# ca18de idle problem



## greenbean699 (Jan 18, 2004)

Ok i have a 87 sentra...just dropped a ca18de. Well it will run great but it will not idle. i know the idle air ajusting valve(the one on the far left that goes in the intake) is not getting any power. I put a tester on the throttle position sensor and it shows nothing. Could this be it?


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## Myetball (Dec 15, 2002)

greenbean699 said:


> Ok i have a 87 sentra...just dropped a ca18de. Well it will run great but it will not idle. i know the idle air ajusting valve(the one on the far left that goes in the intake) is not getting any power. I put a tester on the throttle position sensor and it shows nothing. Could this be it?



http://www.nissanforums.com/showthread.php?t=62703

There's info on how to check the throttle position sensor.

The thing on the left is the "Air Regulator Valve" it's function is to provide an air by-pass when the engine is cold to create a fast idle during warm-up. If there is no power to the ARV then you will always have a fast idle. The electricity to the ARV warms up a heat element that shuts the valve after the element is sufficiently heated.

The thing on the right is the "Idle Air Adjusting Unit." This is comprised of the Aux Air Control Valve, the FICD valve and the idle adjusting screw. The FICD functions to increase idle speed when the A/C is on so it probably isn't the culprit. Here's how to check the AAC vavle:

- Disconnect the AAC connector
- Turn ignition on
- Check voltage from terminal "A" to ground. Terminal "A" will be on the right as you hold the plug with the locking tab up. Should be 12v.

- Reconnect the AAC connector
- Start engine and warm up
- Check voltage between ECU terminal 113 and ground. Should be 7-11v.


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## greenbean699 (Jan 18, 2004)

Myetball said:


> http://www.nissanforums.com/showthread.php?t=62703
> 
> There's info on how to check the throttle position sensor.
> 
> ...


I have not checked that yet, but i noticed that it will idle if just sitting but if i but the brake on it whats to die. The idle will go up and down. Hope this helps. Another thing.....how do i adjust the throttle position sensor?


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## Myetball (Dec 15, 2002)

greenbean699 said:


> I have not checked that yet, but i noticed that it will idle if just sitting but if i but the brake on it whats to die. The idle will go up and down. Hope this helps. Another thing.....how do i adjust the throttle position sensor?


Well, your response jumped right out and slapped me and said "VACUUM LEAK!!!" Sounds like you've got a primary vacuum leak, that is a leak in/on the intake manifold. As you hit the brakes the vacuum booster pulls vacuum off the engine, and with a leak the engine cannot sustain enough vacuum to keep running. Also, the loping idle is indicative of a primary vacuum leak.

Buy a can of carb cleaner and start spraying it around the vacuum hose connections, the various sensor threads, and the manifold to head mounting area. When you spray on the leak the idle will steady out or increase.


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## BennittoMallito (May 20, 2002)

Mine used to die a lot, and I am really bad with electrical stuff so... 

I pulled the Air reg. valve, and it had a lot of crap inside it. Scooping that stuff out helped. 

Then for some reason someone had taken my vacuum line off the end of the fuel rail, that runs to the manifold, and plugged it on the manifold with a rubber cap. Re-hooking that line to the manifold absolutely killed my idle stalling problem, and now to boot my car also fast idles pretty well when its cold. 

I also cleaned the TB with carb cleaner. I did it the right way without blowing that stuff through the engine. Which also helped.


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