Loss of power and engine issues c200 2001 T model w203.

[Wild1]

Hi guys,

I am about pulling my hair out with parts replacement after replacement but still no result. The car is as stated a C Class C200 Kompressor w203 2001 T model Estate UK Import, The car has been running fine and would give me a top seed of at least 130mph with a rapid and smooth acceleration on a flat road.
Where I live is high on a mountain in Malaysia with very narrow windy roads so a lot of driving is very slow and in 2 or 3rd gear.
I have found that after driving some time (maybe 10-15 mins) like this at under 2000 rpm in 2nd gear then putting my foot down to pull away faster on a straight road the car misses and jerks a little for an instant then settles and drives smooth.
On the highway where we can stretch her legs so to speak I used to be able to cruise comfortably at 130 + mph and still feels like it can go more.
But now all of a sudden the car has changed. From the point of acceleration in say 3rd gear as normal, the car feels easy and ready to go, accelerating smoothly and fast until about 4K revs and then it feels as though suddenly something is holding us back. The car still accelerates but slower and does not feel as free, it feels as though we are being held back like it has gotten heavy or something like that. The top speed max with pedal to the floor on a flat road cannot exceed 105 mph.

My mechanic said first off supercharger. I changed a new one, No difference!!
My mechanic said Spark Plugs, we changed those, still No difference!!
We have so replaced the AirconCompressor and the Alternator.
So some major expenses there and still no improvement!!
Today my mechanic wants to change the fuel pump and filter.

I wonder how far I have to go and how much I will have to replace to fix this issue.
Another issue is on the odd occasion that the pump assistant at the petrol pumps over fills the tank to the point she cannot get another drop of petrol in. The car runs smooth for about 45 mins then suddenly looses all power, misses like crazy and stalls. If I remove the petrol cap a loud gurgling sound can be heard and air seems to rush in. After 30 mins the car runs again for another 20 mins before acting up again. During this time the car can start but at idle and will idle for about 30 secs then suddenly rev up and then way down 4 - 5 times then eventually stall, all by itself. However after the fuel level starts to drop and the pointer on the gauge starts to move, the car is back to normal but still with the original issue of occasionally missing and no top speed.

I would really appreciate if someone can throw some light onto this and give me some suggestions to help save money, I fear my mechanic will change everything on the engine before fixing it.

Sorry for the long post but I tried to be as clear as possible.

Thanks in advance.

 

[brucemillar]

Have you access to a mechanic with a STAR Diagnostic computer? That is what is required here.

That my first thought, would be MAF and/or fuel filter. Replacing the fuel filter is probably wise anyway. It is a maintenance item and if blocked? Will cause issues like you describe. However so will a MAF that is faulty.

A MAF is expensive!! You could try simply disconnecting the MAF to see if the engine runs differently? When disconnected the engine should change to a default map. You should notice this change. If you do not have any change in engine running? Then it is possible that the MAF is faulty and the engine has already changed to its default map. Do NOT buy a cheap ebay MAF. They tend to fail very quickly and will leave you doubting your fix.

A session on a STAR computer or a good diagnostic computer should highlight this and save you money.

 

[grober]

Sounds as if your fuel tank vent system is blocked causing a partial vacuum to form in the tank restricting fuel supply . There should be activated charcoal filter system somewhere connected to the fuel tank vent at one side and to the inlet manifold on the other via an ECU controlled solenoid valve to allow it to be evacuated/cleaned periodically. The charcoal filter is supposed to changed at high mileage but rarely is.

the design of these changed over the years
early

later item 77

 

[Wild1]

Hi Bruce,

Many thanks for the reply, This is good news and I will check this MAF, My mechanic has a diagnostic tool but not sure if it is STAR. It is some sort of wireless connection that he plugs a module into the car then can read from it on an iPad like device. So far he has not mentioned the MAF but I wonder should this show up on the diagnostic check.

Hi Grober,
Many thanks also for this info, it sort of ties in with what a friend told me and that was that the fuel filler cap was blocked and had now means of venting. However based on your info it seems like it is not vented from the cap but from the canister. I will look at trying to find one of these here and try to get him to change it.

I really appreciate your input guys it has been a good help. For and english man with a Mercedes (all be it an old one) it is difficult to get good help here in Malaysia and they always charge a bomb, but rarely know what they are doing.