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Fuel and Engines
Dodge Dakota
Nissan 240SX
Honda Accord EX

What wrong with the engine when the idle go up and down 240sx?

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2005-10-20 08:57:03
2005-10-20 08:57:03

the AIV valve is dirty. This is a very common problem, your best bet is to remove the entire AIV box (located behind the airbox on the drivers side) via the 3 screws holding it in place, then remove and plug the 2 hoses that were leading to it. This is completely safe, and all it is doing is keeping exhaust fumes from entering your intake manifold. If this doesnt work, then try installing a new fuel filter, preferably one for a 1990 300ZX, it is a direct fit and will give you a better throttle response

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You can't it is not adjustable, It is controlled by the computor. You have something wrong, Vacuum leak, Dirty Idle air control valve You need to scan engine with a engine scanner to see if something is wrong with the emission system. Is the check engine light on ?? SCAN ENGINE. There is a number of things that could make it idle to fast.

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The idle speed control solenoid controls the idle of the engine when the air conditioning is engaged. Since the ac pump draws down the engine idle the solenoid increase the idle when the ac is on.

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Idle slows down to a stall when you stop or slow down when AC is running. How do I adjust idle or is something else wrong?

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There is no idle adjustment. It is controled by the computer. You need to look for a vacuum leak, And may need to clean the idle air controll that screews into the left rear side of the TBI. throttle body. Is the check engine light on ?? If so need to scan engine with a engine scanner to see what is wrong with the eminssion system.

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It could be the throttle position sensor or the idle air control valve.

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That engine is computer controlled therefore the idle was preset / calibrated from the factory and there is NO adjustment. You need to have the engine scaned with an engine scanner to see what is making it Idle to fast. Check for vacuum leaks first.

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my 96 dodge Dakota wont idle when engine is warm and i changed idle air controle valve what else could be wrong

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It really depends on the make/model of your car. Suspects include: Idle Stepper Motor/control valve, engine CPU, fouled injectors, incorrect spark plugs

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Look for a vacuum leak at the engine.

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do you have a/c switched on when this is happening a/c makes engine idle up and down as it cycles on and off

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The idle control valve works by regulating the idle speed of the engine. The idle speed of the engine is usually controlled by the engine of the computer.

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idle speed motor on the throttle body.

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The engine will idle up and down usually. It can also idle high or real low. But other things factor in on how the idle air works

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The idle solonoid is probably hanging. Remove it from the throtle body and clean it. 240SX? remove the AIV box and plug up the hoses

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Answercoolant temp sensor reading wrong to engine control unit, idle air control motor, vacuum leak, or problem w/airmass sensor. Should be a check engine light on, if so have the codes read, they will help determine the cause of the idle problem.

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The idle speed is NOT adjustable it is computer controled. Is the check engine light on ? if so then you MUST have the engine scanned with an engine scanner to see what is wrong.

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there is an Allen screw and a nut on the throttle cable you loosen the nut and the screw and adjust it to make it idle up or down.

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The most common cause of engine surging (rev up and down) is a dirty air filter.

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If you have an FSM, the procedure is spelled out fully in there. If you don't have an FSM, here's how to do it: Fully warm up the engine. Shut engine off. Disconnect the TPS harness connector. It's located on the passenger's side of the engine just above the throttle assembly. Attach timing light. Start engine and set timing to 20 degrees BTDC. Check the idle speed. It should read 650 RPM; If not, adjust the idle screw until you get 650 RPM. The idle screw is located on the passenger's side of the engine near the firewall below the intake manifold. Stop the engine. Reconnect the TPS harness connector. Start engine. The idle speed should now be 700 RPM

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That is a plug that has been put in there from the factory to keep you from fooling with the idle screw. THE IDLE SPEED IS COMPUTER CONTROLLED AND NOT ADJUSTABLE. YOU HAVE other PROBLEMS if it won't adle right. Is the check engine light on ?? If it is then you need to have the engine scanned with a engine scanner to find out what is wrong.

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does the engine have a carburetor or is it fuel injected? A carbed engine has mixture screws along with a base idle screw, a fuel injected engine the idle is computer controlled.

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you might check your IAC valve (idle air control valve) check your TPS


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