Mercedes-Benz Forum banner

1 - 8 of 8 Posts

·
Registered
G320 & E500
Joined
·
1,198 Posts
Discussion Starter #1
I'm running the M104 straight six. When I floor it, the engine starts to rev up, then hesitates randomly.
If I let up on the accelerator just a little, I get the full power back.
It's got new plugs, new wires, and one new coil. I don't know what else to check. It only happens when the accelerator is all of the way down, but does not matter if I am pushing the kick-down switch.

Chuck
 

·
Registered
95 E320 Cabriolet, 140K
Joined
·
1,332 Posts
It sounds like you're losing high end power. How old is the fuel filter? A clogged fuel filter or weak fuel pump can cause this problem. So can a broken catalytic converter. The monolith inside the converter can crack up, and the pieces lodge sideways restricting exhaust. Give it a kick and see if it rattles. A weak fuel pump sometimes gets noisy toward the end of its life.
 

·
Registered
G320 & E500
Joined
·
1,198 Posts
Discussion Starter #3
The symtoms are not fuel related. I changed the filters six months ago too.
It seems either electrical (possibly computer???) or something with that air flap.
When I got it, one of the three coils were bad. I replaced the coil and while I was at it; I replaced the plugs and the wires too.
When it hesitates, it is not the same as a cylinder not firing. Nothing quite that dramatic.
There have been no computer codes via ODB-II. Other than when I "floor it", she is perfectly smooth.

Chuck
 

·
Registered
300TE 4-Matic 300GD
Joined
·
330 Posts
Hi cfowler.

It seems to me that you have problems with your cam shafts. It might be electrical fault or some other problem with your fuel injection. But in light of what you have written, it fits perfectly with worn cams.

Very often, owners will check and exchange many expensive components, and put the measuring of the cams right at the end of the line. It won't hurt the condition of your car, but it will certainly hurt your wallet.

A good indication of worn cams is when you at first notice it, it's only in extreme output in high revs. Then after a while, gradually you will feel it in lower and lower outputs and revs, and in the end when ever you press the pedal.

Good luck.

Regards

Geir
 

·
Registered
G320 & E500
Joined
·
1,198 Posts
Discussion Starter #5
NordStern - 2/15/2005 6:02 PM

Hi cfowler.

It seems to me that you have problems with your cam shafts. It might be electrical fault or some other problem with your fuel injection. But in light of what you have written, it fits perfectly with worn cams.

Very often, owners will check and exchange many expensive components, and put the measuring of the cams right at the end of the line. It won't hurt the condition of your car, but it will certainly hurt your wallet.

A good indication of worn cams is when you at first notice it, it's only in extreme output in high revs. Then after a while, gradually you will feel it in lower and lower outputs and revs, and in the end when ever you press the pedal.

Good luck.

Regards

Geir
I must admit my lack of knowledge on Mercedes Gas engines. Most of my experience has been with the Diesel engines.
How does the cam shaft have anything to do with the engine's electrical? Where should I look?
 

·
Registered
500E, E320, 190E, E55
Joined
·
1,006 Posts
More than likely a fuel restriction problem.
Filter or clogged injectors. Check these first...
 

·
Registered
300TE 4-Matic 300GD
Joined
·
330 Posts
Hi cfowler.

I didn't mean to say your cams have anything to do with the engines electrical. In hindsight I can see that the first chapter was rather clumsy written. Sorry.

What I meant to say was that it might very well be an electrical fault in your fuel injection system. I'm certainly not saying that it's not the case. It might be some other fuel related problem as well. But from what you describe, it may also very well be worn cams that cause the hestitation. It's easy to measure the cams to rule out worn cams as a possible source for the problem. It seems to me that many owners think camshafts are a work / not work thing. That is definitely not the case.

The classical symtom for worn camshafts is a slight hesitation at first in high output and many revolutions per minute. Typically relaxing just a wee bit on the speeder cures the symtom. But by doing so, you don't get the full power. Then the hesitation increases slowly over time, at a steadily lower RPM. It was the first thing that crossed my mind when I read your post.

If you want to look into it, I suggest you measure the distance between the bottom and the upper pointed end on the cam. What you are looking for is variations in measurments. Watch out for differences between inlet and outlet valves. Also look for groves and mis-colouring. Considering you having a twin-cam, measuring the stretch in your dual timing chain wouldn't hurt. If the stretch is to far, the cams can become mis-aligned. Look for tooth wear. Check that the camshaft bearings are not worn out. Look out for signs of shaft torsion.

I personally think ruling out these things before charging at the CIS-E system, not after, when you have your symtoms, is smart. That's why I gave the advice.

Regards

Geir
 

·
Registered
500E, E320, 190E, E55
Joined
·
1,006 Posts
Please share when you have this problem diagnosed!!
I have been experiencing this same sort of "cut out"
only under full throttle high load conditions. My car has been doing this for years and I have just learned to live with it. I have replaced all fuel and ignition components that could be replaced. I have a 92'400E with the M119 V8 I to am starting to believe that it may be a faulty control unit. Unfortunately I do not have a spare one that I can swap in. 98% of the time the car runs fine. I can even cruise at 145 to 150 mph without a problem. But when I floor it at 70 and the revs near redline it bucks/cuts out ???

Even longtime MBZ techs are stumped...
 
1 - 8 of 8 Posts
Top