Simes.m

Hi everyone.

I am new here and this is my first post.

I have been reading up on the forums for weeks trying to figure out ways to get better fuel economy as some people can get down to 5.9L/100km on the freeway whereas my best was around 7.7L/100km. But before I could start implementing ways to improve my fuel economy, a problem has arisen. Hence why I joined the forum.

Since a couple of days a go, my 2001 C200K's fuel consumption has doubled!

I have only this car for about 3 months and it is coming up for a service in about 500kms.

It has 168K km on the clock.

Usually around town, I'm seeing between 9.5 and 12L/100km. But now, It is hanging between 16 and 20L/100 km and saying that I have a range of about 350km on a full tank of 98 octane! And, I have been driving with an incredible light foot to try and preserve fuel.

Apart from the terrible fuel consumption, I haven't noticed any other problems such as lagging or power loss.

I have one part that I noticed break at the same time of the incident (extreme fuel consumption) and that was the breather hose (part number A111 0182982) on the top side of the crank case. This part is leaking a small amount of oil and I have had to put in about 1 litre since its last oil change.

I have it booked in for a service/repair on the 18th of Feb at an independent mechanic.

One thing I have tested is the MAF sensor. I unplugged it and drove it for a while at operating temperature and didn't notice any improvement in fuel economy.

Sometimes when the car hasn't been started in a week or so, it rough idles very slightly for 5-10 seconds or so. It could be relevant.

I don't have an OBD2 code reader so haven't been able to get codes. I imagine that would be a first step?

Any speculations as to what could have cause this sudden problem?

Cheers,

Simon

Simes.m

Another observation I've noticed is that the excess fuel consumption is not overly prominent when cruise control is on/driving at constant speeds.

But, as soon as I accelerate even a tiny bit or stop and idle, the fuel consumption goes through the roof.

Any thoughts?

O2 sensors, spark plugs, air filter, maf sensor, brakes rubbing?

I will buy an obd2 code reader soon and pull the codes.

112233

Hi, (this is for the M111Evo engine)
Thats not easy. In general, it is not a waste of money to change the Lambda and MAS sensors on a car that old. The Lambda sensor is the main sensor for injection quantity calculation.

If you have a leaking breather hose on the valve cover, the de-oiler (build-in in the black box above the kompressor) is probably blocked. Remove the box (easy, 10 minutes) and clean it with brake cleaner. You will see lots of diluted oil coming out.

Next, generate log files. (BT reader + Torque on Android) Unfortunately, analyzing that log files is not so easy, but worth to learn. There are only a few sensors via OBD available, so record as much as possible. Do some test runs. 3. or 4. gear, full pull.
Take a look at the boost pressure. e.g. if you have not enough boost, you need more fuel. (you automatically press the pedal deeper )
The boost disappears over time due to a tired belt tensioner.

If you are lucky, you will get some trouble codes to help you out.

Good luck

PS: Rough idle, or a ticking noise? After some days of rest, the oil runs out of the hydros completely, a ticking noise is in that case normal.

samaritrey

Have you kept up with maintenance? I would invest in a code reader so you can get a cheap one on the internet that will do the basics.

Boom vang

those numbers are about right, I get around 7-8.5L/100km highway especially in the winter, the best I have ever gotten is around 6.8L/100km keeping it a steady 95km/hr, the faster you go the worse off.
In city driving the car can be a bit of a pig on fuel and I average about 11-14L/100km depending how you drive and how cold it is outside. The worse I ever got was 18.7L/100km for a tankful and that was strictly city driving, tons of snow and a major cold spell which averaged -22C

I've had my car for 8 years I have 136,000km and got it when it was 3 years old and 42,000km and this has been the consistent fuel mileage

Right now it is winter in toronto, cold and I am running 4 snow tires and some weight in the rear.

Smaller stressed engines actually use more fuel than a larger engine when driven with vigor. Top Gear did a test with a Prius and an M3 around a track, The Prius drove as fast as it could and the M3 basically followed with ease, at the end the Prius got worse fuel economy http://www.bbcamerica.com/top-gear/v...thirsty-prius/

Simes.m

Thanks for your replies, everybody!

When I get it serviced next week, I will have them potentially replace the O2 sensors and clean the MAF and throttle body.
Or maybe I could clean those two by myself. Is it a safe job?

In regards to cleaning the oil separator above the supercharger, can I use MAF cleaner as that's all I have?
But I can buy brake cleaner if so.

