Hi William,

I doubt that poor gas quality is the issue. There is no difference when either Techron, Valvoline System Cleaner or an octane booster are used. I've also tried adding "Heat" to remove any water in the system. Again, no effect. The car always gets Chevron Supreme.

My guess is a sensor is failing (something key in maintaining the idle speed) or the fuel pressure isn't high enough. I haven't noticed any performance issues while driving the car and its highway performance is very strong. On recent trips, it has been averaging 25 to 26 mpg on the highway.

The car is headed for the dealer later this week to see what they come up with. So far, this is what has been done:

85k - Motors mounts & transmission mounts
90k - 90k service, replaced caps & rotors
95k - replaced wiring harness
- pulled the injectors and had them cleaned, seals replaced, etc.
- checked voltage at each cylinder (measured equally)
- checked alternator
- checked & re-hung exhaust (wasn't rubbing against anything)

I'd like hear what sensors should be checked & how the fuel system should be checked. I'm not concerned about the dealer not doing their job, I just want to know in advance a good strategy - otherwise, I'm just taking their word for it and that doesn't set too well with me.

Thanks for the help.

The search continues for the vibration... The cold start issue has been resolved (replaced crank shaft sensor & air temperature sensor). The shop has a new master tech (MBz certified) and he recommends replacing ignition wires - although he admits that will NOT resolve the vibration (he said the scope the showed alot variation in the voltages - the prior tech said it was fine --- hmmmmmm). So, that's on hold pending resolution of the vibration.

The new tech's guess thus far on the vibration is: possibly harmonic balancer (it has a hard rubber out edge that can break away over time); something in torque converter or there-abouts; hydrallic lift adjuster on the cams???; or fuel pump. He has not checked any of these items yet - this was just in discussion. He is very sure it is a rotational item - nothing to do with ignition, vacuum, etc.

The vibration can be felt when the car is any gear including nuetral or park. It is amplified when the engine load changes - such as putting the car in gear, turning on electrical items, etc. The tech seemed very "tuned" into the vibration I was talking about and could even feel it when the car was in nuetral/park (because the car idle higher in nuetral - it's pretty tough to feel unless you know what you are really looking for). The car goes back in on Wednesday for diagnosis (she's spent more time in the air than on the ground ).

The shop looked at the car again today and determined the torque converter is the cause of the vibration (in their opinion). The tech said he could see it wobbling when he looked through the bell-housing grates. He said without removing the transmission he could know for sure and that the fly wheel could also be the problem, but he leaned toward the torque converter. They knew the transmission was still under MBZ warranty so they called the dealer and tried to arrange an appointment for me.

Proceeded to the dealer, explained the situation and problem and set up an appointment for tomorrow morning. The service advisor spoke with his shop foreman who speculated either the balance weight had fallen off or the shaft on the torque converter was bent. The dealer was relunctant, but after $4500 for the transmission and two follow up visits (before going to the indy) for $100/each citing this very problem, there isn't much argument in their favor.

Back at the indy, they replaced the ignition wires which had been ordered earlier, but not installed. I haven't thoroughly road tested the car, but i think that resolved the intermittant (and very minor) mis-fires. To credit the indy shop, despite alot of parts:

For the vibration:
Rebuilt the fuel injectors
Replaced the infamous wiring harness
Replaced fuel filter
Replaced ignition wires

For the cold start problem:
Replaced crankshaft sensor
Replaced air temp sensor

General diagnosis included:
Electrical test & scoping the ignition
Fuel pressure test
Various other guesses & head scratching!

They waived their labor and sold the viscous fan for 1/2 their cost (paid around $200; the fan was part of earlier problem with the engine temp). As mentioned before, everything thus far is reasonable maintenance or preventive maintenance for a car with 96k, so I'm not too upset about the money. But what I appreciate the most - they waived their labor without my asking are worse yet, having to argue.

The indy is Park Place Ltd. in Bellevue, WA and they have a new MBZ tech, Dave, who came from the Phil Smart MBZ in downtown Seattle. Dave, the new tech, also nailed the cold start issue in one shot. I would definately recommend Park Place Ltd - and considering the MBZ of Bellevue charges $115/hour, Park Place is very, very reasonable (around $60/hour).

How do I get back on Ritter/Easley's mailing list? I tried re-registering but, the website says you cannot due, to technical difficutly for more than a year. Is there a alternative website now or form I can fill out?

Hi S60 --- I can't help you on that one - I didn't know there was a mailing list.

The car is sitting at the dealer and I left with very little optimism; their track record on this problem has been pretty poor. They are supposed to call around two this afternoon - time to get my game face on!!!

If you find out the problem, let me know I have the same problem in a E320 94.

I can check on the hold-up on the Ritter/Easley list and report back. I know there has been a wait but a year seems like a long time.

__________________
Steve
'93 400E

I seem to remember a discussion with a Volvo mechanic saying they provide motor mounts that resonate at different harmonics. Normally the installed version is designed to dampen vibrations at the near idle speed, the alternates move up higher on the rpm level.

The reason I ask is I wonder if you should just be turning the idle speed up a slight amount and forget it. You have mentioned that touching the gas ever so slightly makes the vibration all but non-existant. Could your tach be reading slightly high?

