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Caravan mileage still sucks
#184923
01/05/09 07:57 PM
01/05/09 07:57 PM
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Joined: Mar 2008
Posts: 293
salem, oregon. usa
elmor
OP
enthusiast
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OP
enthusiast
Joined: Mar 2008
Posts: 293
salem, oregon. usa
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1990 Caravan, 2.5 turbo, automatic. If my 02 sensor was bad, wouldn't I get a code flashing when I check for one? The thing runs perfect, just gets lousy gas mileage. When I rebuilt the head 2 years ago, it got 24 mpg highway, and 18 in town. Now it only gets about 13, or 14 in town ,haven't been able to check highway lately. It still runs pretty strong, no problem breaking the tires loose from a dead stop by just stomping it. Cant find any vacuum leaks, recent tune up. Doesn't show any codes when I checked it. Any ideas?
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Re: Caravan mileage still sucks
[Re: elmor]
#184924
01/05/09 08:03 PM
01/05/09 08:03 PM
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Joined: Jul 2006
Posts: 1,475
Ontario, Canada
78D150CLUB
My avatar is a self portrait!!
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My avatar is a self portrait!!
Joined: Jul 2006
Posts: 1,475
Ontario, Canada
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Check that the turbo is spinning freely. Just went thru the same sort of problem with a turbo diesel loader at work. It was fine one week, and started eating fuel and smoking the next. Journal bearings went south and it bound up, restricting/limiting air flow and causing a rich mixture. With EFI and an O2, it might not be the cause, but ya never know. 
I want to die like my Grampa, peacefully, in his sleep. Not screaming in terror like his passengers.
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Re: Caravan mileage still sucks
[Re: elmor]
#184925
01/05/09 08:17 PM
01/05/09 08:17 PM
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Joined: Jan 2003
Posts: 4,395
The Pale Blue Dot
Skeptic
master
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master
Joined: Jan 2003
Posts: 4,395
The Pale Blue Dot
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Quote:
1990 Caravan, 2.5 turbo, automatic. If my 02 sensor was bad, wouldn't I get a code flashing when I check for one?
Nope, o2 diagnosis is not a priority for that old of a system. Even OBD2 systems can have faulty o2 sensors and not flag a code and they have many potential codes for o2 sensor issues. Since they are cheap and fairly easy to replace that would be my recomendation. Next would be to check cam timing. 
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Re: Caravan mileage still sucks
[Re: elmor]
#184927
01/05/09 08:47 PM
01/05/09 08:47 PM
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Joined: Jul 2006
Posts: 1,475
Ontario, Canada
78D150CLUB
My avatar is a self portrait!!
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My avatar is a self portrait!!
Joined: Jul 2006
Posts: 1,475
Ontario, Canada
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If the seal were still intact, it shouldn't. Maybe a small amount, not major leaks. The oil should just flow past the journal to the drain as usual.
Don't quote me on that, though. I've had some experience with diesel turbos in loader engines, but not an expert by any stretch of the imagination.
Feets would likely know for sure on something like that.
I want to die like my Grampa, peacefully, in his sleep. Not screaming in terror like his passengers.
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