At what Rpm is my 97 civic suppose to be when I start it at cold. I know that after the motor is hot, the rpms drops to 750 but at cold, it revs up to 2000 sometimes.
What is the problem if there is any? IACV??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by snouka &raquo;</TD></TR><TR><TD CLASS="quote">What is the problem if there is any? IACV??</TD></TR></TABLE>

, 1500 rpm's

 

So you're saying that I could have a IACV problem. My car is stock and I didn't change my Idle speed manually so other than a IACV problem, what could it be.

 

ttt

 

have you played with the idle screw on the tb yet? if not, try that. your ecu adjusts your idle to try to get to 1500 cold and 750 warm. If you jump the 2 pin connector by your ecu, your ecu will not change the rpm's while it idles. Do not drive the car, or rev it with the connector in, I've heard this can cause ecu damage. Never seen it first hand, but better safe than sorry. Adjust your idle screw so the car idles where it should, then remove the jumper and see how it does.

 

thks I'll try that

 

If im correct the Car runs way rich when its way cold so that would be your high idle. I believe becuase your 02 sensor only works when its warmed up so to get it warmed up the car runs extra rich and when its warm the o2 sensor tells the car to even the mix and lower the idle.
sean

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EG_Black_Hatch &raquo;</TD></TR><TR><TD CLASS="quote">If im correct the Car runs way rich when its way cold so that would be your high idle. I believe becuase your 02 sensor only works when its warmed up so to get it warmed up the car runs extra rich and when its warm the o2 sensor tells the car to even the mix and lower the idle.
sean</TD></TR></TABLE>

nope. your o2 sensor works the same warm or cold. You run rich when the engine is cold because fuel doesn't atomize with the air well because the injectors spray on the retainers and they aren't hot enough. When they are, the fuel will dissapate into the air faster. This is why you shoot a lot of that gas out the exhaust before you hit operating temp (especially for people with test pipes like me).

 

A non-heated sensor relies on the exhaust gases to keep it at its operating temperature which works most of the time but during extended periods of idling or low speed operation can cause the sensor to drop below its operating temperature and show a false lean mixture. Oxygen sensors must warm up to at least 400 degrees Celsius before generating an accurate signal. This is why cars remain in open loop (preprogrammed fuel map) when the engine is cold and don't switch to closed-loop (relying on the O2 sensor readings) until the engine has warmed up.

3 and 4 wire sensors are heated. One wire sends Lambda information to the PCM while the 2 additional wires are for either additional ground wires or 12v heater voltage (delivering power whenever the ignition is turn on). Heated sensors have several advantages over non-heated sensors. Heated sensors warm up more quickly than non-heated sensors and provide an accurate voltage signal regardless of the operating conditions. Also, with turbo charged cars the turbo absorbs so much heat that it prolongs the oxygen sensor warm-up which can yield false sensor readings. Using a heated sensor is highly recommended for turbo applications and in some cases less expensive than the factory replacement.


6+7th paragraph http://www.turbosaturns.net/ar...s.htm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by snouka &raquo;</TD></TR><TR><TD CLASS="quote">So you're saying that I could have a IACV problem. My car is stock and I didn't change my Idle speed manually so other than a IACV problem, what could it be. </TD></TR></TABLE>

This happens during cold starts, right? Mabe its the fast idle control valve. I was having a warm idle problem. The car would idle between 800 and 1800 rpm. (not cool at stop lights. I felt like such a ricer) I heard that the FICV controls the car when you first start it, and then it switches to the IACV after it reaches running temps.

I would reccomend cleaning both with throttle body cleaner. 12mm wrench for the IACV (1/2" standard). Car might have a little problem starting right after you clean them.

I've been told not to touch the idle screw unless its as a last resort.

 

sounds fine to me....my 99 si was like 1500 ..then i installed IM and TB and tightened the tb cable and now its close to 1800-1900...i mean as long as it goes down to normal idle rpm..who cares?

 

My bad on that, I didn't know they needed to be at 600 F to work, but what I said about the fuel injection is true too. Also, your link did not say why it doesn't work when cold, which is the most important information (this is a tech site). I dug this up this morning.

An Oxygen sensor is a chemical generator. It is constantly making
a comparison between the Oxygen inside the exhaust manifold and air
outside the engine. If this comparison shows little or no
Oxygen in the exhaust manifold, a voltage is generated. The
output of the sensor is usually between 0 and 1.1 volts. All
spark combustion engines need the proper air fuel ratio to
operate correctly. For gasoline this is 14.7 parts of air to one
part of fuel. When the engine has more fuel than needed, all
available Oxygen is consumed in the cylinder and gasses leaving
through the exhaust contain almost no Oxygen. This sends out a
voltage greater than 0.45 volts. If the engine is running lean,
all fuel is burned, and the extra Oxygen leaves the cylinder and
flows into the exhaust. In this case, the sensor voltage goes
lower than 0.45 volts. Usually the output range seen seen is
0.2 to 0.7 volts.

The sensor does not begin to generate it's full output until it
reaches about 600 degrees F. Prior to this time the sensor is
not conductive. It is as if the circuit between the sensor and
computer is not complete. The mid point is about 0.45 volts.
This is neither rich nor lean. A fully warm O2 sensor *will not
spend any time at 0.45 volts*. In many cars, the computer sends
out a bias voltage of 0.45 through the O2 sensor wire. If the
sensor is not warm, or if the circuit is not complete, the computer
picks up a steady 0.45 volts. Since the computer knows this is
an "illegal" value, it judges the sensor to not be ready. It
remains in open loop operation, and uses all sensors except the
O2 to determine fuel delivery. Any time an engine is operated
in open loop, it runs somewhat rich and makes more exhaust
emissions. This translates into lost power, poor fuel economy
and air pollution.

The O2 sensor is constantly in a state of transition between high
and low voltage. Manfucturers call this crossing of the 0.45
volt mark O2 cross counts. The higher the number of O2 cross
counts, the better the sensor and other parts of the computer
control system are working. It is important to remember that the
O2 sensor is comparing the amount of Oxygen inside and outside
the engine. If the outside of the sensor should become blocked,
or coated with oil, sound insulation, undercoating or antifreeze,
(among other things), this comparison is not possible.