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I would say its very much terrain and speed related.
If its flat at a steady cruise of say 58 to 65mph, cruise is probably almost identical.
If ot gets hilly amd you wanna go a wee bit quicker, then driving the car and letting speed bleed by say 10mph on the steeper sevtions then using the downslope to regain momentum, probably manual use of the loud pedal wins
This is something that is coming, smart cruise. Linked to route calculation, traffic and road profile. Needless to say, it's really ****ing complicated...
If ot gets hilly amd you wanna go a wee bit quicker, then driving the car and letting speed bleed by say 10mph on the steeper sevtions then using the downslope to regain momentum, probably manual use of the loud pedal wins
I do this regularly, particularly on the drive through Europe. Works a treat.
If ot gets hilly amd you wanna go a wee bit quicker, then driving the car and letting speed bleed by say 10mph on the steeper sevtions then using the downslope to regain momentum, probably manual use of the loud pedal wins
I do this regularly, particularly on the drive through Europe. Works a treat.
This is a big one!
It can be surprising (well, not any more once you know) how hard the car is accelerating up steep or long climbs when you knock cruise off, and realise you have to push the gas really hard to maintain what cruise control was doing. Thus scrubbing 10-15mph means a lot less throttle in those situations. And naturally the other side you can just roll back up to whatever pace you were going with minimal throttle
Not in my experience.
Years ago Jeremy Clarkson attempted a trip from London to Glasgow on a single tank of fuel.
He found that cruise control is more thirsty overall if you want to save fuel.
When I press resume on my car it accelerates at a "non-efficient" rate compared to manual acceleration.
Years ago Jeremy Clarkson attempted a trip from London to Glasgow on a single tank of fuel.
Was Lands End to John O'Groats wasn't it?
When I press resume on my car it accelerates at a “non-efficient” rate compared to manual acceleration.
Do you use eco mode? I know mine is marginally better but not by much, sometimes I wonder if it's just designed to make you think it's more economical by reacting slower.
Was Lands End to John O’Groats wasn’t it?
No, it was London to Edinburgh and back on one tank
Do you use eco mode?
Umm no it's a Porsche.... It doesn't understand "eco" 😬
No, it was London to Edinburgh and back on one tank
Ahhh.
I think it rather depends on the car. The most efficient trips I have done in the Merc by a significant margin involve the A34 south from Newbury. This is a dual carriageway with lots of fairly sharp hills that need quite a bit of throttle. I do this with the cruise control on. In this car it seems that it's more efficient at higher loads than other cars I've had, but it still coasts down the other side of the hills.
In some cars, a tiny bit of acceleration causes the instant MPG to plummet. So when it's not particularly hilly, the slight acceleration and deceleration you end up doing when not using cruise cost you fuel. The Prius was particularly sensitive to this. In my experience in that car, using cruise was more efficient than not unless it was particularly hilly. A38 in Cornwall for example, the car was thrashing itself on those hills at 70mph which clearly wasn't effective. That's where mert's intelligent crusie would have come in handy because the car would have been able to use battery power to get up the hills knowing it would be able to recharge coming down.
Of course, if you are letting your speed drop on hills you are going slower overall, which would have a significant effect in itself.
Of course, if you are letting your speed drop on hills you are going slower overall, which would have a significant effect in itself.
Not hugely, most of your issues around journey time (especially in europe) is the getting to and from the main/arterial roads.
Slowing from 70 to 60 on a mile incline will make so little difference to total journey time, it's all but irrelevant. Masked by a bad traffic light cycle or a pelican crossing. (Though dropping speeds generally makes a massive difference to FE, just reducing mine by 5kph gained me about 5%.)
The precharging of the electric drive system in a hybrid before inclines/recharge on descent (and using electric power to change speed) is already in a few cars on the market.
Anyway. I tested my car with the MAF disconnected and it went straight into limp mode.
My MAFs don't read the same according to the app the @colp suggested, but I don't know what variance is acceptable. Or if it a MAF issue or an air filter issue.
That's a bit of a giveaway. What percentage are they out?
MAF A is reading approx 15.5-16 kg/hr and MAF B is reading approx 11-11.5. So a lot.
That's definitely wrong. There's no way that's within normal range. Good thing you have two to compare with each other! You don't need to know which one is wrong - buy one MAF, measure the new one, and whichever doesn't agree is the problem unit.
Not sure about your engine but mine is sat on the top and should be a 5 min job with a screwdriver.
Buy a decent brand though. They aren't cheap, but neither is diesel or a DPF. It's worth giving Merc a ring as they aren't always a rip-off, and you're guaranteed quality. Sometimes aftermarket ones aren't as good, even with the same brand.
Get a Berlingo 😀
Its called the batwing and it contains both mafs. You change both at the same time.
