Spiegea

Hello All! Have a 2007 E350 with Sport Package. Car has 43,000 miles and is a daily driver. I have already had the CPS issues which has already been corrected by dealer about 4,000 miles ago / 4 months ago. Figured I'd get to that first as this doesn't seem to be the same scenario I had when I lost power at 80 MPH on a busy freeway in LA.

My new problem: While starting the car the starter engages just fine, car starts, tachometer hits about 1,200 RPM as usual, then the tach starts to drop as usual toward the 500 RPM mark. However when it hits about 800 RPM the engine either dies completely or boggs down to a very low 300 rpm and catches itself quickly revs back to 1,200 RPM and then returns to a normal idle around 500 RPM. If the car catches itself and eventually hits a normal idle, there are no issues and the car runs beautifully. There is no smoke from the exhaust during starting issues so don't think its mixture problem.

What have I done already? Cleaned the MAF with CRC MAF cleaner, Used OBD II to scan for codes and there are NONE! No "check engine light! Listened for any hissing for vacuum leaks, visually inspected for any type of electrical short, made sure all electrical connections have not come undone. Air filters were replaced 1,500 miles ago. Oil was changed 1,000 miles ago with Mobile 1 0-40. Only use hi-test Chevron w/ Techron gas. Fuel pump is heard whining as usual and seems to be just fine since the car runs great after the starting issues.

Had an old 1973 Norton Commando with a similar issue but that ended up being the timing chain off by 1 tooth! Doubt that is the case here!

Thanks in advanced for any help.

Spiegea

UPDATE: Started the car cold this morning and the car completely died. No check engine light, no other dash lights on. Tried starting again and engaged the key, car cranked for 5 seconds straight until it finally started. Did once again this afternoon and same thing happened.

Any takers?????

Plutoe

Rather strange that you do not have a fault.

In any event, assuming you have checked the obvious, I just do not know how you can analyze the very complicated fuel and electrical starting and idle circuits with out good diagnostics. Oh well!!

There has to be an indy close by who could do a quick scan

vettdvr

New CPS doesn't have to mean a GOOD CPS.

Spiegea

UPDATE: Took the car to an indy shop who replaced the CPS with a new MB part to see if that was the issue. Car still stalled on start up. The car was not throwing any codes. He even hooked it up to MB Star program which showed no issues. The indy shop found low pressure at the fuel rail when starting so referred me to the dealer. He did so as he told me it was a fuel pump issue and the whole tank needed to be replaced for $1,900. However, California EPA law requires this part covered under the EPA warranty so the dealer had to do the work.

Took it to the dealer where the car stalled immediately when the mechanic tried to drive it to his bay to test it. The response from the MB dealer so far is that the mechanic has hooked everything up to the car and cannot replicate the problem. Said there are no codes stored and no CEL. The dealer also says fuel pressure is okay and not an issue.

Dealer told me to drive the car until the problem becomes a bigger problem. Doesn't seem right to me. Any thoughts?

vettdvr

problem is still there it will be back.

ozusa

just a thought, but if your car's diagnostics system is incapable of throwing any codes....then it won't throw any codes.

I suggest you disconnect a plug wire or two to force it to create some codes and a CEL. If it doesn't, it may indicate that you have generalized issues with the engine electronics and control module(s). (I hope not)

Running the car with a vacuum hose disconnected may throw a code, too.

Plutoe

I think you have issues with the folks that are diagnosing your car!!

Spiegea

Just pick the car up at the dealer. We have a conclusion! Dealer had to replace the ECU completely as they finally were able to replicate the stalling. They found the "Engine Control Unit (ECU) has internal electrical fault" so replaced the ECU. Let me begin by saying that the car runs like the first day I bought the car. Unbelievable! Car starts great every time.

Kind of had that same thought that if the CEL or codes weren't being thrown maybe it could be the computer. Sure enough it was.

By the way, this was done at no cost to me because of the 8yr / 80,000 Mile emissions warranty in California.

Thanks to all for your thoughts.

Spiegea

Well whatever gremlin is in my W211 is driving me nuts once again. After the dealer replaced the ECU the car starting stalling once again. The stalling began about 12 hours after the car got home from the dealer so doubt it really went away.

Car is back at the dealer with stalling on start issues as well as lengthy cranky before starting. I assumed it was the fuel pump but Dealer says fuel pressure at the rail is measuring just fine and they are just as stumped as anyone. They even sent me a video of the mechanic starting the car with the fuel pressure guage registering with good pressure on startup.

