that_boy_sammy

alright my car's idle is around 200rpms...very low....ive already replaced the throttle body and thermostat. It still is idling low, but when i turn on my air hot or cold it idles just fine?any ideas?

that_boy_sammy

nothing?

Simkin314

Just to be sure... you replaced the throttle body, did you adjust your idle via the idle screw on the throttle body?

Former User

Any CEL codes?

Is the coolant level full in the radiator? Have your tried to bleed the cooling system?

vtecgoesmmmbah

i am havin the same problem can you pm me what you have done already so i know whatworks and doesnt work thanks dude

that_boy_sammy

i got a new throttle body from honda, i dont think the idle needs to be set on that...and coolant levels are fine...another weird thing...when its idling rough,i press the button to roll up my window(with them already rolled up, like trying to force it more up) the idle will be fine..but then drop badly seconds later...alternator? cant be right

Simkin314

You may be thinking of TPS (throttle position sensor, which, on an OEM Honda throttle body, is riveted (model dependent))...

When any adverse electrical load occurs (detected by the electrical load detector in the USDM fuse section), the ecu compensates by raising the electric field induced within the alternator which naturally increases the load on your crankshaft slightly. To compensate for this extra load, the ecu adjusts the idle higher... This explains the idle 'fixing itself'.

I still recommend unplugging the idle air control valve (after warming the engine a bit) and adjusting the idle to the appropriate level via the idle adjustment screw. At least so we can roll out the simple possibility that it is your problem.

that_boy_sammy

hey so i did what u said, to unplug the iacv after the car warms up...so when i unplugged it, it started to idle normally after plugging it back in i took it around the block...stopped a few times and it idled fine...when i turned my car off and back on...started to idle low again......

cityslicker1606

have you tried cleaning your IACV? it could also be your FITV.

Simkin314

Things involved with idle control:

NOTE: Any extra air will confuse the ecu thereby causing rough/hunting idle. Check all vacuum lines, electronic plugs, CELs, etc


Idle control screw (throttle body)
function: allows more or less air directly into the intake manifold thereby raising/lowering the idle.
Recommendation: adjust the idle via this screw.


Throttle body vapor purge port (throttle body)
XXX unlikely

Throttle body gasket (between throttle and intake manifold)
XXX unlikely

intake manifold air ports (intake manifold)
XXX unlikely

Intake manifold gasket (between engine and intake manifold)
XXX unlikely

Fast idle thermo valve, FIT (bottom of throttle body)
function: allows more air into the intake manifold via a thermowax plastic insert thereby compensating for colder climates (and cold starts).
Recommendation: Depending on you global position/typical environment...open the end plate and tighten (to lower the amount of air) or loosen (to raise the amount of air) the white insert, thereby allowing less or more air through.


Idle air control Valve, IACV (back of intake manifold)
function: controls air flow during all stages of driving, opening and closing to keep intake manifold vacuum stabilized.
Recommendation: Clean, test, alternatively replace.


Throttle position sensor, TPS (side of throttle body)
function: allows the ecu intimate knowledge of the current angle at which the throttle plate is situated. This allows the ecu to compensate for many things including idle conditions, ecu tables (ignition and fuel), etc.
Recommendation: Test the center wire (make/model dependent) with your engine off, key in the ON position. This value should be 0.5 volts closed throttle and 4.5 volts wide open throttle.


Manifold absolute pressure sensor, MAP (top of throttle)
function: allows the ecu knowledge of the current vacuum value inside the intake manifold. This value is also used in conjunction with the TPS for the ecu's control of ecu tables and the sort.


ECU, PCM, (passenger kick panel)
function: overall control of the engine and peripherals.
Recommendation: check all else first... twice.


Coolant lines
function: in this context, the coolant lines are ran through the FIT and IACV to warm the thermowax inserts in order to lower the amount of air going through the individual valves. This helps stabilize the volumetric airflow for a warmer climate/warm engine.
Recommendation: Make sure they are tight with no kinks/hard unusual bends.


Coolant
function: Cools the engine. Warms the IACV and FIT valve thereby closing the thermowax inserts.
Recommendation: Make sure your coolant is topped off an your lines of bled of air (bleed the system). This will make sure the IACV and FIT get to appropriate temperature at appropriate speeds thereby not confusing the ecu (by the quantity air throughput.


Wiring (IACV, MAP, TPS, ECU)
function: to power and read the appropriate values accordingly.
Recommendation: Check to be sure signals are appropriate, plugs are appropriately situated (i.e. it is not an uncommon occurrence in HT to have the TPS and MAP plugs switched, alternatively the IAT and IACV plugs switched). Get an electrical schematic for your vehicle/engine and test all nodes for continuity to their respective locations.
------------

After warming up the engine with the IAC unplugged, the idle should be roughly 450rpm (of course engine dependent). If it is not, adjust the idle via the idle adjust screw on the throttle body. If that doesn't solve the issue, I suggest cleaning the Idle Air Control Valve, and testing it... This is the most common issue (IMO). Go through the checklist above.

Hope this helps, good luck.

that_boy_sammy

f this idle problem, man imma have to get to crackin..

Simkin314

Concentrate on the idle adjust first, then the Idle air control valve. Clean.

https://honda-tech.com/forums/showth...+control+valve

Jimster480

Is it only when the car is cold? if so it sounds like your FITV is clogged, on automatic D16Y8's the FITV is part of the IACV on the bottom of the throttle body.

that_boy_sammy

ummm its not an automatic, but how should i clean?pbblaster?

that_boy_sammy

oh yeah and the throttle body is brand new from a honda dealership

Simkin314

Check this thread (same as linked earlier)

https://honda-tech.com/forums/showth...+control+valve

This is a decent generalized thread showing a way of cleaning the IACV...In this thread, he said to use brake cleaner or simple green. Be careful using too strong of a cleaning agent because of the possibility of ruining internal seals. Otherwise, you should be fine.