Car jerks/hesitates when accelerating...
Sue Edelstein
few weeks. I first noticed that the car seemed to jerk at highway
speeds (over 60mph) but had no problems at lower speeds. This seemed
to be correlated with the car overheating. I took the car to the
dealer and it turned out that my radiator was clogged which they then
replaced and claimed that probably as the car was overheating-it was
vaporizing the fuel/causing a lean fuel mix and causing the
jerking-hestitation problems.
The car seemed to do okay for about a week after the radiator was
replaced...but the jerking has started to occur again (w/o the
overheating problem). I've been following when this occurs.
There appears to two be two different scenarios. The first is after a
weekend of not using my car for two days...the hesitation/jerking
seems to occur at different speeds...with or without
acceleration...whether the engine is warmed up or not.
The second scenario occurs once the car has been used. Usually by
Tuesday the car resorts back to the normal hesitation/jerking problem.
I usually have no problem initially and no problem at lower speeds or
after stopping for a light, etc. I usually notice the problem when
the car is accelerating at highway speeds--mainly when having to go up
a long steady (but not necessarily steep) hill. I usually have less
problems when the road is flat or I am going downhill.
The mechanic told me that this may just be water in the fuel. I have
used about three tankfulls of higher octane gas and even put in a
bottle of STP octane booster. But the problem hasn't gone away. The
octane booster seemed to help initially...but then after the car sat
unused for the weekend...the hesitation/jerking came back.
Does anyone have any ideas? Is this something I should be concerned
about or should I not worry (as the mechanic told me...since it wasn't
happening all the time).
Thanks
ron
>The mechanic told me that this may just be water in the fuel. I have
>used about three tankfulls of higher octane gas and even put in a
>bottle of STP octane booster. But the problem hasn't gone away. The
>octane booster seemed to help initially...but then after the car sat
>unused for the weekend...the hesitation/jerking came back.
If it is water (and the mechanic could have checked in 5 minutes) the
stuff you have done wouldn't help much. What you want is gas dryer.
It's available at K-Mart for less than a dollar a bottle. You might
also try some fuel system cleaner which runs a bit higher. They have
some in a tall yellow metal can which works well but I don't remember
the name. It's about $3.50.
What the mechanic should have done is disconnect the fuel line and let
the fuel pump into a glass jar. If there is water you will see it on
the bottom. The rule of thumb is that if it is just isolated bubbles
then gas dryer will work. If there is a complete layer of water on
the bottom then you need to have the tank drained.
>
>Does anyone have any ideas? Is this something I should be concerned
>about or should I not worry (as the mechanic told me...since it wasn't
>happening all the time).
Since it's an 85 you may have bad sparkplug wires. Find a really dark
spot (in the open not in a garage please) and pop the hood and turn
off the headlights. (Turn off your dome light too so it won't come on
when you open the door.) Wait until your eyes are used to the dark (5
mins) and then start the engine. Get out and look but don't try to
touch anything. If you see blue sparks jumping anywhere you need to
get new sparkplug wires. (You can change them yourself for less than
$20. Get them at Pep Boys or whatever. Just make sure you get the
resistance wires not the solid copper. Just do one at a time and go
from the longest to the shortest. Just run each one the way the old
one ran. They just pull off/push on but make sure they go all of the
way on.)
You might also replace the rotor while you are at it. Other less
likely possibilities are fuel filter, air filter, sparkplugs,
distributor cap, O2 sensor, thermo-sensor, EGR valve.
By the way: I'd find a new mechanic. This one seems to be awful
lazy.
Ron
Tom Sweet
The air hose leading from the air filter to the throttle body had slice almost
half way through deep down in one of the ribs designed for bending. When I
accelerated, the ribbed slice would open up allowing more air into the engine.
Since this happened after the air flow sensor, the engine was getting the
incorrect readings. Remedy, new hose $70.00