The car is a 95 Ford Escort, manual transmission. The jerking is somewhat variable in onset, but very noticeable both while driving at a constant speed (around 30 mph and at other speeds not just in 3rd gear) and accelerating uphill. The car also gets somewhat poor gas mileage (30 when it should be 35+), has a hard time accelerating uphill, and I can occasionally smell a small amount of gas. There is NO check engine light.
What I've done (don't laugh):
-checked the air filter was clean
-changed the fuel filter
-new spark plugs
-spark plug cables are fine
-cleaned MAF sensor
-cleaned throttle body intake
-ran a couple cups of fuel injector cleaner
I'm not really sure what the problem is at this point, possibilities include transmission (?), O2 sensor, timing belt, random other sensor, or worse? I can add details as necessary.
Thank you!
What causes a car to jerk forward %26amp; backward, other than fuel filter?
Doesn't sound like a trans problem to me I guess it could be possible, but clutch slip is usually not intermmitant especially if it cable operated, and an automatic would be much more likely to cause a buck or surge. It sound to me like a miss. Are all plugs gapped correctly? Are you sure cables are fine or do they just look okay? Pay attention to the specific RPM range the problem occurs at and the engine load? See if you can get it to happen at the same approximate RPM in different gears. If it does then it's most likely a spark problem? may also be a coil prob, or slipping timing belt. Good luck P.S. you should never smell gas, get that checked out!
What causes a car to jerk forward %26amp; backward, other than fuel filter?
transmission. take it to aamco.
Check fuel pump pressure...
Some of the jerkiness under acceleration can be caused by a slipping clutch plate.
Edited post:
I've had another thought. I had a car once which had a damaged brake caliper. When the brakes would heat up, the piston would jam and drag on the rotor. What did this feel like? General sluggish performance, sudden intermittent jerkiness, reduced gas mileage, serious heat buildup in the wheel assembly, and a constantly frying clutch plate. The car burnt up 2 clutch plates before we found the real problem.
It would be a long shot, but your description reminded me of this.
i would check the compression on all cylinders. if they are all around the same reading then you may have a bigger problem some where else. start their.
The transmission is slipping between gears. In addition to that the accelerator is worn the hell out. Go to Aamco and they'll find out what else is wrong in their free vehicle diagnostic and get it fixed at a reasonable price.
