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Brabus SL55 K8 2003
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20 Posts
Discussion Starter #1
Hi all, I am trying to find out if anybody can shed some light in to the cause of one of my many, and long standing problems, this problem was very, very intermittent at first but seems to have got really bad all of a sudden, I believe its in the list of my problems.
Under brisk acceleration or kick down there is a massive amount of power loss but when driving normally around town all seems to be OK but as soon as I drive on an A Road or Motorway and try to overtake I have very little power, the rev's increase but only up to around 3,500 then (with my foot full to the floor) there is no kick down and the speed increases very slowly, even the engine sounds different! If I pull over and restart the engine then immediately my power is back, restarting the engine always solves the problem, but how long it lasts varies quite vastly sometimes 5 minutes and sometimes up to 1 hour or so!

I have had the charge cooler pump changed and the Air intake temperature sensor changed but the problem still still persists. I am not sure but after searching through the forums I have found that people with problems not to different to mine have found that they have a faulty MAF sensor (Mass Air Flow Sensor) I am not sure if my car has a MAF, MAP sensor or both, I would like to replace my MAF sensor just to exclude this from a possibility of being the cause of my problem. Is this MAF sensor easy to change and where is it located on a SL55 AMG, my car has been plugged in to Star but a fault does not show. Any input would be appreciated.
 

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03 SL55, '90 SEC
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34 Posts
Loss of power

Hello - Sorry I don't know the answer. Mine has a similar problem (03 sl55). In cold weather (my only experience so far) very sluggish engine response - about a 2 second delay before the engine increases RPM. Annoys people behind me at stop lights. I havn't had an opportunity to drive much at hiway speeds yet, only had the car a few weeks. There are no check engine faults, no pending faults, both batterys are brand new, entire car was checked out by a local dealer before I bought it. It had no problems for the first 3 weeks, now the last 2 weeks almost always low power.

Has anyone had this problem and found the fault? Any ideas would be appreciated.

I'm about to throw myself on the mercy of the local dealer, but knowing the fault going in would be nice.

Regards to all,

Rich R
 

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SL55
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103 Posts
@Cliffav, I also don't have the answer to your question. Do you think that maybe taking the car to an aftermarket tuner like Renntech would be a good idea (assuming you've taken it to an authorized MB repair shop). These guys probably know these cars very well and especially around the area of loss and or gain of power. Just a suggestion.

In most cases like these it turns out to be a faulty intercooler (heat exchanger) pump. Can you confirm that the pump you have is operational (even if it's been recently replaced)?
 

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Brabus SL55 K8 2003
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20 Posts
Discussion Starter #6
Hello - Sorry I don't know the answer. Mine has a similar problem (03 sl55). In cold weather (my only experience so far) very sluggish engine response - about a 2 second delay before the engine increases RPM. Annoys people behind me at stop lights. I havn't had an opportunity to drive much at hiway speeds yet, only had the car a few weeks. There are no check engine faults, no pending faults, both batterys are brand new, entire car was checked out by a local dealer before I bought it. It had no problems for the first 3 weeks, now the last 2 weeks almost always low power.

Has anyone had this problem and found the fault? Any ideas would be appreciated.

I'm about to throw myself on the mercy of the local dealer, but knowing the fault going in would be nice.

Regards to all,

Rich R
Sorry for late reply, I have been away for a Christmas break!
My problem may be different as the issue gets cleared when I restart the engine.
I have not been using my car for several reasons,
1) power issue,
2) Weather.
I am at my wits end with this, I am going to continue my quest early January, thanks for those who have replied, I will keep you all informed of the outcome.
 

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Brabus SL55 K8 2003
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20 Posts
Discussion Starter #7 (Edited)
@Cliffav, I also don't have the answer to your question. Do you think that maybe taking the car to an aftermarket tuner like Renntech would be a good idea (assuming you've taken it to an authorized MB repair shop). These guys probably know these cars very well and especially around the area of loss and or gain of power. Just a suggestion.

In most cases like these it turns out to be a faulty intercooler (heat exchanger) pump. Can you confirm that the pump you have is operational (even if it's been recently replaced)?
I have taken it to 2 specialist so far and have spent over £500 for Dyno diagnostics but still without any conclusion.
If it was an issue with one of the items you mentioned, would the problem be cleared for a while after restarting the engine?
 

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Brabus SL55 K8 2003
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20 Posts
Discussion Starter #8
I'm relatively certain that the SL55 does not have a MAF sensor, but I could be wrong.
You are right, there is no MAF on the SL55, apparenly they use something else which I am not exactly sure what it is!
 

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2003 SL500
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41 Posts
Here is what you can try

I had the same problem and this is how I resolved it.
It sounds like your car goes into limp mode after hard acceleration.

After restart my problem went away as well.

Accelerate hard, let your car go into this limp mode, and without restarting the car hook it up to the computer and read off the codes.
(if you restart your car, certain simple errors are reset)

In my case:
There was no errors after I restarted the car.
But when we checked the errors with the car in limp mode, computer gave us an error (accelerator pedal out of range)
I these cars if the computer senses that the pedal is in different position than it should be (due to faulty sensor) it will "limp" the car for safety reasons.

Basically every time i floored the car it would go into limp mode.
But when accelerating slowly (pedal pressed like 80%) it would get up to like 140mph+ with no problems.

Solution was simple in my case:
Accelerator Pedal Sensor was replaced and it solved my problem.
It was like $250 in my case.
 

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03 SL55, '90 SEC
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34 Posts
Power loss ...

Mine was also the accel. pedal. Dealer replaced for around $200 plus labor. Now works fine, no power loss.

I think the owners manual describes 'limp' mode as second (maybe third) gear only. I con't find the page now.

Sadly, while car was on dealers lot after pedal fix, a storm blew through and cracked the windshield.

Regards,

Rich R.
 

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SL55
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103 Posts
I have taken it to 2 specialist so far and have spent over £500 for Dyno diagnostics but still without any conclusion.
If it was an issue with one of the items you mentioned, would the problem be cleared for a while after restarting the engine?
Yes, the symptoms you describe are exactly what happens when the pump goes bad and happens to everyone eventually. The pump failure does not cause any fault codes and unless you know the cars well or at least know how forced induction systems work, you probably will have a very hard time figuring this one out.

The replacement is very cheap too.
 

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2012 EClass, Rolls-Royce Silver Seraph LOL, Mercedes Eclass
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67 Posts
My SL55 use to hesitate when I push the pedal down specially from a cold start have changed the inline filter and pump and solved the problem.
 
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