So far the dealer has tested fuel pressure regulator, coils, plugs, fuel pressure, fuel pump / sending unit, MAF Sensor, Replaced the cranks position sensor 2X, Replaced one camshaft magnet, replaced the entire ECU and programmed with up to date software.

A so called "short test" did not reveal any codes and the CEL has not been tripped. I am going absolutely nuts considering this car has only 43,000 miles on it. I feel there is some sort of short in the fuel pump. This is a California car so has emissions warranty to 8 yrs / 80,000. Mercedes wont even touch the fuel pump unless it has a fault code in the computer. Seems like I got the short end of the stick on this one.....

Any thoughts?

Spiegea

When did I ever post that my neighbor gave me an idea regarding the CPS? The car has been at a Mercedes Dealership for the last month undergoing diagnostic after my indy shop told me to take it there. My service advisor has said he is 90% sure it is fuel pump. That is how I came to that conclusion.

My only intent of posting information is to not only assist myself but to help others who have or may encounter a problem in the future.

There is no need for a stuck up a**hole response.

ozusa

1. You need to know the fuel pressure when it WON'T start. The video of the fuel pressure when the car starts and runs is a whole lot let less useful than the video of the fuel pressure when it won't start. Of course a car that is running OK has fuel pressure. Does it have fuel pressure when it WON'T start is the real question. Perhaps you may have an intermittent fuel blockage.
2. Does it smell flooded when it won't start?
3. It does crank fast enough to start, right? The starter motor is not struggling to turn-over the engine?
4. What about some basics of the engine's physical health. Has someone checked the compression on each cylinder? Low compression and cold weather can make for hard starting.
5. There is more capability to diagnostic machines than just getting a list of codes. They can give a running commentary, too, like the machines in intensive care that monitor the patient. Is anyone watching the various sensor's outputs, that can be watched with a diagnostic tool, to see if they make any sense as they go up and down? For example, an air intake temp reading that has no relation to the ambient temperature would point to a bad IAT sensor. Perhaps one or more sensors is crazy, affecting start-up, yet not producing a code. Observing the data flow will help detect such a thing. I can do that with my "home" scantool. Surely your dealer can do that with their's if they haven't already. Or you can. (Labor cost may be the issue.)

Spiegea

See Attached Video of Problem. Any thoughts?

Spiegea

1) Dealer won't touch the fuel tank ($2,100) under California Emissions Warranty unless there is a fault code or CEL triggered. Even though it stalled on them multiple times, they did check fuel pressure and said at ALL times it was acceptable.

2) Yes it initially smells rich but then goes away in approx. 1 minute. I have noticed excessive black soot all over my exhaust pipes now.

3) Yes it does crank fast enough as outlined in the second video.

4) Living in LA, there is not much cold weather! Indy checked compression as says its okay.

5) Dealer had the car for 1 month and ran diagnostic every morning. They have indicated that nothing has tripped any code and the STAR diagnostic shows everything normal.

The dealer was tired of paying for my rental car so they called and advised that I must pick up my car. They told me to drive it until it died and then they could figure it out. In the mean time, I've replaced the fuel pump relay (just in case), and water temperature gauge. I have a knock sensor in hand but don't know exactly where it is located on the engine. Any help would be appreciated!

Also noticed some oil in the crankcase vent valve and hose going to the throttle body ( under MAF sensor). Is that normal?

Spiegea

Here is stalling on the first start. Then second start goes just fine and car runs and drives great.

Spiegea

Anyone have any thoughts? Anyone?

otto6457

There are too many variables involved to get a correct diagnosis on a forum. If the dealership is stumped your best bet would be to contact Mercedes Customer Service directly at 1-800-367-6372. Explain the problem and have them contact the dealership. The dealership should have already started a technical assistance case since this is a repeat problem. If they haven't, then you should probably look for another dealer in your area.

E55Greasemonkey

You need to check the injectors. You may have one bleeding down (leaking) when the engine is shut off, thus flooding a cylinder and causing a hard start. It's not hard to test. A lot of experienced MB techs are leaving the dealers because of the way we have been treated by them and MBUSA, sounds like the dealer you go to has very little experience, they probably ran out the experienced guys with cheaper labor (kids). Sorry for the rant, but try to find another dealership to take it to. Another thing is your engine may fall into the production range with faulty balance shafts, causing a cam timing issue. Usually this will set a fault code. Some other thoughts to try first, they are easy- unplug your MAF sensor and see if the problem goes away, it may simply be a faulty MAF sensor. They do not always set codes when bad. You mentioned air filters 1500 miles ago- are they OEM? if not, some aftermarket filters do not seal well in the airbox and allow dirt to pass, damaging the MAF sensor. K+N filters also may cause this, if the oil residue hits the MAF. Take the air cleaner assembly off and check the black rubber seal that attaches to the MAF sensor. These are easily kinked/distorted/cut when reinstalling the air filter housing, and will also cause issues. Check the plastic elbow and seals between the MAF sensor and intake manifold.