I don't have an android unfortunately. Is there an equivalent on iphone that I can get?
And do I need to buy a wireless obd2 scanner?

I haven't noticed a ticking noise but rarely it bunny hops very slightly when first started after it's been sitting for a while.


I have only had this car for 3 months and it has a reasonably good service history.

I have noticed that it looks like it hasn't had spark plugs replaced for over 100K kms so I will be replacing those in next weeks service.



Ok. That's not too concerning then as they are rather consistent figures as to which I've been getting. I live in Australia so it doesn't get that cold.

I have read on some forums of people getting around 5.9-6L/100kms for extra urban traveling. I would love to get something like this.
Have people on here ever got something like this on their m111 engines? Or is it the M271's that can do this?

I wonder if I'll notice a change in economy after I replace and clean some of these parts.

Btw, I'm buying a new breather hose for the crank case tomorrow morning.

If that part is cracked, is that considered a vacuum leak?
Could this be causing my bad around town fuel economy?

Thanks again.

Boom vang

5.9L/100km is not reality in our cars, I think it is only possible with bad math. A gas engine with 15 year old technology (ie when it was designed) can not get 47mpg in a car that weighs over 3300lbs, if it was a diesel i'd believe that. But not a suppercharged motor pumping out 105bhp/L

Unless your car is throwing codes to replace the O2 then I would not waste the money to change it for the sake of changing. The cost of the two sensor will pay for a lot of gas

Not aware of a wireless OBD11 reader that works wirelessly off our car. Just buy the standard that plugs in ~$130

Simes.m

That's good to know those figures are unreachable and I shouldn't expect anything like it.

I will scan for codes and see what comes up.

Also, I have the new crank case breather hose part but I haven't a clue on how to get the old one off (and put the new one on)?

Any tips?

wvadam

my car in picture. 5.9L/100km personal best

Simes.m

Wow!
That's super good. And is that with M111 engine?
Are there any mods you have done to achieve this?

Boom vang

doing a trip of 65km is not a true indication of 5.9 (it could be downhill and coasting) and besides that is an estimate via the car's computer, if you do the real math and calculate the physical fuel that went in over at least a distance of 160km or more you will find that it is no where near the 5.9 fuel economy

What the car's computer shows and the real actual fuel economy is perception vs reality. I wish I got the actual mileage on what the dash shows, in fact I noticed that on highway run over 100km it showed that I was getting 6.4 but when I put in the actual fuel and did the math it was considerably more ie 7.3

wvadam

that is correct that it wasn't typical, but it wasn't 65km downhill coasting either. Typical commutes to work were around what you were getting depending on traffic.

izbeekhan

hi hve a good day
There is a knocking in my car at start up. It looks like galloping like a horse. Stroke is not uniform from the engine and the sound is very unpleasant.
Khan

Simes.m

Hi everyone.

Here is an update on the situation.

I have been out of the country working for 3 months so haven't been able to do anything about it while I was away.

Before I left it had a big service done. (Engine oil flush and oil, oil filter, front brake pads, fuel filter, spark plugs, air filter, MAF and throttle body cleaned). All this and it made no difference. No codes came up from memory. Maybe there was something about a coil pack. Could faulty coil packs result in high fuel consumption? Anyway, that is something I probably need to check out regardless.

I recently did a 1000km journey in the car and only got 9.1 l/100km. Usually on these trips it does 7.7 or so. There is definitely still a problem. I had the thermostat replaced as it faulted when I just got back (4 weeks ago) and was running cold (50-60 degrees) and thought this could have been the problem as the engine was in constant warm up mode, but this made no difference. I am going to take it to the mechanic to ask more questions and see if anything comes up on the diagnostic machine.

So what I am thinking now is potentially the supercharger isn't working correctly. Or, something is telling the engine to mix the fuel at a higher ratio. I should get 7.7 on the freeway and 11 around town, but I'm getting 9 and 14 respectively.

What are your thoughts?

I will let you know if anything conclusive comes from the chat with the mechanic tomorrow.

Cheers,

Simon

shimon cohen

Hey bro, i am kompressor c200 and it's like your car, as your discription, but i don't see any error let alone check with computer!, r u watching any lamp error to check it ?

Karachi2174#

Hi 1/- While engine idling un plug the MAF connector, if it engine dies MAF is Ok if it keeps on running then you need to replace , it , if there is black corbon inside the silence then replace the O2 sensor.if no improvement in the consumption then buy a Totoa corolla or Nissan Sunny