I changed my air filters yesterday, what a faff. You have to remove the cold air feed, then drop the airbox off the batwing, remove from car, then swap them over. Full of leaves and black from road grime
Service book states changed 11,000 miles ago. I think not.
The next question is what does the ecu do with the maf readings? Average them out would be my guess as the air is combined into the turbo downstream of the mafs anyway. But if you have 1 maf at plus 40% then your potentially overfuelling by 20%
Shame your s o far from me, its an easy swap to see what a different batwing shows
There's only one turbo??
Re filters, on mine apparently the fuel and air filters are on a different schedule to the normal service, every 45k apparently. So it's easy to miss them if you are not always using the same garage.
Haven't read it all but aware you have a very thirsty engine...however, check the brakes aren't sticking...I've just replace a caliper, disc and pads and I'm not back to over twice the mpg.
On the om642 3.0td mb engine in my car, yes 1 x turbo. 224 bhp version.
His is a later model, 260bhp. Apparently whilst a twin turbo version is mooted in the internet I cannot confirm it's existence.
Seems bonkers to have two air filters and two MAFs when you've only got one turbo though.
I did read an article that said at low load they throttle one intake more than the other to increase turbulence. If @doomanic was measuring at idle this might be what he's seeing.
That was at idle.
https://www.google.co.uk/aclk?sa=l&ai=DChcSEwjznKrqvfn9AhWQrdUKHb1wDrwYABBNGgJ3cw&sig=AOD64_0PHoSX949QMSfEisFS0lXDeNRn1w&adurl&ctype=5&ved=0CAIQz7YHKCZqFwoTCIDb1Iu--f0CFQAAAAAdAAAAABA M" alt="om642" />
How the hell did you try to post that image? 🙂
MAF readings are still wildly different when driving. Time to get the spanners out and locate a part number.
Even at speed or hard throttle? Very interesting.
I recommend Autodoc for CLS parts and compare with Mercedes. Euro Car parts don't have much for this car, and GSF are a bit rubbish. Autodoc will take a few days to post though. And the usual advice, don't by cheapo knock-off parts. Looks like OEM MAFs are made by Bosch, Pieburg or Hitachi, but sometimes the aftermarket same branded ones are either slightly different the actual ones suppled to the manufacturer, so check Merc first - I reckon it's worth a small premium for slightly higher peace of mind - but perhaps not a large premium!
Also you could try a clean first with MAF cleaner. Spray only though don't touch anything.
I dunno if this has already been suggested but ....
Turn the aircon off ??? it's really bloody thirsty in my old Mondeo
Or if it a MAF issue or an air filter issue.
I’d repeat the test on the driveway with both air filters out or swap the 2 filters with each other, see if the MAF readings equalise (filters out) or swap, or stay the same.
Might also be worth trying some EGR cleaner spray, it should clean the MAFs too
Wynn's Diesel EGR Cleaner Spray Cleans Air Intake MAF Sensor Inlet Valves & Turbo https://amzn.eu/d/gz2viHo
I have bought some MAF cleaner spray for mine, just to see. I think they get dirty over time. When you think about how they work, it's clear that a slow accumulation of crud would gradually affect readings slightly year after year.
One thread I read suggested that the OP's engine and car are particularly susceptible to dirty air filters for some reason - not sure how that would vary by car but that's what was said. Air filters would have to be hugely clogged to make that much of a difference though, I'd have thought.
I cleaned my MAF. The difference is amazing..
..ly small. As you'd expect. It has made it slightly smoother I think, and it has affected the gear changes. When the car changes gear it has to adjust the throttle exactly to create a smooth change and if the sensors are slightly out the torque might not quite be what it's expecting so it gets slightly jerky or the transmission slows the changes down to avoid the jerk. Shifts were better after cleaning and with less of no break in power delivery.
No worries mate, here’s a post I did with loads of setup info etc on a Vito Facebook group
Cheers for that group link, they seem a knowledgeable and helpful bunch.
Hadn't realised yours is a 447, mines a face lift 639. App works well with my old elm scanner but doesn't give any dpf info, I'll have a play with the settings and see what happens.
Just a heads up to the OP and anyone on here who has a similar year, Mercedes C, E, or CLS.
Mine went in for its MOT last week and failed as the rear sub frame was corroded both sides, this is a warranty issue as an anti corrosion coating was incorrectly applied by Mercedes, the corrosion guarantee is twenty years so I'd get checking your rear sub frames as they'll go at some point. Mercedes are fixing these ( and mine) free of charge as it's a recognised common issue but I may be waiting for some time as the part is on back order, so carless for a while as Mercedes won't supply a courtesy car except when it's actually in for repair.
Yes, I read about this a couple of weeks ago. It has been serviced by a Merc specialist twice now, and looked at briefly by me, and mine doesn't look bad. But yeah it's not well publicised so good shout.
I don't suppose you have a pic of what to look for do you? Some garages send you pics.
