monty13

Hey all,

Recently I've noticed a considerable loss in power from my engine - approx 40% reduction. At higher rev's the classic AMG sound is lost and replaced by a high pitched whooshing sound. Any thoughts where to begin?

C43AMG

While we are more than willing to help you as much as we can ..we need more info - mileage , maintenance history etc.You could have a mass air sensor going bad....a bunch of things.Please provide as much info as you can.

BTW.....welcome!

monty13

Thanks for the quick response…greatly appreciated!

Car Info:
-128,000 miles, original engine, new transmission (30,000 miles ago)
-oil is regularly changed every 6-7,000 miles with Castrol synthetic 0W-30 euro spec
-I’ve owned the car for about a year now

Within the last week:
-Just completed some regular suspension maintenance – left front control arms (bushings and bearings), right rear control arms, and
-transmission mount
-oil cooler seal and both valve cover gaskets (oil leak)
-Spark plugs and wires

Current Symptom:
-Car did not have the reduced power (coupled with the whooshing noise) after it sat for a week in the shop, but I did notice this symptom before taking it to the shop. 3 days after driving it (20 mile drive to work) the noise started again. Not sure why this didn’t occur after sitting for a week?


I haven’t touched the mass air sensors or any other similar items since purchase. I also don’t have records of them ever being replaced by previous owners

tasho3

my car did the same thing couple of times, i put sea foam in the oil cap and fuel tank and it was gone

monty13

Really? How many miles were on your c43 when you used seafoam?

tasho3

somewhere between 110k-120k i m at 141k now and the problem hasn't occurred. actually somebody from this forum recommended it. put half of the bottle in the gas tank, fill it up half way, put the other half in the oil tank, drove it hard till the fuel tank was about to run empty and than took it in for a oil change and everything was fine after

C43AMG

How about a new fuel filter for starters, just to make sure she's getting the fuel. Then we can go after the MAF.How do the air filters look ?

monty13

I'm due for an oil change shortly so I may give the seafoam a shot this weekend before I change it. I did some digging, and it seems like other people have had success with seafoam. While I'm working on the car, I'll be sure to check out the air filters.

Depending on how she runs post seafoam, I may replace the fuel filter. I will also be sure to let you guys know the outcome. Thanks for the advice!

503C43 ////AMG

Sea foam is good....... I use redline, it's for higher performance/ higher temp engines. I use this on my C43 and 99 accord. The difference in power, throttle response, hesitation is noticeable INSTANTLY. I had a slight loss of power in my C43 and a misfire during idle in my accord. I ran the redline through both and the C43 was INSTANTLY back to normal as well as my accord. You put it in your tank when you are almost empty and then go fill up. Halfway through the tank you should see the difference. That being said, it sounds like you have a much bigger problem on your hands than a slightly clogged fuel injector. Sea foam and redline are more for preventative maintenance as well as curing a SLIGHTLY clogged fuel injector. If its bad it really wont help. Techron is one of the best fuel injection system cleaners out there but once again it is a preventative maintenance, I run nothing but chevron supreme as it has techron in it and will prevent any clogs. Good luck and I hope you are back on the road soon with FULL power

AMS Performance

sounds like vacuum leak of some kind. Make sure all the air hoses are air tight and there are no cracks or leaks of any kind. Also check gaskets such as valve cover gaskets & etc. Hope that helps.

hcetzneb

Any check engine light... Any noticeable missfiring? Before you go and put parts check the fuel presure.. Maybe vacuum at idle with a gage just to start getting some ideas..

503C43 ////AMG

Agreed, check the Valve cover gasket..... mine was bad when I got it, had loss of power.

jumph4x

Could be something like this. Especially if the change is sudden. Especially since Mercedes are freaking in bed with vacuum EVERYTHING.

Not so much on the fuel\air filter and injector gig. Doubt that has anything to do with it.

AMS Performance

Does not sound fuel related at all...

monty13

I just had the valve cover gaskets replaced recently due to a leak and that didnt seem to have any affect on it. The noise / symptom isnt really noticable untill higher rpm's (4,000).

503C43 ////AMG

vacuum, vacuum, vacuum that's all I can say.

AMS Performance

there are two sets of valve cover gaskets, most replace the bottom one, but do not replace the upper gaskets so you may still need to do this. The upper ones are usually the ones that create vacuum leaks the most.

DRBC43AMG

Could it be the engine fan which is turning on a permanent basis? Makes a real racket at high revs? Perhaps the fan auto coupling is not disengaging. However it would not be the cause of the great power loss you are talking about.

monty13

The "great" loss of power may have been an initial over statement due to my own personal frustration. There is a definite loss of responsiveness and slight loss of power - the car absolutely behaves differently than before. I'm changing the oil tonight so I'll have my head under the hood to check out some of the above suggestions.

DRBC43AMG

Sorry if this is a hijack, but I need to know what are Seafoam and Redline??

monty13

Sorry missed this question:
No check engine lights or missfirings....There is a slight pinging or ticking that is noticable at certain rpm's (especially next to buildings with the windows down). I assumed this was a small muffler leak and was not related.

C43AMG

Fuel additives

503C43 ////AMG

Fuel system cleaners..... I suggest REDLINE, I have had great experiences with it in my C43 and my Accord. Will help smooth out rough idles and restore lost performance. That being said this isn't a miracle in a bottle, it won't fix major issues. It simply gives your fuel system a good cleaning and will help remove any deposits etc.....