92 Civic VX poor mileage code 12, 48
09-05-2013, 09:49 AM
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92 Civic VX poor mileage code 12, 48
92 VX w/ 300,000 miles.
Still getting Codes 12 (EGR valve lift) and 48 (LAF) not having attempted to fix, just some more clue gatherng. The EGR killed the idle when I applied vacuum to it from an external source, so I think the valve is opening and the passages are not clogged (completely.)
Tires are 175/70-13, inflated 35/32 (lbs f/r) and the revs per mile adjustment factor (from tire tables and actual observation) is 0.975.
The first tank of gas, driving with spirit, not conscious of keeping revs down, and using the A/C judiciously, I got 37.33 mpg indicated (adjusted to 36.39).
Second tank, nursing it as much as possible, no A/C (yikes!), upshifting at 2000 rpm, cruising no higher than 2000 rpm (~60 mph in 5th), I got 39.636 indicated (adjusted to 38.66.)
Note: In addition to > 300k miles on the big clock, I live in Reno at 4700 feet, with all surrounding passes considerably higher. There simply is less oxygen up here, and fuel efficiency (and power) does suffer somewhat.
If the EGR valve seems to work, and passages are not clogged, does the Code 12 implicate the EGR control box? ECU itself?
Brian
Still getting Codes 12 (EGR valve lift) and 48 (LAF) not having attempted to fix, just some more clue gatherng. The EGR killed the idle when I applied vacuum to it from an external source, so I think the valve is opening and the passages are not clogged (completely.)
Tires are 175/70-13, inflated 35/32 (lbs f/r) and the revs per mile adjustment factor (from tire tables and actual observation) is 0.975.
The first tank of gas, driving with spirit, not conscious of keeping revs down, and using the A/C judiciously, I got 37.33 mpg indicated (adjusted to 36.39).
Second tank, nursing it as much as possible, no A/C (yikes!), upshifting at 2000 rpm, cruising no higher than 2000 rpm (~60 mph in 5th), I got 39.636 indicated (adjusted to 38.66.)
Note: In addition to > 300k miles on the big clock, I live in Reno at 4700 feet, with all surrounding passes considerably higher. There simply is less oxygen up here, and fuel efficiency (and power) does suffer somewhat.
If the EGR valve seems to work, and passages are not clogged, does the Code 12 implicate the EGR control box? ECU itself?
Brian
Last edited by 94EG8; 09-05-2013 at 11:24 AM.
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