Bronco, is it getting into Overdrive

I haven't had time to check it out yet but my daughter's '88 Bronco gets horrible gas mileage. Usually 10-12 mpg or less, on the highway. It takes her almost a full tank (32 gallons) to drive from Woodbridge Va to Camp Lejeune NC, a little over 300 miles. The Bronco has a 5.0L engine, Auto (overdrive ????) trans, and P235 tires. I asked her what does the tach show when she is on the road, and she said it turns 2500 rpm at about 56mph. I don't think it is going into overdrive.

Reply to
J
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snipped-for-privacy@apexmail.com posted:

I don't find that mileage shocking for an 88. But between it being on the low side, and the RPMs you mentioned, I'd check the axle ratios. Sounds like she might have 4.11s

Reply to
Spike13
10-12 mpg is right where it should be!
Reply to
351CJ

Are you sure she has an OD trans. 2500 is about right for direct drive with a 3.55 or 3.73 axle with those tires. The '88 was still available with a C6 trans which was a 3 speed. If the quadrant has 1-2-D, it is a 3 speed C6. If it has

1-D-OD, it should be an AOD. If it is an AOD, the throttle pressure cable may be adjusted improperly which will lead to slippage and very early trans failure because there is not enough pressure to fully lock the clutches or OD band.
Reply to
lugnut

Yes it is the AOD transmission. It has P-R-N-O-D-1 shift pattern. I drove it today and it sometimes makes it into Overdrive. One out of every three or four times when reaching 50-55 mph it will shift into Overdrive. Occasionally two or three times in a row, occasionally five or ten times it won't shift to OD. When it does shift into OD, the tach drops from about

2500 rpm down to about 1750-1800 rpm at 55mph. This is closer to the rpm my pickup turns with its standard trans in high gear.

It may very well be a linkage problem as I posted recently (during the Holidays) about the cruise control not being smooth, on the gas/off the gas/on.../off.... etc. Its just a little too cold for me to get out there and do anything at the moment. Also the shift linkage pointer doesn't quit line up with the letters or the gear selected.

Oh well my labs like riding in it, they get to sit on the seats. This is better than riding in the back of my Pick-up in cold weather.

Reply to
J

Is she shifting it into overdrive? My 87 you put the gear selector on D=20 until about 45 mph and then you moved it to the "O" to shift into=20 overdrive. When she shifts to "O" she should see a slight drop in RPM=20 if its working. My 92 holds about 2200-2300 RPM at 55 mph and roughly=20

13-14 mpg.

--=20 S t i =A9 k y

Reply to
Sti©ky

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