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OldBlueSyncro
Samba Member
Joined: April 24, 2018
Posts: 206
Location: British Columbia
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 Posted: Thu Dec 20, 2018 6:50 pm Post subject: Terrible, atrocious, pitiful fuel economy... [SOLVED] |
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87 syncro with 2.1
I just filled up my tank after work, in preparation for our drive home tomorrow for Christmas.
It was my first tank after fixing my odometer. It hadn't worked since I got the van on the road in October. I've been just driving to work and back, and a bit of driving around town.
I calculated out my mpg's and got 7.5mpg! What?! Itll cost like $450-500 to get home, plus a $80 ferry on top of that. I dont know if we can take the vam if itll cost that much. Havent told the girlfriend yet.
It's been cold up here so I've been idling the van in the morning for like 15-20 minutes before leaving for work. Theres no o2 sensor thanks to the previous owner, and the tps is pretty worn so it idles high at red lights a lot of the time. Could all this really create such terrible fuel economy? I have a new tps on route to my parents place and I was going to use my dads welder to weld an o2 bung into the exhaust and get an o2 sensor in there. But that's all after the 1300km drive.
I cant imagine the fuel economy will be much better on the highway.
SOLUTION: Poor mpg caused by lack of o2 sensor and short driving distances not allowing engine to warm to optimal temps.
Last edited by OldBlueSyncro on Wed Mar 06, 2019 11:38 am; edited 1 time in total |
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?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Thu Dec 20, 2018 7:03 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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Automatic or manual trans?
FYI, extended idling like that is one of the worst things you can do to your engine, just saying. A coolant heater would have all the benefits of quick heat without the downside of damaging your engine. |
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OldBlueSyncro
Samba Member
Joined: April 24, 2018
Posts: 206
Location: British Columbia
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| Posted: Thu Dec 20, 2018 7:06 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| ?Waldo? wrote: |
Automatic or manual trans?
FYI, extended idling like that is one of the worst things you can do to your engine, just saying. A coolant heater would have all the benefits of quick heat without the downside of damaging your engine. |
Manual trans
Any recommendations on a coolant heater? |
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[email protected]
Samba Member
Joined: April 29, 2015
Posts: 704
Location: Berkeley Ca
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| Posted: Thu Dec 20, 2018 7:09 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| Something is wrong for sure. Do the easy stuff first. |
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OldBlueSyncro
Samba Member
Joined: April 24, 2018
Posts: 206
Location: British Columbia
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| Posted: Thu Dec 20, 2018 7:10 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| ?Waldo? wrote: |
Automatic or manual trans?
FYI, extended idling like that is one of the worst things you can do to your engine, just saying. A coolant heater would have all the benefits of quick heat without the downside of damaging your engine. |
I've considered getting one of those magnetic heaters and attaching it to the block or H-pipe |
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bobbyblack 
Samba Member
Joined: May 21, 2015
Posts: 4349
Location: United States, Iowa
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| Posted: Thu Dec 20, 2018 7:14 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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Not a chance that idling for 15 minutes would drain your tank that much.
Take a sniff of the tailpipe fumes. I'm guessing if you stick your finger in there too, you'd find BLACK soot. Way rich.
The TPS isn't it either. Not that it won't help some, but not 10+MPG, no way.
How does the power output feel? I mean, you've driven a 2.1 in a Vanagon before, I'd imagine?
I'd say, maybe check to see you've got your AFM hooked up, that you are firing on all cylinders, and that your dizzy advance isn't super out of wack.
I'm not sure why your O2 would have been deleted, that's NOT good, IMHO. But, 10 MPG hit for the 02? I guess possible.
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'87 Westy 'Flossie','86 Westy 'R1','86 tintop GL - Subi2.2 'J2','83.5 stock tintop L 'ZoomBus','74 Karmann Ghia, '63 Notch |
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wcdennis
Samba Member
Joined: July 20, 2004
Posts: 955
Location: Winston-Salem NC
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| Posted: Thu Dec 20, 2018 7:16 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| The O2 sensor is a pretty important part of the fuel injection system. The computer uses the O2 readings to constantly trim the fuel/air mix. I'm not sure how much your mileage would improve with one installed, but it couldn't possibly make it worse. |
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wcdennis
Samba Member
Joined: July 20, 2004
Posts: 955
Location: Winston-Salem NC
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| Posted: Thu Dec 20, 2018 7:23 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| Also, keep in mind that short trips in cold weather are the worse MPG situations. You should do a longer run so the van gets fully warmed up and use a GPS to determine actual milage, your odometer may not be exactly accurate. |
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OldBlueSyncro
Samba Member
Joined: April 24, 2018
Posts: 206
Location: British Columbia
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| Posted: Thu Dec 20, 2018 7:25 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| bobbyblack wrote: |
Not a chance that idling for 15 minutes would drain your tank that much.
Take a sniff of the tailpipe fumes. I'm guessing if you stick your finger in there too, you'd find BLACK soot. Way rich.
The TPS isn't it either. Not that it won't help some, but not 10+MPG, no way.
