99 Civic DX idle issue
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99 Civic DX idle issue
Hi, I own a 99 Civic DX 5 speed and recently swapped the motor for one with less miles (still a D16y7). Since the swap, it idles like it has a vacuum leak, once its driving it goes away. However, I cannot keep the car at a constant speed. Slight pressure on the throttle accelerates it slowly, any less pressure on it and the throttle closes and slows down. Ive checked/sprayed all my hoses to try to find a vacuum leak with no success. With my air box off, if I place my hand over the throttle body while its running and create the right amount of suction, it idles normally. Throttle position sensor has been replaced and did not solve the issue. Any tips/suggestions/guidence is greatly appreciated!
#2
Re: 99 Civic DX idle issue
Hi, I own a 99 Civic DX 5 speed and recently swapped the motor for one with less miles (still a D16y7). Since the swap, it idles like it has a vacuum leak, once its driving it goes away. However, I cannot keep the car at a constant speed. Slight pressure on the throttle accelerates it slowly, any less pressure on it and the throttle closes and slows down. Ive checked/sprayed all my hoses to try to find a vacuum leak with no success. With my air box off, if I place my hand over the throttle body while its running and create the right amount of suction, it idles normally. Throttle position sensor has been replaced and did not solve the issue. Any tips/suggestions/guidence is greatly appreciated!
#3
Re: 99 Civic DX idle issue
Cover the IACV hole in the TB with your finger. Does the idle speed settle down?
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Re: 99 Civic DX idle issue
I did exactly that, and yes, the idle corrects itself once the IACV hole is covered. Assuming I'll need to replace that now? I've got another on a spare manifold, I'll swap them and see if that resolves the issue.
#6
Re: 99 Civic DX idle issue
You can check the function of you iacv by simply removing it, and checking to see if it spins freely. If it spins freely then chances are it's working properly. It can also not function properly if there is any air in the coolant passage of the iacv, or you may not have the proper voltage running to it.. Do you have a coolant leak anywhere?
#7
Re: 99 Civic DX idle issue
Start by cleaning the IACV.
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Re: 99 Civic DX idle issue
You can check the function of you iacv by simply removing it, and checking to see if it spins freely. If it spins freely then chances are it's working properly. It can also not function properly if there is any air in the coolant passage of the iacv, or you may not have the proper voltage running to it.. Do you have a coolant leak anywhere?
#9
Re: 99 Civic DX idle issue
Im not sure of a way to really check for air pockets, but you can burp/bleed your coolant system to assure that there is no air in the system. There is a video on YouTube on how to do that, it's basically just a matter of starting the car, letting it cool, topping off the coolant, repeat. You will definitely create an air pocket when you remove the iacv from the manifold, so this is a procedure that you'll want to preform anyway. When you remove the iacv you should have coolant pour out of it and the manifold, if you don't see any coolant then chances are there was air in the coolant passage. If it doesn't spin back and forth freely as it should, try cleaning it. Sometimes debri and goup will build up on it over time restricting the function of the iacv. If it seems to be working properly, and you burp the coolant system and the issue isn't resolved, next I would research and see what voltage should be running through which wire that goes to the iacv, and then check the voltage when the engine is both cold and at operating temperature, as the voltage changes when the engine reaches operating temp to close the iacv. I'm just not sure of voltage that you should expect to see, or which wire to check.
#10
Re: 99 Civic DX idle issue
The only purpose for coolant circulation through the IACV is to prevent it from freezing up during the winter.
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Re: 99 Civic DX idle issue
Im not sure of a way to really check for air pockets, but you can burp/bleed your coolant system to assure that there is no air in the system. There is a video on YouTube on how to do that, it's basically just a matter of starting the car, letting it cool, topping off the coolant, repeat. You will definitely create an air pocket when you remove the iacv from the manifold, so this is a procedure that you'll want to preform anyway. When you remove the iacv you should have coolant pour out of it and the manifold, if you don't see any coolant then chances are there was air in the coolant passage. If it doesn't spin back and forth freely as it should, try cleaning it. Sometimes debri and goup will build up on it over time restricting the function of the iacv. If it seems to be working properly, and you burp the coolant system and the issue isn't resolved, next I would research and see what voltage should be running through which wire that goes to the iacv, and then check the voltage when the engine is both cold and at operating temperature, as the voltage changes when the engine reaches operating temp to close the iacv. I'm just not sure of voltage that you should expect to see, or which wire to check.
#12
Re: 99 Civic DX idle issue
Adjust the idle speed.
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