CL500 lacking power under load

[Craiglxviii]

Hi all,

Just bought my first MB and have some issues. I picked up a secondhand W reg CL500 on 120k miles for what I'm hoping is a bargain, however there are a couple of things that may prove an expensive fix. Nb the car has black leather interior in vvgc, no apparent corrosion, is dead straight everywhere.


Second issue (first already posted re seat)- the engine seems to lack grunt while driving. When sat in neutral or park and revving it, it will redline no problem. While driving though, it doesn't seem to want to "go", acceleration seems sluggish.

The transmission doesn't seem to have any issues, both in manual shift and auto it changes up and down readily enough.

Any ideas please?

 

[alexanderfoti]

Its likely in limp home mode.

Have it plugged into star and checked. Likely to be the MAF if no check engine light.

 

[television]

The MAF is one thing as Alex said

 

[Craiglxviii]

I think I cracked it....

Transmission was in W mode!!!

 

[television]

I think I cracked it....

Transmission was in W mode!!!

That second gear start is a very good reason

 

[AMGeed]

I think I cracked it....

Transmission was in W mode!!!

That only means it starts in 2nd gear. Hardly makes any difference with the torque of a 5ltr. The car should still pull strongly in every gear.

As the others, get the MAF checked.

 

[Craiglxviii]

2nd gear start and change up at lower revs. I think that's it.

Waiting on brake fluid service before I can test.

 

[Craiglxviii]

Well chaps, some developments on this score.

The car is due back today (I will pick it up shortly). I have just got off the phone to Millenium Mercedes in Bedford, very helpful people indeed and an interesting conversation to boot. Not wanting to waste my time or charge me unnecessarily, I was taken through a fairly quick fault-find over the phone, went something like this:

1. Does the car change gear in auto? Yes.
2. Does the car change gear with tiptronic? Yes.
3. Are gear changes jerky or does the car shudder under load? No.
4. Does the engine rev upto & past 5000 in neutral? Yes.
5. Does the auto kickdown work? No.

It's your MAF sensor.

So, dear members of the forum, a question for you. Before I lash out £200 of my finest English coin on a replacement part, is there any way to test whether the sensor is at fault- can I remove it and run without to see if "open circuit" will deliver full power, or will that cause explosions, black smoke and much unhappiness?

NB it STILL hasn't been on STAR yet, but that's another story.

 

[television]

You can open the MAF plug and measure the voltage on pin 5 the output, I cannot remember the correct working voltage but a search should bring it up

 

[Craiglxviii]

Oh no Malcolm, you're talking electrickery here. I'm no good with the electric fluid.

(Voltage between pin 5 and where, by the way? Earth?)

 

[television]

Always with reference to ground (chassis), I am hopeless with it as well.

Do ask your local Bosch agent for a MAF price and ECP

 

[00slk]

I have a MAF sensor for a 113 engine if you want to try this, I am in Cambridgeshire so not too far from you. It only takes a short time to fit and it will definitely tell you whether yours is faulty.

Peter

 

[television]

I have a MAF sensor for a 113 engine if you want to try this, I am in Cambridgeshire so not too far from you. It only takes a short time to fit and it will definitely tell you whether yours is faulty.

Peter

What a lovely post

 

[Craiglxviii]

That's a really nice offer, thank you. I'm going to check voltages first (have a few other jobs to do on it this weekend) so will let you know in due course.

 

[television]

~2v at idle rising to ~4.8v at full revs and boost.

 

[Craiglxviii]

And thank you Malcolm!!

 

[Craiglxviii]

This morning was the first time I have had to do anything to the CL. I took the engine cover and air boxes off and found this- can someone please confirm if the MAF sensor is located in the round mesh thingy?

 

[television]

That is it, at the rear of engine.

 

[Craiglxviii]

Thanks Malcolm. Do I need to remove the mesh to get at the sensor, or is the sensor assy that round mesh unit as a whole?

 

[television]

Thanks Malcolm. Do I need to remove the mesh to get at the sensor, or is the sensor assy that round mesh unit as a whole?

The mesh does come off, or you can remove the whole thing.