'95 E420 - Vibrations in Steering Wheel at Idle
 

Hi,

I've spent about 6 hours going through all the posts trying to coming up with a short list of possible causes, but I haven't found any posts describing a similar problem. So, here is goes...

Before this started, if the car was in Drive or Park, you barely knew if the car was on. There were no vibrations in the cabin nor the steering wheel.

When in drive or park, there is a vibration easily felt through the steering wheel. It has varying degrees. Sometimes you it is not there at all (about 5% of the time). Most of the time it is noticeable has oscillates from not too bad to very noticeable in 2 second intervals (think of a sine wave). Other times it is much more noticeable and can be felt in the seats, gear selector and you can hear it too - like the timing is off and exhaust has more of thumping sound.

Often when coming to a stop at a red light, the first couple of seconds, there are no vibrations. After a couple of seconds the the oscillation cycle starts.

On occasion (maybe every 4 to 6 weeks) the cars shakes alot when first started - this last for 30 seconds at the most. Happens more frequently when it is cold outside.

Electrical load makes a difference for a couple of seconds - for example, if all the electrics are off and then I flip on fan, then headlights, then stereo, etc. there is a spike in the vibrations, but the goes back to the usual range of vibration after about 2 seconds.

If you are really tuned into the vibration, you can feel it in nuetral or park, but it's much less than if the car is in Drive or Reverse. It's very faint in park or nuetral, but the car goes from vibration to a subtle rock or kick every couple of seconds. Put the car in drive and it sounds like you put front wheel drive 4 cycle japanese econo-box into drive.

The car has 95k miles; at 86k miles (Nov. '91) it had the transmission replaced and motor mounts. The vibrations were occurring before this repair and continued afterwards. At 90k miles it had its schedule service. Every 2 to 3k miles it gets a bottle of techron.

I bought the car about 2 years ago and did NOT have any of these vibrations. they started last summer and have gotten alittle worse - meaning, occurring on a more regular basis, but but the range of the vibration is about the same.

Seeking suggestions and order to ruling out causes - I don't want to spend $2k only to find out a $50 part replaced at the started would have solved it all!

Thank you very much for your input. John.

It sounds to me like broken motor mounts.

In Nov. 2001 (you typed '91, though, which is impossible), you had the transmission and mounts replaced. Were these the transmission mounts or the motor mounts?

Yep - the November '91 would be impossible! Ooops - it was late. I pulled the receipts from MBZ and it states the motor mounts were replaced, so I'm guessing the transmission mounts were not... So, they are "officially" on the list to be checked. After reading alot of posts, here's a list mounts I've come up with:

Transmission Mount
Engine Mounts -- repalced already! - maybe defective?
Engine Shocks -- applicable to w124/E420?
Rack Dampner -- applicable to w124/E420?

Anything you would add or remove from the list? Thanks, John.

I would say this is definitely the engine mounts - I had the same vibration on my '93 S500 and new mounts cured it 100%

Hi Andy,

The motor mounts were already replaced in November 2001 - and made no difference.

As I go through the chronology, if any of this starts sounding too familiar to anyone, please provide input/suggestions.

UPDATE SINCE YESTERDAY:

The car went into the shop this morning; after a test drive and speaking with tech for about 20 minutes, we're going to start with cleaning the fuel injectors. This would coincide with the general recommendations of BG 44 (I think I got that right) or the Penzoil Fuel System Cleaner.

There is a slight miss-fire every 30 to 60 seconds (noticeable when just sitting in Park or Nuetral). The tech said is was probably variances in the fuel pressure psi. He'll also try cleaning the throttle body alittle; he is very hesistant about going into the throttle body since that is an expensive part.

Also, the car has a serious mis-fire every 4 to 6 weeks when first started (last for about 10 to 30 seconds); this suggests that one or more fuel injectors is losing pressure or is blocked.

I'm hoping cleaning the fuel injectors works, but I am doubtful. This might be one of several problems, but I don't think it is "the" issue. The car always gets it gas from Chevron and a bottle of Techron every 2 to 3k miles.

When I check-in this afternoon, I'll ask about the condition of the vacum hoses. I want those replaced anyway.

ITEMS RULED OUT:

The wiring harness was ruled out because the timing issues are very subtle and there are not any of RPM spikes or stalls noted by other owners.

Flex-disc only applies to when the vehicle is moving - vibration should ne noticeable around 35 to 38 mph. Mine is smooth as silk.

