Ponton-Jetronic
Active Member
Is it a blockage or ventilation problem.? What change did you make, or what service was done when it started ? Are you Carb or Injection ? What was your normal consumption [ or per £10 usage ] before this thirst ?
Ponton-Jet.
Ian B Walker
MB Enthusiast
- Joined
- Jun 7, 2003
- Messages
- 7,668
- Location
- Freckleton
- Car
- 300-24, saloon and coupe, E300 24 valve diesel estate
I would have your car on a Star machine to diagnose the problem. It could be one of many things rangine from plugs to maf and beyond.
st4
Banned
Ian B Walker
MB Enthusiast
- Joined
- Jun 7, 2003
- Messages
- 7,668
- Location
- Freckleton
- Car
- 300-24, saloon and coupe, E300 24 valve diesel estate
Its not a 211 Steve and only has 5 gears 
- Joined
- Nov 1, 2008
- Messages
- 19,769
- Location
- Bournemouth/Poole Dorset
- Car
- W210 E280 x2, w211 E55, W212 E63 biturbo, S204 C180K
Just drove my fathers C200K to Heathrow and back. Average speed 53MPH, Average 30.6MPG. It took almost 80miles to get out of the 20's per gallon.
st4
Banned
Its not a 211 Steve and only has 5 gears
The 203's after a 210 are the scappiest of the lot. I've seen a few here with holes in the bonnets, wings etc and the rear arches go.
Since you seen mine, its had waxoil from me. Never thought I would do that as I tend to run cars under 7yo usually. Shocking, and its MB that are to blame as its their dealer that repainted mine!!!!
mauno
Active Member
- Joined
- Dec 26, 2011
- Messages
- 306
- Location
- Braintree
- Car
- W203 C200K T model classic/ W168 1.4 avantgarde
I'm a c200k owner and give you the answers: if it does not pull like a train when you push the pedal down above 2500rpm,then it will be the secondary air injection system.which includes few sensors tubes and the supercharger all the way down to the exhaust system.It will be a long search.do it yourself or prepared to pay a lot.after i have fixed mine,i get around 35-37mpg
tali
MB Enthusiast
Quote:
Originally Posted by Rock
Hi All,
my C200k, 51 plate seems to be drinking too much petrol lately. short and long drives brings 24-25mpg as its giving me approx. 30 miles for £10 petrol.
Any advise will be appreciated
cheers
Is it a blockage or ventilation problem.? What change did you make, or what service was done when it started ? Are you Carb or Injection ? What was your normal consumption [ or per £10 usage ] before this thirst ?
Ponton-Jet.
CARB? i thought Merc stopped them with 190 ?
Originally Posted by Rock
Hi All,
my C200k, 51 plate seems to be drinking too much petrol lately. short and long drives brings 24-25mpg as its giving me approx. 30 miles for £10 petrol.
Any advise will be appreciated
cheers
Is it a blockage or ventilation problem.? What change did you make, or what service was done when it started ? Are you Carb or Injection ? What was your normal consumption [ or per £10 usage ] before this thirst ?
Ponton-Jet.
CARB? i thought Merc stopped them with 190 ?
MAUNO did you do it yourself? im a newbie to all this so very unlikely i will know what to look for. Do u know anyone that cam do it? im based in essex or can come down london
unless your able to give me a step by step guide? the B service is due should i get the andie to check this as well?
email: [email protected]
cheers
unless your able to give me a step by step guide? the B service is due should i get the andie to check this as well?
email: [email protected]
cheers
If you could post the instructions here, it would be great. This problem in something I've been trying to address for quite a while and I am close to selling my car in frustration!
Thanks!
