Mysterious power loss of Mercedes S320 W221 2007

[Salah]

Hi

My car (Mercedes S320 CDI W221 2007) has done 75,000 KMs and for last 6 months there is this very strange problem.

After every 3-4 days the car looses power and drives very heavy as there is some extraordinary weight on it and after i use a blower to clean engine compartment it again regains power and drives very light (blow air).

Before and after is huge difference in car power.

I am not a technical person but i suppose there is some exposed censor which get dusty or something or some electrical connection problem.

Star diagnoser is not showing any trouble.

Can you guide what can be the cause or what should i look for.

Thanking you in advance.

 

[00slk]

Im no Technician either, but I have a similar issue with my car, it is intermittent and gives no warning as to when and if it decided to do it. I think in my case it is something to do with the MAF sensor?

 

[Salah]

Thanks SLK but do you know that MAF censor is exposed i mean a blower air can hit it?

 

[John Laidlaw]

Have you checked your fuel filter recently?

 

[Salah]

Just changed yesterday.

 

[alexanderfoti]

What codes are stored under the engine ECU?

If its going into limp mode (which it is) then a code will be stored.

 

[00slk]

Not always Alex, mine shows nothing on star, and it has been checked twice. Well that could also mean that mine isn't an ECU fault

 

[alexanderfoti]

Not always Alex, mine shows nothing on star, and it has been checked twice. Well that could also mean that mine isn't an ECU fault

It's quite possible that it's logging a pending code then self clearing when the fault doesn't come back in x number of ignition cycles.

 

[00slk]

It's quite possible that it's logging a pending code then self clearing when the fault doesn't come back in x number of ignition cycles.

That would certainly make sense

 

[bembo449]

this " blowing the engine and power returns " sounds like a coincidence to me , I presume you turn the car off to use this blower ? that will more than likely reset the issue , could be a number of things , electronic wastegate , EGR , MAF . . . . . . if the EML doesn't come on when it occurs , live data will be the only way forward to finding the issue I feel

 

[Salah]

this " blowing the engine and power returns " sounds like a coincidence to me , I presume you turn the car off to use this blower ? that will more than likely reset the issue , could be a number of things , electronic wastegate , EGR , MAF . . . . . . if the EML doesn't come on when it occurs , live data will be the only way forward to finding the issue I feel

Thanks Bembo...

Though looks weird but actually blowing helps each and every time and yes i switch off vehicle before doing that.

As you suggested will look for live data.

 

[bembo449]

is it 100% reproducible , by that I mean , once its turned off and then on again , the fault clears ?

 

[Salah]

is it 100% reproducible , by that I mean , once its turned off and then on again , the fault clears ?

No just turning on and off does not help.

 

[bembo449]

no matter how long you leave it ?