Author Topic: Poor mileage help  (Read 221 times)

January 29, 2020, 07:22:01 am

old_man

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Poor mileage help
« on: January 29, 2020, 07:22:01 am »
Good day,

I have a 1.6TD JX that resides in a single cab vanagon. My latest mileage was 11.25L/100km. I know it should be better than that, I was expecting more along the 8L/100km

What I have done so far:
-New timing belt and set timing for 1.00mm
-Cold start was cable incorrectly installed/jammed on. I fixed that and reset timing for 1.00mm.
-Ran some diesel purge through it.
-New fuel fliter
- Increased boost, max is now around 15psi. I did this to try to keep my EGTs under control. I can easily exceed 1500 in 4th gear with little effort. I don't know if that is normal for a vanagon or if that is a problem that is related to my mileage issues.
I checked the pressure regulating bolt to see if it was jammed but it is not.

I haven't touched the fuel screw, it still has a metal band around it. There is no black smoke ever.
There is a clear supply fuel line and no bubbles present. The return line is not clear.


What's left? Bad pump, bad injectors, or tired engine?

I keep reading about checking the pump pressure but all information leads to a thread on a now defunct website.
« Last Edit: January 29, 2020, 07:25:09 am by old_man »



Reply #1January 29, 2020, 03:41:02 pm

libbydiesel

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Re: Poor mileage help
« Reply #1 on: January 29, 2020, 03:41:02 pm »
Hi old_man.  I'm actually ?Waldo? on the Samba.  11.25L/100KM is 20.9 miles per US gallon.  One thing to note is that winterized fuel gets worse fuel economy by 5-10%.  Higher viscosity due to cold weather will also negatively affect overall fuel economy especially from shorter drives.  Your 20.1 MPG in the winter might turn into 22+ in the summer without any other changes.  IMO, that is still worse that normal.  8L/100KM (29MPG) is better than I have typically seen with a 1.6TD in a Vanagon although within the realm of reason.  Round trip no wind highway cruising @ 70MPH with everything in good condition, I typically saw 27MPG with the 1.6TD.  That would be in a pop-top camper or high top.  A tin top would do better.  I am not sure how significant the truck body is to that equation.  A TDI will typically do better for fuel economy and power as well. 

I am not sure what you mean by pressure regulating bolt.  Do you mean the pressure regulator?  It is threaded into the pump case, but is not a bolt.  The business end is a plunger and spring and the adjustable side is a pressed plug. 

Injectors could be affecting the fuel economy as could a tired engine.  It wouldn't be a bad idea to have the nozzles replaced and the injectors calibrated.  A compression check wouldn't be a bad idea either.  As far as other things that can affect fuel economy, there are lots.  Here's a non-exhaustive list: low tire pressure, bad tire alignment, imbalanced tire, bent rim, bad CV joints, sticking brakes, worn wheel bearings, incorrect temperature or non-functioning thermostat.  I'm sure there's more I haven't thought of. 
Use, abuse or ignorance of any information is at your own risk, confirmation or refutation is your own responsibility, no further 'proof' will be given, take it or leave it, YMMV,terms subject to change without notice, avoid contact with eyes or skin, contents known to cause cancer in California

Reply #2January 29, 2020, 05:44:45 pm

old_man

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Re: Poor mileage help
« Reply #2 on: January 29, 2020, 05:44:45 pm »
Hi old_man.  I'm actually ?Waldo? on the Samba.  11.25L/100KM is 20.9 miles per US gallon.  One thing to note is that winterized fuel gets worse fuel economy by 5-10%.  Higher viscosity due to cold weather will also negatively affect overall fuel economy especially from shorter drives.  Your 20.1 MPG in the winter might turn into 22+ in the summer without any other changes.  IMO, that is still worse that normal.  8L/100KM (29MPG) is better than I have typically seen with a 1.6TD in a Vanagon although within the realm of reason.  Round trip no wind highway cruising @ 70MPH with everything in good condition, I typically saw 27MPG with the 1.6TD.  That would be in a pop-top camper or high top.  A tin top would do better.  I am not sure how significant the truck body is to that equation.  A TDI will typically do better for fuel economy and power as well. 


I am not sure what you mean by pressure regulating bolt.  Do you mean the pressure regulator?  It is threaded into the pump case, but is not a bolt.  The business end is a plunger and spring and the adjustable side is a pressed plug. 

Injectors could be affecting the fuel economy as could a tired engine.  It wouldn't be a bad idea to have the nozzles replaced and the injectors calibrated.  A compression check wouldn't be a bad idea either.  As far as other things that can affect fuel economy, there are lots.  Here's a non-exhaustive list: low tire pressure, bad tire alignment, imbalanced tire, bent rim, bad CV joints, sticking brakes, worn wheel bearings, incorrect temperature or non-functioning thermostat.  I'm sure there's more I haven't thought of.

Hey, I recognize you. Yes, I did mean the pressure regulator. I took it out to inspect it and make sure it was clean and clear. It was. Don't know if it ever needs to be adjusted. I talked today to a local diesel injector shop about cleaning/testing the injectors. It will be pricey but maybe I should do it regardless. It's either that or get my own pop tester but this might be one of the rare times it's best to let some pros do it.

Bearings and brakes don't seem to drag. I repacked the CV joints not too long ago, I suppose I could IR temp them after a highway drive to see if any are hotter than the others. Thermostat appears to be functioning, needle goes to the middle of the LED and stays there, warms up quickly. I removed those salt bags from the rear that I was using as ballast for snow traction, maybe it will make a considerable difference. The only other thing I haven't really investigated is my tire pressure setting. I will research this further. 

I'm not out to lunch am I, this is the right TDC mark right?



Reply #3January 29, 2020, 07:05:51 pm

libbydiesel

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Re: Poor mileage help
« Reply #3 on: January 29, 2020, 07:05:51 pm »
That is the correct TDC mark. 
Use, abuse or ignorance of any information is at your own risk, confirmation or refutation is your own responsibility, no further 'proof' will be given, take it or leave it, YMMV,terms subject to change without notice, avoid contact with eyes or skin, contents known to cause cancer in California