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 ...

__________________
Steve
'93 400E

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.

__________________
93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

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

__________________
93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

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).

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

__________________
93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

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.

__________________
Brian Toscano

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.

__________________
Steve
'93 400E

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.

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.........