WHAT'S NEXT:

If this doesn't cure the vibrations, then we'll look at the transmission mounts, motor mounts (again) and engine shocks. Before doing this, I will try the Penzoil Fuel System Cleaner; people have had good results, so another $8 is cheaper than a cup of coffee at the service shop!

GENERAL INFO ON E420 / W124 VIBRATIONS

As for the vibration itself, if the engine was in the S-Class it would not be noticeable because the additional size and mass of the vehicle would better absorb the vibration. Whereas with the V-8 in the E-Class, the chasis easily transmits/transfers any engine vibration.

My money is on the motor mounts.

A slight miss a big sign of a bad engine wiring harness, especially since so many are bad between '93 and '95.

Have your tech examine the wiring harness for cracking insulation.

I don't know why he's focusing on a fuel supply / pressure problem, which doesn't seem characteristic of this at all.

I would have focused on an ignition-related problem - a bad plug, plug gap too small, but probably a bad spark plug wire, or a short at the spark plug wire resistor "boot" or end. A bad connection at the resistor boot would be my guess for the missing, if the engine wiring harness is fine.

Hi Suginami:

MOTOR MOUNTS:

The car was purchased 2 years ago and did not have this vibration. The vibration developed about 9 month laters. At the one year mark it had the transmission replace and the motor mounts replaced. After the repair, the vibration remained unchanged. So, unless the old mounts failed and the news ones were equally defective from the time of install, they are not the cause.

BAD PLUG, GAP, etc.:

About 3 months ago the car had its 90k mile service including replacing the rotors, caps, plugs, etc. No difference from before to after.

WIRING HARNESS:

During the 90k tune up, the harness would have been removed. One would expect the movement to cause additional stress on the cable, thus more cracking of insulation etc. Thus if there was a slight problem before, it would be even worse afterwards.

But, I won't totally dismiss the wiring harness yet. Called MBZ and gave them the VIN; the are looking up the history to see if it has already been replaced. If not, hopefully they will honor a parts replacement. I'm alittle doubtful; I've had alot work done Mercedes Benz of Bellevue, but they've left me less than satisfied, so I have not been there in about 10 months.

NEXT STEP:

The car is supposed to be ready this evening. I'll take a long test drive and see if there are any changes after this work. If the problem is there, then onto checking a couple such as the vacum hoses and fuel pressure check. If all that checks out, then back to the wiring harness and alittle exploratory surgery.

The tech doing the work seems to know his cars; most importantly he has felt the vibration I'm obssessing on, so at least he knows if the problem has been fixed or not.

Is there a steering shock on your car? My 92' 190E 2.6 had one that needed to be replaced and caused a vibration up thru the wheel.

Hi Jim,

Yes there is a steering shock (or dampener); that was replaced alittle over a year ago as part of front suspension maintenance check.

Update to the car's status:

After the fuel injectors were cleaned, the slight mis-fire (about 45 to 60 seconds) was fixed. This is NOT the problem though, it was just another little issue. This mis-fire was very, very slight. It would barely cause a ripple in a glass of water. The engine ran smooth before, now the response is even smoother. A love that engine!!!

For those you who have suggested the mounts; the tech checked all the mounts and said they were okay (there's more on this, read on). Also, keep in mind, the motor mounts were already replaced last November.

Some more observations about the vibration - in drive, the car idles at 500 RPMs with very little variance. With my foot on the brake, if a nudge the RPMs up to what looks like 550 RPMs, it goes away most of time. However, that throttle point you can tell there's more stress on system than usual. The vibration is gone, but the car just doesn't sound like its usual, happy resting point. Next, there is a slight, gentle shaking around 1100 to 1200 RPMs when the car is in nuetral or park. Finally, the vibration I'm ranting about has a 3 second cycle - while idling at 500 RPMs in drive, the vibration oscillates about 20 times per minute. Meaning, the vibration hits its high and low points 20 times. That's not 20 thumps, it 20 periods. I'd say there is probably about 20 to 30 little pulses in each period. That's really hard to count!!! So, it could be an exhaust vibration transferred through chasis at some point. - This is just my opinion and I'm not tech.

So, what's next...?...

This Monday we will pull one belt off the car at a time to see if the compressor, power steering or alternator are the problem. I doubtful about this because if they were the problem, I think the vibration would be same whether the car was in gear or not. However, we need to eliminate some variables, so what the heck.

