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My vehicle is a 2008 C300 4Matic. I have made several posts about other problems related to this issue, but none have solved it.
My car drives smooth as silk when cold, minus vibrations at idle that I believe are from a pulley somewhere. The reason I think that is that when I run the engine with the belt off, no vibrations. I’m also stumped on what pulley is causing this as there’s nothing obviously wrong, but that’s a different problem. Tensioner, belt, and both idler pulleys are new already, genuine or OE parts. As soon as the gauge cluster’s temp sensor reaches 60°C, it begins to have a stutter when accelerating or under a moderate load. As it warms up, it gets worse. It is an audible difference as well as visual, as you can see the RPM needle bouncing up and down rather dramatically. Sometimes it can only be 100-200 RPM’s and just be uncomfortable, and sometimes it’s really bad and jumps 5-600 RPM when accelerating. It’s a very concerning issue and I’m stumped and honestly debating on selling it if I can’t figure it out, which would suck as I’ve done over $1,000 in repairs and maintenance in the last two months as I just bought the car.
There’s a new MAF sensor along with a resealed intake elbow, new air filters, new plugs and coils, fuel cleaner has been ran a bunch, new oil a few times since I bought it, among a lot more.
I’m really stuck here and I need some help. The only thing I have left is to drain and fill the transmission and change the filter, but I honestly don’t even know if that will fix it or help, given that it only happens when warm rather than most transmission symptoms that either only happens when cold or it’s all the time.
Edit: Forgot to mention that sometimes when the stuttering is happening, the vibrations throughout the cabin are REALLY bad. It feels like the whole car is being thrown around in a blender, and it sounds like it too. Sometimes there’s minimal vibration and only a jerking movement from the RPM fluctuating, but sometimes it’s that bad. There’s no consistency either, just sometimes it does and sometimes it doesn’t.
Last edited by hmclaughlin67; Jan 29, 2025 at 10:59 AM.
I haven’t gotten an MB specific scanner yet, but I did use my Innova on it and no codes. No codes from OEM enhanced either. I’d rather buy the scanner for $190 than pay over $200 for a diag fee at the dealer.
I get completely sidetracked reading the manual. I was just reading thru the maintenance section under Idle Speed to see how everything operates. Not saying this is your issue, but could lead to a better understanding of what to check.
I get completely sidetracked reading the manual. I was just reading thru the maintenance section under Idle Speed to see how everything operates. Not saying this is your issue, but could lead to a better understanding of what to check.
I can only find it on Amazon for $189, mind sending a link?
And much appreciated. I might pick up a scanner and see if my throttle body is toast but not enough to set off a CEL. It was caked in oil when I bought it and I cleaned it as best I could over a few different sessions, but it’s not impossible that it was just too far gone.
Oh yeah, it was completely disgusting. It was the worst one I’ve ever seen. I’m going to pick up that scanner and see if I have anything pending at all. Does anyone know if it can read transmission fluid temp and level on our W204’s? Would make my transmission drain and fill much easier.
Read this thread for more information: https://mbworld.org/forums/e-class-w...al-more-9.html
The vertical screen one is version 1.0, the horizontal one is version 2.0, and finally there is the BenzBmwAudi version, it is 109(?) on a different site, I think the link is on page 6 or 7 of that thread, the item location is probably in the usa so you might get it pretty quick. You could always get the none BenzBmwAudi version if you don't have a need for it, link on page 9.
I appreciate all the help with the scanner, I’m still going to get one but I’ve actually got a really weird update for you all.
Just out of general curiosity because I finished siphoning out and refilling my power steering fluid about a week ago, I went to check and make sure the level was good last night. It was the tiniest bit overfilled, so I drained some out and then went to bed. This morning I woke up and was driving to work and noticed that the vibrations were extremely minimal now, much closer to how it was when I first got the car. Also the vibrations at idle weren’t nearly as bad. I suspect that that little bit of overfilled fluid was putting too much pressure on the pulley and causing some problems with the drive belt. The vibrations and RPM needle having some bouncing isn’t 100% gone, but it’s much more manageable. I never would have guessed that could cause what it did, but I wanted to throw it out there for general information.
I appreciate all the help with the scanner, I’m still going to get one but I’ve actually got a really weird update for you all.
Just out of general curiosity because I finished siphoning out and refilling my power steering fluid about a week ago, I went to check and make sure the level was good last night. It was the tiniest bit overfilled, so I drained some out and then went to bed. This morning I woke up and was driving to work and noticed that the vibrations were extremely minimal now, much closer to how it was when I first got the car. Also the vibrations at idle weren’t nearly as bad. I suspect that that little bit of overfilled fluid was putting too much pressure on the pulley and causing some problems with the drive belt. The vibrations and RPM needle having some bouncing isn’t 100% gone, but it’s much more manageable. I never would have guessed that could cause what it did, but I wanted to throw it out there for general information.
I dont have a Launch scanner but I have a Foxwell and it shows the transmission fluid temp. Im pretty sure the Launch shows the transmission fluid temp.. It does not show the level though.
I’m attaching a video of what it’s like, if anyone has any ideas with a visual representation. This one wasn’t accompanied with vibrations, but you can feel the car lurching forward and back with the RPM as well as hear it. It literally sounds like I’m just fluttering the gas and it feels like it too but it’s constant and incredibly uncomfortable. Another way to describe it is how a car feels when it shifts and you can feel your moment “lock up” for a second while it shifts. This feels like it’s happening constantly because the engine RPM just jumps up and down by 200 RPM at a time and throws the cabin around.
Edit: For context, I had cruise control set and wasn’t adjusting or on the throttle at all. Also had been driving for a little under 3 hours at the time of the video and as soon as the temp hits just below 60° is when that starts happening and it doesn’t get better or worse no matter how long I drive. If you zoom in you can really see how dramatic the bouncing is. It happens on acceleration every single time and it’s never a “smooth” incline. It’s always a bounce like that, usually accompanied with some really really nasty shuddering.
Last edited by hmclaughlin67; Feb 3, 2025 at 12:09 AM.
I would put my money on a transmission related issue, TCU input....as previously touched on , a scan to include transmission input/outputs would clarify things, no ? Or live with that narrow window of "weirdness" until more errors appear. Feel like bonding with your C300 and getting dirty doing that trans fluid fluid/filter change out you initially mentioned ?
I would put my money on a transmission related issue, TCU input....as previously touched on , a scan to include transmission input/outputs would clarify things, no ? Or live with that narrow window of "weirdness" until more errors appear. Feel like bonding with your C300 and getting dirty doing that trans fluid fluid/filter change out you initially mentioned ?
Oh yeah I’m definitely going to do it. I have all the parts I need minus the fluid and a fluid pump, already have the adapter. They’re just sitting in my room until I can buy the fluid but it’s the next thing on my list. I am going to get the scanner as well so I can get the fluid temp reliably rather than use a temp gun.
I was hoping it’s not a valve body issue or anything since it only happens when up to temp, but I’m not too sure. I have rarely ever touched a transmission minus fluid changed and I swapped one out one time, but never done any sort of repairs. It’s pretty much the only thing I’ve never done actually but always down to experiment.
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