ML270 No kick down sometimes !

[Colm00]

Hi, I have changed the MFS sensor and returned to the garage they said now that the turbo needs replacing as I have a fault shown ! (exhaust gas) If you drive the car max RPM is 2000 with no kick-down while driving switch eng off and on the problem goes away lots of RPM 3000+ and power ?

 

[BlackC55]

I very much doubt a turbo has blown as they are very very relaiable unles they have been run out of oil.

Get a second opinion.

 

[Colm00]

Thanks Olly, I am thinking the same ! Is there a enging protection relay on the Ml ?

 

[BlackC55]

No.

 

[gtvlusso]

Mine is slow to kickdown.....remap to 210BHP sorted it out. They are not very powerful for their weight.

Turbos going pop are very rare......

 

[Colm00]

Tks for info, how do I remap ?

 

[gtvlusso]

There are allot of threads on here recommending good remappers!

I used South West In Car Tech - Technology...Working

Around £300 to unleash hell.

Before you do anything like that though - get it to a specialist MB mech and get the car looked at with STAR. Gearbox oil and filter change can make a huge difference and is not that expensive.

 

[Colm00]

Hi can anyone please help with this problem. The remap did not clear the fault ! It is clearly a electrical fault relay or something, does anyone know of a relay that limits enging power ?

 

[BlackC55]

Get it on a Star diagnostic machine. There are many reasons why.

 

[tony jr]

Hi, I have changed the MFS sensor and returned to the garage they said now that the turbo needs replacing as I have a fault shown ! (exhaust gas) If you drive the car max RPM is 2000 with no kick-down while driving switch eng off and on the problem goes away lots of RPM 3000+ and power ?

This could be due to a whole range of problems!

From what you describe it sounds like your ML has gone into limp home mode due to a fault. When in limp home mode the kickdown function and turbo is disabled and the eng revs are limited to around 2500 rpm. If you stop and restart the car this temporarly clears the fault and you can drive normally until it returns. This will continue to get worse until eventually you will be permanent limp home mode. This most common reason for this is the MAF sensor - but you say you have changed this. Did you used a genuine MB part (around £50 from main dealer) or one from a well common site that are known to sell faulty non genuine ones? The next most common issue usually occurs around the 100k miles mark and is associated with the functioning of the inlet manifold. You find that a combination of oil mist and carbon particulates from the egr system block up the EGR valve and or the swirl flaps in the manifold. When the stepper motor trys to move the swirl flaps they stick and through an error putting the ml in limp home mode and inhibiting the kick down function. Another similar cause is a failed stepper motor usually because oil leaks onto it from the worn swirl valve seats in the inlet manifold onto the motor below having the same effect. It is worth checking to see if oil if leaking from under the inlet manifold and also try and see if the swirl flaps can move freely by manually moving the linkage bar under the manifold connecting each of the 5 swirl valves to the stepper motor. I would also get the codes read. Turbo failure is rare.

 

[Colm00]

Thank you, Thank You, Thank you tony jr so much for the information. I did bring the car back to garage where we fitted the MAF and is now showing no faults on the plug-in Snap-On test unit...! I agree the with yourself and will check all items that you state, no person has said anything about Limp Home mode before now all you say make perfect sense.

 

[Colm00]

"O yes" the MAF part in a origional cost of £120

 

[gtvlusso]

Yes - I had "limp" when the MAF went pop - cost about £80 to replace at a specialist.

Anyway - I would get the EGR looked at/cleaned and I think there is a problem with the servo motor that controls the swirl flaps in the inlet manifold that can produce problems - motor fails as manifold clogs with oil mist. Personally- I cleaned mine last week....easy enough to do and Sudesh put up a great thread about doing it.

 

[tony jr]

Thank you, Thank You, Thank you tony jr so much for the information. I did bring the car back to garage where we fitted the MAF and is now showing no faults on the plug-in Snap-On test unit...! I agree the with yourself and will check all items that you state, no person has said anything about Limp Home mode before now all you say make perfect sense.

Take a look at this thread on another forum - it shows some good pics of the inlet manifold with the stepper motor and linking rods controling the swirl flaps:
ml 270 2000 manifold - Mercedes-Benz Owners' Forums

 

[Vlad]

Thank you, Thank You, Thank you tony jr so much for the information. I did bring the car back to garage where we fitted the MAF and is now showing no faults on the plug-in Snap-On test unit...! I agree the with yourself and will check all items that you state, no person has said anything about Limp Home mode before now all you say make perfect sense.

You need to get it hooked up to a STAR machine....a plug in Snap On test unit is only going to tell you so much.

 

[Colm00]

Hi All, I have checked the turbo inlet and found it full of oil ! On close inspection I found that a small amount of oil had leaked onto the waste gate actuator shaft as well, so I applied a small amount of vacuum to the actuator only to find no movement of the actuator arm !!!! (I was unable to apply a proper vacum indicating a leak on the sealed unit) I am now thinking that the turbo has not been working for some time as the inlet manifold in clogged with carbon. I cleaned all the oil out, MAP sensor, MAF sensor, crankcase breeder into inlet and re started the car but I am now in permanent LIMP mode, which is ok as I now have a permanent fault rather than a intermittent one. Any thoughts ?????? Turbo broken !!! I need to check manifold today and swirl valves. Thanks to all for your help Colm

 

[Colm00]

One thing I missed was the actuator arm is free to move just unable to secure a vacuum seal that controls the arm. MB and Essex turbo only sell a full turbo, which is crazy, do you know of any alternative actuators that will fit?