How does the power output feel? I mean, you've driven a 2.1 in a Vanagon before, I'd imagine?
I'd say, maybe check to see you've got your AFM hooked up, that you are firing on all cylinders, and that your dizzy advance isn't super out of wack.
I'm not sure why your O2 would have been deleted, that's NOT good, IMHO. But, 10 MPG hit for the 02? I guess possible. |
Never driven a 2.1 or even a vanagon before this one. It accelerates and has the power of what I'd expect an engine of this size to push around something this big. AFM is hooked up but the ground strap on it is quite old looking. That's another thing on the list of things to do.
The previous owner removed the stock exhaust system and installed some grumbly muffler. Theres no cat on it either. |
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szegedin7
Samba Member
Joined: April 03, 2017
Posts: 117
Location: Southern California
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| Posted: Thu Dec 20, 2018 7:25 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| wcdennis wrote: |
| The O2 sensor is a pretty important part of the fuel injection system. The computer uses the O2 readings to constantly trim the fuel/air mix. I'm not sure how much your mileage would improve with one installed, but it couldn't possibly make it worse. |
I had my o2 sensor out for a while, and mileage was significantly worse. I get about 15mpg in city driving on a good day with it in there, so my ballpark estimate would be that it running full rich all the time gets you about 10-12mpg. Just my experience, probably other factors.
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dobryan
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Joined: March 24, 2006
Posts: 16503
Location: Brookeville, MD
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OldBlueSyncro
Samba Member
Joined: April 24, 2018
Posts: 206
Location: British Columbia
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| Posted: Thu Dec 20, 2018 7:35 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| dobryan wrote: |
| O2 sensor is important for efficiency. |
Could it really cause my fuel economy to be this bad though? |
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dobryan
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Location: Brookeville, MD
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AZ Landshaper
Samba Member
Joined: February 08, 2009
Posts: 1698
Location: The Old Pueblo
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| Posted: Thu Dec 20, 2018 7:45 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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your no doubt running in open loop all the time. 10 mpg from a vehicle typically delivering 15-17 is prob whats to be expected. certainly not much better. in concert with old plugs other oddities. sure 7.5 isnt that crazy
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dobryan
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bobbyblack
Samba Member
Joined: May 21, 2015
Posts: 4349
Location: United States, Iowa
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| Posted: Thu Dec 20, 2018 7:48 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| OldBlueSyncro wrote: |
| The previous owner removed the stock exhaust system and installed some grumbly muffler. Theres no cat on it either. |
Hmm, sounds like an interesting situation. Find a used stock exhaust and reattach the O2. Take your sweetheart on the trip in a more efficient ride, if possible. Save the gas money, I'd guess a used but good enough exhaust would pay for itself in that gas $ difference... Of course, Syncro exhaust is a tad bit different, so that is probably why the PO did what they did. ??
PS. I used to want a Syncro.
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'87 Westy 'Flossie','86 Westy 'R1','86 tintop GL - Subi2.2 'J2','83.5 stock tintop L 'ZoomBus','74 Karmann Ghia, '63 Notch |
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OldBlueSyncro
Samba Member
Joined: April 24, 2018
Posts: 206
Location: British Columbia
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| Posted: Thu Dec 20, 2018 7:53 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| dobryan wrote: |
| Also does it ever warm up? If the thermostat is stuck open and keeping the engine too cool the fuel consumption will be more. |
Actually it doesnt ever seem to warm up entirely now that you say that. The needle never reaches the led. I just assumed it was from the cold weather and all the plumbing that's in these things. |
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0to60in6min
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Joined: November 27, 2006
Posts: 3416
Location: OR & CA (Oregon/California)
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| Posted: Thu Dec 20, 2018 8:25 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| is the AFM well connected and functioning? |
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sethpat
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Joined: March 02, 2017
Posts: 134
Location: Orlando
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| Posted: Thu Dec 20, 2018 8:44 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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I just finished a trip from Orlando to the Boone area of NC and my average fuel economy was about 16.1 mpg while running on the highway between 3400 and 3600 RPM. Occasionally I would creep up to 3800 because it easily wanted to, but I would bring it back down unless I was passing someone. This is in my loaded down Syncro with the 2.1.
In my experience the waterboxer, wasserboxer, or whatever you'd like to call it, is quite particular. I would try and source a stock exhaust system and also verify that your AFM is functioning properly. This can be done with a multimeter and a quick search.
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bobbyblack
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Posts: 4349
Location: United States, Iowa
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| Posted: Thu Dec 20, 2018 9:14 pm Post subject: Re: Terrible, atrocious, pitiful fuel economy... |
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| OldBlueSyncro wrote: |
Actually it doesnt ever seem to warm up entirely now that you say that. The needle never reaches the led. I just assumed it was from the cold weather and all the plumbing that's in these things. |
I've got a digital temp gauge and it reflects the stock analog needle as I would expect. Also, mine doesn't get warmer than half way to the LED, and around 150F max on a 20 minute drive city/highway mix. Been in the high 20's at those conditions. Front heater seems to be wimpy, too. Rear heater seemed like usual.
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