FrenchBenz

Hey guys,

I’m new to the forum, just registerd. I live in Boston MA and I recently bought a 1999 C43 AMG. The car has 133k miles and I have all the history of it. Very clean car owned by a passionate before. My friend who sold it to me spent $4k on the car before selling it to me back in February. He changed all the A/C system, changed all the spark plugs, spark plug wires, new battery, retuned the engine, changed tires etc.

That was back in February but now I have some trouble with the car and it’s worrying me. The car is seriously bogging under acceleration, like I have no power after 3,000 rpms. Then, around 4,500 / 5,000 the car starts accelerating smoothly again but is still really low on power. I took the car to MB to get a diagnostic and they told me that I had to change the cat converters and the exhaust muffler for around $7,000 !!!!

I then took it to an (awesome) mechanic, European Car Doctors, and the guy told me to first use Techron 3 times. Put it in when empty fuel tank, refuel and then drive. Repeat it 3 times and then come back to him if nothing changed…

I’m not a specialist on mechanic stuff but I really want my car to run properly as it is my daily driver. Did smbd had a similar issue or have any suggestion?

Thanks for the answers.

Arnaud.

eundaddy

sounds like the car is in limp home mode. has your friend mentioned anything wrong with the tranny?

503C43 ////AMG

Any codes??? I was quoted around $4000 to replace the stock AMG exhaust system but you could definitely replace it with after market parts for WAY cheaper and get more power.

MarcusF

Take it to a good muffler shop. They’ll pull the O2 sensors and install pressure gauges. The gauges will show abnormal pressure levels. That’s assuming they aren’t rattling. If they rattle, they can be tossed without testing. The dealer wants $7K because they use factory parts. Metal core Magnaflow cats will outflow the factory parts for less than 15 cents on the dollar.

C43AMG

While you're having all this looked at , take a look at the basics - when was the last time the fuel filter was changed? When was the MAS - mass air sensor changed out ? A bad mass air sensor doesn't always throw codes.

DRBC43AMG

That's true, those are two items worth looking at before checking other more expensive items....

grane

It is a good idea to try the Techron first. There has been a lot of dodgy gas since the change over to the summer formula. It a lot cheaper than throwing parts at the car. Use shell 93 gas and I bet the problem goes away. I had similar problems with my 55 that I can only attribute to changeover gas on a recent road trip. I used an off brand in NJ uugh but I had no choice. I live thek idea of changing the fuel filter even if it was just changed if there is junk in it it's toast.

Where are European car doctors. Sound savvy.

FrenchBenz

Thanks guys for all the tips. My mechanic told me to change my gas too and use only Shell VPower 93. I already used Techron 2 times and shifted to Shell 93, and I clearly see a difference, even if all the power is not back yet. the car bogging issue has diminished significantly. I'll do it a last time as my mechanic told me and then I guess I'll start with checking the MAS and fuel filter.

I guess I'll ultimately have to change to the cat converters later. My mechanic also told me about changing them but he wanted to take a step by step approach to avoid throwing money at it for nothing.

@eundaddy: The tranny shifts perfectly, very smoothly and I didn't hear or feel anything weird coming from there. I might have a look at it but later I guess.

@grane: European Car Doctors are located in Boston, 61 Brookline avenue next to Kenmore. Just check their reviews on yelp, pretty impressive.

Thanks again for the advices !

ECTurboGSX

You'll feel symptoms similar to this before the MAS ever throws a code. If it feels stronger at partial throttle than at full throttle, that is the main symptom I had before mine threw a code.

FrenchBenz

@ECTurboGSX. Yes, it's kind of the symptom I have on the car. Btw, it might sound dumb but what do you mean by throwing a code???

503C43 ////AMG

Your ECU will log problem codes, you need a scanner to retrieve them

ECTurboGSX

Correct, it will log a fault code in the ECU and then turn on the check engine light. I don't remember the exact code, but it is something to the effect of Fuel Trim Bank 1 and Fuel Trim Bank 2.

FrenchBenz

Ok I see. Sounds good. Do you where and how much a scanner cost? Also is it really useful to get one personally to locate issues?

Thanks

sheinz_57

I have been dealing with the same thing recently. I was receiving P0170 and P0173 codes. I changed the MAF and then the power was back, but it boggs down around 5k RPM and I am getting P0300, P0302 and P0304 codes now.

I am considering changing the plugs on cylinders 2 and 4 as well as the wires. I may even go as far as to change the coil packs on those cylinders if necessary. I just want my speed back.

Anyone else experienced these symptoms, any advice is appreciated.



BTW, you can get a scanner at AutoZone or any auto parts store. There is no need to buy the expensive ones. You can pull the codes with the $70 unit and find the codes in the MB forums.

C43AMG

Harbor Freight..under $50.00

FrenchBenz

Heads up. So as recommended by my mechanic, I just used Techron to clean the injectors and boy there is a huge difference. I put a full bottle (for 20 gallons fuel tanks) in an empty fuel tank and repeated the operation 3 times. I'm down with it now and my C43 seems even more powerful than before the power loss issue. It's a beast again, easily spinning the tires until 3rd gear under the wet with no problem whatsoever! The car also breaks the traction in the dry in first no problem. God I love this car !

I dropped the C43 this morning at the stealership for a tranny and reaf diff flush. They'll also change the filter in the mean time. That should hopefully smooth the shifts, which tend to be a bit rough when the car is cold and make it even more enjoyable to drive.

DRBC43AMG

I hope you drive the car nice and cool until the oil and tranny warms up unless you want very expensive problems...

FrenchBenz

Don't worry about that ! That's the first thing my father told when I learned driving. I never hit the car before it was fully warmed up. Specially with high-perf cars ... as you said, the damages would be freakin' expensive !!!

503C43 ////AMG

Did you fill up after adding the techron to the empty tank?

FrenchBenz

Yes I put the Techron in the empty tank first and then I filled up the tank.