20L / 100km!?

  #1  
Old 06-23-2019, 02:18 AM
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Default 20L / 100km!?

Hey guys,

Now I've replaced the odometer gear (25 tooth gear) on the auto '92 240 GLE wagon I can calculate fuel consumption.
I used E10 fuel and got 211km from 46L!

This tells me one of 2 things:
1) the odometer gear is severely over-geared (which I will check with GPS next time I take a decent length drive
2) something is severely wrong with the car

I don't drive like Colin McCrea on the streets and its a stock car.
I take short trips (which may contribute to higher fuel consumption)

Where and what should I be looking at to change this insane figure?

Cheers,
Cris
 
  #2  
Old 06-23-2019, 02:32 AM
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I'd verify your speedometer readings. if you have a android device that has a GPS in it, get the app 'gps status' free from the google play store. fire up that app and drive in a straight line at a steady speed, compare what it says with what your speedo says. note the GPS speed will lag several seconds behind changes in your actual speed.

you're getting 11-12 US MPG, which is way worse than awful, I doubt I ever got much below 18 US MPG average (13 l/100km) lead footing around town all day. short trips *are* bad but no way they should be that bad. on the open highway, a long run at a steady 65MPH (a bit over 100 km/h), you should get about 26-28 MPG, which is 8.5 - 9 l/100km.

things that can really knock your gas mileage down include non-functional coolant temp sensor, but these should throw check engine lights, and show an error code on the LH2.4 diagnostic block, assuming you have one. guessing because you're using metric, you're not in the USA.
 
  #3  
Old 06-25-2019, 07:06 AM
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So yeah - gps confirms the odometer is correct.

What should i be looking at to improve this fuel economy?
 
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Old 06-25-2019, 01:49 PM
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well, if the mileage is that bad, it must be running really rich...

any blink codes on pin 3 or 6 of the diagnostic block?
 
  #5  
Old 06-25-2019, 02:07 PM
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you could pull a spark plug.. see what condition it is in...
 
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Old 06-25-2019, 06:01 PM
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Originally Posted by silvermine View Post
you could pull a spark plug.. see what condition it is in...

Plugs looked ok.
Granted - I only pulled out CYL 1 to have a look - but I have a spare set ready to go in.
I may look at all of them and see what they look like and just replace them





lugs
 
  #7  
Old 06-25-2019, 06:03 PM
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Originally Posted by pierce View Post
well, if the mileage is that bad, it must be running really rich...

any blink codes on pin 3 or 6 of the diagnostic block?
Long shot here - but could the flap on the air filter box be stuck open?
Sucking hot air from the exhaust manifold for cold start?

"any blink codes on pin 3 or 6 of the diagnostic block?"
I'm not sure what you mean here.
Could you explain this please?
 
  #8  
Old 06-25-2019, 08:48 PM
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1989+ B230F and 1990+ B230FT have a diagnostic block under the hood, its near the left hand steering hump, has a plastic cover, and under the cover there's a pushbutton, an LED, 8 jumper holes, and a jumper wire. you plug the wire into hole 2 to read codes from the ECU (fuel injection) and hole 6 to read codes from the ICU (ignition control).

Engine and OBD Diagnostic Codes

mostly you want to do DTM1 in both 2 and 6. plug wire into position 2, turn ignition on without starting engine, press the button for 3 seonds, release it, and count the blinks. if you get anything other than 1-1-1, then press it again for 3 seconds to get another code til you see the first code again. repeat this process with the wire plugged into position 6.
 
  #9  
Old 06-28-2019, 08:52 AM
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you could also check for any cracks in the accordian hose that goes to the intake after the MAFS.
 
  #10  
Old 06-29-2019, 09:54 PM
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Originally Posted by pierce View Post
1989+ B230F and 1990+ B230FT have a diagnostic block under the hood, its near the left hand steering hump, has a plastic cover, and under the cover there's a pushbutton, an LED, 8 jumper holes, and a jumper wire. you plug the wire into hole 2 to read codes from the ECU (fuel injection) and hole 6 to read codes from the ICU (ignition control).

Engine and OBD Diagnostic Codes

mostly you want to do DTM1 in both 2 and 6. plug wire into position 2, turn ignition on without starting engine, press the button for 3 seonds, release it, and count the blinks. if you get anything other than 1-1-1, then press it again for 3 seconds to get another code til you see the first code again. repeat this process with the wire plugged into position 6.
Just when I couldn't love this car more - I find out it can do this!

All clear of Fault codes in pins 2 & 6.
I threw a new set of plugs at it - it runs smoother and confirmed the odometer is running correct over a distance of 20km.

Let's see how this next tank of fuel goes.
 
  #11  
Old 06-29-2019, 10:05 PM
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Originally Posted by silvermine View Post
you could also check for any cracks in the accordian hose that goes to the intake after the MAFS.
I did do a bodgey fix with electrical tape - will check this too.
 
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Old 07-06-2019, 01:07 PM
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Originally Posted by Slo240 View Post
I did do a bodgey fix with electrical tape - will check this too.

yeah, that won't cut it, *any* pinhole sized airleak downstream from the MAF will mess up low RPM operation
 
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Old 07-06-2019, 05:15 PM
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Originally Posted by pierce View Post
yeah, that won't cut it, *any* pinhole sized airleak downstream from the MAF will mess up low RPM operation
Hmmmm. Does explain a bit of a rough idle when cold. But this would me the mixture would be running lean - not rich. Doesn’t really explain high fuel consumption.
 
  #14  
Old 07-07-2019, 06:40 AM
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If you are running rich, check for exhaust leaks upstream the oxygen sensor. Any upstream the sensor let in clean air which is sensed by the ECU as a lean condition causing it to enrich the mixture.
 
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Old 07-07-2019, 06:42 PM
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Originally Posted by act1292 View Post
If you are running rich, check for exhaust leaks upstream the oxygen sensor. Any upstream the sensor let in clean air which is sensed by the ECU as a lean condition causing it to enrich the mixture.
Very nice.

This sounds like it has legs.

I'll get under it this weekend when I service the transmission and have squiz.

Thanks mate.
 
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