Hello I am new to the Honda Accord Forum but have found it to be extremely helpful in finding answers to problems with my latest vehicle. About a month ago I purchased a 91 Accord EX Auto with 106,000. It is in fairly good shape but has had shotty work done to it throughout it's life. ie: aftermarket tuneup parts, timing belt change but no cam seals valve cover gasket or water pump etc., cv boots replaced but with no grease repacked, bad exhaust job etc..... Since I have owned it I have replaced: plugs, wires, air filter, pcv, o2 sensor(honda parts), egr cleaning, tranny fluid, and axles. This work resolved a check engine light(code43 I believe) and clicking axles.
There is still one major issue that I cannot find an answer to that I had hoped the axles would fix but did not...When maintaining a speed of between 35 and 50 the drivetrain will shake vigorously untill you either let off the gas slightly or give it more gas then it stops. At highway cruising and below 35 it is smooth as a clock.
Another issue that is happening is I am only getting 20 to 22 mpg - mostly highway driving between 65 to 75 mph. At first I thought these two problems were related to a torque converter lockup solenoid but I do not get any tranny light when driving. The one thing I have not replaced yet that is mpg related is the fuel filter. So...

Will a new fuel filter make a significant difference in mpg?
Could it be related to the tranny issue?
If not has anyone experienced this type of vibration and resolved it?

Thanks for any help.
(Sorry so long winded just wanted to get in all the details.)

 

a new fuel filter will help. the vibration you are feeling could be other worn suspention compnents I.E. bad struts, bad springs, tie rod ends, your tires could be out of balance, all of that will also kill your mileage. most shops will onl charge 20-30 bucks to look over your suspention and tell you whats up with it.

 

Check out your motor mounts and make sure they are in good shape. Secondly make sure that your thermostat is functioning properly. My thermostat was stuck open and would not allow for lock up and it killed my MPG significantly. Hope this helps. Thanks.

 

Thanks for the response. I know my front(dogbone) motormount is bad the guy at the Honda dealership told me this at my last oil change. I mentioned changing the fuel filter to him but he said it would not make that much of a difference which is not what I would think based on what I have heard in forums. Next oil change I am going to get the mount and filter replaced odds are it's never been changed.

 

The throttle lever cable from the trans to throttle body might need adjusted;
Rolling along at 50-55 mph with a light throttle you should feel the Trans go in and out of lock up, or see about a 300 RPM change.
Driving test for cable adjustment;Engine at full operating temp.
Get going along a level road at 25 MPH light throttle, then floor the gas, the trans should down shift to first gear.
Repeat the same drive at 28 MPH, floor the gas, the trans should only down shift to second.
This could be a reason for poor gas mileage.