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Question:
2002 Chevy Cavalier mileage: 70,000. My car's idle is
supposed to be 900 rpm. Instead it idles around 1500
rpm. Also, it is a manual transmission and when I shift
around 4000 or higher, the engine rpm remains high
instead of going lower during the shift. I have replaced
the IAC. I also have access to a Snap-On scanner. No
codes are present and everything looks good. The scanner
has the ability to vary the idle, which it does, but the
idle is exactly twice as much as the scanner is
programming it to do. I have checked the wire
connections between the IAC and the computer and they
are good. I have also checked the TPS with the scanner
and the voltage and throttle position is accurate. At
this point, I am leaning towards a computer. Thanks for
any advice.
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:
2003 Chevrolet 1500 Truck Mileage: 82,000. My truck is
in the shop now and the mechanics are stumped The
truck was idling at a high rpm when you start it up and
as you drive, it would be ok and then rev up. It would
stall at a stop. I would have to press hard on the brake
to stop and it would rev and push my foot. Well they
changed my EGR valve, a complete tune up; they said some
sensors were out. So they fixed that and the truck still
does it. They put in a new computer, still doing it.
They checked the mass air sensor, still doing it. They
said they just don't know; they are looking into maybe a
faulty wire. I am getting so stressed and so are they.
Answer:
If the computer has not been scanned for fault codes,
this should be done first. There may be a faulty
idle air control motor and/or oxygen sensors.
Question: 2004 Toyota Camry mileage: 34,000.
Upon cold start-up, my new Camry jumps to approximately
2,000 RPM for about 5 seconds and then the Rpm's drop to
about 1,500 Rpm. I fear that this initial jump is too
high for cold warm-ups. Is this initial jump typical of
the new Camry's? Should it be taken in? It does this
every time it is cold started.
Answer: The cold fast idle rpm is controlled by
the computer. Its sounds like the IAC control motor is
sticking or shorted. Also
there may be a faulty idle air control motor and/or
oxygen sensors.
Question: 2003 Honda Accord,
mileage: 46,000. I have a same problem as listed in
another posting, on cold start the car goes into fast
idle mode and after a minute the idle starts to jump
between 1,500 rpm and 1,800 rpm. I've been trying to fix
this for a year. I've replaced the O2 sensor and PVC
valve as you told the other poster to do. I've also
replaced the Air Temp sensor (TA), Water Temp sensor
(TW). I've stumped the dealership, as they find nothing
wrong. I even replaced the fast idle valve and EACV! The
engine has been tuned and I have no clue what else to
do? After the engine is warm, everything is great and
runs really well and car is like new after constantly
doing the service on time.
Answer: The data stream from the
engine to the computer should be read to determine the
values of the various sensors on the car. In addition,
check to see if the ground wires are properly attached
and making good connections.
Question:
2002 Ford Focus, miles: 98,000. I have had my car to
three different mechanics in the last month. No
one can fix it. It idles high. It will
get to 58 mph with out ever putting my foot on the gas
pedal. We have had the throttle sensor and the
idle air control sensor changed. The computer
showed that the I.A.C.sensor was bad. Please help.
Answer: Replace the Mass Air Flow Sensor as
it may be failing.
Question:
2002 Dodge 1500 truck mileage: 65,400. It started
to idle at 2000 rpm's after we steam cleaned the engine
and we just did an oil change. Any suggestions?
Answer:
The moisture in the wire connections changes the
resistance fed to the computer. Try disassembling
the wire connections and drying them.
Question:
2004 Ford F-350 mileage: 59,000. After filling the
tank recently the engine speed became erratic: it
would race while driving (tach at 1800 forcing me to
keep my foot on the brake in a 25 mph zone); when
braking for a turn it would vary wildly between a couple
hundred and 1500 rpm; if breaking quickly rpm would fall
to under 400, would sputter and stall unless I would
two-foot. It continued to do this intermittently,
sometimes stalling while cornering. I took it to
the dealer for its 60,000 mile scheduled maintenance;
they found no problem except a possibly partially
clogged fuel injector. I used some OTC fuel
injector cleaning stuff to no avail. Took it to a
very good independent mechanic. He spent three
days checking sensors, motors, valves, computer,
draining and replacing the fuel. Everything
independently checked out A-OK. He's mystified.
What do I do now?
Answer:
Read the data stream at the computer. Check for
vacuum leaks and check the operation of the idle speed
motor.
Question: 2003 BMW 740il mileage:
56,000. I really, really hope you can answer this one.
Let me know if you need more details or if it is
something that doesn't have a clear answer. My carl
periodically increases its idle while at the same time;
the antilock brake light comes on. This behavior occurs
at 10 or 15-minute intervals at times, or many times the
car just idles fast with the ABS light on. Idle is as
fast as 20,000 rpms. It has a new alternator and a new
battery. I did notice there was no blow-by smoke seen
when looking inside the breather with the motor running.
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: 2003
Chevrolet Lumina mileage: 70,000. My mom’s car
sometimes races and is hard to stop, sometimes it stalls
and other times it idles so low it's close to stalling
and sometimes it runs fine. Her mechanic has
replaced ($$$) every item he could think of and nothing
has helped. She took it to a Chevy dealer and they
did not know what the problem was and wanted to replace
the computer. Well, she knows two other people
with 1990 Luminas with the exact same problem. No
one has been able to fix them. One did have the
computer replaced and it did not help. Any
suggestions?
Answer: Replace the
idle speed motor, as it may be faulty. In
addition, service the fuel injection system. Clean
the carbon deposits from the throttle bore and idle
passages.
Question: 2003
Ford Focus mileage: 62,000. Hi Guys, there
are two symptoms, possibly related. Both problems are
intermittent, but occur approx. 70% of the time. 1. High
idle at around 2200 RPM, only when fully warmed up,
especially when stopping at a traffic light after
highway driving. It will stay at 2200, and then
gradually reduce to around 1500 RPM before returning to
normal. This process usually takes 30 or
more seconds, sometimes over a minute. 2. When in
"high idle mode", the engine will cut out at full
throttle. I noticed this one-day when the high
idle made, me made and I tried to make a jackrabbit
start when a light turned green! Through each gear
(5 spd), it will drown out at full throttle, and I have
noticed that it smokes (gray) when I hold the pedal down
during this cutout time, and smells really fowl-- like a
combo of a catalytic converter and raw gas. Any
ideas? I have been putting this off for a few
months now, but it is getting worse. I drive about
2500 miles per month and feel like I may be stranded
soon!
Answer:
Your car is equipped with a computer controlled engine
management system. An independent auto service
center can scan your computer for fault or error codes.
The information should pinpoint the malfunctioning
components.
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