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Car Engine Runs and Idles Rough Questions - This category contains featured questions
as examples. They relate to most vehicles.Question:
2001 Ford Ranger mileage: 64,000. We have had this truck
to the dealer time after time, and it seems to work just
fine for a few hours, and then acts up again. The
problem is it runs rough at slow speeds/RPM, cuts out
and seems to want to stall. One thing we noticed is that
when first started, it only runs the fast idle for a
couple seconds before dropping down to normal idle. You
just can't take off from a stop without giving it a lot
of gas. At higher speeds, there is some hesitation, but
it does run better. We have had a complete tune up,
plugs, wires, EGR checked and nothing seems to help. The
Ford dealer does not seem to be able to solve the
problem. Any assistance would be greatly appreciated.
Answer: Your problem sounds
like you have a idle air control motor that needs
replacing.
Question:
2000 Volkswagen Passat V6 30V
mileage: 74,000. Rough idle and stumble on
acceleration. Engine idles best when warming (not
perfect), but becomes worse a full warm up. At
normal operating temperature, there is an associated
popping perhaps pinging sound with the poor idle; also,
one tends to think engine could be missing at idle.
Engine appears to run fine at or above idle (above
approx. 1200 to 1500 RPM). Once going, the car
runs nicely at highway speeds. Things that have
been replaced trying to correct the problem are: spark
plugs, fuel filter, fuel pressure regulator, oxygen
sensor, water coolant temperature sensor, and air
filter. Timing, and idle adjustments (idle bypass
adjustments) have been made a number of times.
Also, I would like to add that I have run injector
cleaner in three tanks of gas. Even sprayed
considerable cleaner in the throttle body to cleanse the
intake area (at times I thought this showed idle
improvement). Any ideas would be
appreciated. I have gone full circle a couple
times so I would appreciate your thoughts.
Answer: This is difficult
because the computer can't detect a problem, your car
thinks everything is ok. In reality what is happening is
the electrical component inside the
MAF sensor becomes contaminated by the impurities in
the air (heavies) These containments imbed themselves to
electrical component that senses the air flow causing
the sensor to be slightly off, but not enough to trigger
the MIL (malfunction indicator lamp). Replace the
MAF sensor with a new sensor and you're problem will
go away, plus your car get better mileage and
performance. (Mass Air Flow MAF sensor or Air Intake
Sensor AIS, depending on manufacture. It does the same
thing with different names).
Question:
2001 Ford F150 mileage: 83,800. New spark plugs,
control module, switched computers but still low gas
mileage and runs rough at hill or when I give it the
gas. Runs like a new engine when going down the
road. It will also backfire sometime when I
go to shut it off. Have tried everything.
It's driving me crazy.Answer:
It sounds like you have a
fuel pressure regulator that needs replacing.
Replace fuel pressure regulator with new to recheck
system.
Question:
2002 Chevrolet 1500 mileage: 68,000. Recently my
truck has had what I call a hiccup. Before it
would usually happen at speeds between 50 to 70.
Now it happens during idling and at other speeds.
The tachometer will flutter or jump from 500 to 1000 rpm
during idle, and from 1500 to 2500,3000 rpm at higher
speeds. Had transmission serviced, recently did
complete tune-up (plugs, wires, fuel filter, air filter,
oil change) no effect on the problem. Suspect
oxygen sensor but wonder if it could also be the
catalytic converter.
Answer:
Your problem is more than likely caused by a faulty fuel
pump. Remove fuel tank to install new
fuel pump to recheck system.
Question:
1999 Ford Contour mileage: 73,300. Hey guys.
My Contour has had what feels like a "missing" problem
for the past several months. Between the speeds of
45-65 mph, the car will "miss" on gradual acceleration.
Additionally, the car sometimes stutters on acceleration
after a stop. Both of these problems are
erratic (some times it seems like I'm not going to make
it to where I'm going, and other times I can go days
without a problem). I have taken the car to Ford
several times, but each time they insist that no codes
have been set, and that they cannot duplicate the
problem. I took the mechanic on a test drive
myself, but (of course) the car ran fine.
Coincidentally, my extended warranty is almost up.
I get the feeling that Ford is putting me off until my
warranty is up. I have another appt. with Ford for
March 18th, because these problems are getting worse.
I realize that many things could probably cause the
symptoms I've described, but I'm completely without
options in the face of Ford's denial of any problem.
It has a mystery problem that doesn't show up on Ford's
computer. Any advice you could give me would be
greatly appreciated.
Answer:
Your car is ready for a tune up including spark plugs,
spark plug wires, fuel filter and air filter. Replace as
needed to repair problem.
Question:
2001 Dodge Ram 1500 mileage: 115,000. The car has
a computer code for oxygen sensor running too lean, but
the car runs very rich. I have replaced the oxygen
sensor but yet the code remains. Do you have any
idea what may cause this code to remain and not go away?
It is the only code I have in the computer so I tried
several times to erase the memory on computer by pulling
battery cables 10 minutes and even overnight. I
have also checked the wiring on the fuel pump pressure.
What do you suggest?
Answer: This is a difficult
problem because the computer can't detect a malfunction,
your car thinks everything is ok. In reality what is
happening is the electrical component inside the
MAF sensor becomes contaminated by the impurities in
the air (heavies) These containments imbed themselves to
electrical component that senses the air flow causing
the sensor to be slightly off, but not enough to trigger
the MIL (malfunction indicator lamp). Replace the MAF
sensor with a new sensor and you're problem will go
away, plus your car get better mileage and performance.
