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Discussion Starter #1
2000 ML 430 100k - when idling, the engine would not go above 4000 RPM. Once 4000 RPM reached, the engine starts shake a lot, please see video here: http://www.youtube.com/watch?v=eyTLINTnPgI
The MAF sensor was replaced a year ago (check engine light was on), sparkplugs where replaced last year (regular maintenance), crank shaft position sensor was replaced recently (due to no start when hot).
Check engine light is off now, no codes as well.
So, I'm thinking - cam shaft position sensor?
 

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2000 ML55
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565 Posts
I second that opinion.

Wish they were all that easy...

Question is, what causes the rev limiter to cut in at 4000. Is it possible that this is indicative of another problem, i.e. harmonic balancer?
 

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Discussion Starter #3
It really feels like there is something wrong with the engine. Vibration level is unusually high, even when idling at 600 RPM, fuel consumption has increased from 15 to 12 mpg.
My HB's part number is A112.35.09.00 and as far as I know it wasn't affected by the recall
 

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2004 ML350
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381 Posts
All of em are wrong its probably the catalytic converter its a typical sign cant make it to high RPM and a lot of shaking plus i hear alot of exhaust noise when u rev the car take it to shop
 

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2000 ML430 SOLD, 2007 BMW 328i Coupe, 2014 BMW i3
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What is the reason to rev up unloaded engine that high?
That was my first question. I'll follow that up with are there any other symptoms that lead you to believe there is a problem when operating the truck normally? If not, then I have a solution: stop wasting your gas.
 

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Black 2005 ML 500
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My former 2001 ML 320 used to do that when I was on neutral only. On 2001, my MB dealer said that there was no problem and that the engine was protecting itself. It did this, in neutral only, until I traded it at 108,000 miles, but never had a problem related to this neutral behaviour.

Only on idle should this happen. If this happens during driving, then there is something else wrong i.e. induction coils, etc.

If you are in a specific gear and you pass 6100 RPMs, or so, your ML will shut the injectors to avoid engine damage, and your ML transmission will go into limp mode until you restart your engine.. This happened to me a couple of times with my old ML, when I floored the gas pedal, and I did not noticed I had my ML was fixed in 3rd gear and it went past 6000 RPM.

There are various engine software updates along all these years, so there may be some variations between model years and engine software revisions..

AC
 

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2000 ML430 SOLD, 2007 BMW 328i Coupe, 2014 BMW i3
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OK, I stand by my statement. I just revved up to 4000 and sure enough, there was a shake. This is basically an issue of who ever revs an unloaded engine up that high?
 

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1999 MTrash 430, its a joke
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190 Posts
Bobabenz is right. Its a soft rev limiter that is set just above 4k when the vehicle is in park or neutral.
 

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Your engine is operating normally

I had the same "issue", and took it to a Certified Independent MB repair shop. They kindly explained that the engine while in Neutral or Park will not go over 4000 RPM because of a electronic limiter programmed into the computer to protect the engine from damage. If for some reason the car does run rough however, please check the following.

1. Vacuum Leaks in the main air intake hose. This hose runs from the air box all the way to the back of the engine where it clips into the manifold. If there is a small crack in it, the engine will run like total crap because of unmetered air leak. It should be perfectly neutral, no leaks. Don't bother trying to fix with duct tape, the parts are cheap enough to just replace outright. There are several breather hoses as well that branch off of the main arterial hose, and all those need to be inspected as well. Most are no more than $20 each, so again, don't go cheapo, just replace them if there is any cracking from age.

2. EGR Valve. Pull that sucker off the back of the engine with the two bolts holding it down and carefully take it out of the engine. If you haven't done so, you'll find it's plugged up with tons of carbon. Looks like a clot in a heart valve. You can clean it out with heavy duty carb cleaner, I used brake cleaner, and soak the entire part in carb cleaner overnight, or, just replace it with a nice clean new part. Most likely, any rough idle will disappear.