Next, the exhaust will be loosened and then re-tightened will the car is on the rack (the type where the tires are NOT hanging in the air). On similars models they have seen problems where exhuast is slightly out of alignment, thus stressing the drive-line and created a vibration. This may have some merit; on occassion a weird vibration/rattling sound comes the tail pipe area when the car is first started (last around 60 seconds).

While they have the car in the air, any other mounts passed the motor will be checked again, and I'm leaning towards replacing them. I want them ruled out 100%.

Next, the wiring harness does not appear to be a problem. The idle is stable, there are no weird kicks or hic-ups under acceleration. However, we're cutting it open to take peek. And, those vacuum hoses are going to be checked.

All this will be done in my presence (they expect 2 hours) and I'll be the one saying whether the vibration is better or worse as we change or check eacy item.

FUN FUN FUN! If anybody has anything we should add to check list, please let me know before Monday. Thanks a million.

After going through the invoice when the transmission was replaced, the transmission mount was also replaced (Thanks MB Doc for helping with part numbers). So, the motors mounts and transmission mount have been replaced within the last 12 months. The vibrations was the same before and after this work, so it's doubtful they were contributing to vibration.

I am very interested in the outcome of your search for the source of the engine vibration. I too have had a engine vibration that fits your description. I have had this vibration in my 95 S500 since it was around 45,000 miles, and the car currently has 62,000 miles. I have brought the car to the dealer on many occassion without success. These are what was replaced: Engine mounts, plugs and rotor, reset computer fuel injection pressure checked. I hope that you're able to find the problem.
By the way does the vibration occur only in park and nuetral? Because, I can only feel the vibration in park and nuetral in my car.
Good Luck.

My vibrates noticeably in Drive/Reverse. Park and Nuetral is very sublte, but you can still feel the peaks.

I've owned my 400E (same M119 engine as yours) since it had 25 k miles. It has always had a less-than-smooth idle. I've had it back to the dealer under warranty and was told "All the V-8's do that." Not sure I believe it, mind you, but whatever it is, it is persistant and not progressive. I now have 119 k miles. It got a bit better after replacing motor mounts but there is still a subtle vibration at idle, in gear, esp. in warm weather. I notice it more after I've been stopped (say at a red light) for 10 seconds or so. Personally, in my case it's minor enough I've learned to live with it since the engine performs so well otherwise.

Hi 400E -

I could live with the vibration but... It didn't start until about a year ago. If is the vibration was constant and uniform, I'd consider it normal. But, it varies, has cycles, has highs & lows and similar to what you said, it starts a couple moments after stopping at a red light. I've contributed that part to the idle going from 600 to 700 RPMs will coming to a stop, and once the car is completely stopped the idle settles to 500 RPMs. Sometimes, giving the car just alittle more gas (while in gear and the brake is applied) and nudging the idle to 525/550 RPMs eliminates the vibration. This doesn't always work - but 60% or more - it works. I don't think this is the problem, it just hides it. At 525/550 RPMs there is too much resistance and you can hear it in the engine, etc.

The vibration is minor in the steering wheel, but it also causes noise in the cabin similar to back pressure in the exhaust - that probably gets to me the most. The car is due for its inspection, maybe the emissions test will shed some light on the culprit. The exhaust has the rotten-egg smell from time to time (e.g. the catalytic converter), but the shop said that occurs when the car burns rich. Techron is added every to 2k to 3k miles, so that's probably the cause. However, after 8 years and 96k miles, alittle exhaust work would not surprise me. Also, just about every sensor could be at fault.

Overall, I think it is a combination of factors - some mounts or bushing intended to absorb vibration need replacing, rehanging the exhaust is a good idea and finally the injectors probably need more than just a cleaning.

One final comment, this started after moving to Seattle from Dallas, TX. My first thought was the gas. It always gets premium from Chevron - however it 93 octane in Dallas, but only 92 Octane in Seattle. I've tried water removers in the gas, octane boosters, etc., No difference. So, I don't think it's the gas, but it's still an interesting coincidence.

John,
I'll be interested to hear what you find. You are taking a very methodical approach so you will very likely figure it out soon.

I have read recently on the Ritter/Easley list that some aftermarket motor mounts are pretty lame. Even the factory ones don't last as long on our vehicles due to the V-8 (though sounds like yours check out OK). Did you know that the corrugated plastic ducts under your front bumper (if it's like mine) are there to route air to the motor mounts to keep them from frying from the higher underhood temps of the 400/500E?

