yippyskippy107

Has anyone else had this problem? Car is all stock.

The first sign is when merging onto the freeway and just giving it moderate throttle, say about 25-35% the car stutters, not super noticeable but very subtle, like rolling over several very small bumps in succession, and not changing gears as I can see the gear stays the same.

The second sign which is more apparent and noticeable is cruising on the freeway around 70-75 mph (in 7th gear) giving it moderate throttle (say to pass someone) 25-35%, the stuttering will start subtle but then get worse and worse to where your just starting to headbob in your seat just a bit and I 'think' i can hear the exhaust note cutting in and out too. Car also stays in 7th gear at this point. I tried changing from C to S mode, no difference. Also bumped it down to 6th gear and same result. Under WOT the problem does not seem to show up, either that or i'm too busy admiring the exhaust notes

No CEL either. I did have the intake manifold gasket changed a few weeks back at the dealer however from a CEL. On a C230 board guys were saying all differnt things like fuel filer to O2 sensor so i'm wondering if anyone here has this same issue?

sandmane63

I'm having the same problem and have tried the same throttle/tranny modes with same results. Took it to the dealership and told me that the problem was due to a vaccuum leak according to the OBD readout. After resetting the ECU and "working" on the problem, they never found the leak and according to them was due to "bad gas" and the problem was fixed. Keep in mind that this is after explaining to them that the problem had persisted through several tank refills, one of them being Sunoco 100 oct.

15 minutes after leaving the dealership, engine starts misfiring under the same engine/throttle/tranny conditions. Although the misfiring is more subtle than when I left it at the dealership, it's still annoying as s**t. Especially when you're trying to leisurely accelerate while getting the "bobblehead" effect.

This is the second time this has happened with the previous time the condition were more pronounced and would happen through the entire RPM range and the misfiring more "violent", jerking the car back and forth when starting.

Other than changing the intake gasket, any other suggestions from our fellow MBWorlders? Is the intake gasket covered by a TSB?

Peter_02AMG

I had the same problem a few week ago. CEL came on. I check it with OBD reader and it said something like engine running rich, forgot what the code was than I reset it but CEL came back on a few day later. Dealer said it was the intake gasket and they replaced it under warranty. It's been a weeek and problem hasn't come back.

sandmane63

Thanks Peter. I'll be stopping by the dealer and again help them find the problem!!

I also found a thread from a previous post in 2008 which found that the root cause for the misfiring and CEL was the intake gasket.

BTW, what brand/model ODB reader do you use?

Thanks!!

Peter_02AMG

This is the brand I have, come with case and laptop cable. Really easy to use.

http://www.amazon.com/OBD-AutoScanne.../dp/B000K8S6CG

shardul

iTrader: (1)

has anyone looked at the motor and transmission mounts, they can also cause vibration when accelerating.

sandmane63

The car is not vibrating. It's a very distinctive behavior as it hesitates and misfires with accompanying intermitent loss of power.

Paul, thanks for the link and info.

yippyskippy107

Ya, I had my intake gasket changed already based on a CEL coming on. I'm assuming they did it right as no CEL has come back. In any case I have an appt tomorrow to have it checked...

jicl55

I had very similar hesitation on my CL55. Changed tranny mounts, helped a little but still there. Ended up being a gasket on the tranny had deteriorated and was slowly leaking tranny fluid and was a quart low. It wasn't leaking enough to where I could see it. May be that?

citylightva

I'm taking mine in soon for some warranty work. The driver rear air spring will completely deflate overnight when it's below 50 in my garage BUT also my engine isn't idling rough, it sticks on 600 with no hunting, but my car is idling rough. I'm thinking mounts. Those misfires sound bad though, hope they clear that up for you guys..!!!

sandmane63

Thanks for the feedback to all. I don't think it's tranny mounts or the like. There's a definite intermittent loss of power and does not feel as if the tranny is hunting either. The first time I took the car to the dealer the CEL was diag'd as a vaccuum leak but the tech could not find it. So they cleared the CEL, told me the problem was gone and chucked it off as "Bad Gas". That "Bad Gas" was spread across several fillups which included Sunoco 100...so much for bad gas which spread across several fillups kills the theory it's bad gas. I've filled up the car again and the misfire continues.

Also, the misfire does not happen at higher RPM (i.e. 3500 or above), only at below and in all gears, though more pronounced in 4-5-6-7 at low RPM's.

I can tell you it's annoying as s**t when you're trying to conserve some gas and you're trying to accelerate slowly in the higher gears only to be met with misfire....which forces you to step down a couple of gears and kill a couple more trees and $$$.

Anyone have info on the TSB # for the intake gasket leak?

Thanks in advance

yippyskippy107

2 weeks in the shop and 350 miles later finally got it knocked out. Previous owner had some off-brand air filters in (red colored frame) which had gotten dirtier then normal mileage/wear would expect, also some corrosion on MAF sensors, possibly related to *****ty filters. Put OEM filters in, cleaned the sensors, reset the ECU and problem appears to be gone. The stuttering was a result of the car running just a tad fat since the ECU would expect more air then was getting in but was not off enough to allow it to adapt. Props to the guys at Beshoff in San Jose for figuring it out.

jpohl402

Interesting....
Lots of good comments from others in here