# More clean injectors = more consumption?

• posted on May 23, 2004, 6:55 pm
My car: 190 D 2.5 1987.
Since I got the car in feb. 2004 I have driven 12.000 kilometers and changed oil 4 times and added fuel additive to clean injectors such as Redex diesel
fuel treatment.
Does the car now use more fuel or is it the same or does it even use less?
Is the fuel intake controlled somehow i.e. it only intakes so much no matter how clean/dirty it is (injectors)?
The car is much more responsive since my first ride in it.
Regards Niels Reinwald
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• posted on May 23, 2004, 7:14 pm
Probably less since you got more power and uses less acceleration to achieve or maintain same speed.
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• posted on May 23, 2004, 7:41 pm

Can you do 2nd grade math?
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<%-name%>
• posted on May 23, 2004, 8:41 pm

You make your own fun. Since more power it seems would equal higher fuel consumtion - but maybe not - boolean algebra, that is.
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• posted on May 24, 2004, 12:38 am

Fuel consumption = miles driven / gallons used. Always has been. Always will be. 2nd grade math.
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• posted on May 24, 2004, 7:43 am

Thank you. I will do just that on my next fill up and press the miles-counter and fill up once nearly emty and do the math - which I also did shortly after my purchase of this mb. I had 15 km/l before and my guess is now 17-18 km/l. I just wondered and asked because maybe there was someone who knew how the engine consumed fuel when injctors are stuffed with carbon or clean top notch clean.
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<%-name%>
• posted on May 23, 2004, 7:44 pm
Clean injectors will keep the spray pattern as it was designed to be. As a result, your fuel mileage will be better and the chances of a cylinder miss-firing will be less.

changed
diesel
matter
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<%-name%>
• posted on May 23, 2004, 11:56 pm

The injectors are designed to put out an optimum spray pattern that will result in the efficient burning of fuel.
If the spray pattern changes due to wear in the mechanical parts of the injector, the fuel will burn less efficiently, so you will start using more right foot than you should to get the desired effect.
Additives in the fuel, such as the Red-ex diesel additive you speak of, will only dissipate carbon build-up but will do nothing to cure mechanical wear. If you suspect that your injectors are not doing what they should, then lift them out and take them to a specialist injection shop, where they will be brought back to new and re- calibrated. While they are out, and before you get them fixed, get the cylinders compression-tested.
An indication that the injectors are not performing as they should will normally show in the exhaust output. If there is black smoke in your rear-view mirror when you are flooring it, then there is incorrect combustion.
Take the injectors out and get the cylinders compression-tested. If the compression in the cylinders is up to scratch then the problem is more than probably the injectors. If the compression test gives very low readings, then your engine is buggered, and you may as well forget about the injectors, as you are looking at a replacement engine or a re-build.
--
All the best,
Stubbsy.
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• posted on May 24, 2004, 7:32 am

Thanks. No black smoke from the exhaust. After treetment with redex and oilchanges I can now go in 4. gear (aut.) uphill places where it would shift down to 3. So the carbon-dirt seems to have gone. It is probably due to the fact that the engine has hight torqe now and runs alot better. An engine like this 190 D 2.5 should easyly run without beeing buggered for a very long time. When I had the topgasket off there was no noticeable ware and the crankshaft looked fine as well as the valvelifters. The injectors did look dirty but since the topgasket was broken and oil from cylinder 1 was pouring into the coolant it surely made a vast inpact. New gasket is now fitted and engine has a change now to work and burnout carbon.
I belive buying a secondhand car is ok but one never knows what the others guys having did or did not do. Listening to the car nok since my first drive in it is very different. Noise is much less. As I mentioned to the previous owner: "It sounds a bit like an old tractor". He smiled. Now it sounds much more like a Mercedes and I can barely hear the engine run and only hear the tires as I believe a mb should sound like. So my advise is that a good cleanout of the engine with lots of oilchanges and additives to clean out the carbon and some hight revs. burst are worth it. A diesel engine is suppose to run for hours and hours and that is why I purchased this mb. I would not have gotten a diesel if I was not travelling many kilometers this summer down through Europe. Running this mb 190 D 2.5 at 110-130 km/h down he highway makes the engine sound like that is the speed (torqe) it likes.
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<%-name%>
• posted on May 24, 2004, 8:59 am
On Sun, 23 May 2004 20:55:10 +0200, "Niels Ulrik Reinwald dgdf" wrote:

You could do far worse than getting it put onto an exhaust gas analyser and having it set up so you know that it is fueling as best as it can. The injector cleaner is a good move, as it is about getting your car to run as efficiently as it can. Obviously clean injectors sporting an even spray cone is the thing you want here.
I think you are getting slightly mixed up with regards to fuel efficiency and fuel consumption. 300 Essie
--
1994 Mercedes E280 [W124] 99,000 miles (R.I.P)
1992 Mercedes 300 SE [W126] 230,000 miles
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<%-name%>
• posted on May 24, 2004, 1:51 pm

Ok, I see. I also just made an adjustment to the fuel pedal linkage making the aut. shift much more smoothly and the sound I heard before seems to have gone. A slight "thu thu thu..." sound. Maybe the gear-ration is better now with the fuel-linkage. It feels more like a mb aut. shift now. Smooth.
Regards, Niels