(Mass Air Flow MAF sensor or Air Intake Sensor AIS,
depending on manufacture. It does the same thing with
different names).
Question:
2002 Acura NSX 3.0
mileage: 50,000. My car started stuttering while
on the freeway. When I got home a checked the sparkplugs
and two had oil (not burned but liquid). Why is
that? Is it the head gasket? It really
cuts into the performance of the engine. Is this
something that I can fix by following the manual?
Please., any suggestions would be greatly appreciated.
Answer:
The spark plugs may be fouling because your valve cover
gasket This is normally repair buy changing the
valve cover gasket and replace it with new. As for the
poor running condition your car maybe ready for a tune
up including spark plugs, spark plug wires, fuel filter
and air filter. Replace as needed to repair problem.
Question:
2002 Chevrolet Express 2500 mileage: 77,000. The van ran
like it was new, then after our blizzard this past week
it started running poorly, vibrating and not wanting to
idle and trying to stall when it's put in gear
(automatic), so I get it back & rechecked vacuum leaks,
vacuum is 18-20 in. start it & run it up & it isn't
smooth, put it in gear & it wants to die, I know it's
something stupid I'm overlooking as I've been wrenching
on cars & semi-trucks since 1970, I'm sure U got ideas &
I'm a waiting, THANKS & HAVE A GREAT DAY.....
Answer: This is a difficult
problem because the computer can't detect a malfunction,
your car thinks everything is ok. In reality what is
happening is the electrical component inside the
MAF sensor becomes contaminated by the impurities in
the air (heavies) These containments imbed themselves to
electrical component that senses the air flow causing
the sensor to be slightly off, but not enough to trigger
the MIL (malfunction indicator lamp). Replace the
MAF sensor with a new sensor and you're problem will
go away, plus your car get better mileage and
performance. (Mass Air Flow MAF sensor or Air Intake
Sensor AIS, depending on manufacture. It does the same
thing with different names).
Question:
2002 Mazda B3000 mileage: 65,823. In the mornings and in
cold weather it tends to hesitate or miss between 50 and
60 MPH until it gets hot. I am experienced
mechanic, so I did a compression test, pulled the head
off and reground the valves. I even replaced
all the electronic sensors including the one that screws
into the bottom of the block. I sniffed out a lot
of bizarre problems in my time but this one takes the
cake. Is there something that I have overlooked or
is this a quirk that I have to live with?
Answer:
Scan the computer for fault codes. It sounds like
you have
oxygen sensor that is operating out of range,
replace with new to recheck system.
Question:
2001 Mazda MPV mileage: 75,000. I have a hard
starting condition when cold. In addition, occasionally
the idle is rough, and then the car just stalls, and I
have to let it sit a few minutes before I can get it
start. I retrieved trouble codes, none. I
tested the resistance of the ignition coil and it was
within specs. I tested the resistance of the pick
up coil and it was within limits. What else should
I be looking at? Thanks!
Answer:
Your problem is more than likely caused by a faulty fuel
pump. Remove fuel tank to install new
fuel pump to recheck system.
Question:
2003 Ford F-350 mileage: 110,000. We have replaced
the fuel pump, oxygen sensor, temp sensor, troubleshoot
the map sensor, EGR, injectors, PCM, comp test, we
used a breakout box to check circuits and a snap-on
analyzer for codes. We still get code "running
rich" and continually stays. The fuel pumps were
replaced because the pressure was over 80 psi. The
vehicle is a security truck that sits at idle for long
periods of time, rarely drives over 30 mph, also lack of
power. Thanks for your time.
Answer: Check the fuel pressure
regulator, remove vacuum line to check for the presents
of fuel, if so replace fuel pressure regulator with new
to recheck system.
Question:
2001 Dodge Pickup 3500 mileage: 88,000. I get a
really bad miss in the engine when I put it under a load
such as acceleration. If I floor the pedal it will
go away but I cannot cruise, if I take my foot off the
pedal to where there is no miss the truck slows. I
was told the injectors so I replaced them.
But still the same problem. I have replaced the
filter, spark plugs and checked the compression (all
cylinders come in at spec) Air filter is clean.
My gas pedal seems to have a range where there is no
miss from a little gas or a lot of gas, no in between.
Answer: Check the fuel
pressure regulator, remove vacuum line to check for the
presents of fuel, if so replace fuel pressure regulator
with new to recheck system.
Question:
1999 Pontiac Bonneville SE
mileage: 105,000. The car sounds as though it is
fuel starved, (the fuel filter is new, fuel pump is
working, and there is pressure at the fuel rail) it will
only catch with the gas pedal to the floor but will
stall when you let off the gas. All this occurs
after the car is warmed up.
Answer: Your problem sounds like you
have a idle air control motor that needs replacing.
replace with new to recheck system.
Question:
2001 Ford T Bird mileage: 66,000. I just bought
this car, and it runs good most of the time.
Periodically it misses and jerks, and then runs ok
again. At idle, the rpm's dip sometimes, but it
does not die. Could this be a fuel filter problem?
Answer:
The spark plugs may be fouling because your valve cover
gasket This is normally repair buy changing the
valve cover gasket and replace it with new. As for the
poor running condition your car maybe ready for a tune
up including spark plugs, spark plug wires, fuel filter
and air filter.
MORE: Engine runs rough questions
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