Do you get your engine to do some heavy breathing (aka Italian tune-up) regularly? I started doing this about every week and it helps at least a little. The first time I did it, the engine started missing at about 5000 RPM. I persisted, and that's a thing of the past. (Stu Ritter had said that that would happen-- you just need to not lose your nerve and keep pedal to metal ...)

5k RPMs in nuetral - nope, can't say that I have. But on the highway - yes! On the highway entry ramps, it gets dropped in 2nd and stays in second until 70 mph. Likewise, alot of 4th to 3rd downshifts. In Texas there were alot of open roads with no radar, so the car was routinely driven between 80 and 90 mph on the freeway and on occassion topped out between 137-138 mph.

I read in one of the posts +/-150 mph being the top speed. Around 5000 RPMs in 4th and the car will not go any faster. I assumed it was a governor. Common says dictates who really cars if car tops out at 138 or 150 - either way, that's straight to jail and a suspended license. But... still makes you wonder if something isn't quite right under the hood.

Since moving to Seattle - the roads suck (rough, narrow, pot holes, rocks), terrible traffic, more police cars and radar guns than I've even seen. So, I get nervous just doing 80 on the freeway; usually you're lucky to get above 65. Last night some guy missed his exit, STOPPED in the right lane and proceeded to back-up! The truck in front of me locked up his brakes and dove to the right. I stood on my brakes and thought for sure I was going to rear ended. Fortunately not. At the time I was going 55/60 mph; had I been doing 70 I wouldn't be writing this post!

During some vacations over the past year we've driven up and down the state, so alot of highway driving. The car still hits a 100 in a blink of an eye without any hesitation, so I figured all is good.

Can you point me to the post you were talking about - I'm curious!

Back to the vibration; I bought some gloves and start touching various parts of the engine and drive train. In nuetral/park you can feel the vibration which is getting transferred to the steering wheel as plain as day if you put your hand on the engine. Likewise, you can feel is through the exhaust pipes too. Inside the car, you feel nothing - so I assume that means the motor mounts are doing their job. Then, put the car in gear and the vibration creeps into the steering wheel, gear selector, etc. along with the noise.

The transmission mounts were also replaced, so that leaves the differential mounts. Anyway, on Monday I'll point on the vibration to the tech by touching the engine. Then we can put the car in gear and see how it changes from the engine back. To me, the vibration is very obvious from the inside of the car. So when the car is on the rack, I would think it would be pretty easy to feel around and see what vibrating.

I use an old stethoscope and a dowel rod to probe for sound of course this is an old trick but it works like a charm and makes you look like a real pro when your friends are around.......
William Rogers.......

John,
Yes, I wasn't entirely clear -- I meant getting the revs up on the road, not in the driveway. This approach can sometimes help with idling problems.

I believe the top speed is electronically governed at 135 mph.

RE: the post, if you're referring to my references to Stu Ritter, he is on another list ...

Just thought I'd add my 2 cents in.

I have a 92 400E, and does on occasion have a slight miss. IT almost seems to idle smoother when cold, and then when it warms up, it is more likely to miss.

I personnally feel, after reading all these posts, that the motor mounts/tranny mounts dont have anything to do with his problem. Especially since he just had his replaced. I just replaced mine 3 months ago, only cause both of mine were collapsed. It made a world of difference, but you can still feel slight misses.

What I WOULD pay attention to is the ignition/fuel system, such as wires, rotor/caps/ etc. Also, check your wiring harness. My harness is SHOT, but it still is working. Half of my fuel injection wires are exposed. So when I feel a slight miss, its probably because of that. Its going to get replaced soon.

I find that diagnosing intermittent (or even persistant) rough idles on mercedes is an all out nightmare, both financially and labor wise. I cant tell you the countless number of DAYS I spent diagnosing one on my older 420. But that is a entirely diff. fuel injection system.

I hope you figure out whats causing this, and let us know what you find!! good luck

p.s. I have personnaly had my car up to about 152 MPH. I believe the 94 and 95 were limited to 130MPH, due to the "gentlemans agreement" that took place in that era between all european auto manufacturers to limit there cars to 130. This was done I believe to deter top speed wars.

400E -

I check out Stu's post. I'm going to add the 'Cool Harness' and a 80 or 82 C thermostat. After that I'll consider cruising at 5000 RPMs ;-)

AMG280 -

As we've been working through vibration with the shop, we cleaned the fuel injectors. This didn't help the vibration but it did help a minor mis-fire that could be felt every 45 seconds or so. After sitting for a couple minutes, hours a day (it's very random) my car has an extra sputter for about a 1/2 second while starting. The mechanic feels that one of the injectors (or possibly more than one) is losing pressure and has a leak at the seal. They want to remove all the injectors, clean them and then replace the seals.

