Mercedes-Benz Forum banner
1 - 20 of 25 Posts

·
Registered
1996 Mercedes Benz S320
Joined
·
25 Posts
Discussion Starter · #1 ·
My son's 1998 E320 has begun to have some idling issues. When the car is in idle at a traffic light, stop sign, etc., the car tends to vibrate and the engine doesn't sound "smooth". No warning message are showing either. The car is running fine other than this one issue. The car currently has 156K miles. If anyone may know what the problem is, I would greatly appreciate the input!

Thank you in advance!
 

·
Registered
1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
Joined
·
7,035 Posts
Check for changes in the vibration between the car in neutral and the car in drive, and also the vibration change when going from Drive to Reverse. If the mechanical vibration go down in Neutral (seat of the pants feeling) then it could be your motor mounts. Do a froum search on that and you will get more information.
 

·
Registered
1998 E320
Joined
·
196 Posts
Same here

I have the same issue. I replaced two motor mounts... both of which were shot. The issue is still there. Drives fine. Idles in park and neutral just fine... smooth. Put it in drive and pull up to a light... the motor bogs down a tad and the roughness can be felt. Deep shudder. It lightens up a bit then does it at the next light. Again... idle in P or N is excellent and butter smooth.

Is there a transmission motor mount which could cause this? Perhaps my MAF is dirty/malfunctioning which could cause this?? I have new Bosch Super plugs, a clean air filter, 93 octane gas, a one year old fuel filter and normal temperatures. I would love to have some suggestions.

My 98 E320 has 208K miles on the clock. I have heard that the MAF will not read the quantity of air/oxygen when it start to fail which would lead to low or rough idle.

Thanks in advance to all.
R/
Scuddog:cool:
 

·
Registered
1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
Joined
·
7,035 Posts
Yes - there is a tranny mount and at 208K it could be suspect. It's a affordable aftermarket part, I haven't done the install myself to comment.

On the engine mounts, actually China no names can be a problem in themselves.

A "failing" MAF (going to far spec range, still short of CEL) the normal characteristic shows when coming to a braking stop, when braking the RPM's will drop as normal and instead of catching itself and settling in to normal idel, the engine will feel like it's "choking", which includes a vibration/engine shimmy, might drop a hair unsteadily below normal idle, then most times catches itself before the engine really cuts off, then tends to dart up a hair past normal idle when it catches itself and compensates.

MAF replacement should be done with genuine Bosch part, from reputable internet source (most often mentioned autohausaz.com) since there is so much MAF trash and misdirection out there with China no names, and rebuilts using China sensors.

Good luck - and keep the faith !
 

·
Registered
1996 Mercedes Benz S320
Joined
·
25 Posts
Discussion Starter · #5 ·
I have finally had a chance to further check the idling/vibration issue of my son's E320 Mercedes. There are absolutely no vibrations when the car is in neutral, reverse, etc. The car only has rough idling/vibration issues when the car is in idle at a stop sign, traffic light, etc. Otherwise, the car sounds and runs smooth. So does this definitely mean I need new motor mounts? By the way, what is the correct idle speed for an E320?
 

·
Premium Member
2001 E320 - Brilliant Silver/Ash: 107,000+
Joined
·
17,193 Posts
I still think the motor mounts are the #1 suspect. And as mentioned, at that mileage the transmission mounts are the #2 possibility. My car idles at 600 RPM after a 10-15 second initial warmup at around 1200.
 

·
Registered
96 E320 Black, 98 E320 White
Joined
·
18 Posts
Hi emcee007,
My 98 E320 V6 is recently developing same vibration at traffic lights, I had motor mounts replaced at mechanic cost $120 + parts. One day, last week, car won't start because of the MAF. Yes, expensive, cost me $275 on Bosch MAF from the mechanic. Vibration continues, so I went ahead replaced all 12 plugs to NGK 7090 last Sunday. Rough idle still there. Please advice if your vibration is fixed, and how?
 

·
Registered
'01-E320 & 02-ST2
Joined
·
31,631 Posts
Hi emcee007,
My 98 E320 V6 is recently developing same vibration at traffic lights, I had motor mounts replaced at mechanic cost $120 + parts. One day, last week, car won't start because of the MAF. Yes, expensive, cost me $275 on Bosch MAF from the mechanic. Vibration continues, so I went ahead replaced all 12 plugs to NGK 7090 last Sunday. Rough idle still there. Please advice if your vibration is fixed, and how?
Wow. Your mechanic should send you a nice fruit basket for Christmas. ;)

Have you replaced the transmission mount?

