skyfreedom

Went on a road trip this past weekend and while doing 80mph I noticed a loss in power. It seemed that when I punched it, to pass, my gas pedal was floored and I could not get any acceleration from the engine?!?
Only when I pushed the switch under the gas pedal the engine would then kick into low gear.

Now driving around town and I wanna get up and go the engine does the same thing, pedal is floored and no power. No engine lights on.

Anyone ever had this issue?

sosh

Have a dealer pull the data from the computer and examine all the perameters of the various components. They can be degraded and not turn on the CEL but can cause a power loss to some extent. The items that should be checked are the MAF, O2 sensors, computer itself, and the myriad of other sensors. Could also be a partially clogged CAT. But without a complete diagnosis anyone will be guessing.

marcelc

It can also be fuel supply, either faulty fuel pump or partially clogged fuel filter or faulty pressure regulator valve on the fuel filter.

skyfreedom

Thanks for the reply.

Im a car noob , where can I find the fuel filters?

marcelc

I believe the filter and pump are near the tank, I've read something about having to remove a rear seat and lift carpet, etc.

Searching on this and other forums (fora?) might get you some pics.

There ought to be some way of checking the fuel supply before pulling up the rear seats and so on - I'm not an expert on that.

skyfreedom

while parked i pushed the gas when the rpm's reached 3500 and the engine started to spuder and would not go above 4000 rpms.
the engine almost cut out.

skyfreedom

Taking the old ML to the shop on wednesday. I will post results.

Yazovets!

Speaking of pushing the gas while in park, why is it that the engine only revs like halfway. But if you push the gas in neutral, it revs all the way to redline?

What is the point of this limitation in park?

PaulX608

The filter is mounted to the frame in the left rear wheel well behind the plastic inner fender. The fuel pump/fuel sender assembly is in the tank. Your dealer or any qualified mechanic can check fuel delivery without directly accessing these parts. And to those wondering about revving in Park, there's a rev limiter that prevents you from going beyond about 4k or so when in Park. It's there to prevent you from damaging the engine. I've seen people ask about this before, and I always ask, "why would you want to redline your engine in Park?"

samsonobas

having similar experience, how did you solve the problem

Kurths

MAF sensor. If you have a friend with the same Benz and part #. Swap it and see if the problem stops. That will save you some cabbage at the dealer to read the code.
For some reason these can't be fixed with a can of maf sensor cleaner.
$150 ~ $190 on line = plug and play

GERALDRESN

Having the same problem, no downshift and seems starved for fuel with gas pedal either not reacting or taking a few seconds to do so...serviced at dealer replaced sensors, spark plugs/cables....now suggest gas pedal sensors. Replaced cat on one side last year. I own since new, now 225,000 miles...always used 91 or higher octane fuel

justinkaseyhood

Same thing ^ my Ml430 was studdering out here and there when I was stopped at red lights. Replaced Maf sensor. Solved the idle problem but created issue when putting the gas pedal to the floor. Rpm's slow to climb and it acts like it is getting held back. Severe loss of acceleration when floored.

Maj. Dundee

This new problem is an indication of a faulty MAF Sensor. If you didn't buy an original Bosch you will continue to have problems. Did you buy one off the internet/ebay?

As a test, put back your old one and see what happens.

justinkaseyhood

^ so I got an over seas maf sensor for like 50 bucks check engine came on in a series of 10 cranks would go back off and re appear. Put on a new Bosch maf that I got for 150. Same problem. Will spudder out here and there at red lights/ will run rough before spuddering out/runs ok on highway as long as you do not try to excelerate to much/ still has severe loss of acceleration when floored and even just down shifting/it feels like it is being held back. IT IS NOT THE MAF SENSOR. I have replaced the fuel pump and fuel sensor around 20,000 miles ago (I have 165,000 miles on her). I DO NOT BELIVE IT IS THE FUEL PUMP/assembly. Hellllp!!!! it seems electronic the way it is acting . I do have a k/n air filter however the problem was present before replacing that(to see if it was the problem).....These cars are bugged/ but I love her. Hellllp!

Maj. Dundee

The next step would be to check for a vacuum leak anywhere on the engine, especially at the rear.

mmikew36

i have the same power loss, but my problem didn't start until my girl friend ran it out of gas. Could it be air in my gas lines or maybe a plugged fuel filter?

Maj. Dundee

Try the filter first.

mmikew36

ok thank u

Mikeml3502004

I have the same issue when overtaking or up a steep hill and you push the accelerator beyond half way it then has extremely slow response when you try to accelerate. If you turn the car on and off it goes back to normal. I had an issue starting the car a while back so I changed the fuel filter which sorted that out. I changed the fuel pump recently but the problem persists. It has also just started to drop revs when going around a bend so not sure if it’s related in anyway. Any help would be great if there are any solutions out there. Thank you

Maj. Dundee

Mike, you must check for codes in the ECM , namely the two codes that are bracketed in the PDF.

Mikeml3502004

thanks mate I’ll get a scan tool.

Maj. Dundee

Which ever scanner you choose, make sure it says it can scan all modules.