Thanks!
joe prosser
Member
Many times the issue with poor mpg is the ECU is unable to switch from open loop (warming up) to closed loop (normal running). The switch is triggered by the coolant temperature sensor indicating to the ECU that the engine has reached threshold running temperature. Open loop is characterized by long injection times to warm the engine up and to fire up the catalyst; secondary air injection is to provide enough additional oxygen into the fuel-rich exhaust to accelerate this catalyst heating up process. First check that you have coolant at correct level, too low and the temp sensor is no longer in contact with the coolant. Next check that your thermostat is not left jammed open, it should take some time after the engine is started before the top pipe to the radiator begins to warm. If thermostat is permanently open the coolant is circulated through the radiator and the engine will take significantly longer to reach running temperature. Check that your throttle throat and throttle plate are clean of oily grime. Next examine your O2 sensor condition. If caked in black soot it will be unable to detect the true oxygen levels in the exhaust and will report in error to the ECU that there actually high levels present. The ECU will try to compensate by injecting yet more fuel, further exacerbating the problem. O2 sensors can be fixed by using a plumbers gas burner to heat the tip enough for the soot to burn off. Finally check your fuel regulator valve on the fuel rail. Pull off its vacuum tube and check for any dribbles or smell of fuel from it. If the fuel pressure regulator is 'healthy' you will find that, when the car is idling, if you remove its vacuum tube that the car first picks up in revs for a few seconds (the loss of vacuum in the regulator allows the pressure in the fuel rail to jump up, so more fuel is suddenly injected) and then the car will drop in revs and run unevenly (as the ingress of un-metered air via the open tube now begins to upset the fuel air balance in the engine). Replacing the tube now will restore order . If you feel the MAF is at fault simply disconnect it, the car should run on default parameters, not perfectly but OK. Do this simply as a diagnostic to determine unambiguously that the MAF is at fault.
Before the service A been done, the average mpg I could get was around 25mpg. After the service A (changed new oil, oil filter & spark plugs, etc.) an average of 30-35mpg now. I have noticed from the cluster board that 15mpg when the engine just started at freezing temperature and up to 27mpg when it get warmed.
Last edited:
joe prosser
Member
The steps to take are not too scary or time consuming. Do the simplest first:- Start you engine.
1) look at level of coolant and top up as necessary..time taken, 30 seconds.
2) Locate the fuel pressure regulator (FPR) and disconnect the vacuum line. Sniff and look for fuel from the line and FPR and at the same time note any increase in revs for few seconds and then a stumbling idle. Reconnect the vacuum line. Time taken about 60 seconds.
3) Disconnect the MAF sensor and note any changes to idle, then reconnect. Time taken, 30 seconds.
4) Switch engine off and remove air duct between air filter and throttle. Measure Clean throttle throat and plate with WD40 and kitchen towel. Replace ducting. time taken, 15 minutes max.
5) start engine and allow to warm up whilst feeling the top radiator hose. If the thermostat is open the hose will feel slightly warm quite quickly but will take a long time to get hot. If thermostat OK then hose will suddenly become hot only after the engine has been running for a while. Time taken, about 10 minutes.
6) switch off and locate O2 sensor on the exhaust manifold. Disconnect lead at junction on bulkhead and slip a 22mm open spanner over the flex and down to the sensor nut. Remove sensor and check the tip for soot or white build up. If caked, heat it with a plumbers butane burner until residue burns off. Allow to cool, replace and reconnect the flex... time taken 30 minutes.
Inside an hour to perform a full diagnostic check and possible remedy.
1) look at level of coolant and top up as necessary..time taken, 30 seconds.
2) Locate the fuel pressure regulator (FPR) and disconnect the vacuum line. Sniff and look for fuel from the line and FPR and at the same time note any increase in revs for few seconds and then a stumbling idle. Reconnect the vacuum line. Time taken about 60 seconds.
3) Disconnect the MAF sensor and note any changes to idle, then reconnect. Time taken, 30 seconds.
4) Switch engine off and remove air duct between air filter and throttle. Measure Clean throttle throat and plate with WD40 and kitchen towel. Replace ducting. time taken, 15 minutes max.
5) start engine and allow to warm up whilst feeling the top radiator hose. If the thermostat is open the hose will feel slightly warm quite quickly but will take a long time to get hot. If thermostat OK then hose will suddenly become hot only after the engine has been running for a while. Time taken, about 10 minutes.
6) switch off and locate O2 sensor on the exhaust manifold. Disconnect lead at junction on bulkhead and slip a 22mm open spanner over the flex and down to the sensor nut. Remove sensor and check the tip for soot or white build up. If caked, heat it with a plumbers butane burner until residue burns off. Allow to cool, replace and reconnect the flex... time taken 30 minutes.
Inside an hour to perform a full diagnostic check and possible remedy.
