Re: Bad mpg
First off, is it an automatic, or a manual trans?
If it's an automatic, I'd say that you probably are having an issue with either the torque converter clutch solenoid or the transmission bands; this is usually located on the side of the transmission. This controls both upshifts as well as down shifts. Also, as the transmission has overdrive, I'd go out on a limb and say that you need to have the transmission bands checked and tightened, and the valves at least looked at, and possibly replaced. If that happens, you should also have the O-rings replaced for the valves.
As for the fluid, depends on how many miles the truck has, and if the transmission has ever been flushed. If it hasn't, I would flush it first, run new fluid in it for 3,000 miles, then change it two more times, doing the same thing. Do this if you pull the old fluid out, and notice that it either looks or smells burned. Also, check your torque converter--it may have fluid missing as well, which could cause the shaking at idle. If the fluid you pull out looks and smells normal (not burned), then DO NOT FLUSH IT. The dirt inside the transmission, if it isn't that much, actually is good for it, as it provides some friction to transmit engine power to the rest of the powertrain.
As for the jerking, have your driveshaft checked for balance, and check the fluid level and condition in the differential. All these things--fluid in the torque convertor, fluid in the transmission, and gear oil in the differential--can cause a vibration if they are not up to the proper level. The driveshaft, if not balanced, can cause a horrendous vibration at 45+ mph; a speed shop can check it for you, and rebalance it, if need be.
Lastly, check to see if your truck has a PCM (Powertrain Control Module). If that is malfunctioning, it could also cause the vibration you're dealing with, as it would not be sending the proper electrical signals to the ECM, which in turn would force the ECM to compensate by forcing the engine out of balance.
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Billie, my "sparkly" blue 1992 Ranger
SPECS: 2.3 I4; Rebuilt motor at 194,263 miles; straightened driveshaft when engine was rebuilt
FIRST MODS: 2" suspension lift and rear disc brake conversion
Last edited by zekew64; 11-16-2013 at 02:16 AM.
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