Problems when idle and now power at low revs

[Hot.Azn]

I just started having this problem & im very confused. I noticed that when i was driving and taking off from 1st gear between 800rpm -> 2000 rpm there is no power, however after 2000rpm the car goes fine.
Along with this problem i noticed that when the car is idle at a set of lights the revs start fluctuating between 500rpm -> 1100rpm. Noticably this happened on that very hot Sydney weekend (last week)
BTW. in both occasions the engine temp gauge stays below the 1/2 way mark.

I only recently had it service and replaced the air filter. I was wondering if anyone has any ideas on what is wrong with my car.

Thanks in Advance!

[SiR JDM]

Your idle is hunting, this can be caused by ALOT of reasons....

My idle is currently doing something similar time to time, i narrowed it down to being the IACV (idle air control valve)

This is a good time to firmiliarise yourself with your engine and its idle workings =] i took this opportunity and learnt alot =]

Firstly check all your hoses for any leaks.. any extra air will throw the ECU off.. spray some carbi cleaner on your vacume hoses .. if there is a leak it will be sucked in and the engine will rev.. revealin the leak ... (i also read that bubbles may appear? not sure how true that is)

Next inspect your throttle body.. make sure all the nuts on the TB and the intake manifold are tight and no air is escaping thro that... also take off your intake pipe and make sure your throttle plate is closing properly... if your idle screw isn't waxed over (like alot are and i guess should be) try adjusting that to any avail

Clean and check the IACV (see bennjamin's guide here <-- VERY helpful ben

Check where the IACV and FITV (Fast Idle Thermal Valve) connect to the intake manifold and make sure there is no leaks, if so replace the gasket or reseal it.

If still nothing, unlikely but possible circumstances from my reseach include
- Bleed (not drain, bleed from the engine) your Coolant as air bubbles may have formed and can set off your FITV, (See Wyondes guide here <-- another great guide props to Win)

-TPS (Throttle Positioning Sensor) NB Ive only researched, read and collected info about this

With the TPS still connected and the car on AC using a volt meter stab the middle wire with the positive and ground the negative... should be .5 volts

If none of this helps, it could be a problem with your fuel?
When was your fuel filter replaced? Are there any other problems with your car beside what you have mentioned?

[ECU-MAN]

Sir JDM covers your idle problem,
your loss of power under 2000rpm is due to bad leads/rotor/cap. more leads though

[tinkerbell]

your loss of power under 2000rpm is due to bad leads/rotor/cap. more leads though

whoah!?!

can you explain this a bit more?

ie how are you certain?

[ECU-MAN]

lead can cause a miss ( flat spot ) under 2 to 3 k on high engine loads, eg taking off from the lights hard, once revs pick up there is less stress on the ignition system. the spark will always take the path of least resistance, so if it can find its way to ground by cracks in the neck of the lead or on the rotor button causing loss of power.

and im certain cos Iv seen it many many many times

[tinkerbell]

yep, cool.

sorry, to keep on it, but why is there less stress on the ign. system at higher RPM?

(i have never really had to consider ign. systems before)

[SiR JDM]

Would that be due to roadspeed, ie Inertia?

Less force is needed to move the car than it is in early RPM?

[VTEChnique]

my vote is for IACV...

[ECU-MAN]

Tinkerbell

ever notice when you drive a car with a vacuum gauge that when you take off your Vacuum goes almost to 0, also when you boot it, as we know this means there is more air in the combustion chamber so the ignition system has to work harder to make the spark jump the air gap of the plug.
get what I mean,

[tinkerbell]

ah, yes, i knew it was an issue for boosted cars, but not stockers...

but yes, it is a good point that it "works harder"

i would begin looking elsewhere, then move onto ignition.

but as you said - Sir JDM covered the basics

(doesnt look like azn has checked back in though...)

[Hot.Azn]

I have been a bit busy (with xmas and all) but i will give all the suggestion ago.

I did notice that the problem with idling was occuring when i was either:
1. operating all the power windows
2. air con is on
3. stock stereo is pumping tunes
I suspect there is a problem with the amps/current being drawn from the battery?

I have also been suggested to do an ecu reset...what do you guys think?

[jords]

Try the DIY ECU test,

http://www.ozhonda.com/forum/showthread.php?t=8218

I did it recently and I had to change an oxygen sensor.