Solved: 4Runner 3VZE A/C idle dropped
09-11-2012, 07:42 PM
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Solved: 4Runner 3VZE A/C idle dropped
After reading lots threads from this forum, I successfully solved my idle issue after A/C turned on. I would like to share my experiences in return...
I have 95 4Runner 3VZE with unstable idle issue. Due to head gasket broken, I had replaced with a rebuilt engine about 10K miles ago. Not to mention I got this lemon car for only two months before HG broken.
After warm up, still difficult to adjust the idle screw to 750rpm. It is unstable and drifts between 1000~1400rpm when in park or natural. Put into gear either R or D, the idle speed will drop about 250rpm to 750rpm. It looks right but still drift up.
During the CA hot air, I have to turn on A/C. The idle speed will drop down to 450rpm while in D. It is about 300rpm difference.
I took the throttle body off and cleaned the Aux. air valve. Nothing wrong on the TB.
I took some pictures on the passenger side. Guess what I found? The vacuum hoses for A/C idle up valve and steering pump valve are all messed up! What a mechanic
Here are the pictures:
1) messed up hoses for steering pump valve - they all go to steering pump valve from the same Y adapter in the intake manifold.
2) messed up hoses for A/C idle up valve - they all go to A/C idle up valve from filtered air.
3) closed look of A/C idle up valve.
After exchanged hoses to the correct adapter, fired up engine, warm up, the idle is at 1100rpm. Now, I know that I overly adjusted the idle speed in order to compensate the power loss of A/C on. When the A/C is off, the idle speed bounced back to 1400rpm. When the A/C is on, the idle dropped to 1100rpm. When in gear, the idle is right at around 750rpm.
So, I turned on A/C to max. Re-adjust idle screw to 750rpm. Then, turned off A/C, still 750rpm. Turned on A/C, still 750.
Quite happy, right? NO!
When I put into R or D gear, the rpm dropped to 500rpm
Is it normal on dropping idle rpm when put into gear? Something wrong?
Thank you!
I have 95 4Runner 3VZE with unstable idle issue. Due to head gasket broken, I had replaced with a rebuilt engine about 10K miles ago. Not to mention I got this lemon car for only two months before HG broken.
After warm up, still difficult to adjust the idle screw to 750rpm. It is unstable and drifts between 1000~1400rpm when in park or natural. Put into gear either R or D, the idle speed will drop about 250rpm to 750rpm. It looks right but still drift up.
During the CA hot air, I have to turn on A/C. The idle speed will drop down to 450rpm while in D. It is about 300rpm difference.
I took the throttle body off and cleaned the Aux. air valve. Nothing wrong on the TB.
I took some pictures on the passenger side. Guess what I found? The vacuum hoses for A/C idle up valve and steering pump valve are all messed up! What a mechanic
Here are the pictures:
1) messed up hoses for steering pump valve - they all go to steering pump valve from the same Y adapter in the intake manifold.
2) messed up hoses for A/C idle up valve - they all go to A/C idle up valve from filtered air.
3) closed look of A/C idle up valve.
After exchanged hoses to the correct adapter, fired up engine, warm up, the idle is at 1100rpm. Now, I know that I overly adjusted the idle speed in order to compensate the power loss of A/C on. When the A/C is off, the idle speed bounced back to 1400rpm. When the A/C is on, the idle dropped to 1100rpm. When in gear, the idle is right at around 750rpm.
So, I turned on A/C to max. Re-adjust idle screw to 750rpm. Then, turned off A/C, still 750rpm. Turned on A/C, still 750.
Quite happy, right? NO!
When I put into R or D gear, the rpm dropped to 500rpm
Is it normal on dropping idle rpm when put into gear? Something wrong?
Thank you!
02-27-2020, 09:08 AM
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Are these photos posted the messed up hose order or the corrected order ? Having a hell of a time finding consistent vacuum diagrams for the PS and A/C idle routing
After reading lots threads from this forum, I successfully solved my idle issue after A/C turned on. I would like to share my experiences in return...
I have 95 4Runner 3VZE with unstable idle issue. Due to head gasket broken, I had replaced with a rebuilt engine about 10K miles ago. Not to mention I got this lemon car for only two months before HG broken.
After warm up, still difficult to adjust the idle screw to 750rpm. It is unstable and drifts between 1000~1400rpm when in park or natural. Put into gear either R or D, the idle speed will drop about 250rpm to 750rpm. It looks right but still drift up.
During the CA hot air, I have to turn on A/C. The idle speed will drop down to 450rpm while in D. It is about 300rpm difference.
I took the throttle body off and cleaned the Aux. air valve. Nothing wrong on the TB.
I took some pictures on the passenger side. Guess what I found? The vacuum hoses for A/C idle up valve and steering pump valve are all messed up! What a mechanic
Here are the pictures:
1) messed up hoses for steering pump valve - they all go to steering pump valve from the same Y adapter in the intake manifold.
2) messed up hoses for A/C idle up valve - they all go to A/C idle up valve from filtered air.
3) closed look of A/C idle up valve.
After exchanged hoses to the correct adapter, fired up engine, warm up, the idle is at 1100rpm. Now, I know that I overly adjusted the idle speed in order to compensate the power loss of A/C on. When the A/C is off, the idle speed bounced back to 1400rpm. When the A/C is on, the idle dropped to 1100rpm. When in gear, the idle is right at around 750rpm.
So, I turned on A/C to max. Re-adjust idle screw to 750rpm. Then, turned off A/C, still 750rpm. Turned on A/C, still 750.
Quite happy, right? NO!
When I put into R or D gear, the rpm dropped to 500rpm
Is it normal on dropping idle rpm when put into gear? Something wrong?
Thank you!
I have 95 4Runner 3VZE with unstable idle issue. Due to head gasket broken, I had replaced with a rebuilt engine about 10K miles ago. Not to mention I got this lemon car for only two months before HG broken.
After warm up, still difficult to adjust the idle screw to 750rpm. It is unstable and drifts between 1000~1400rpm when in park or natural. Put into gear either R or D, the idle speed will drop about 250rpm to 750rpm. It looks right but still drift up.
During the CA hot air, I have to turn on A/C. The idle speed will drop down to 450rpm while in D. It is about 300rpm difference.
I took the throttle body off and cleaned the Aux. air valve. Nothing wrong on the TB.
I took some pictures on the passenger side. Guess what I found? The vacuum hoses for A/C idle up valve and steering pump valve are all messed up! What a mechanic
Here are the pictures:
1) messed up hoses for steering pump valve - they all go to steering pump valve from the same Y adapter in the intake manifold.
2) messed up hoses for A/C idle up valve - they all go to A/C idle up valve from filtered air.
3) closed look of A/C idle up valve.
After exchanged hoses to the correct adapter, fired up engine, warm up, the idle is at 1100rpm. Now, I know that I overly adjusted the idle speed in order to compensate the power loss of A/C on. When the A/C is off, the idle speed bounced back to 1400rpm. When the A/C is on, the idle dropped to 1100rpm. When in gear, the idle is right at around 750rpm.
So, I turned on A/C to max. Re-adjust idle screw to 750rpm. Then, turned off A/C, still 750rpm. Turned on A/C, still 750.
Quite happy, right? NO!
When I put into R or D gear, the rpm dropped to 500rpm
Is it normal on dropping idle rpm when put into gear? Something wrong?
Thank you!
05-18-2022, 07:49 AM
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Hope this helps you or possibly someone else as this caused me some headache before i figured it out
1992 3.0 Slow 4Runner
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