Rev problems with 4200 CC

R

richi

New Member
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Hey there! I signed up for this forum after I bought a '04 4200CC last year and was already able to benefit from your knowledge. I am located in switzerland, even though there is a german forum, I found the UK one more resourceful.
Had a problem with the CC pump and was able to resolve it! So let me say thank you first!!

Now I have another problem and I hoped that you guys could point me into the right direction:

When the car gets to certain revs (lets say about 5-6K) it suddenly stops revving as if it has no air or the sparks don't work anymore..

Any ideas? Should i replace the sparks first?

Cheers Richard
 
CatmanV2

CatmanV2

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Either fuel pressure or spark failure I'd have *thought*.

Have you got a code reader at all? There may be some pending codes stored that will give you a clue.

C
 
hladun

hladun

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149
Is the tach accurate? You need to find maximum speed at max engine rpm in different gears to check. For example in third gear what should the rpm be at 100 kph?
 
R

richi

New Member
Messages
14
Thank you for your response, no unfortunately i don't.. I saw some screenshots of a reader that can be linked to a smartphone.. maybe I should try to get one of these.. But I think the best readers are only for official dealers, SD2 if i recall that right.. ?
 
CatmanV2

CatmanV2

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Yes, SD2/3 or Leonardo. They are many thousands.
The cheap ones should give you some idea of what's happening, as the engine management system is pretty accessible.

There's an application called Torque for android phones which is well thought of.

C
 
conaero

conaero

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34,639
Could be either your throttle or pedal pot gone.

Try a battery reset first and see if that sorts it.

If your taco is reading false and you are at max revs, then you should feel it bounce of the limiter.
 
R

richi

New Member
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14
I honestly think that it is not revving that high.. from my limited experience with the car I would say that it stops at about 2/3 of the maximum revving capacity and sometimes it also exceeds that, so I think that shouldn't be a problem
 
CatmanV2

CatmanV2

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richi said:
I honestly think that it is not revving that high.. from my limited experience with the car I would say that it stops at about 2/3 of the maximum revving capacity and sometimes it also exceeds that, so I think that shouldn't be a problem
Click to expand...

Matt makes a good point about the throttle, and the battery reset
C
 
R

richi

New Member
Messages
14
Thanks guys, I will have a go with this.. but i might add that I had all kinds of battery resets due to the CC pump issue.. Now it is off the battery for a week already and I will try as soon as the weather allows it! Salt on the streets, etc.
 
Contigo

Contigo

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Could be bad batch of fuel too. Try running a full tank of super unleaded through it from a different supplier and give it a run. I had exactly this on my 3200 where it literally cut power as if cylinders were stopping! When driving the car under load (about 5k+) the engine misfired and made you headbutt the steering wheel so savage was the jolt!

The other things to check are Spark Plugs and MAF but without a code reader you are stabbing in the dark (a bit like Dem)
 
R

richi

New Member
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14
Thanks phil both for the intel and your lively description! :) I will check that as well.. I must admit i thought that "more or less" modern cars don't mind the type of gasoline anymore, thats why I chose a rather simple fuel company (its called AVIA) and their standard 95 fuel.. my mercedes doesnt mind of course but maybe the diva does!
 
CatmanV2

CatmanV2

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48,836
richi said:
Thanks phil both for the intel and your lively description! :) I will check that as well.. I must admit i thought that "more or less" modern cars don't mind the type of gasoline anymore, thats why I chose a rather simple fuel company (its called AVIA) and their standard 95 fuel.. my mercedes doesnt mind of course but maybe the diva does!
Click to expand...

It shouldn't according to the manual, but it's slightly possible and an easy test. I run mine on 95, and have never noticed a difference when on 98 <stands back having re-lit blue touch paper>

C
 
conaero

conaero

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CatmanV2 said:
It shouldn't according to the manual, but it's slightly possible and an easy test. I run mine on 95, and have never noticed a difference when on 98 <stands back having re-lit blue touch paper>

C
Click to expand...

Same here Chris.
 
Zep

Zep

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CatmanV2 said:
It shouldn't according to the manual, but it's slightly possible and an easy test. I run mine on 95, and have never noticed a difference when on 98 <stands back having re-lit blue touch paper>

C
Click to expand...

Has there been some discussion about fuel grades before? I must have forgotten
 
Zep

Zep

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9,297
When you say it won't rev beyond 5-6k revs, is it like a limiter, cutting the ignition? Do you have an ABS / MSP fault?

When I had a problem with one of my wheel speed sensors the ECU would limit the engine speed for safety to 5500 rpm.
 
CatmanV2

CatmanV2

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48,836
Zep said:
When you say it won't rev beyond 5-6k revs, is it like a limiter, cutting the ignition? Do you have an ABS / MSP fault?

When I had a problem with one of my wheel speed sensors the ECU would limit the engine speed for safety to 5500 rpm.
Click to expand...

In top? :)

C
 
Contigo

Contigo

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CatmanV2 said:
It shouldn't according to the manual, but it's slightly possible and an easy test. I run mine on 95, and have never noticed a difference when on 98 <stands back having re-lit blue touch paper>

C
Click to expand...

I knew someone would pull me up on the SUL recommendation and you were safe bet:D

I was just thinking put a tank of THE most expensive fuel you can buy (not 102RON!) and then run it on that!
 
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