parts on my Chevota, which is a '79 Toyota 4x4 with a 400 Chevy and the front shaft has a double cardan joint, which is a bad idea but I guess it's all there is. Anyway, it broke at speed and the carnage was excessive! Destroyed my transfer case and tranny! And it put a massive dent in the crossmember for the T-case which I could never duplicate with a sledge hammer unless I gave it a lot of whacks. Prior to that, as an experiment, I made a shaft without the double u-joints. It was literally a rear shaft shortened. I knew the angle at the T-case was too much but I had to try. It didn't even come close to working. It felt like it was binding and releasing twice per rotation, like break something level of binding which it probably was. I took it to like 10mph before stopping and removing it. Reason I tried that is the double joints were rather short lived, like only a few minutes of full throttle and they're done, and they're not cheap. I usually used the oem Toyota joint which is actually really strong, but I once tried a Spicer that the driveline place who put it together said "You won't break this!" I think the Toyota one is stronger...

I really wanted an elect pump because I'd often get a too hot because I play in the sand dunes which is a real workout for it, and it's usually hot out. Being so hot out it takes a long time to cool down so I wanted to be able to kill it and let the new super pump cool it. Oh well. I did fix the problem with some redneck engineering: I drilled a hole in my holley carb so it would end up in the center, then had a vacuum line on that led to inside the cab. When it got hot I just let it suck water from a gallon jug. Problem solved! I planned on mounting a small tank with a switch so I could do it style but never got around to it. What I did do, however, was mount a second radiator under the bed which solved the problem.

So I'm curious; why replace the whole driveshaft if just the U-joint was worn? I know the oem shaft is pretty small in diameter so I wondered if it's a weak link? If so, was the new one supposed to be stronger?

 

u-joint caps are staked, no c-clips. cannot be serviced, I tried

 

I tried to have one custom made, told them I was making over 700lb/ft, they said "Nope!".

 

Staked? And here I was starting to assume you were a fellow redneck... Staked is just an annoying obstacle.
Unless it's some weird unusual staking I've never seen, so post some pix and allow me to provide a redneck perspective.