Did you test the ignition wires when you changed the plugs, replacing any that had excess resistance?

If the answer to those questions is no, then get it to be yes and your issue is likely to be resolved.

Good luck.
 

·
Registered
96 E320 Black, 98 E320 White
Joined
·
18 Posts
LOL, I make sure my mechanic and his family has a wonderful xmas this season.
Yes, my next item is tranny mount.
Check Codes - How to check ignition coil, and its spark plug boot? I did notice some are loose while plug back in after new spark plugs. thx
JeffreyP recommended this long list of items to hunt for vibration, what should be the next thing to look at after tranny mount?
 

·
Registered
98 E-320, 2003 E-500
Joined
·
685 Posts
JeffreyP recommended this long list of items to hunt for vibration, what should be the next thing to look at after tranny mount?
No, the link showed my saga hunting for vibration. As I have repeated multiple times in the thread CHECK YOUR MOUNTS (both motor and tranny)
 

·
Registered
'01-E320 & 02-ST2
Joined
·
31,631 Posts
LOL, I make sure my mechanic and his family has a wonderful xmas this season.
Yes, my next item is tranny mount.
Check Codes - How to check ignition coil, and its spark plug boot? I did notice some are loose while plug back in after new spark plugs. thx
The modular V6 engine isn't like the prior M104 iteration with the shared coils and connectors/boots.

Rather, you have one coil for each cylinder, with two separate wires to each of the sequential-fire plugs. Note that the coil is marked a and b and there are marks on the head (or head cover?) A and B as well. You have to keep that aligned properly, a to A and b to B or you'll have misfires.

If your wires are loose at the plug end, you've either damaged the snap-on connector in the boot or it's not snapped on all the way (either of which will create a misfire).

But you need to actually TEST the wires individually to ensure none have excessive resistance; if they do they will create a very mild misfire that may not even trigger a code, which is when it's the hardest to find the issue. Inspecting and testing by itself is a bit of time and effort (that's why I always suggest to check them when replacing plugs as half the work is getting the darn wire off and on the plug!) and if you don't want to expend it, you can always just buy a new set of wires. They're not cheap, but a replacement set of Bosch will come with a lifetime warranty.

Otherwise remove them and inspect and test each one, replacing any that are (now?) damaged or have too great a resistance. Note that there are also two different lengths, so get them back where they belong (the four longer ones go to the frontmost and rearmost plugs on each bank). And of course be sure to get the A to a and B to b when you're reinstalling them.

Good luck.
 

·
Registered
96 E320 Black, 98 E320 White
Joined
·
18 Posts
I tested the vibration on my way home tonite, noticed similar vibration/rattling in neutral at traffic light. Engaged in "D", engine idles at 650~750rpm, and in "N" it fluctuate between roughly around 800~900. Both produces obvious rattling. 30miles later through the stop n go traffic, I tested again vibration both "D" and "N" mode at traffic light. There was no improvement neither with or without a/c.
Do you have the wiring schema on the plugs to coil? and testing detail/procedure on those boots and coils? I'd like go through all 12 of them once more this weekend. I suspect my "rich" mechanic had messed up previously since vibration started on my last visit to mechanic for tune up. When I did the plug myself, I drew down the connections prior unplug them, and marked coils to be sure I place them back where it belonged.
What other items I should inquire from Autohausaz.com when purchase tranny mount?
thx guys to stay with me.
 

·
Registered
'03 Z4, '02 E55, '11 ML350
Joined
·
710 Posts
Kuo,

Just a small tip. When pulling or installing those plug wires, use a spark plug boot pulling tool. (example Lilse 51750). Also use a bit of dielectric grease on the connections (coil and plug) and the inside of the boot itself to ease sliding it over the porcelain insulator. MB, Wurth or Permetex offer the grease.

Good luck getting your problem resolved.

Mike K.
 

·
Registered
'01-E320 & 02-ST2
Joined
·
31,631 Posts
Rattling? This is the first mention of that.

Given that description, it could be clogged cats. That would explain both the vibration/rough idle as well as the rattle.