Spiegea

E55Greasemonkey, thanks for your reply! Your post is very helpful and I didn't ever think of the injectors. The MAF was replaced and a new seal between the airbox and and MAF was also installed. That was the first thing the dealer thought of as well.

Air filters are MANN filters from Autohaus and are OEM.

To add fuel to the fire regarding the MB dealers, I completely agree. This MB dealer in Arcadia, CA broke the wiring harness when installing a new Crankshaft Position Sensor. Instead of replacing the harness connector to the CPS, they simply zip tied the broken part together. Not what I would expect from an MB dealer.

Is the faulty balance shaft identifiable by the VIN#?

E55Greasemonkey

There is an engine serial number break for the shaft issue. The serial number is listed on your VMI available at the dealer, and there is a bulletin from MB with the affected engine #s

Spiegea

Well, I did a fuel pressure test at the rail yesterday. When the car is running, the fuel pressure fluctuates between 55 PSI and 60 PSI. Doesn't seem right to me. In addition I turned the car off and let is sit for an hour and ten minutes and fuel pressure at the rail decreased from 56 psi to 43 psi. From what I remember, the fuel pressure is supposed to stay at or close to 56 psi with the car off. Am I correct?

I'm leaning toward "E55greasemonkey" that there is a leaking injector. The loud clunk must be unused fuel sitting in the cylinder then igniting on start with a large explosion (detonation). Or when it continuously cranks when cold and sitting for a long time, the cylinder(s) are flooded so much that it just won't start. Would fall in-line with the rich smell if it does start.

Since this car is a PZEV car in California, the CA Emissions Warranty would cover fuel pump, regulator, and injectors. It must be done at the dealer however I am hesitant to take is back to the MB dealer in Arcadia, CA from past experience with this problem. It seems as if there technicians can only work on cars if the computer tells them something is wrong. Here I've had to do the legwork with common sense. I'm concerned that the MB Dealership told me to continue to drive the car until it died. If the above is true, then I've likely bent a connecting rod or possibly a cylinder, piston, ring, valve, etc...

VII

Sounds fuel pressure related to me, I would go for pump/filter change if it was my car. Injectors can be a problem but doubtfull at that milage. You can remove the spark plugs and check for gas leak. Also might be worth cleaning?

E55Greasemonkey

The fuel system on your model is an on-demand type system, I would not be concerned with the fluctuation at idle just yet. It is also normal for some pressure to bleed down after shut-off. Watching your second video, this system does NOT prime the pump with key "on" only when the engine is cranking, just FYI..What you need to do is verify that pressure is not bleeding down through an injector. To do that, you need to connect your gauge, idle the engine, then shut it off- and quickly isolate the pressure in the fuel rail/injectors...the tricky part is you'll need to physically block the fuel from returning to the tank/pump. Take out your back seat lower cushion and remove the drivers side fuel sender access cover. Being a PZEV car, hopefully it's not different than what I'm thinking...There should be a plastic or rubber fuel line that runs from the pump to the engine. Using some pinch-off pliers or other appropriate tool- NOT vice grips-avoid sharp edges!! - you'll need to pinch that line and watch the fuel pressure- It should remain stable. I'm not real happy about pinching a hard plastic hose- as it could kink or damage it, but not much choice. Provided the outside temp is not cold or the hose is not brittle from age, you should be OK. Unfortunately this is where professional judgement comes in, along with a risk of damaging the hose. So, be careful...

I'd like to see your fuel pressure when the problem occurs, it may be as simple as a faulty pressure regulator and/or pump.

Spiegea

Update: After a long battle with Mercedes and my local dealership (several letters) they agreed to replace the fuel tank, fuel pump, filter (all one unit) and pressure test each injector for "leakdown". I took the car into the MB dealership on Friday morning and by that evening they called me to advised they replaced the fuel tank and pump and found the injectors to be good. I've driven the car for 3 days and have had no issues whatsoever. Only time will tell if that truly solved the problem! Thanks for thehelp

E55Greasemonkey

Good news!