High idle. Goes to normal when AAC is disconnected - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Stunt'nSlide · 10-28-2012, 02:39 PM

I got a 89 ka24e. My tps is set at 0.45 volts. And it idles at 2,000 rpms and runs rich. When I disconnect the plug to the AAC valve on the iacv it drops down to normal idle. What's the problem and how can I fix it? Thank you

2.5T_/<ouki · 10-28-2012, 02:55 PM

I had the same problem on my RB and it turned out to be a bad TPS for me. Has it always been this way or did it just happen out of the blue? Have you checked the little screw on the IACV?

Stunt'nSlide · 10-28-2012, 03:55 PM

Quote:

Originally Posted by 2.5T_/<ouki

I had the same problem on my RB and it turned out to be a bad TPS for me. Has it always been this way or did it just happen out of the blue? Have you checked the little screw on the IACV?

Yea it's been like this. I tested my tps and it came out good. I guess I'll try my friends tps on mine then. I'm trying to figure out why the aac valve would make the idle high. Also I pinched the hose going to the air regulator and the idle dropped so I guess that means its stuck open

cotbu · 10-28-2012, 04:29 PM

I've dealt with this a lot, and there are somethings you can do that I have done. First check to make sure the coolant lines to the IACV are connected. Yes/NO
Next adjust the IACV screw closed, reset the ecu. Does this work or not?
If No, add a restriction in the line, I use screen mesh, to allow air to flow thru.
That coupled with, reset and a test drive works every time. after removing the mesh the ecu has relearned the new air flow. You may have to open the screw more now.

You could always try replacing the unit, but I never have.
PS this was on sr20's but it is what it is?!................Magic!

Stunt'nSlide · 10-28-2012, 05:39 PM

Quote:

Originally Posted by cotbu

I've dealt with this a lot, and there are somethings you can do that I have done. First check to make sure the coolant lines to the IACV are connected. Yes/NO
Next adjust the IACV screw closed, reset the ecu. Does this work or not?
If No, add a restriction in the line, I use screen mesh, to allow air to flow thru.
That coupled with, reset and a test drive works every time. after removing the mesh the ecu has relearned the new air flow. You may have to open the screw more now.

You could always try replacing the unit, but I never have.
PS this was on sr20's but it is what it is?!................Magic!

Ok cool and where do I put the screen mesh in?

cotbu · 10-28-2012, 10:32 PM

in the Auxiliary Air Intake Hose

Stunt'nSlide · 10-28-2012, 10:53 PM

Quote:

Originally Posted by cotbu

in the Auxiliary Air Intake Hose

I only have one hose and it goes to the bottom of the iacv. That one?

Stunt'nSlide · 10-29-2012, 06:10 PM

Quote:

Originally Posted by cotbu

in the Auxiliary Air Intake Hose

So i reset the ecu and the idle was normal at cold start but once it warmed up to operating temp the idle was high at 1,500 rpms. And when I drive it around if I come to a stop the idle drops down significantly to like 200 rpms and wants to die then kicks back up to 1,500 rpms

cotbu · 10-30-2012, 10:38 PM

You should have been able to bring the idle down lower than 1500rpm, the rest is normal. Have you checked for vacuum leaks? If you have that hose blocked off completely and still idle high you probably have a vacuum leak. Make sure the throttle body is fully closed.
All you are trying to do is help the ecu relearn. So make sure the engine is at operating temp. restrict that line. If you can get it to idle normally check the timing. Don't adjust anything until the ecu relearns or you fix the problem.

Stunt'nSlide · 11-01-2012, 03:00 PM

Quote:

Originally Posted by cotbu

You should have been able to bring the idle down lower than 1500rpm, the rest is normal. Have you checked for vacuum leaks? If you have that hose blocked off completely and still idle high you probably have a vacuum leak. Make sure the throttle body is fully closed.
All you are trying to do is help the ecu relearn. So make sure the engine is at operating temp. restrict that line. If you can get it to idle normally check the timing. Don't adjust anything until the ecu relearns or you fix the problem.

it's the hose that goes to intake pipe right?

10-28-2012, 02:39 PM	#1
Stunt'nSlide Zilvia Junkie Join Date: Oct 2010 Location: nor cal Posts: 310 Trader Rating: (-1) Feedback Score: -1 reviews	High idle. Goes to normal when AAC is disconnected I got a 89 ka24e. My tps is set at 0.45 volts. And it idles at 2,000 rpms and runs rich. When I disconnect the plug to the AAC valve on the iacv it drops down to normal idle. What's the problem and how can I fix it? Thank you

10-28-2012, 04:29 PM	#4
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 47 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	I've dealt with this a lot, and there are somethings you can do that I have done. First check to make sure the coolant lines to the IACV are connected. Yes/NO Next adjust the IACV screw closed, reset the ecu. Does this work or not? If No, add a restriction in the line, I use screen mesh, to allow air to flow thru. That coupled with, reset and a test drive works every time. after removing the mesh the ecu has relearned the new air flow. You may have to open the screw more now. You could always try replacing the unit, but I never have. PS this was on sr20's but it is what it is?!................Magic! __________________ LoverTechnologies "Half Broken Things!"

10-28-2012, 10:32 PM	#6
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 47 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	in the Auxiliary Air Intake Hose __________________ LoverTechnologies "Half Broken Things!"

10-30-2012, 10:38 PM	#9
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 47 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	You should have been able to bring the idle down lower than 1500rpm, the rest is normal. Have you checked for vacuum leaks? If you have that hose blocked off completely and still idle high you probably have a vacuum leak. Make sure the throttle body is fully closed. All you are trying to do is help the ecu relearn. So make sure the engine is at operating temp. restrict that line. If you can get it to idle normally check the timing. Don't adjust anything until the ecu relearns or you fix the problem. __________________ LoverTechnologies "Half Broken Things!"

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10-28-2012, 02:55 PM	#2
2.5T_/<ouki Zilvia FREAK! Join Date: Oct 2011 Location: SoCal Posts: 1,150 Trader Rating: (13) Feedback Score: 13 reviews	I had the same problem on my RB and it turned out to be a bad TPS for me. Has it always been this way or did it just happen out of the blue? Have you checked the little screw on the IACV?