Using the wire wrench/tool makes it easier to pop the wires back on.
 

·
Registered
96 E320 Black, 98 E320 White
Joined
·
18 Posts
Storm knocked out power for the past 4 days, without internet and phone!
I managed to replace tranny mount on Friday (thx to G-AMG DIY posting), Vibration issue had become less. I noticed one more thing in past 2 days is that as my car inches forward when green lights on, my 98 E320 jerk and jerk a little. Could this caused by fuel system? or Air intake? Is there a DIY on cleaning throttle for 98 E320?
Check Codes - I was ready to look into either emission or exhaust systems. Possible clogged cat? I loan friend's INNOVA code reader and find nothing. Any comment is welcome.
Thx guys
 

·
Registered
'01-E320 & 02-ST2
Joined
·
31,631 Posts
Storm knocked out power for the past 4 days, without internet and phone!
I managed to replace tranny mount on Friday (thx to G-AMG DIY posting), Vibration issue had become less. I noticed one more thing in past 2 days is that as my car inches forward when green lights on, my 98 E320 jerk and jerk a little.

Check Codes - I was ready to look into either emission or exhaust systems. Possible clogged cat? I loan friend's INNOVA code reader and find nothing. Any comment is welcome.
Thx guys
When you changed your plugs, did you inspect and test all of your plug wires?

Your description of the "jerk and jerk" when creeping at red lights sounds very much like how mine was when I had a failing ignition wire. It took a very long time for it to set a pending misfire code, which is when I finally was able to track it down.

Basically it's just your time to pull and inspect/test them all, which is the next thing I'd look at. (Of course, be sure they are connected properly too, a to A, b to B.)

Of course if you have a rattle and it's coming from a cat, that might be increasing backpressure and causing a mild stumble at loaded idle. But that's harder to diagnose, so I'd first focus on the wires.

Good luck.
 

·
Registered
2006 S430
Joined
·
48 Posts
1996 E320, 266,000 miles on it. All new spark plugs within the past 6 months. I noticed a very slight vibration on the highway with 2800 RPM's felt in the steering wheel. At a stop sign or light (in drive) the engine would occassionaly start to die then comes back to life. Back at highway speeds it was mostly smooth yet a slight vibration.

Last night, at a light, the engine almost died, the idle became very rough then the check engine light came on. Stepping on the gas the engine lacked power and the pep I am used to.

I drove at 70 MPH (2800 RPM). During deceleration the engine smoothed out a little but going up hills the vibrations increased.

I know I need to get the code checked for more specifics but does anyone have an idea if this sounds like the MAF, a misfiring or possibly an 02 sensor?
Thanks.
Ed
 

·
Registered
2006 S430
Joined
·
48 Posts
I went to Advanced auto where they plugged the code machine in and found that the number 4 cylinder was misfiring. I purchased a new coil since the plugs and spark plug caps were replaced within the past 4 months. This fixed the rough idle and the car is running normally again.
 

·
Registered
Joined
·
8 Posts
When you changed your plugs, did you inspect and test all of your plug wires?

Your description of the "jerk and jerk" when creeping at red lights sounds very much like how mine was when I had a failing ignition wire. It took a very long time for it to set a pending misfire code, which is when I finally was able to track it down.
My 2001 E320 with 176K miles recently developed this problem one day after I hosed the accumulated grime from the engine bay. I did not use degreaser and cleaned a cold engine. Engine ran fine after the clean up until it developed a rough idle the next day in or out of gear. No codes, no pending codes, idled smoothly when first started cold on open loop but slightly rough idle on closed loop and reduced idle rate. Pronounced "popping" from exhaust at idle---not a misfire but more like the ignition timing was too far advanced or EGR valve partially stuck open. Off idle performance was almost normal but surged under heavy acceleration when run up through the gears. My first thoughts were that this was caused by a defective ignition wire or coil but I assumed a partial misfire would set a code or pending code. Based on performance I cleaned the MAF and considered checking the EGR valve but since access to the EGR is limited, I didn't have a replacement EGR valve handy and I did have spark plugs and wires I replaced them first. Problem solved. Based on the rust rings on the plug wires it would appear that the pockets in the cylinder heads for the spark plugs are designed to retain water which caused at least one original wire to fail. However, at 176K I shouldn't complain. Mark
 
1 - 20 of 25 Posts
Top