W203 Cold Start Acceleration Hesitation

[columbo]

I have a 2000 C180.
In the morning when I start the car it idles erractically and when you pull away down the drive with little or no throttle it moves fine but when I try to join the road by pressing the accelerator nothing happens for maybe upto 5 seconds then the car will surge forward.

I live on a busy main road and it can take a while in the mornings waiting for a clear road before I can try to join the road.

After a minute or so the car will drive normally. I have had the MAF replaced but it has had no effect, the mercedes specialist does not know what it is because no codes come up.

Please help

 

[BlackC55]

The values for the throttle flap need to be read.

A star will be able to do this for you as it has the ability to read live data.

Was the air mass replaced with a bosch item or a cheap alternative.

 

[columbo]

Thanks for the speedy reply.
I had it done in Manchester by a Mercedes specialist. I assume they would use original items.

Is there an easy way I can check the MAF myself?

I've just checked the invoice it says Parts Desc 434220250 Air Mass Sensor Assembly, does that mean anything to you.

What is A star?

 

[BlackC55]

A star is the MB diagnostic equipment.

 

[columbo]

Would you know from the part number if the Air Mass Sensor is a Bosch unit or not?

 

[miro]

I have a 2000 C180.
In the morning when I start the car it idles erractically and when you pull away down the drive with little or no throttle it moves fine but when I try to join the road by pressing the accelerator nothing happens for maybe upto 5 seconds then the car will surge forward.

I live on a busy main road and it can take a while in the mornings waiting for a clear road before I can try to join the road.

After a minute or so the car will drive normally. I have had the MAF replaced but it has had no effect, the mercedes specialist does not know what it is because no codes come up.

Please help

Sit down.

The cam magnet on the front of the engine leaks and so does the transmission sump plug. Essentially if you pull out the engine harness at key points the connectors are soaked in oil.

Pull up the passenger carpet and check for puddles of oil. That is the leaking sump oil pooling inside the car.

To fix the engine harness you need to disconnect all of the major junctions and flush them with a high grade solvent from WURTH. Then install a 10 pound adapter harness which plugs into the cam magnet (making the harness longer but more importantly stopping the flow of oil).

To fix the sump. Drain all of the oil from the sump - since it needs to be done every 60,000km anyway - and replace the sump wiring plug while you are there. Replace filter and gasket also.

No go back and clean the ECU from oil contamination and also the ground point and passenger footwell.

Now top up the transmission and install the new filter. Reset adaptations with a dealer type diagnostic (STAR) and let us know how your 2000 model runs now.

You need to sort this out before you go spending more money on replacement parts. Should take about 2 hours and cost around 40 pounds in parts. One is special cam magnet adaptor cable and the other is 722.6 service kit and also revised sump plug.

Make sure that every 60,000km you repeat the gearbox oil change.

When left unchecked this is the damage caused by the engine harness oil
- engine control unit
- updated CAM magnet
- engine main wiring harness
- MAF
- oxygen sensor
- some other sensor

That comes to about 2000 pounds with the Mercedes special discount for known problems.

 

[merc man]

Sit down.

The cam magnet on the front of the engine leaks and so does the transmission sump plug. Essentially if you pull out the engine harness at key points the connectors are soaked in oil.

Pull up the passenger carpet and check for puddles of oil. That is the leaking sump oil pooling inside the car.

To fix the engine harness you need to disconnect all of the major junctions and flush them with a high grade solvent from WURTH. Then install a 10 pound adapter harness which plugs into the cam magnet (making the harness longer but more importantly stopping the flow of oil).

To fix the sump. Drain all of the oil from the sump - since it needs to be done every 60,000km anyway - and replace the sump wiring plug while you are there. Replace filter and gasket also.

No go back and clean the ECU from oil contamination and also the ground point and passenger footwell.

Now top up the transmission and install the new filter. Reset adaptations with a dealer type diagnostic (STAR) and let us know how your 2000 model runs now.

You need to sort this out before you go spending more money on replacement parts. Should take about 2 hours and cost around 40 pounds in parts. One is special cam magnet adaptor cable and the other is 722.6 service kit and also revised sump plug.

Make sure that every 60,000km you repeat the gearbox oil change.

When left unchecked this is the damage caused by the engine harness oil
- engine control unit
- updated CAM magnet
- engine main wiring harness
- MAF
- oxygen sensor
- some other sensor

That comes to about 2000 pounds with the Mercedes special discount for known problems.

sound simmilar to what i am experiencing!

 

[ljy90]

Mine is also a little hesitant in the morning while reversing off the drive and can be a little jumpy. Only done 27k miles though. In for service A at stealership on Mon.

 

[columbo]

Thanks miro for your advice I'll try that before the ECU blows up

 

[merc man]

hi i think my car is suffering form the same problem its a 111 engine 2001 w203 model, i have chnaged the camshaft acctuator and added the extra wiring to stop anymore contamination, and cleaned all the connection point that were full of oil. The car is still sluggish, i have yet to change the 02 sensor and the air mass meter, but what is the other sensor? is it the purge valave also known as the mot valve?

