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low idle problem, help would be awesome.!


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alright, ive been on honda tech. and nobody helps me with my questions. they are all dicks!!


I have always got help on this site.


My car idles really low after it is warmed up. We replaced the tps. but it does the same thing. We havnt adjusted it correctly yet, but i dont think its the tps.


I will be going 35. then i push in on the clutch to brake, and the idle goes allll the way down to like to like 0 and goes back up a little. it stays under 500. and it dies sometimes.


or if i just let off the gas to let it slow down through the gears. it starts popping under 2k. like its not getting enough fuel. It has gotten worse over time. Do you think it could be a partially clogged fuel filter? its hard to start sometimes too.


I think i need a new o2, but that was out when i got the car. and it never did it back then.


I know its something really stupid, and i need to get it figured out ASAP. because i gotta auto x in less than a month.



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  • 1 month later...

chances are its your o2 your ecu probably reading a code one and thats the oxygen content you could try a new sensor but if youre running rich or lean it might run the same ive had the same problem and im running turbo so messing with crap is a pain. try using a tester to your o2 sensor plug and make sure its that before spending the 50 or 60 for a new one

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  • 5 months later...



The Problem


Problems starting the car, usually after a short run (when the interior is warm), though in bad cases the car may fail to start at any time. A classic time for the problem to occur is at the petrol station, or if you park for a minute to get something from a shop. If the car is parked for a long period, the interior usually has cooled enough for the joint to make contact again, and you won't notice a problem. As the cabin temperature is a major feature of this problem, it might appear worse on cold or rainy days when you have the heater running to clear the windows etc. Extremely cold temperatures can also cause the problem to be more apparent.


The engine will usually fire, run for a split second and then stall, as the remaining fuel under pressure is used up. When you turn the ignition key to position II (ignition on) you should see the PGM-Fi indicator on the dash light up and extinguish. Exactly timed with this lamp, you should hear a click and the fuel pump turn on and off. If you do not hear a click and the fuel pump, then the main relay is likely to be at fault.


The Cause


The problem is caused by dry joints in the PGM-FI main relay. This relay controls power to the ECU, and the fuel pump. Without power to the rest of the fuel-injection system, or fuel pump, you won't be going anywhere!


PGM-FI has constantly evolved over the years but the function of the relay is the same in all Honda cars - to supply power to the fuel pump, and fuel-injection components.

On recent cars such as the 2001 Civic the current draw by the main relay is monitored by the ECU, this way the ECU can tell if the main relay is faulty.


Dry joints are caused by vibration and changes in temperature cracking the solder round a joint which has not flowed correctly. They have a characteristic look, and sometimes are very hard to spot, even to a trained eye.

Remember it is not the actual relay itself that is at fault, just the soldering. To repair the fault all we need to do is remove the old solder and re-apply fresh.

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The main relay isn't the issue here. what it most likely is is either the fitv or like said the o2 sensor...I'm having a similar issue at the moment..here's the quote from the honda shop service manual.


Fast Idle Thermo Valve


To prevent erratic running when the engine is warming up, it is necessary to raise the speed. The fast idle thermo valve is controlled by a thermowax plunger. When the engine is cold, the engine coolant surrounding the thermowax contracts the plunger, allowing additional air to be bypassed into the intake manifold so that the engine idles faster. When the engine reaches operating temperature the valve closes, reducing the amount of air bypassing into the intake manifold.



Note: The fitv is factory adjusted; it should not be disassembled.

1. Remove the intake air duct from the throttle body.

2. Start the engine.

3. Put your finger over the lower port in the throttle body and make sure that there is air flow with the engine COLD(engine coolant temperature below 86*F,(30*C)).


**If no air is present over that hole, replace the fitv and retest.


4. Warm up the engine (the radiator fan comes on).

5. Check that the valve is completely closed. If not, air suction can be felt at the lower port in the throttle body.

>>If and suction is felt, the valve is leaking. Check engine coolant level and for air in the engine coolant system. If OK, replace the fitv and recheck.



EDIT**Why do I have a shop manual in my room lol

Edited by lastresort576
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normally , one would NEVER touch the idle screw , so people , dont go playing with them after i say this.


theres a flat head screw in the throttle body on top. unscrew it some pal till its good.

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  • 7 months later...

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