3. How long has it been since you've replaced the spark plugs? Did you get bosch platinums? If you have some other total crap taking up space, you'll want to go ahead and get 16, yes, 16 Bosch Platinum Plugs and replace each and every one of them. Inspect the boots on your plugs as well, and be sure to use electrical grease while installing them to ensure good connectivity.

4. Your MAF needs to be changed out if you car has more than 75k miles on it. Your ML simply wears that part out, and it's a given to change it out. The Mass Air Flow Sensor (MAF) is easy to change. It takes 5 minutes flat. Get a new one, and eliminate it from this list.

Do all this. Your ML will run like brand spanking new.
 

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2002 ML55 AMG, 2005 Chrysler Crossfire Coupe Limited, 1999 C280
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I had the same "issue", and took it to a Certified Independent MB repair shop. They kindly explained that the engine while in Neutral or Park will not go over 4000 RPM because of a electronic limiter programmed into the computer to protect the engine from damage. If for some reason the car does run rough however, please check the following.

1. Vacuum Leaks in the main air intake hose. This hose runs from the air box all the way to the back of the engine where it clips into the manifold. If there is a small crack in it, the engine will run like total crap because of unmetered air leak. It should be perfectly neutral, no leaks. Don't bother trying to fix with duct tape, the parts are cheap enough to just replace outright. There are several breather hoses as well that branch off of the main arterial hose, and all those need to be inspected as well. Most are no more than $20 each, so again, don't go cheapo, just replace them if there is any cracking from age.

2. EGR Valve. Pull that sucker off the back of the engine with the two bolts holding it down and carefully take it out of the engine. If you haven't done so, you'll find it's plugged up with tons of carbon. Looks like a clot in a heart valve. You can clean it out with heavy duty carb cleaner, I used brake cleaner, and soak the entire part in carb cleaner overnight, or, just replace it with a nice clean new part. Most likely, any rough idle will disappear.

3. How long has it been since you've replaced the spark plugs? Did you get bosch platinums? If you have some other total crap taking up space, you'll want to go ahead and get 16, yes, 16 Bosch Platinum Plugs and replace each and every one of them. Inspect the boots on your plugs as well, and be sure to use electrical grease while installing them to ensure good connectivity.

4. Your MAF needs to be changed out if you car has more than 75k miles on it. Your ML simply wears that part out, and it's a given to change it out. The Mass Air Flow Sensor (MAF) is easy to change. It takes 5 minutes flat. Get a new one, and eliminate it from this list.

Do all this. Your ML will run like brand spanking new.
Fabulous response; but it's been almost a year since the original poster asked the question!:D
 

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1997 W210 E320, 1999 W163 ML430, 2002 W203 C240
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Im having the same issue with my ML430. I think I have an exhaust leak because I changed the MAF, changed the spark plugs, wires, and cleaned the EGR, but i still have rough idle. Can a leaking brake booster cause this also?
 

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1999 ML430
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1,660 Posts
uuuuum....exactly why would you want to rev it up to 4000 rpm in neutral ?

Its a lot more fun to let the big dog eat...say up to redline in third !!
 

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1997 W210 E320, 1999 W163 ML430, 2002 W203 C240
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uuuuum....exactly why would you want to rev it up to 4000 rpm in neutral ?

Its a lot more fun to let the big dog eat...say up to redline in third !!
The funny thing is a I actually thought something was wrong with my truck. I took it into the shop today and was happy to hear I have no leaks, plus the engine cut off is in fact a safety feature so you dont damage the engine while in park or neutral. hahaaa..

My rough idle has more to do with a bad plug wire. Im getting that checked out tomorrow with an ohm meter.
 

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So does anyone know why it does it at 4000 RPMs even while driving? My just started doing this out of nowhere. I'm leaning more towards the the catalytic converter. But the exhaust doesn't smell like rotten eggs it smells really rich. My first thought was the secondary air pump.
 
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