[NGough]

Re: our 1993 300E 2.8 with 203k on it.

I've had an issue with stumbling whilst driving and having a surging idle. After having codes (006) thrown which indicates a Throttle Body issue, I sent it to BBA Reman in Mass. They rebuilt it and sent it back, it was installed and all was okay for awhile. Then, in Dec., it began again. The shop checked a lot of items but since it wasn't throwing any Check Engine codes, we were not able to come up with anything but a faulty EGR valve. So, we disconnected it and plugged it up on the line to the intake manifold side. It ran fine, never had a surging idle and never stumbled when driving. All was okay until late January after returning home from a trip overseas when it began the same symptoms all over again. So, I reconnected the EGR and it ran just fine with zero issues for a couple of days, then it began once again to show the same issues. Then, it threw the same Check Engine code of 006, which indicates a Throttle Body issue. So, I had it packaged up and sent back to BBA. They called yesterday to tell me it checked out okay on their bench tests. So, it's on its way back for it to be reinstalled.

The wiring harness has been replaced. It runs strong with no problems, most of the time. It has an original CAT and has newer coils.

So, BBA mentioned that the '006' code could mean more than just the TB as M-B has other problems associated with that code. Huh? Is this true?

Anyone experience a similar issue and discovered a solution? I'm not sure where to go on this one since the dealer no longer has W124 diagnostic computers anymore. I've tried to contact a shop whose owner used to work at the dealer as a certified mechanic and has the computer, but no one answers. My mechanic has lots of experience with W124s and Benzes and is puzzled as they've not seen this before.

Comments? Any more info needed?

Thanks!!!

 

[sbaert]

Did you replace the throttle body gasket with a brand new one when you swapped units?

BTW, a faulty EGR on a W124 is a extremely rare occurence. When you pulled codes, did you get a code 5?

If so, then the EGR tube from the EGR valve to the intake manifold is clogged or restricted.

 

[NGough]

Yes, I believe so.

I am in the midst of looking up the code and seeing what all it means... again.

 

[sbaert]

Even though you are reinstalling the same throttle body, you really should use a brand new gasket and make sure the mating surface is 100% clean.

 

[NGough]

After some research, it could be the idle speed control valve or a vacuum leak at the intake manifold.

I will check with the mechanic and then have them first clean the idle speed control valve and see if it was dirty enough to cause the issue.

From my investigation, it appears vacuum issues could be the culprit here. Those are sometimes very difficult to eventually solve.

I've located the Fault Code Scanner PDF from a Google search. See attached file.

The fault code '006' or '6' seems to really indicate the idle speed control being faulty.

I will post as I learn more.

Plus, it seems that others (even in other forums) have had similar issues, all with (seemingly) different solutions. My apologies if this thread is a repeat.

 

[sbaert]

The possibility of a vacuum leak is the exact reason why I asked if the gasket had been changed during throttle body swaps.

 

[NGough]

Good point, Sbaert.

Thanks!!

 

[red67fairlane500]

I have used Carb Cleaner to check for vacuum leaks - would this be a possible way to check with the ISC? I know it is kind of hard to get the tub under the ISC close enough to the mating surface, just a thought though. If it is a possibility, the idle would raise up and it could help pinpoint the issue.

Have you put a vacuum gauge on the engine to see what it's pulling at idle and at operating temperature?

I am guessing you got the 006 code from the DM pin 3 or push button and counted blinks? Have you tried pins 8 and 14 as well with a LED tester?

All the more threads on the HFM-SFI engines as possible - for me they are a bit finicky to work and diagnose when they are using a fuel injection system that seems to suit OBDII better - just my .02

 

[NGough]

latest info

Hokay,

I had the TB (which had been rebuilt by BBA Reman) sent back to BBA. They ran tests on it and found zero, nothing wrong. So, they sent it back, the shop re-installed it, tested it, reset or "taught" the ECU (???) and gave it back to me. I let it idle until warm and then drove it home. On the way, at a stop, it began once again. The shop tested for vacuum leaks and found nothing.

I've tried a shop which allegedly has an analyzer from MB, but they have not answered their phone and not returned my calls.

