very high idle

02blkhonda

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93 hatch with b20/b16a head, when car is first started it wants to idle like around 3k but then as it warms up the idle goes back down to bout 1500, but kid i bought it from says it has no thermostat in it, i checked the idle screw checked the throttle cable checked the distribitor cap. idk nothing seems to fix it. could it not having a thermostat make it wanna idle so high, also when driving i guess the engine cools down while on the highway so the idle goes back up until i sit still for a few minutes. idk wtf lol please help
 

chuewy

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thats what happen to my coupe. maybe its that or you have a loose nut on the trottle body
 


98civikdx

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My 98 sedan idles at about 1500 rpm for the first few minutes, but when it warms up, it drops to between 500-800 rpm.
 

chuewy

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mine use to idle at 4500rpm and did the same thing. recheck everything over
 


jason_guy_yeah

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Depending how cold it is where you're at. Installing a thermostat might do it.
 

02blkhonda

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mine use to idle at 4500rpm and did the same thing. recheck everything over
what did you do to fix yours, also would having a vacum leak be the cause of it, i hear the way to check it is to cover the tb while the car is running and if it dies u have no leaks right?
 

chuewy

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what did you do to fix yours, also would having a vacum leak be the cause of it, i hear the way to check it is to cover the tb while the car is running and if it dies u have no leaks right?
i had a loose nut/bolt on my trottle body and it caused the piece on the bottom of the trottle body to open up taking in more air. causing it to be at 4500rpm. i just screw the nut/bolt back on and it was fine again. and yeah if theres a leak it can cause it and im sure you can check it like that for a leak
 

SuperSize

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well my first thought would be a vacuum leak..check all your hoses or get a smoke machine. second the reason it's prob idling so high when you start the car is because cold coolant is flowing past the ECT sensor and the ECM is lengthening your injector on time to warm the car up faster. so go buy a $20 thermostat and see if that fixes the problem.
 

02blkhonda

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got the thermostat in, still idles high as hell! so f**k it im taking it up to the shop where they do swaps and pay some cash to have it fixed but thanks for the help
 

Kaotic_Zeus

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check your spark plugs, make sure they're torqued down to 13 ft/lbs

might wanna try reseting the ECU, and have the engine learn it's idle. refer to: how to reset ECU properly.
 

98civikdx

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Now that it's warmer, my car was idling at 300-400 rpm the other day. I've kind of got the opposite issue I guess. Hope you get it figured out.
 


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