4000 RPM Governor?? - PeachParts Mercedes-Benz Forum

TROVERMAN · #1 10-07-2003, 12:07 PM

Another question on my 1995 E320 Wagon--
When in park or neutral the engine will not rev above around 4,000 RPM's. It just sort of shakes like a governor is on the car. Then when I went to pass someone on the road it wouldn't go above that mark either. There's lots of pedal left at the cutoff point. I'm confident there isn't any kind of engine problem because the car runs perfect and has only 41k on it.

One More: When in Drive and on a slight incline (like when pulling out of a street), is the car supposed to slip backwards? It goes when you press the gas, but my Volvo 960 (and all my other auto transmission cars) never roll back on hills. Is this normal in the E-Class?

Thanks.

#2 10-07-2003, 12:16 PM

4000 rpm is the governed limit in Park and Neutral. If your car will not go over 4k rpm while driving, that is a problem. You might have a faulty gear selector switch.

And yes these cars tend to roll back a bit while on a slight grade in gear. Normal.......

haasman · #3 10-07-2003, 12:32 PM

You know, here in California, we are very concerned that we are going to end up with a 4000 RPM Governor after the elections today.

Haasman

David C Klasse · #4 10-09-2003, 03:00 AM

Yes, a 4,000 RPM engine speed in Neutral is the limit. Firstly, anything over 4,000 RPM in N when kicking into gear is not good for the tranny! Also, so I've heard, it is not good for the engine to be revving high under zero load.

So, your 'problem' is not a problem.

blackmercedes · #5 10-09-2003, 09:30 AM

Quote:

Originally posted by TROVERMAN
Then when I went to pass someone on the road it wouldn't go above that mark either.

That's not normal. Most later MB's have a rev limiter to keep you from over-revving the engine while in neutral (or park) but the limiter is not engaged during normal driving. You do have a rev limiter at, or just past, the redline mark for the engine rpm. Is the problem persisting? I also fail to see the need to exceed 4000rpm while sitting still.

TROVERMAN · #6 10-09-2003, 09:57 AM

O.K., I just replaced the plugs which were original from 1995 and put in new Bosch Platinum 4's. Also changed the very dirty MB airfilter with a K & N. Problem Soved! Just passed someone on the interstate in 3rd gear at around 5,000 RPM. Smooth as silk.

You're right, there's no need to rev the car in the driveway. I accidentally stomped the gas when sitting in the seat doing something else, and noticed it wouldn't go above 4k, so it made me wonder...

_________________
1995 MB E320 Wagon, 41k
1992 Land Rover Range Rover County, 186k
1996 Volvo 960 Wagon, 105k
1996 Ford "Exploder" Limited 2wd
1982 Volvo 240 GL Diesel, 157k (61k on new gas engine conv.)

blackmercedes · #7 10-09-2003, 10:08 AM

Quote:

Originally posted by TROVERMAN
O.K., I just replaced the plugs which were original from 1995 and put in new Bosch Platinum 4's.

You may regret that. The Bosch Plat's don't usually work very well in MB engines, and if memory serves, I don't think they're recommended for the M104 engine. Generally, unless it's one of the newer M112 or M113 engines, the rule is to use conventional copper-core plugs for the best performance.

Glad to hear your high-rpm miss has been solved. Also glad to hear you're not sitting in your driveway revving the piss out of your car just for the fun of it!

TROVERMAN · #8 10-09-2003, 10:28 AM

To be honest, I just assumed the Bosch plugs would be great. They guarantee the engine will be smoother or they will pay for the plugs. On the interstate run, the engine was smoother, but it could be because the plugs were original. I have the same plugs in my 960 Volvo (They were in it when I bought it) and now some miles later they appear perfect and the car runs great. (Is Bosch better in Volvo's?) By the way, I don't have my maintenance book, do you know what the plug gap should be? I want to see how bad my original plugs were, if they were at all. Thanks...

_________________
1995 MB E320 Wagon, 41k
1992 Land Rover Range Rover County, 186k
1996 Volvo 960 Wagon, 105k
1996 Ford "Exploder" Limited 2wd
1982 Volvo 240 GL Diesel, 157k (61k on new gas engine conv.)

blackmercedes · #9 10-09-2003, 10:51 AM

Do a quick search on "plug gap" and "M104" and I'm sure you'll find lots of info. If memory serves, it's .8mm. Also, the correct plugs and gap are located in your owner's manual.

It sounds like your car needs a thorough going-through. You should change all the fluids and filters, including the brake fluid and coolant. Ignore the 41,000 miles. Mileage is less important than time. That car is nine years old.

BenzOnline · #10 10-09-2003, 12:35 PM

my w126 can rev wherever you want it to in N or P.

David C Klasse · #11 10-09-2003, 10:49 PM

I will also just back-up the suggestion to stick with the Bosch COPPERS, not the platinums. I have heard the many many stories regarding the issue, and I also recommend sticking with the coppers.

BTW, Glad you got it working again!

TROVERMAN · #12 10-14-2003, 08:20 AM

O.K., I just went 1000 miles in two days, with the plugs installed and it seemed smoother than ever and got 26 mpg. However, I am concerned with these replies--do they hurt the car to have them in?? What sort of problems were people having? I called my local MB dealer and they have heard nothing about this...

Ali Al-Chalabi · #13 10-14-2003, 10:20 AM

I would stick with the OEM Bosch copper plug.

#14 10-14-2003, 03:55 PM

After my recent unpleasant experience I'm just going to stick with cheap champions and change them more often. I've run the Bosch Plats in my E320 and didn't notice any difference with mileage, the way the car performed, etc. etc. I had good luck with them.

I replaced them with the Bosch Supers just because so many people on this list recommended against using platinums. Oh well, I doubt you'll have any problems with them. They do have a built in resistor whereas the Supers don't. The champions I'm using have a built in resistor too, they work great too.

I would run them for a while, if your car runs great then leave them alone, if your having idle or running problems than I would try something different.

haasman · #15 10-14-2003, 03:59 PM

Since your plug connectors have built-in resistors, it is unnecessary to run resistor plugs and can actually lower performance.

Hows your gas mileage?

Haasman

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