So, I contacted a place in Cincinnati and spoke to them about the issue. After telling them what's been done to the car, and the problem, including the 006 check engine code, they mentioned another problem could be setting off the 006 code and not being recorded.

Hmm... I am at a loss for words, here. I will likely take it down to the shop in Cincy (it comes highly recommended) in the next few weeks and only drive the car sparingly (too much going on). I keep popping the hood and going through the connections and see nothing visibly wrong, but I keep hoping that something pops into my mind when tracing the vacuum lines, wiring, etc.

It runs fine when cold and runs okay most of the time. When it gets warm, it will surge at idle and every so often surge under just keeping the throttle steady at one speed. That seems to me to be a TB issue. However, could it also be tied to the engine temp sensor (engine temp is always fine)? EGR system? Electrical Over Voltage component? When accelerating, it runs very strong with the great DOHC engine noise as pleasant as ever, so the plugs and other ignition components should be okay.

Finally, has anyone ever heard of resetting the ECU after a TB has been removed and re-installed?

 

[visal911]

It runs fine when cold and runs okay most of the time. When it gets warm, it will surge at idle and every so often surge under just keeping the throttle steady at one speed.

I'm not too familiar with m104 engines but running fine when cold could also be a CPS or a O2 sensor problem. Sometimes a bad o2 doesn't throw off the CE light.

I wonder if you can test the o2 sensor voltage like the older CIS cars?

 

[LeftCoastGeek]

same O2 sensor technology, should behave the same, swing between near 0V and near 1V a few times a second. I typically see 'low' as 0.1-0.3V and 'high' as 0.7-0.9V. at idle, they swing slower, at higher RPMs, they swing faster.

re: resetting the ECU, they likely just did that to be sure it was properly calibrated.

 

[NGough]

I'm not too familiar with m104 engines but running fine when cold could also be a CPS or a O2 sensor problem. Sometimes a bad o2 doesn't throw off the CE light.

I wonder if you can test the o2 sensor voltage like the older CIS cars?

Hmmm... an O2 sensor? It would not be the first time that has been replaced. I cannot find a receipt for ever replacing the CAT, so it might still be running with the original CAT. Still has the original exhaust system, including muffler and resonator. All this original with 203k on the clock. Which brand of O2 sensor is the one with which most of you have had good luck?

 

[sbaert]

Use Bosch O2 sensors. Amazon has the best price. Remember, these O2 sensors are good for about 60K miles and are as done as Thanksgiving turkey after 100K.

[ame="http://www.amazon.com/Bosch-13314-Oxygen-Sensor-Fitment/dp/B000BZI1J6/ref=sr_1_1?ie=UTF8&qid=1426078904&sr=8-1&keywords=bosch+13314"]Amazon.com: Bosch 13314 Oxygen Sensor, OE Type Fitment: [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/[email protected]@[email protected]@41Y8E0GBQ9L[/ame]

 

[NGough]

A quick way to find if it's the O2 sensor, is to disconnect it. I will do that either later today or tomorrow. My buddy at the shop mentioned it is possible, but not likely, as it would have to be a short in the wiring. We shall see and I shall post results of my tests. At least the Bosch O2 sensor from Amazon is around $70. (As an aside, I've had the O2 sensor replaced twice in the 100k miles I've owned the car, since 2002.)

 

[jndaigle]

Good luck finding the problem.

It sounds as though anything you mess with fixes the problem for a couple of days. It is possible you have a lose electrical connection and when you change something you simultaneously knock the lose connection around. For example, if you disconnect the battery negative to work on the car, you could be hitting a connector in the area and changing something.

I had the following whacky problem with a CPS. The car would run great for long periods of time. Then out of the blue, it would die. Then I would crank and after a while it would start. Might run 10 days or a month or 10 miles. One day it stopped restarting. I called a wrecker, but they were real busy and after a while the car started. I drove it about 20 miles and it died. It would restart, but I thought the situation was dangerous because it was getting dark and the road was high speed. I called a tow truck and we had a great ride home in the tow truck and enjoyed chatting with the driver.