 

[miro]

hi i think my car is suffering form the same problem its a 111 engine 2001 w203 model, i have chnaged the camshaft acctuator and added the extra wiring to stop anymore contamination, and cleaned all the connection point that were full of oil. The car is still sluggish, i have yet to change the 02 sensor and the air mass meter, but what is the other sensor? is it the purge valave also known as the mot valve?

I will tell you what I saw at a dealer. They took out the ECU and with a large screwdriver opened the sealed edge, took out the PCB and poured out the oil. They were a WURTH customer so they had many sprays to clean the residue.

Whatever the harness connects to can be contaminated. I think it also includes the CRANKSHAFT sensor and the CAMSHAFT sensor.

Also, the erratic idle is a software defect called "IDLE HUNTING" and it happens when the adaptations (normal) over time become outside the expected range. This was corrected with newer ECU modules at a future date. One a hot day with AC running it puts the car into limp mode. The only thing to do is restart the motor and switch off the AC.

Mercedes knows about the idle hunt and the lucky ones complained to DC and got a free fix. When the RPMS at idle vary by as much as 400rpm then this is usually the cause.

Really rough engine behaviour and high fuel consumption in the W203 M111 combination is usually contamination on the wire harness first and damaged sensors thereafter.

Now .... remember that Wide Open Throttle reset trick that someone wrote up. It refreshes the throttle response. I did that a petrol station and about 500km later on the freeway my fuel consumption just nosedived. About 20% lower than before. I was amazed. Does anyone have that method handy ?

Cleaning all of the connectors with a special solvent and checking the ECU and reset the adaptations with the WOT method will probably help in the short term.

The short spacer cable which attaches to the CAM magnet is a cheap form of insurance. It has a 271 part number so it must also affect M271 engines.

Cars this age probably also have issues with their CRANKSHAFT sensor (a common headache).

 

[merc man]

hi there and thanks for the reply

so as it stands i will order a new cable harness, air flow meter and 02 sensor and then clean out the ecu, will this be the end of the problems and restore the car back to full performance?

P0010, camshaft position actuator A- blank 1 circuit malfunction

P0141 secondary air injection system valve A CKT short

P0135 02 sensor heater circuit malfunction (blank 1 sensor 1)

P0141 02 sensor heater circuit malfunction (blank 1 sensor 2)

P0445 EVAP emission control system purge valve C short

even after resetting the codes they still apper and make the engine check light come on and the car does not accelerate as normal

ANY ideas?

 

[miro]

hi there and thanks for the reply

so as it stands i will order a new cable harness, air flow meter and 02 sensor and then clean out the ecu, will this be the end of the problems and restore the car back to full performance?

P0010, camshaft position actuator A- blank 1 circuit malfunction

P0141 secondary air injection system valve A CKT short

P0135 02 sensor heater circuit malfunction (blank 1 sensor 1)

P0141 02 sensor heater circuit malfunction (blank 1 sensor 2)

P0445 EVAP emission control system purge valve C short

even after resetting the codes they still apper and make the engine check light come on and the car does not accelerate as normal

ANY ideas?

I presume you found oil in all of the junction points or in the ECU. It sure sounds like the ECU has had its teeth kicked in.

 

[merc man]

so on top of all the parts i will need a new ECU? i havent opened the ecu up yet, but will do at some point this week.

 

[miro]

so on top of all the parts i will need a new ECU? i havent opened the ecu up yet, but will do at some point this week.

You will know when all the other parts are installed and nothing changes .... have to wait and see.

Get your local dealer to plead your case.

 

[columbo]

I've just had my car checked out for oil, it is all clear, in a previous service they changed the sump plug and harness as a precaution. I asked them to look at the cam magnet and it is fine. They reset the computer and it is showing no malfunctions but the car still hesitates. The mass air sensor was changed last year.
If there is no oil leakage and it is still hesitates can it be anything else or do you think there is a problem with the mass air sensor
Thanks

 

[miro]

I've just had my car checked out for oil, it is all clear, in a previous service they changed the sump plug and harness as a precaution. I asked them to look at the cam magnet and it is fine. They reset the computer and it is showing no malfunctions but the car still hesitates. The mass air sensor was changed last year.
If there is no oil leakage and it is still hesitates can it be anything else or do you think there is a problem with the mass air sensor
Thanks

The engine will be controlled by the oil temp also. Look at having your transmission serviced.

 

[columbo]

The car hesitates more when the air con is on does that make a difference to the diagnosis

 

[miro]

The car hesitates more when the air con is on does that make a difference to the diagnosis

It certainly makes sense but it doesnt cause the problem as it simply adds to the load on the engine.

 

[Bazzle]

Pull the MAF sensor out, read the number on it. Give it a good wet spray of CRC maf cleaner or electroincs cleaner etc, shake dry, reinstall.
Tell us what happens.
Ive seen them get contaminated in 3 months. Usually from a dirty oil seperator and hoses on top of rocker cover.

Bazzle