What years are affected?
The garage I had my car serviced and MOTd at ( Stuttgart in Ponty) send their MOTs to the local KwikFit who said the rear sub frame was corroded and had holes both sides, so I took it to Mercedes Cardiff Gate and they inspected and photographed it and got back to me saying they'd repair free of charge ( £2K otherwise), although it was also looked at at the garage I bought it from who, unsurprisingly, said it wasn't too bad.
I don't have any pics unfortunately, Stuttgart said Mercedes will only repair when it reaches the point where it fails an MOT but I'd keep an eye on it, it'll go at some point.
Doomanic Mk2 CLS ran from 2011-2018, it also affects similar year E and C class models.
Hm, I live within walking distance of the Cardiff Gate place, I might ask them to take a look.
(may not apply but when cleaning MAFs, make sure you actually clean the maf. Lots of times people will spray around the housing or whatever but the actual key part is sometimes quite tucked away. I suspect of people who've cleaned it on my car, probably about half totally missed it)
I sprayed into the hole in the white plastic piece in the middle of the airflow. Looks like a Venturi effect sucking air into a little channel with the actual sensor in it.
The quality of the Bluetooth adapter can make a difference. I’ve got a cheap Ebay ELM one and it doesn’t play well with the app.
It’s still the same engine in the 447 as the 639, not sure if the electronics have changed though.
I've had the engine cover off today so I have a part number to search for. Yay.
The prices seem to range from €88 for a LÖWE from Germany to £250 for a MEAT & DORIA from Autodoc.
A complete batwing is £900...
Or £178 on eBay...
The nearside MAF and surrounding area is covered in dirt and oil, while the offside is clean. As the dipstick is right there it's possible it's spill from the last oil change. I'd post a pic if the forum wasn't so effing ackward.
Hmm, a possible source of contamination.
I tried to search for a sensor for your car on Autodoc, but it didn't come up with a brand I recognised for the car.
Definitely give Merc a ring and ask for their price.
Here's the Bosch part number; 0281002955
I’d post a pic if the forum wasn’t so effing ackward.
I can post it if you WhatsApp it too me.
Check your PCV diaphragm, they do go hard and could be the reason for the gunk
https://forums.mbclub.co.uk/threads/w211-om642-turbo-intake.260524/
Its on the other side of the engine. PCV is offside up near the front shock mount .
Worth checking as failure leads to even more crankcase gas going through the turbine and intercooler.
You need 4 x flat blades, like a junior haksaw blade to lift the tongues over the wedges and it pops open
This is also a reason for the earlier than recommend air filters change. Blocked filter will cause more neg pressure and potentialy increase the pcv blow by.
20 min job to remove, clean, replace.
Looking at those mafs, it appears they are individually replacable. But im not 100% sure, as there's 5 years between ours they might have changed the batwing desigb do the electrics can be removed
The pictures of parts on Autodoc look like they are individual components not integral to the batwing.
They are available to buy separately, just not sure how easy they are to remove from the flexible fitting. I had a brief try yesterday and they seem seem pretty firmly attached and there doesn't appear to be a clamp to undo.
Hm, strange, on mine the MAF housing is bolted to the air filter box and there's a jubilee clip holding on the hose that goes to the turbo. Apparently not on yours though:
If I were you I'd remove the batwing, spray loads of MAF cleaner in the hole in the sensor itself then refit and hope. Also, given the potential cost, you need to find out what the normal readings should be. However, if they both go into the same turbo, then there's no way they should be different as far as I can see.
If they are available separately there ought to be a way to remove. I'd probably do what that guy does and have a go at it. If you break it, then you still need a new batwing anyway.
The air filters are different. One has a black plastic matrix and blanked off area. Christ knows why. Emissions or to create a suction, turbulence, or some other reason
Hmm, I see. I read that each bank could throttle differently to create more turbulence, but then I assumed that didn't apply since I thought each cylinder bank would have its own throttle body.
But if the air filters are different, to add turbulence upstream of the combined airflow, then that's different. That said it seems weird to do that before the turbo as it's hard to imagine how the flow characteristics would be preserved after having been mashed through a turbo - but I guess they know better than I do 🙂
That said, if it's useful, why doesn't every car have two filters? Mine has two ducts at the front, just one is blanked off.
I haven’t read the whole thread so forgive me if this has been covered but have you checked the brakes. A slightly dragging brake will kill your fuel economy. Take it for a run then coast to a stop and feel the callipers and alloys for any excessive heat generated. Can you get the wheels off the ground and check to see how freely they are turning?
I haven’t read the whole thread
I haven't read your whole post, but unless it's something about MAFs it was probably covered in my first post...
Any update....... I'm intrigued!
No updates just yet. I was hoping to get a comparison reading from another 350D but unfortunately the owner's page on FB didn't offer up any volunteers.