Italiano731

I have a 2007 S550 non 4 matic. The issue I have been having anytime I go through a car wash and the car gets wet it starts to shudder on take off. It feels like a loss of power and the car jerks back and forth than corrects itself. The weird thing is it only happens after something gets wet. So I have taken it to the Mercedes dealership and they are doing a great job with working with me trying to fix the issue. Even now recently covering all parts and labor to replace clutch packs in the transmission to solve this problem. $3500 they covered because they recommended the following without fixing it which I paid for.


Replaced radiator - leaking anyway so not really related

New Valve body

New Torque Converter

New pulsation dampner - problem no an issue related to this.


That being said after putting in a new torque converter and valve body didn't solve the issue they tore open the entire transmission and replaced clutch packs and went through it. Today I picked it up went to the car wash again and it started the regular jerking motion on startup.

Does anyone have any ideas on what it could be?

alx

Lol. Tha tranny has nothing to do with it. Check the grommet for the harness that goes into the transmission. Also check your moonroof drain channels. They get clogged and water finds its way into places it has no business being at.

Get a a spray hose and spray water into different areas of the car until you find the spot that causes described behavior. Take it from there. I believe you will find that spraying on the moon roof or the gap between the hood and th windshield will result in the drivetrain shudder. If that doesn't do it spray the undercarriage...

Let us know.

superpop

Or stop going through car washes.

Italiano731

Ok I'll keep you updated. If anyone has any other ideas please let me know ill present them to the tech at Mercedes. Thanks guys

rocky raccoon

Check for a hairline crack in your distributor cap.

Italiano731

Interesting does the w221 s550 have a distributor cap?

steveb9771

No-- These vehicles do not have a distributor. Open the hood immediately after going through a car wash and see if there is any obvious water there. look carefully at the various electrical connections. Remove the air cleaner cover to get better visibility. Most, if not all, of the items that were repaired never could have had anything to do with your problem. It appears the dealer that made the unnecessary repairs is completely unqualified. Take your vehicle to another dealer. Your vehicle most likely recorded a fault code which can assist a competent mechanic to determine determine the cause of the problem.

Italiano731

No fault codes are coming up. I didn't take it to a small mechanic this is a certified Mercedes dealership. They had their lead tech trying to figure this out. Anyone have any issues with a shudder that happens to be prevalent when exposed to water?

mb techman

im astounding that they decided to tear down the transmission and replace parts after explaining to them that this only happens after going through a car wash.

First thing i would do is lift both front carpets and check for water inside the vehicle cabin. there are several can bus distribution blocks along side the door sills on the drivers and passenger side under the carpets.

If theres water there, that would cause an issue.

The transmission control module is part of the conductor plate which is attached to the valve body, so it would be very difficult for water to enter and affect that electrical component. The engine control module is on top of the engine, and again, very difficult for water to reach.

Seems to me its more a water/electrical issue than a transmission issue.

konigstiger

Ditto, check for water issue.

If they have not already done and VIN is below 033538, have dealer check VMI to see if service campaign 2006020007 (water leakage) was completed if not, repair is free see attached bulletin 83.10/108b.

Make sure air/water drain is clear, see attachment.

If above suggestions resolve matter contact MBUSA to assist in reimbursement for valve body, torque converter, and pulsation damper if Xentry diagnose did not warrant replacement.

Italiano731

Thank you guys I'm passing all this information along to the tech.

Italiano731

Went thru the car wash this time opened up the hood looked around this is getting soaked not sure what it is but it is 100% getting soaked. Gonna do some research.

alx

This is your air pollution sensor. If outside air quality falls below certain thresholds it turns recirc on your hvac. This is not your problem. Your problem is that you don't listen to advice get a hose, spray a section of the car, go for a drive. Repeat until car shows behavior in question. That will be your starting point.

steveb9771

If you google "mercedes 2118300472" you will find several sites that show a picture of your part along with the device being called an air pollution sensor. Based on this description, it could definitely be a candidate for your problem. You might want to try wrapping plastic around it before entering the car wash to keep it dry and then remove the plastic immediately after to see if this is in fact the cause of your problem. I would examine the gasket around the hood to determine how the device is getting wet.

Italiano731

I dropped the vehicle off today and showed the tech the pollutant sensor. They are going to start going thru all electrical components. Will keep everyone updated when I get my car back. Maybe this can save someone from going thru all the expensive parts I had to replace for nothing.

alx

Curious how you arrived at that conclusion. This sensor controls the recirc operation. Nothing else.

mb techman

I can assure you that is not the cause of his driveability issues. As already stated, the sensor is involved with the HVAC system. It's not even on the drive train or chassis CAN.

I'm still waiting to see what it looks like under the carpets.

riteoff

Definitely a wiring issue.

Completely different animal but i had the same issue with a Crown vic a while back. During rain id get limp mode, random error codes etc etc. 3 shops couldnt figure it out and threw parts at it for weeks.

Ended up being 2 bad wires from a light front end impact that nicked the sheathing on the wires. 3 weeks to diagnose, $3.50 fix.