I'm not jumping in on this one yet because this is only a minor detail for my situation. If we get the vibration kicked, I'll probably replace the injectors - they want around $20 per injector to clean them, whereas new injectors are around $40 each. It will cost alittle more, but I prefer replacement. Otherwise I'll always be wondering if the next problem is somehow related to the "cleaned" injectors ;-)

Anyway, based on your description it sounds like the injectors might be the culprit for your car. You shop can do a pressure test to verify. I've also read that these cars have long timing chains which stretch over time. 120k miles seems to be the target point for replacement (based on some comments I've read in other posts).

John,

You say new fuel injectors or $40 a piece? They have a list price of $180 / piece and can be had online for $129. Therefore, replacing all 8 would be quite pricey, over $1,000!!!. If you know of a place that has them for $40 a pop, let me know ;)


Your probably right-on about the timing chain. mine has 118,000 on it, and its making a funny noise. The noise almost seems like a "kink" in the chain. Everytime a certain part of the chain goes over the sprockets, it makes a weird noise. Its not the belt or any accessories because the belt was taking off to test it. The noise happens every 3/4 second, about the time it takes a certain point on the chain to cycle past a certain point on the engine. It only does it when the engine is warm. The noise is not present when its cold. It seems more prominent on the pass. side bank sprocket. Any ideas people?

My mechanic suggested I take off the cam cover on that side, in which I was until I noticed that the rear allen bolt is next to impossible to reach. any ideas? I probably will have the chain replaced. But I would be heartbroken if that didnt take care of it.

-Andy

Yikes - if the injectors are $140 each, then forget them replacing them! The shop was ballparking numbers because I was asking how much cost to have each one cleaned. They said they outsource it - I'm guessing they just put the injectors in some sort of solution and let them soak...?... Hmmm, $20 per injector isn't sounding so bad now!

Before going after your timing chain, they cleaned my fuel injectors by hooking it up to the machine that blows the cleaning fluid thru the system. I noticed a difference afterwards. That probably costs around $50 to $75; I'd try that first. If there's no difference, then you can rule out the injectors (assuming the pressure test comes back okay).

Follow up after last visit to the shop...
 

After two hours of tinkering, no improvement... Started with the exhaust and transmission to make sure everything was mounted straight, no rubbing, etc. All that looked okay.

Next, checked the alternator (why not?!?!), the car has a big stereo in it (around 600 watts) so it could be drawing too much from the alternator. That appears to be a non-issue.

Removed the belt and that cured about 80% of vibration. However, the engine still has some mis-firing. I'm guessing removing the belt just reduced the load on the engine; hence, reducing the mis-firing.

The car is going back on Wednesday and they are going to hook it up to a scope and check the electronics at the plugs. Also, they want to send out the injectors for a cleaning ($24 per injector). I'm still asking about the wiring harness, but they don't feel that is the problem. The timing issue is too subtle in their opinion.

The vacuum hoses were checked last week; no leaks.

At this point I feel like the shop is just guessing (and at my expense)... I'd like to compile a very clear check list for ignition system. So, some input as to what others would check 1st, 2nd, 3rd and so would be greatly appreciated. Here's my thinking (if each test checks okay, then move onto the next test):

1) CHECK: Wiringharness (peel back the case).
ACTION: If insulation is failing, replace harness
2) CHECK: Pressure test on the fuel system
ACTION: Injector seals?
3) CHECK: Oscilliscope on the plugs
ACTION: ??? Replace harness ???
4) ACTION: Clean fuel injectors


Thanks for everyone's help,

John

John,

your list seems pretty good. When they check the harness, be sure they peel back diff. parts of it....like make sure they check diff fuel injectors' wires. Also, I would put the engine on the ignition scope before diagnosing fuel problems. It only takes a few minutes, and could show something right away. If one of the eight cylinders is diff than the other, it could indicate a bad wire.

Other than that, good luck.

Let us know what you find.

-Andy

My mechanic replaces fuel heads on 103 engines to cure problems with irregular misses when all else fails - can be irrregular fuel pressure. He checks by banging on injectors with wrench to see if changes, then loosens the fuel lines at the fuel had to check for flow, and check again to see how the pressure builds up. As I'm a "diesel guy", not sure if this even applies to your car.... but I don't like living with vibrations either.