The idle speed on these cars is completely electronically controlled.

It cannot be adjusted up or down.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

The E spent the last week at the MBz dealer. In their opinion the wobble in the torque converter was not sufficient enough to produce the vibration being felt in the car and through the steering wheel. They did replace the engine mounts (which were already repalced a year ago at the time of the transmission replacement), re-aligned the transmission linkage (whatever that means) and tweaked the idle so the car idles higher. HEY - I thought that wasn't possible!!!

I've had the car back for a couple of days and the vibration is still there - but about 25% less than before. Mainly because the car is idling just a tad above 500 RPMs where as before it was just a tad under 500 RPMs. I have been less than kind to Mercedes Benz of Bellevue - however - in this case they been very receptive. All the work was done under warranty and the service advisor, Dean F., has been very pleasant.

Coming back to the idle - the idle is alot different than before. Now, when the car comes to a stop the car is usually idling around 550 to 600 RPMs then over a 3 to 5 second period, it settles to 500 RPMs. Sometimes it sticks around 525 RPMs for around 10 seconds. If it would stick at 525-550 RPMs all the time the vibration would be gone. So, I'm going to ask Dean if they can tweak whatever they tweaked some more.

So, is the problem solved - no. Is it better, sometimes. I don't think the idle setting is the issue, but increasing the idle hides the problem - and at 96k miles that's good enough for me and all I ever wanted.

After all of this - there is a question - why does the idle decrease from 550/600 RPM to eventually 500/510 RPMs during the first 3 to 5 seconds the car comes to a stop at a light? Am I losing vacuum pressure? Also, does anybody know what the adjusted to get the idle higher???

John,
Just got my car back from its 120k service. Was kicking around theories about my intermittant rough idle and after talking about the usual suspects (distributor caps, rotors, etc) an idea struck him. He has replaced the rubber "doughnuts" between the engine and intake manifold on other engines and found this to be helpful. He showed me some which he had replaced and they had visibly deteriorated, causing an air leak.

He said these can be tested by hooking up a handheld tester, monitoring readings from the O2 sensor, and spraying the area around the rubber doughnuts with something (carb cleaner?). This won't produce a noticable change in RPMs but will be seen on the tester.

Just another thought.

__________________
Steve
'93 400E

Hi Steve,

Thank you for the input - I really appreciate your feedback since I'm about ready to push this car off a cliff!!! I'll set up an appointment at the Indy shop to check the same.

I really think that is the right area because it doesn't vibrate when the car first comes to a stop - it takes around 3 to 5 seconds. And, regardless of idle speed, you can feel the vibration when the car first starts. Finally, if driven harder, it takes a little longer for the vibration to start (maybe 7 to 10 seconds). This suggests that pressure of some type builds in the car and then gradually escapes while the car idles. When the car was at the dealer, here is what they did:

071171 Electronic Test Program - For Fuel Inj.
071172 Individual Compents with Fault Codes, Check
431051 Vacuum Hose to Brake Booster, Test for Leaks
071426 Fuel Injectors Hydraulic test Program, Perform
221019 Hypr Motor Mounts, check/Adj. for tension
221260 Front Engine Mounts - Left & Right Side, Repl.

MBz was alittle stubborn; I offered to leave all the paperwork so they could so what the Indy had done (which was 3 out of the first 4). I think MBz was headed in the right direction with the Brake Booster - they just didn't follow up on some other similar possible causes.

Anyway, with the work the Indy has done, I probably can get them to do this for free. How much did the repair cost?

Thanks,

John

Hi John,
I didn't actually have this done on mine yet so am not sure how $$ it is -- probably not TOO bad since the rubber parts don't look very pricey, but not sure how long it takes to R and R the intake manifold.

I agree, from your description I would wonder about this. My tech said that the fuel injection system has a lot of lattitude to "correct" things like air leaks so it's possible that the system is trying to compensate for the air leak and thus producing a variable idle ...

Whatever you've got, I think I have the same thing. Has the same pattern, i.e. not being apparent when first stopping at a red light, but showing up some 5 or 10 sec. later.

Hope you get to the bottom of this soon !

__________________
Steve
'93 400E

Hi Steve,

I was so hoping you already had this done, solved your situation 100% and cost $50!!! I'm going to stop by the Indy on Monday with a print-out of your post and talk with their MBz tech and see what he thinks.

Suignami (I think I mispelled his name) has been nudging me to look into the intake manifold. He had a similar problem, but his car was a 320 - not a 400/420. Also, the shop said they did the carb spray thing, but I don't know if they checked around the intake manifold.

I've thought about trying myself, but saw a very high potential for blowing my head off! And, since you said there wouldn't be a change in idle perse and that the reading the changes in the O2 sensor would be check, I can't do that at home. The perfect excuse to watch college football!

I'll keep you posted.

Yeah, it was me that suggested the intake manifold.

My (former) independent mechanic said he sprayed water at the intake manifold seal to check for a leak and said he couldn't find one. He gave up on the vibration and told me to take it to the dealer.

I took it to the dealer, they declared that the intake manifold seal was leaking. I think it cost around $400 to replace the gasket, and my problem was 100% solved.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".