So then I decided no more driving the car until I fixed it. I started at the most probable cause for a problem of this sort, the CPS. The instant I had the CPS out, I knew the problem. The wiring to the CPS on this vehicle looks like lamp chord (two 18 ga stranded wires). One of the leads on the CPS was cut because a cable had been incorrectly routed. Trying to start would cause the cut part to bounce and reconnect. When it bounced enough after that it would disconnect.

I have experienced a number of other very strange problems from things that have very simple solutions. My favorite so far was on my '93 300E. Started great one time on carb cleaner, then not at all. Had spark on exactly one coil. Problem? No bolt holding the CPS down.

Intermittent relays can also cause weird problems.

 

[LeftCoastGeek]

my 300E had an intermittent stumble coming off idle, it drove OK once you were moving... I chased things for 2 years, thought for sure it was an electrical problem due to its intermittent nature. I diagnosed various marginal things and R&R'd them, but the problem would come back in a few days to weeks. FINALLY broke down and took it to a highly recommended independent mercedes service shop, and they diagnosed it in an hour as being air leaks around the injectors, so I had them replace the seals, and told them to go ahead and test the injectors while they were out (they have an injector tester in house), and yup, several had bad spray patterns and/or were dribbling. so 6 new injectors with new seals, and the car is running like a brand new engine (which at around 60000 miles, it SHOULD be!)

now, this was a CIS M103, and I'm *not* saying this is your problem, what I'm trying to say is, it takes some skilled diagnoses and testing to find root problems. before the injectors, I'd fixed the air flow meter potentiometer, new OVP, new plugs+wires (rotor+cap were already new), new o2 sensor, the HVA started leaking, so that was replaced, and in general, done a ton of testing.

 

[NGough]

I've been fooling around with this stumbling/erratic idle and stumbling whilst driving issue for awhile now and trying to tick off the items as we (including the shop) see them.

This afternoon, I removed the "resonance flap" (P/N VDO 0001400331) and in checking out what it should look like, mine is different. There is no large "flap" underneath, but once it's removed I see a diaphragm and a short rubber hose coming out of the top that is NOT connected to anything else. I've taken a photo of it in this post. Is this supposed to be open to the ambient air? I noticed that on the bottom of this device, once removed, there is a small inlet with a screen which is not connected to anything else once the entire device is re-installed. And, of course, the C/E light is on.

I've checked out all vacuum lines, even those from the EGR diaphragm on the exhaust side. All look fine with no tears or holes or deteriorated rubber. There is a small blue-white check valve (?) underneath the intake manifold. Could this be clogged?

So, there you have it. If someone doesn't let me know about this "resonance flap" device, I will be taking it into a shop which does a lot of W124s with the owner being a certified Benz mechanic. He's incredibly busy and is way out in the countryside, so it's tough to get there when the other car (a 98 Volvo S70) also has issues (vibrating dash and I will not pay an arm and a leg for that one to be tightened up after it's removed and re-fitted as I can just see the $$$ on the number of hours it will take).

 

[LeftCoastGeek]

for our 1994 E320 M104.992, there's no vacuum line or nipple there. EPC says my resonance valve is 0001400431 (superceded 0001400331). the car isn't here right now, so I can't check what PN is actually in it

 

[Jayare]

NGough

With the miles indicated on the car, I would assume there's a number of items that have been replaced. However, I have to ask about the upper/lower harnesses and throttle actuator.. Replaced? Correct Bosch F8DC4's ? Coils? How about the OVP relay? Voltage at the battery with the car running 13.4v+? Changed all the fuses to ceramic copper?

If we know about the history of these things, it will be much easier for us to offer well founded solutions.

Let us know and good luck

Jayare

 

[jndaigle]

This may not be of help to you, but who knows?

One of the odd-ball things that I found on my 1993 W124/M104 that I rescued from the grave was that the pressure regulator had no O-ring on it at all. I cannot imagine how the O-ring went missing, but it was certainly gone. I have no idea what symptoms this would produce because I caught the problem before actually trying to start the car, but I would think a defective O-ring in the pressure regulator could cause erratic fuel pressure and may result in your symptoms. As I recall, this is very easy to check. Put a fuel pressure gauge on the fitting, take a look. Then yank out the regulator and have a look.