Speaking of fuel pressure, my mechanic says he starts with replacing the fuel pressure regulator when faced withan idle problem. It's comparatively cheap ($35) and easy to do. I replaced mine with the official MB part, which has been updated; didn't seem to help but you might try it.

Interesting you should mention the fuel pressure regulator. Now that I've really paid attention to this vibration and tested it under different circumstances, here's a new one...

While stopped at a light, foot on the brake, place my right foot on the accelerator pedal and pushing very, very gently, the vibration goes away. There is noticeable change in the RPMs or change in the engine noise. It's hard to measure, but maybe the pedal is moving a couple of millimeters.

I know nothing about fuel delivery system, but... maybe the accelerator pedals links to some type of pump, vacuum, sensor, idel sensor or something like that is going bad???

Anybody have any opinions on this??? Overall, this is much different before; nudging the gas pedal and pushing the rpm's up another 25 or so has always made it go away (and you could see the tach move just slightly).

And the latest update. The engine was hooked up to an Oscilliscope and the voltages to all the cylinders was equal. So, onto the fuel delivery system check - pressure test, check fuel pressure regulator, clean injectors (pulling them out and sending them over to another shop for cleaning), new injector seals and seats.

The vibration is fairly consistent these days. Giving the car some gas while stopped, foot on the brake and in drive and the vibration goes away. You don't have to give the car much gas - in fact the tach remains constant at 500 RPMs.

May or may not do the fuel injectors, depends on the pressure test and how the other things check out first.

Latest work performed
 

The vibration has not been fixed yet... The wiring harness was replaced and the injectors have been pulled, cleaned and replaced with new seals & cups. But that xxxx steering wheel vibration is still there.

After this last round, it is back to being intermittant instead of continuous. Sometimes it's there, sometimes not (when stopping for red lights & such).

When I first pulled out the service parking lot, it wasn't there. After driving for about 5 minutes it crept back in. Errrgghhh... I'm really having a hard time figuring out what it could be.

The car idles at 500 RPMs when in gear. Placing my foot on the accelerator and giving alittle gas (the tach goes up may a couple RPMs) and vibration goes away. Also, when flipping on the AC - the idle doesn't change at all (I thought the car was supposed to idle about 50 RPMs higher with the AC on???). Turning on the AC definately increased the vibration.

I need suggestions; I'm thinking about leaving the car with the MBz dealer, but I don't want to give them a blank check. Are there any good diagnostic tests they should try? The vibration is still oscilatting, as if something is trying to correct or compensate, but it can't find an equilibrium point. When the car idles in nuetral or park, there is still a misfire every 30 to 45 seconds (just a very little cabin shake - very slight).

Thanks, John.

Take a gasoline supplier out to lunch ,you might find out why you have such problems............
Wiliam Rogers.........

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 :D :D ).

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. :confused:

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.

motor mounts.
 

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.

Update
 

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.

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 !

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.

Hi Suginami -

I'll take the car in and see what they say about Steve's comment. I'm not too excited about spending another $400 if they can't find a problem with gastket. I'd really, really like to know there is a problem with the gasket before it's replaced.

Well, no one likes to spend money unnecesarily, but on the bright side, even if it doesn't cure your problem, you could at least rule out the intake manifold gasket as a source of the problem...:D :(

John,

Is the Indy not interested in doing it, or just not sure that its the problem. He is probably getting frustrated, he already told you the TC looks suspect??
And you mention that it happened (immediately?) after the tranny and torque converter was replaced, so I'm not sure why that would be an intake manifold gasket - could just be a coincidence. You may want to have the Indy re-install or find another torque converter. I'm not saying its the TC, but its possible that the TC or the install of the TC is incorrect and could be causing your problem. He should be able to find a junkyard TC - to see if it CHANGES the behavior. I'm still wondering why both needed replacement by 90Kmi -its NOT common to replace both at the same time.

Hi John,
Just to add yet another wrinkle, has the issue of the engine wiring harness been discussed yet? This thread is so long I didn't go through it to see. On the Ritter/Easley list there has been a discussion about bad wiring harnesses causing funky idle problems as one of their main manifestations. I checked mine our recently and yes, the insulation is fried in spots so looks like that will be a job I will need to have done fairly soon.

Yep, wiring harness has been replaced and made no difference.