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Question: 1967 Ford Mustang 289 2 bbl,
mileage 49,000. The owner had just taken it out of
storage after 5 years and it won't idle right, but it
has gobs of power and smoothes out perfectly above 2000
rpms. He bought a new carb. It still does the same
thing. He did COMPLETE tune up on it. It still won't
idle right. Pigtail wire to ground the breaker plate is
in good shape. It never stalls, just has a very jittery
idle. Also, it starts like new. I'm thinking vacuum
advance may be failed. (Dual system)?
Answer: We would first do a compression check
on the engine. The piston rings could possibly be frozen
to the piston as a result of sitting for 5 years without
running. You may also have a valve hanging up. Vacuum
leaks are also a possibility.
Question: 2004 Chevrolet
Monte Carlo mileage: 79,000. When the car is cold and I
start it the idle goes to 2000 rpm and slowly drops to
around 800 rpm then surges back and forth. It also seems
to be skipping. If I let it sit for 3 or 4 minutes the
service engine soon light comes on but if I just touch
the gas it goes off. I took it to be repaired but they
couldn't find any computer codes so they cleaned and
rebuilt the throttle body but it didn't help. I brought
it back two more times and they replaced the 0� sensor
and the EGR valve and the problem is still there. It
runs fine once it's warmed up.
Answer: We suspect a faulty idle
speed motor. If not done recently, a major tune up,
including plug wires is in order here.
Question:
2004 Mitsubishi Lancer: 70,000. Keep in mind I am
a car amateur, the kind that many mechanics prey on.
When I start the car, it takes a couple of extra seconds
for the idle to go down. When I am driving the car
it seems like I *MIGHT* have lost a little bit of power.
Also, when I come to a stoplight the idle will rev up a
little then go down kind of like this
rrrrrrrRRRRRRRRRrrrrrrrrrrRRRRRRRRRrrrrrrrrRRRRRRRRRRrrrrr.
What could be the problem?
Answer: This is a difficult
problem to detect because the computer can not sense a
malfunction, the vehicles computer system thinks
everything is ok. In reality what is happening is the
electrical component inside the MAF sensor becomes
contaminated by air impurities. These containments imbed
themselves to the 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. NOTE: (Mass Air Flow
MAF sensor or Air Intake Sensor AIS, depending on
manufacturer. It does the same thing only with different
names).
Question:
2001 Dodge Truck 1500 mileage: 72,000. If you can
successfully pinpoint this problem, you should be
President. The problem is rough idle.
Service Engine Soon light comes on intermittently.
We have replaced the wires, plugs, throttle position
sensor, and idle air control valve. Performance
improved (better acceleration, surging stopped), but the
idle problem persists. Have checked for vacuum
leaks, maybe not successfully...? Should we
bother with the oxygen sensor? EGR valve?
PCV? Auughh! Can you help? Mechanics
in our area have been no help.
Answer: This is a difficult
problem to detect because the computer can not sense a
malfunction, the vehicles computer system thinks
everything is ok. In reality what is happening is the
electrical component inside the MAF sensor becomes
contaminated by air impurities. These containments imbed
themselves to the 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. NOTE: (Mass Air Flow
MAF sensor or Air Intake Sensor AIS, depending on
manufacturer. It does the same thing only with different
names).
Question: 1998 Honda
CRX mileage: 116,000. Hello, the car sat for four
months because it needed a head gasket replaced.
Therefore, I did the repair and now it does not want
stay running as if it is starving for gas. If you
keep working the gas pedal, it will just idle. If
you spray carburetor cleaner in the carburetor it will
run?
Answer: From what you
describe, it sounds like you need a set of fuel
injectors.
Question: 1992 Plymouth
Acclaim 2.5 mileage: 78,000. Hi, my Acclaim 2.5L
idles around 1200 RPM when cold but after a few miles on
the highway it starts to idle at 2000-2500 RPM.
The computer gave me fault codes about the TPS (throttle
plate sensor) and the idle speed motor, so I changed
these two parts and the problem is still not fixed.
The idle problem seems to get better when I let the
engine heat up. Any ideas on this problem?
Answer: Our guess
would have been the throttle plate sensor or the idle
speed motor also. The next sensors to try would be
the oxygen and coolant temperature sensors.
Question: 2002 Toyota Pick up
mileage: 67,000. I am simply amazed with these
trucks, mine still runs like a top, however: I live in
California and the EPA regulations here are very strict.
All of my emissions passed with flying colors but I
failed the test because my AC idle up is always
activated (according to the diagnostics I performed with
the engine "short circuit" check engine light [code 11].
Air works great but the idle goes down instead of up
when I start the AC. How can I fix the AC Idle up module
or disable the AC to pass the smog test? I
can only get to 9 degrees BTDC and I need it to go to
3-5 BTDC at idle. I just had a timing chain
installed and it is installed correctly. Where is
the AC idle up computer and do I have to replace it?
The temperature does get hotter than normal in mountain
climbs or long hauls, but I suspect it may be because
the timing may be to retarded at high speeds.
Please advise.
Answer: You should double
check the alignment marks on the timing belt sprockets.
You should be able to set the AC idle speed with the
adjustment screen on the bypass solenoid.
Question: 1999 Chevrolet 1500
mileage: 135,000. My car is in very good
condition; however, it has developed a rough idle upon
coming to a complete stop. The tachometer
oscillates between 200 Rpms to approximately 1300 Rpms.
If I don't even off the idle by giving it a little gas,
the engine stalls. How and where do I adjust
the idle? Thank you in advance for your help.
Answer: The idle speed is
controlled by the computer. Your car may be ready for a
major tune-up including spark plugs, plug wires,
distributor cap, rotor, fuel filter and air filter.
Also, perform a fuel pump pressure test. Clean
fuel injection system including throttle bore, idle
speed control motor and passages. If problem still
exists, scan computer for trouble codes.
Question: 1999 VW Golf
mileage: 130,000. I am experiencing a problem with
the warm up phase. The engine will increase to
2500-3000 revs as it warms up. It will then stay
at this level for anything up to 30 minutes and then
drop back to normal (suddenly). For no apparent
recent the engine will now and again suddenly start
racing again only to drop back to normal just as
suddenly. Any ideas? I wonder if the culprit
is the Stage II vacuum delay. If you have no
probable solution, I would be happy with a list of the
units or components that could be responsible.
Answer: First check the Mass Air Flow
Sensor then
check the thermo time switch for cold start injector,
fuel injection temperature sensor.
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