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  #1  
Old 12-01-2019, 02:01 PM
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Om606 turbo low city mpg

I’m getting some lousy mpg around town in my 99 e300. I resealed the fuel system, it has no leaks. No dragging brakes, no bad wheel bearings. I’m getting 17.5-18mpg around town. 221k. Original injectors. Well maintained car. Does sound a bit clattery even after it’s warmed up. Makes good power little smoke.

I do a lot of short trips making sure it gets up to temp. With my now job, I work about a mile away from home, so all in all weekly I’ve got a 10-15 mile radius. Is it possible that’s why it gets such low mpg city? I’ve had a few of these and remember better mpg. I use quality fuel too.

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Old 12-01-2019, 06:24 PM
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That's crazy, but sounds about right. My brother's E320 when driven extremely short distances would get 10mpg to 16mpg.

Lowest I have seen was 9 mpg.
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  #3  
Old 12-01-2019, 08:07 PM
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How are you measuring MPG? 17.5-18mpg is HORRIBLE fuel economy, even my 3.4L doesn't do that bad - and that's with my lead foot from all the stops!
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  #4  
Old 12-01-2019, 08:14 PM
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Originally Posted by Diseasel300 View Post
How are you measuring MPG? 17.5-18mpg is HORRIBLE fuel economy, even my 3.4L doesn't do that bad - and that's with my lead foot from all the stops!
Usually measuring what I get from about between 3/4 to 1/4 tank. At an 18 gallon tank those marks are roughly 4.5 gallons. So I’m calculating miles on the tachometer divided by how many gallons it takes me to get up where tank was at when I last filled it.

I agree it’s AWFUL fuel economy. So I’m trying to figure out if it’s the injectors or what.
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Old 12-01-2019, 08:20 PM
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Your measuring method leaves a lot to be desired. Brim the tank (fill until the pump handle clicks at least twice). Reset the trip odometer to 0. Drive until you refill with fuel. Brim the tank again (until the handle clicks at least twice). Divide miles on trip odometer by number of gallons inserted into tank. That is the *ONLY* way you're going to get any sort of reliable measurement. Going by marks on the fuel level gauge is never going to be even close to accurate.
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  #6  
Old 12-01-2019, 09:10 PM
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Mine mostly got 21-22 with city and heavy traffic freeway driving, I don't think there was anything wrong with it because I could get 28 on the highway still on a long trip.
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  #7  
Old 12-01-2019, 09:17 PM
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Quote:
Originally Posted by Diseasel300 View Post
Your measuring method leaves a lot to be desired. Brim the tank (fill until the pump handle clicks at least twice). Reset the trip odometer to 0. Drive until you refill with fuel. Brim the tank again (until the handle clicks at least twice). Divide miles on trip odometer by number of gallons inserted into tank. That is the *ONLY* way you're going to get any sort of reliable measurement. Going by marks on the fuel level gauge is never going to be even close to accurate.
I agree with the part about how to measure mileage.

I disagree mildly about what mileage around town is reasonable to expect. I'd expect no more than high teens and low twenties .
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Old 12-01-2019, 10:39 PM
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Originally Posted by t walgamuth View Post
I disagree mildly about what mileage around town is reasonable to expect. I'd expect no more than high teens and low twenties .
My 3.0L 603 turbo 300SDL never did worse than ~20mpg in stop/go city traffic and I live in a hilly area.
My current 3.4L 603 turbo 350SD easily does 21-22mpg in the same traffic conditions, I've yet to ever see it return an mpg value less than 20mpg.
Keep in mind the 126 is bigger, heavier, less powerful/efficient, has fewer gears in the trans, no lockup torque converter, and no electronics to fiddle with fuel delivery or power. I'd expect the lighter, better performing, better breathing, better controlled OM606 powered car to do at least as good. I *DO NOT* drive my cars easy, it's pretty much foot to floor from every stop light (that 3.4L torque is addictive), so don't think I'm hyper-miling either.
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  #9  
Old 12-01-2019, 10:43 PM
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Originally Posted by jake12tech View Post
I work about a mile away from home,
Walk or get a bike.
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  #10  
Old 12-02-2019, 12:07 AM
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The oil drag is too signifigant to ignore. Especially on trips that short with the cold oil. I would be surprised if you are even getting what you think you are.

I leave the dash indicator on all the time in the wives diesel. It indicates a very high burn rate per 100 miles for the first mile or two. I can assure you that the synthetic oil seems to be dragging to some extent. Or the engine is just cold and requires more fuel to function.

On really cold mornings never expect a 240d for example to have any real usable power until the oil drag reduces. Even with a gas car your cold start injector may not be totally off on a one mile trip.

Really mechanical cars are not designed for the service you are using your car for. Yet we do this at times. I suspect this would be considered really severe service.

At least give the car a decent run once a week or you may have undesirable components accumulating in the oil. Like condensation and diesel fuel.

Also the engine will not even reach expected operational temperatures coollant wise. If I had no other choice than to use a car in this fashion I would use a timer with a block heater. Your distance between work and home is really both too short and too frequent. Remember it is claimed that most wear occurs on cold engines.

On days with reasonable weather I might consider a bicycle or just walking.
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  #11  
Old 12-02-2019, 08:02 PM
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Originally Posted by barry12345 View Post
The oil drag is too signifigant to ignore. Especially on trips that short with the cold oil. I would be surprised if you are even getting what you think you are.

I leave the dash indicator on all the time in the wives diesel. It indicates a very high burn rate per 100 miles for the first mile or two. I can assure you that the synthetic oil seems to be dragging to some extent. Or the engine is just cold and requires more fuel to function.

On really cold mornings never expect a 240d for example to have any real usable power until the oil drag reduces. Even with a gas car your cold start injector may not be totally off on a one mile trip.

Really mechanical cars are not designed for the service you are using your car for. Yet we do this at times. I suspect this would be considered really severe service.

At least give the car a decent run once a week or you may have undesirable components accumulating in the oil. Like condensation and diesel fuel.

Also the engine will not even reach expected operational temperatures coollant wise. If I had no other choice than to use a car in this fashion I would use a timer with a block heater. Your distance between work and home is really both too short and too frequent. Remember it is claimed that most wear occurs on cold engines.

On days with reasonable weather I might consider a bicycle or just walking.
I agree I need to drive it more. I do however warm it up before I drive it and let it get to full OP temp on the coolant gauge before I shut it off. But Iím thinking the idling isnít good, and I really need to run it down the highway at 70 once a week.
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Old 12-03-2019, 12:17 AM
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On a mile trip if I warmed the engine up for a minute at the end of a mile my engine would not have made normal operating them yet. If the Engine is not up to temp part the energy from combustion is going to warm up the coolant and not burning as well and that energy is not going to the Wheels.

Then there is Winter Fuel which gets poorer mileage.

I would also be suspicious of 221k original injectors. I would gestimate that at 100-125k the Injector Nozzles would be at the end of their life and that the Pop/Opening Pressures would be off.

Once in awhile you need to take the Car for a hour run on the freeway (when it is open to traffic). Short short trips you spoke of can cause sticky piston rings.
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Old 12-19-2019, 05:36 PM
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Car hits OP temp on the coolant gauge before I arrive. I warm up 3-5 min before driving. Two tanks 18.1 mpg. I drive it around 20 min after work. Full tanks brimmed as suggested. ***** MPG. Sending injectors out.
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  #14  
Old 12-20-2019, 02:14 PM
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That is very odd, I've topped 38mpg on my 1997 E300.

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1992 Mercedes 300D 2.5 202,000 - Pure junk
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Don't forget to grease the screw and threads on the spring compressor.
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